Reversible Multi-Mode Optical Modification in Inverse-Opal-Structured WO₃: Yb³⁺, Er³⁺ Photonic Crystal

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

INTRODUCTION

I suggest giving a brief introduction to inverse opal structure.

Lines 32-35 clarity. How could you perform structural modification? Does the composition influence it? or just the presence of co-dopants with different atomic ratios?

Lines 46-48 are not clear.

Methods

Instead of "was weighed” you should indicate the mass or molarity employed.

You must be more precise in your methodology, what is "specific concentration" and "appropriate amount"? 

The use of firstly, secondly, and thirdly in the text reduces the text fluidity.

XRD

You claimed that the XRD diffractograms do not exhibit impurities in your samples. However, around 21° appears one peak that can not be associated with JCPDS 72-1465. Also, the shape and intensity of your measurements vary with Yb and Er concentration. What do mean such changes? Did you consider doing a Rietveld assessment?

Consider that the presence of lanthanides in your matrix could influence the crystal arrangement. I suggest taking a look at:

Journal of Alloys and Compounds 910 (2022) 164922

SEM

Line 121 – It is Figure 2 (b) instead of Figure 2 (a).

Inset at figure 3a – Considering that W and O are almost in all samples, maybe you could use just two elements (Yb and Er) in your color mapping, this will provide a better understanding.  

OPTICAL PERFORMANCE

Line 145 – why does it appear an absorption band at the 500-550 range in WO3 and diminish with the Yb-Er co-doping?

I suggest to review: Review Chemical Engineering Journal 394 (2020) 124967.

In the same line, you said that the absorption at the NIR region the WO3 absorption is relatively weak. However, I did not observe any absorption peak. Also, the absorption story is not complete since WO3 containing 0.5 and 4% of Yb is not present. But, their UC emission is there, which makes me wonder if the absorption of these is in concordance with the UC emission.

Line 165-172. Since we have few upconversion mechanisms, I suggest determining the number of photons involved in the energy transfer process, then based on the results you can go deep into the mechanism.

Maybe you can take a look at Optical Materials: X 21 (2024) 100289.

REVERSIBLE OPTICAL MODULATION

Line 189 - Why is it remarkable the color change and why did it occur?

Line 196 – How could you corroborate the W transition?

I suggest to review: Chemical Engineering Journal 394 (2020) 124967

In addition to XPS, you should consider Raman or FTIR.

In figure 4 you said that the absorption in the NIR region was favored which caused an increase in the UC emission. But, in figure 5 is the opposite, could you clarify, please?

Figure 5c – line 245. You claimed that the UCL properties are effectively restored when air calcination occurs. However, this is not completely restored and it is not possible to determine in which percentage, maybe instead of the intensity you should make such an analysis using percentages.  This part is critical since in real applications such a variation could cause information lost.

Sensors & Actuators: A. Physical 357 (2023) 114367

Comments on the Quality of English Language

Consider the use of different words. E.g. Lines 29 and 40 you used "aforementioned".

In general, I suggest to review clarity and fluidity. 

 

Author Response

Reviewer 1:

1. I suggest giving a brief introduction to inverse opal structure.

Following the reviewer’s instruction, inverse opal structure have further analyzed.

In the revised manuscript, the following description is added.

“The inverse opal structure exhibits an ordered three-dimensional macroscopic porous structure with interconnected pores, with three small dark regions corresponding to the voids in the lower layer in each larger air.”

 

2. Lines 32-35 clarity. How could you perform structural modification? Does the composition influence it? or just the presence of co-dopants with different atomic ratios?Lines 46-48 are not clear.

Following the reviewer’s instruction, Structural modification can disrupt the local symmetry of the crystal field and improve rare earth luminescence. By adjusting the concentration of doped rare earth ions, the energy transfer of rare earth ions can be adjusted to enhance luminescence.

 

3. Instead of "was weighed” you should indicate the mass or molarity employed.You must be more precise in your methodology, what is "specific concentration" and "appropriate amount"? The use of firstly, secondly, and thirdly in the text reduces the text fluidity.

Following the reviewer’s instruction, the synthesis method has been modified and supplemented.

In the revised manuscript, the following description is added.

“(1) Preparation of Polystyrene (PS) Opal Templates:

The glass substrate is vertically immersed in a solution of monodisperse polystyrene microspheres with a concentration of 10% by the vertical precipitation method. Polystyrene microspheres self-assembled on the substrate to form ordered opal templates.

• Preparation of Precursor Sol:

A precursor sol was prepared using (NH₄)₆H₂W₁₂O₄₀·xH₂O), Yb₂O₃, Er₂O₃, and HNO₃ as raw materials. The stoichiometric Yb₂O₃ and Er₂O₃ was dissolved in hot nitric acid to form Er(NO₃)₃ and Yb(NO₃)₃, which are then dissolved in anhydrous ethanol. The (NH₄)₆H₂W₁₂O₄₀·xH₂O) was dissolved in deionized water and then added dropwise to an alcohol solution of rare earth nitrates to obtain a precursor solution.”

 

4. You claimed that the XRD diffractograms do not exhibit impurities in your samples. However, around 21°appears one peak that can not be associated with JCPDS 72-1465. Also, the shape and intensity of your measurements vary with Yb and Er concentration. What do mean such changes? Did you consider doing a Rietveld assessment? Consider that the presence of lanthanides in your matrix could influence the crystal arrangement. I suggest taking a look at: Journal of Alloys and Compounds 910 (2022) 164922.

Following the reviewer’s instruction, the XRD are supplemented and discussed. The peak at 21°belongs to the (111) crystal plane in JCPDS 72-1465.

In the revised manuscript, the following description is added.

“The all XRD diffraction peaks exhibited excellent agreement with the standard PDF card JCPDS: 72-1465 for monoclinic WO₃, without any discernible impurity peaks. However, as the doping of rare earth elements increases, the diffraction peak intensity of WO₃ increases, which may be due to the doping of rare earth elements changing the space group of WO₃ [25]”

25. Popov VV, Menushenkov AP, Yastrebtsev AA, Rudakov SG, Ivanov AA, Gaynanov BR, Svetogorov RD, Khramov EV, Zubavichus YV, Molokova AY, Tsarenko NA, Ognevskaya NV, Seregina ON, Rachenok IG, Shchetinin IV, Ponkratov KV. Multiscale study on the formation and evolution of the crystal and local structures in lanthanide tungstates Ln₂(WO₄)₃. Journal of Alloys and Compounds2022, 910, 164922.

 

5. Line 121 – It is Figure 2 (b) instead of Figure 2 (a).Inset at figure 3a – Considering that W and O are almost in all samples, maybe you could use just two elements (Yb and Er) in your color mapping, this will provide a better understanding.  

Following the reviewer’s instruction, the error on Line 121 has been corrected. The elemental analysis showed a uniform distribution of W, O, Yb, and Er elements in WO₃ in Figure 3(a). The successful doping of the rare earth ions Yb³⁺ and Er³⁺ into the WO₃ photonic crystal as show in Figure 3(b).

 

6. Line 145-why does it appear an absorption band at the 500-550 range in WO₃and diminish with the Yb-Er co-doping? I suggest to review: Review Chemical Engineering Journal 394 (2020) 124967. In the same line, you said that the absorption at the NIR region the WO₃ absorption is relatively weak. However, I did not observe any absorption peak. Also, the absorption story is not complete since WO₃ containing 0.5 and 4% of Yb is not present. But, their UC emission is there, which makes me wonder if the absorption of these is in concordance with the UC emission.

Following the reviewer’s instruction, the absorption spectra are supplemented discussed. The absorption of the sample mainly depends on the WO₃ matrix, while the luminescence mainly depends on the rare earth ions.

“The absorption peak located between 500-550 nm belongs to the bandgap peak of WO₃ photonic crystals. Doping with rare earths weakens the bandgap peak due to the decrease in WO₃ photonic crystals structural order. However, with the increase of Yb³⁺ concentration, the absorption ability of the sample in the near-infrared region above 700 nm gradually enhances due to the increase of oxygen vacancies in the matrix caused by the doping of rare earths [26]”

26. Zhan Y, Yang Z, Xu Z, Hu Z, Bai X, Ren Y, Li M, Ullah A, Khan I, Qiu J, Song Z, Liu B, Wang Y. Electrochromism induced reversible upconversion luminescence modulation of WO₃: Yb³⁺, Er³⁺inverse opals for optical storage application. Chemical Engineering Journal2020, 394, 124967.

 

7. Line 165-172. Since we have few upconversion mechanisms, I suggest determining the number of photons involved in the energy transfer process, then based on the results you can go deep into the mechanism.

Maybe you can take a look at Optical Materials: X 21 (2024) 100289.

Following the reviewer’s instruction, the photon logarithmic diagram is supplemented, and the luminescence mechanism is discussed.

In the revised manuscript, the following description is added.

“In general, the equation I = Pⁿ can be used to investigate the UCL mechanism, where I, P, and n are the UCL intensity, the 980 nm laser power, and the number of photons, respectively. Figure 4(c) shows the shows the red and green UCL intensity of WO₃: Yb³⁺, Er³⁺ as a function of laser powers. The n of 525 nm is about 2, and the n of 657 nm is about 1 because of the saturation effect, due to the competition between linear decay and upconversion processes caused by depletion of intermediate excited states[32].”

[32] Lei Y, Song H, Yang L, Yu L, Liu Z et al. Upconversion luminescence, intensity saturation effect, and thermal effect in Gd₂O₃:Er³⁺,Yb³⁺ nanowires. The Journal of chemical physics 2005,123, 174710.

 

 

Figure 5. (a) Absorption spectra of WO₃ and WO₃: xmol%Yb³⁺,1 mol%Er³⁺ (x = 0.5%, 2%, 3%, 4%); (b) The UCL spectra of WO₃: x mol%Yb³⁺, 1 mol%Er³⁺ (x = 0.5%, 2%, 3%, 4%) excited at 980 nm; (c) The UCL stability (inset) and logarithmic plot of UCL intensity of WO₃: 3 mol%Yb³⁺, 1 mol%Er³⁺; (d) Diagram of the UCL mechanism of the WO₃: Yb³⁺, Er³⁺ inverse photonic crystal.

 

8. Line 189 - Why is it remarkable the color change and why did it occur?Line 196 – How could you corroborate the W transition? I suggest to review: Chemical Engineering Journal 394 (2020) 124967. In addition to XPS, you should consider Raman or FTIR.

Following the reviewer’s instruction, the phenomenon of color transition can be attributed to the significant increase in oxygen vacancies in the reducing environment, which facilitates the accumulation of a large number of electrons and the transition from W⁶⁺ to W⁵⁺, exhibiting a significant absorption promoting effect, leading to a deepening of the sample color. To verify the transition of W valence state, the Raman spectroscopy has also been supplemented.

In the revised manuscript, the following description is added.

“The Raman peaks of WO₃^: 1mol% Yb³⁺,1 mol% Er³⁺ inverse photonic crystal located at 806 and 719 cm^-1 are attributed to the stretching vibrations of δ(O-W-O) and the peak at 272 cm^-1 belongs to the bending vibration of δ(O-W-O), exhibits monoclinic structure characteristics[26].”

 

Figure 4. (a) The EDS spectrum of the WO³: 1mol% Yb³⁺,1 mol% Er³⁺ inverse photonic crystal and the corresponding (b) element mapping images; (c) The Full XPS spectrum of the WO₃^: 1mol% Yb³⁺,1 mol% Er³⁺ inverse photonic crystal; (d) The Raman spectra of the WO₃: 1mol% Yb³⁺,1 mol% Er³⁺ inverse photonic crystal.

 

26. Zhan Y, Yang Z, Xu Z, Hu Z, Bai X, Ren Y, Li M, Ullah A, Khan I, Qiu J, Song Z, Liu B, Wang Y. Electrochromism induced reversible upconversion luminescence modulation of WO₃: Yb³⁺, Er³⁺inverse opals for optical storage application. Chemical Engineering Journal2020, 394, 124967.

 

9. In figure 4 you said that the absorption in the NIR region was favored which caused an increase in the UC emission. But, in figure 5 is the opposite, could you clarify, please?Figure 5c-line 245. You claimed that the UCL properties are effectively restored when air calcination occurs. However, this is not completely restored and it is not possible to determine in which percentage, maybe instead of the intensity you should make such an analysis using percentages. This part is critical since in real applications such a variation could cause information lost.Sensors & Actuators: A. Physical 357 (2023) 114367.

Following the reviewer’s instruction, the percentage change of UCL in WO₃: Yb³⁺,Er³⁺ was supplemented during the cyclic process of alternating calculation in N₂/H₂ atmosphere and air as shown in Figure 5(d).

 

Figure 5. (a) Absorption spectra of WO₃ and WO₃: xmol%Yb³⁺,1 mol%Er³⁺ (x = 0.5%, 2%, 3%, 4%); (b) The UCL spectra of WO₃: x mol%Yb³⁺, 1 mol%Er³⁺ (x = 0.5%, 2%, 3%, 4%) excited at 980 nm; (c) The UCL stability (inset) and logarithmic plot of UCL intensity of WO₃: 3 mol%Yb³⁺, 1 mol%Er³⁺; (d) Diagram of the UCL mechanism of the WO₃: Yb³⁺, Er³⁺ inverse photonic crystal.

 

36. Jimenez GL, Lisiecki R, Starzyk B, Vazquez-Lopez C, Lesniak M, Szumera M, Szymczak P, Kochanowicz M, Dorosz D. Temperature sensing properties of upconverted-emission materials based on a fluoroindate glass matrix. Sensors and Actuators A: Physical 2023, 357, 114367.

 

In summary, we have addressed the points raised by the reviewers. I assure you that the experiments were done with care, and that the results are accurate and reproducible. We look forward to receiving notification that the manuscript has been accepted for publication in Journal of alloys and compounds, and we look forward to seeing the article in print.

 

Yangke Cun

College of Materials Science and Engineering

Kunming University of Science and Technology

Kunming, 650093, China

1. R. China

E-mail: [email protected]

 

 

 

April 16^th, 2023

Prof. Wenna Dai:

 

Re: “Reversible multi-mode optical modification in inverse opal structured WO₃: Yb³⁺, Er³⁺ photonic crystal” by Bokun Zhu¹, Keling Ruan¹, Cherkasova Tatiana² and Yangke Cun^1,*

 

Dear Prof. Dai:

 

We have carefully considered the reviewers’ comments, and revised the manuscript accordingly.

 

Reviewer 1:

1. I suggest giving a brief introduction to inverse opal structure.

Following the reviewer’s instruction, inverse opal structure have further analyzed.

In the revised manuscript, the following description is added.

“The inverse opal structure exhibits an ordered three-dimensional macroscopic porous structure with interconnected pores, with three small dark regions corresponding to the voids in the lower layer in each larger air.”

 

2. Lines 32-35 clarity. How could you perform structural modification? Does the composition influence it? or just the presence of co-dopants with different atomic ratios?Lines 46-48 are not clear.

Following the reviewer’s instruction, Structural modification can disrupt the local symmetry of the crystal field and improve rare earth luminescence. By adjusting the concentration of doped rare earth ions, the energy transfer of rare earth ions can be adjusted to enhance luminescence.

 

3. Instead of "was weighed” you should indicate the mass or molarity employed.You must be more precise in your methodology, what is "specific concentration" and "appropriate amount"? The use of firstly, secondly, and thirdly in the text reduces the text fluidity.

Following the reviewer’s instruction, the synthesis method has been modified and supplemented.

In the revised manuscript, the following description is added.

“(1) Preparation of Polystyrene (PS) Opal Templates:

The glass substrate is vertically immersed in a solution of monodisperse polystyrene microspheres with a concentration of 10% by the vertical precipitation method. Polystyrene microspheres self-assembled on the substrate to form ordered opal templates.

• Preparation of Precursor Sol:

A precursor sol was prepared using (NH₄)₆H₂W₁₂O₄₀·xH₂O), Yb₂O₃, Er₂O₃, and HNO₃ as raw materials. The stoichiometric Yb₂O₃ and Er₂O₃ was dissolved in hot nitric acid to form Er(NO₃)₃ and Yb(NO₃)₃, which are then dissolved in anhydrous ethanol. The (NH₄)₆H₂W₁₂O₄₀·xH₂O) was dissolved in deionized water and then added dropwise to an alcohol solution of rare earth nitrates to obtain a precursor solution.”

 

4. You claimed that the XRD diffractograms do not exhibit impurities in your samples. However, around 21°appears one peak that can not be associated with JCPDS 72-1465. Also, the shape and intensity of your measurements vary with Yb and Er concentration. What do mean such changes? Did you consider doing a Rietveld assessment? Consider that the presence of lanthanides in your matrix could influence the crystal arrangement. I suggest taking a look at: Journal of Alloys and Compounds 910 (2022) 164922.

Following the reviewer’s instruction, the XRD are supplemented and discussed. The peak at 21°belongs to the (111) crystal plane in JCPDS 72-1465.

In the revised manuscript, the following description is added.

“The all XRD diffraction peaks exhibited excellent agreement with the standard PDF card JCPDS: 72-1465 for monoclinic WO₃, without any discernible impurity peaks. However, as the doping of rare earth elements increases, the diffraction peak intensity of WO₃ increases, which may be due to the doping of rare earth elements changing the space group of WO₃ [25]”

25. Popov VV, Menushenkov AP, Yastrebtsev AA, Rudakov SG, Ivanov AA, Gaynanov BR, Svetogorov RD, Khramov EV, Zubavichus YV, Molokova AY, Tsarenko NA, Ognevskaya NV, Seregina ON, Rachenok IG, Shchetinin IV, Ponkratov KV. Multiscale study on the formation and evolution of the crystal and local structures in lanthanide tungstates Ln₂(WO₄)₃. Journal of Alloys and Compounds2022, 910, 164922.

 

5. Line 121 – It is Figure 2 (b) instead of Figure 2 (a).Inset at figure 3a – Considering that W and O are almost in all samples, maybe you could use just two elements (Yb and Er) in your color mapping, this will provide a better understanding.  

Following the reviewer’s instruction, the error on Line 121 has been corrected. The elemental analysis showed a uniform distribution of W, O, Yb, and Er elements in WO₃ in Figure 3(a). The successful doping of the rare earth ions Yb³⁺ and Er³⁺ into the WO₃ photonic crystal as show in Figure 3(b).

 

6. Line 145-why does it appear an absorption band at the 500-550 range in WO₃and diminish with the Yb-Er co-doping? I suggest to review: Review Chemical Engineering Journal 394 (2020) 124967. In the same line, you said that the absorption at the NIR region the WO₃ absorption is relatively weak. However, I did not observe any absorption peak. Also, the absorption story is not complete since WO₃ containing 0.5 and 4% of Yb is not present. But, their UC emission is there, which makes me wonder if the absorption of these is in concordance with the UC emission.

Following the reviewer’s instruction, the absorption spectra are supplemented discussed. The absorption of the sample mainly depends on the WO₃ matrix, while the luminescence mainly depends on the rare earth ions.

“The absorption peak located between 500-550 nm belongs to the bandgap peak of WO₃ photonic crystals. Doping with rare earths weakens the bandgap peak due to the decrease in WO₃ photonic crystals structural order. However, with the increase of Yb³⁺ concentration, the absorption ability of the sample in the near-infrared region above 700 nm gradually enhances due to the increase of oxygen vacancies in the matrix caused by the doping of rare earths [26]”

26. Zhan Y, Yang Z, Xu Z, Hu Z, Bai X, Ren Y, Li M, Ullah A, Khan I, Qiu J, Song Z, Liu B, Wang Y. Electrochromism induced reversible upconversion luminescence modulation of WO₃: Yb³⁺, Er³⁺inverse opals for optical storage application. Chemical Engineering Journal2020, 394, 124967.

 

7. Line 165-172. Since we have few upconversion mechanisms, I suggest determining the number of photons involved in the energy transfer process, then based on the results you can go deep into the mechanism.

Maybe you can take a look at Optical Materials: X 21 (2024) 100289.

Following the reviewer’s instruction, the photon logarithmic diagram is supplemented, and the luminescence mechanism is discussed.

In the revised manuscript, the following description is added.

“In general, the equation I = Pⁿ can be used to investigate the UCL mechanism, where I, P, and n are the UCL intensity, the 980 nm laser power, and the number of photons, respectively. Figure 4(c) shows the shows the red and green UCL intensity of WO₃: Yb³⁺, Er³⁺ as a function of laser powers. The n of 525 nm is about 2, and the n of 657 nm is about 1 because of the saturation effect, due to the competition between linear decay and upconversion processes caused by depletion of intermediate excited states[32].”

[32] Lei Y, Song H, Yang L, Yu L, Liu Z et al. Upconversion luminescence, intensity saturation effect, and thermal effect in Gd₂O₃:Er³⁺,Yb³⁺ nanowires. The Journal of chemical physics 2005,123, 174710.

 

 

Figure 5. (a) Absorption spectra of WO₃ and WO₃: xmol%Yb³⁺,1 mol%Er³⁺ (x = 0.5%, 2%, 3%, 4%); (b) The UCL spectra of WO₃: x mol%Yb³⁺, 1 mol%Er³⁺ (x = 0.5%, 2%, 3%, 4%) excited at 980 nm; (c) The UCL stability (inset) and logarithmic plot of UCL intensity of WO₃: 3 mol%Yb³⁺, 1 mol%Er³⁺; (d) Diagram of the UCL mechanism of the WO₃: Yb³⁺, Er³⁺ inverse photonic crystal.

 

8. Line 189 - Why is it remarkable the color change and why did it occur?Line 196 – How could you corroborate the W transition? I suggest to review: Chemical Engineering Journal 394 (2020) 124967. In addition to XPS, you should consider Raman or FTIR.

Following the reviewer’s instruction, the phenomenon of color transition can be attributed to the significant increase in oxygen vacancies in the reducing environment, which facilitates the accumulation of a large number of electrons and the transition from W⁶⁺ to W⁵⁺, exhibiting a significant absorption promoting effect, leading to a deepening of the sample color. To verify the transition of W valence state, the Raman spectroscopy has also been supplemented.

In the revised manuscript, the following description is added.

“The Raman peaks of WO₃^: 1mol% Yb³⁺,1 mol% Er³⁺ inverse photonic crystal located at 806 and 719 cm^-1 are attributed to the stretching vibrations of δ(O-W-O) and the peak at 272 cm^-1 belongs to the bending vibration of δ(O-W-O), exhibits monoclinic structure characteristics[26].”

 

Figure 4. (a) The EDS spectrum of the WO³: 1mol% Yb³⁺,1 mol% Er³⁺ inverse photonic crystal and the corresponding (b) element mapping images; (c) The Full XPS spectrum of the WO₃^: 1mol% Yb³⁺,1 mol% Er³⁺ inverse photonic crystal; (d) The Raman spectra of the WO₃: 1mol% Yb³⁺,1 mol% Er³⁺ inverse photonic crystal.

 

26. Zhan Y, Yang Z, Xu Z, Hu Z, Bai X, Ren Y, Li M, Ullah A, Khan I, Qiu J, Song Z, Liu B, Wang Y. Electrochromism induced reversible upconversion luminescence modulation of WO₃: Yb³⁺, Er³⁺inverse opals for optical storage application. Chemical Engineering Journal2020, 394, 124967.

 

9. In figure 4 you said that the absorption in the NIR region was favored which caused an increase in the UC emission. But, in figure 5 is the opposite, could you clarify, please?Figure 5c-line 245. You claimed that the UCL properties are effectively restored when air calcination occurs. However, this is not completely restored and it is not possible to determine in which percentage, maybe instead of the intensity you should make such an analysis using percentages. This part is critical since in real applications such a variation could cause information lost.Sensors & Actuators: A. Physical 357 (2023) 114367.

Following the reviewer’s instruction, the percentage change of UCL in WO₃: Yb³⁺,Er³⁺ was supplemented during the cyclic process of alternating calculation in N₂/H₂ atmosphere and air as shown in Figure 5(d).

 

Figure 5. (a) Absorption spectra of WO₃ and WO₃: xmol%Yb³⁺,1 mol%Er³⁺ (x = 0.5%, 2%, 3%, 4%); (b) The UCL spectra of WO₃: x mol%Yb³⁺, 1 mol%Er³⁺ (x = 0.5%, 2%, 3%, 4%) excited at 980 nm; (c) The UCL stability (inset) and logarithmic plot of UCL intensity of WO₃: 3 mol%Yb³⁺, 1 mol%Er³⁺; (d) Diagram of the UCL mechanism of the WO₃: Yb³⁺, Er³⁺ inverse photonic crystal.

 

36. Jimenez GL, Lisiecki R, Starzyk B, Vazquez-Lopez C, Lesniak M, Szumera M, Szymczak P, Kochanowicz M, Dorosz D. Temperature sensing properties of upconverted-emission materials based on a fluoroindate glass matrix. Sensors and Actuators A: Physical 2023, 357, 114367.

 

In summary, we have addressed the points raised by the reviewers. I assure you that the experiments were done with care, and that the results are accurate and reproducible. We look forward to receiving notification that the manuscript has been accepted for publication in Journal of alloys and compounds, and we look forward to seeing the article in print.

 

Yangke Cun

College of Materials Science and Engineering

Kunming University of Science and Technology

Kunming, 650093, China

1. R. China

E-mail: [email protected]

 

 

 

 

 

 

 

Reviewer 2 Report

Comments and Suggestions for Authors

Manuscript materials-2974323 Round 1

Dr. Bokun Zhu manuscript is devoted to study obtained upconversion luminescent WO₃:Yb⁺³ Er⁺³ photonic crystal with different content of rare earths . The studied parameters were the upconversion luminescence intensity, optical absorption. The work has a practical orientation and is saturated with experimental methods. However, it has a number of significant shortcomings and cannot be published in this form. The methods are described poorly and are not contain temperature conditions at all. The research design is not appropriate, and need to be improved, because of low-resolution figures. A very poor description of the experimental section. Discussion and conclusion section should be expanded. The following are some comments on the text:

 

1.        In the introduction, the authors should note the fundamental difference between their work and others. This is an extremely important point. The authors should show the scientific significance of their work through the purpose of the paper and conclusion. The title does not reflect the content of the work. The introduction should end with a clearly stated purpose of the work.

2.         Abstract should be rewritten. It must contain the following parts: what was obtained by what methods, the main result. What research methods were used. If numerical results have been obtained, they should be in the abstract

3.        The Keywords should not be repeated in the title and abstract.

4.        Line 56. I would recommend the authors to note that niobium oxide nanowires 10.1016/j.matpr.2021.05.263 and 10.1088/1742-6596/987/1/012006 can be used as photocatalytic materials.

5.        Line 73: Different substrates were used, but then the difference in the substrates does not appear at all in the text. Then why are you using three different substrates. Moreover, you do not specify the annealing temperatures and temperature conditions during calcination. This raises doubts about the reliability of the results obtained. For example, ordinary glass is not suitable for thermal processes above one hundred degrees.

6.        Section 2: The numbering of subsections is broken. The subsections must be numbered 2.1 2.2….

7.        Line 75: ITO is a indium tin oxide

8.        Line 75: The clearly concentrations of polystyrene microspheres solution is commercial secret? Why is it not written how the solution was obtained purchased or prepared?

9.        The description of preparation of Precursor Sol is not suitable for a scientific publication. Sol gel process should be described by a paragraph-by-paragraph. All important parameters of solution concentration, temperature conditions, heat treatment, time and sonication modes (preferably) should be shown.

10.     Section 2: Methods of reversible Optical Modulation in WO3: Yb3+, Er3+Photonic Crystal should be add in section 2. This means a brief description of the experimental methodology, which equipment was used, which modes.

11.     Section 3.1: You are using three different substrates and samples with 4 different concentrations of rare earths. You are using three different substrates and samples with 4 different concentrations of rare earths, that is at least 12 samples. But the pictures from SEM, XRAY, XPS, EPS do not indicate which substrates were examined.

12.     Section 3.1: How was the concentration of Er and Yb ions studied in the obtained structures? This does not follow from the experimental part and not from the presented EDS and XPS. EDS analysis should be shown  at% and wt% content.

13.     Line 122: In this case, the more appropriate term is inverted or inverse opal structure.

14.     Subsection 3.3. The calcification process is not an appropriate term. It's a technological operation which result is thermal decay of components or getting new properties. The properties of your material are not lost after annealing, that is, they are restored with each cycle A more suitable is cyclic heating or heat–treat.

15.     Subsection 3.3. Without specifying in which temperature regims the experiment was carry out, this section cannot be consider seriously.

16.     Subsection 3.3. Without specifying in which temperature regims the experiment was carry out, this section cannot be consider seriously.

17.     Subsection 3.3. It is useful to compare your result with the result of this work [10.1021/acsami.8b03616]. Because a similar result was obtained without the use of a photonic crystal. The role of the photonic crystal in this context is unclear. It will be useful to speculate on this topic

18.     The design of the work is terrible, it is necessary to improve the format of the figures.

19.     Line 254: The paragraph does not relate to the main text of the work.

20.     The conclusion should be rewritten and begin with a general result that accomplishes the purpose of the paper noted in the introduction, followed by a paragraph-by-paragraph listing of the main results with numerical values on which the general result is based.

21.     I recommend that authors improve their figs style. Work on the layout on the sheet, bring all fonts and notations to the same form. Make the figs like Picasso's paintings, beautiful, to be admired.

22.     English is very poor. It is recommended to use an English improvement service or ask a native speaker to read their manuscript.

Comments on the Quality of English Language

1. Pronounce cant be used in scientific works.

2. Sentences must be rewritten according to the style of scientific works.

Author Response

Reviewer 2:

1. In the introduction, the authors should note the fundamental difference between their work and others. This is an extremely important point. The authors should show the scientific significance of their work through the purpose of the paper and conclusion. The title does not reflect the content of the work. The introduction should end with a clearly stated purpose of the work.

Following the reviewer’s instruction, the introduction has been modified and supplemented.

In the revised manuscript, the following description is added.

“However, it is difficult to achieve reversible and repeatable regulation of the luminescent properties of photonic crystals. The present reports still exist a potential risk of structural collapse during optical modulation, which will significantly impact the reversibility and repeatability in practical applications [19].”

 

2. Abstract should be rewritten. It must contain the following parts: what was obtained by what methods, the main result. What research methods were used. If numerical results have been obtained, they should be in the abstract. 

Following the reviewer’s instruction, the Abstract has been modified and supplemented.

In the revised manuscript, the following description is added.

“Reversible optical regulation has potential applications in optical anti-counterfeiting, storage, and catalysis. The reverse opal structure has a larger specific surface area and an increased contact area for optical regulation, which is expected to achieve higher regulation rates. However, it is difficult to achieve reversible and repeatable regulation of the luminescent properties of photonic crystals, especially with the current research on the structural collapse of photonic crystals. In this work, the WO₃: Yb, Er photonic crystals was prepared by the template approach, and reversible multi-mode optical modification was investigated. Upon heat treatment in the reducing atmosphere or air, the color of the photonic crystals can reversibly change from light yellow to dark green, accompanied by changes in absorption and upconversion luminescence intensity. The stability and fatigue resistance of reversible optical modification ability were explored through cyclic experiments, providing potential practical applications for photocatalysis, optical information storage and electrochromism.”

 

3. The Keywords should not be repeated in the title and abstract.    

Following the reviewer’s instruction, The Keywords has been modified and supplemented.

In the revised manuscript, the following description is added.

“Keywords: upconversion; inverse opal structure; reversible modulation”

 

4. Line 56. I would recommend the authors to note that niobium oxide nanowires 10.1016/j.matpr.2021.05.263 and 10.1088/1742-6596/987/1/012006 can be used as photocatalytic materials.

Following the reviewer’s instruction, the niobium oxide nanowires has been modified and supplemented.

In the revised manuscript, the following description is added.

“In the field of photocatalysis, commonly employed metal oxide materials encompass TiO₂, WO₃, ZnO, SnO₂, and niobium oxide nanowires among other notable examples [20-24].”

23. Pligovka A, Hoha A, Turavets U, Poznyak A, Zakharau Y. Formation features, morphology and optical properties of nanostructures via anodizing Al/Nb on Si and glass. Materials Today: Proceedings 2021, 37, A8-A15.
24. Pligovka A, Zakhlebayeva A, Lazavenka A. Niobium oxide nanocolumns formed via anodic alumina with modulated pore diameters. Journal of Physics: Conference Series 2018, 987, 012006.

 

5. Line 73: Different substrates were used, but then the difference in the substrates does not appear at all in the text. Then why are you using three different substrates. Moreover, you do not specify the annealing temperatures and temperature conditions during calcination. This raises doubts about the reliability of the results obtained. For example, ordinary glass is not suitable for thermal processes above one hundred degrees.

Following the reviewer’s instruction, the synthesis method has been modified and supplemented.

In the revised manuscript, the following description is added.

“(1) Preparation of Polystyrene (PS) Opal Templates:

The glass substrate is vertically immersed in a solution of monodisperse polystyrene microspheres with a concentration of 10% by the vertical precipitation method. Polystyrene microspheres self-assembled on the substrate to form ordered opal templates.

• Preparation of Precursor Sol:

A precursor sol was prepared using (NH₄)₆H₂W₁₂O₄₀·xH₂O), Yb₂O₃, Er₂O₃, and HNO₃ as raw materials. The stoichiometric Yb₂O₃ and Er₂O₃ was dissolved in hot nitric acid to form Er(NO₃)₃ and Yb(NO₃)₃, which are then dissolved in anhydrous ethanol. The (NH₄)₆H₂W₁₂O₄₀·xH₂O) was dissolved in deionized water and then added dropwise to an alcohol solution of rare earth nitrates to obtain a precursor solution.

(3) Preparation of Inverse Photonic Crystals:

The appropriate amount of precursor sol was slowly added to the PS opal template, and after complete filling, the PS microspheres were removed by sintering at 480 ℃ for 3 hours to obtain WO₃: Yb³⁺, Er³⁺ inverse photonic crystals.”

 

6. Section 2: The numbering of subsections is broken. The subsections must be numbered 2.1 2.2….

Following the reviewer’s instruction, the numbering of subsections has been modified and supplemented.

 

7. Line 75: ITO is a indium tin oxide

Following the reviewer’s instruction, the synthesis method has been modified and supplemented.

In the revised manuscript, the following description is added.

“(1) Preparation of Polystyrene (PS) Opal Templates:

The glass substrate is vertically immersed in a solution of monodisperse polystyrene microspheres with a concentration of 10% by the vertical precipitation method. Polystyrene microspheres self-assembled on the substrate to form ordered opal templates.

 

8. Line 75: The clearly concentrations of polystyrene microspheres solution is commercial secret? Why is it not written how the solution was obtained purchased or prepared?

In the revised manuscript, The clearly concentrations of polystyrene microspheres solution is 10%。

 

9. The description of preparation of Precursor Sol is not suitable for a scientific publication. Sol gel process should be described by a paragraph-by-paragraph. Allimportant parameters of solution concentration, temperature conditions, heat treatment, time and sonication modes (preferably) should be shown.

In the revised manuscript, the synthesis method has been modified and supplemented.

“(2) Preparation of Precursor Sol:

A precursor sol was prepared using (NH₄)₆H₂W₁₂O₄₀·xH₂O), Yb₂O₃, Er₂O₃, and HNO₃ as raw materials. The stoichiometric Yb₂O₃ and Er₂O₃ was dissolved in hot nitric acid to form Er(NO₃)₃ and Yb(NO₃)₃, which are then dissolved in anhydrous ethanol. The (NH₄)₆H₂W₁₂O₄₀·xH₂O) was dissolved in deionized water and then added dropwise to an alcohol solution of rare earth nitrates to obtain a precursor solution.

(3) Preparation of Inverse Photonic Crystals:

The appropriate amount of precursor sol was slowly added to the PS opal template, and after complete filling, the PS microspheres were removed by sintering at 480 ℃ for 3 hours to obtain WO₃: Yb³⁺, Er³⁺ inverse photonic crystals.”

 

10. Section 2: Methods of reversible Optical Modulation in WO₃:Yb³⁺, Er³⁺ Photonic Crystal should be add in section 2. This means a brief description of the experimental methodology, which equipment was used, which modes.

In the revised manuscript, the Methods of reversible Optical Modulation in WO₃:Yb³⁺, Er³⁺ Photonic Crystal has been supplemented.

“To further explore the potential applications of WO₃: Yb³⁺, Er³⁺ in the field of optics, the original WO₃: Yb³⁺, Er³⁺ inverse photonic crystals materials were sintered again at 600 ℃ for 3 h in an N₂/H₂ atmosphere in a tubular furnace.”

 

11. Section 3.1: You are using three different substrates and samples with 4 different concentrations of rare earths. You are using three different substrates and samples with 4 different concentrations of rare earths, that is at least 12 samples. But the pictures from SEM, XRAY, XPS, EPS do not indicate which substrates were examined.

Following the reviewer’s instruction, Four samples of WO₃ and WO_3: x mol% Yb³⁺, 1 mol% Er³⁺(x=1, 2, 3) were prepared.

 

12. Section 3.1: How was the concentration of Er and Yb ions studied in the obtained structures? This does not follow from the experimental part and not from the presented EDS and XPS. EDS analysis should be shown at% and wt% content.

Following the reviewer’s instruction, the EDS analysis is unable to display the content of at% and wt% due to the low doping concentration, so that we just only exhibit the EDS mapping images.

 

 

13. Line 122: In this case, the more appropriate term is inverted or inverse opal structure.

In the revised manuscript, the more appropriate term is inverted or inverse opal structure has been modified.

“Furthermore, the surface morphology of WO₃:Yb³⁺, Er³⁺ inverse photonic crystals was analyzed by SEM images in Figure 2(b), showing the successful synthesis of inverted opal structure with a pore size of about 300 nm, a honeycomb-like three-dimensional macroporous ordered structure.”

 

14. Subsection 3.3. The calcification process is not an appropriate term. It's a technological operation which result is thermal decay of components or getting new properties. The properties of your material are not lost after annealing, that is, they are restored with each cycle A more suitable is cyclic heating or heat–treat.

In the revised manuscript, the calcification has been modified to heat treatment.

 

15. Subsection 3.3. Without specifying in which temperature regims the experiment was carry out, this section cannot be considered seriously.

In the revised manuscript, the temperature regims has been modified.

“To further explore the potential applications of WO₃: Yb³⁺, Er³⁺ in the field of optics, the original WO₃: Yb³⁺, Er³⁺ inverse photonic crystal materials were sintered again at 600 ℃ for 3 h in an N₂/H₂ atmosphere in a tubular furnace.”

 

16. Subsection 3.3. It is useful to compare your result with the result of this work [10.1021/acsami.8b03616]. Because a similar result was obtained without the use of a photonic crystal. The role of the photonic crystal in this context is unclear. It will be useful to speculate on this topic.

Following the reviewer’s instruction, the role of inverse Photonic Crystals is analyzed.

In the revised manuscript, the following description is added.

“Compared to powder materials, WO₃: Yb³⁺, Er³⁺ inverse photonic crystals have a larger comparative area, which increases the contact area during heat treatment in N₂/H₂ reducing atmosphere and air atmosphereand therefore has a higher optical modulation rate.”

 

17. The design of the work is terrible, it is necessary to improve the format of the figures.

Following the reviewer’s instruction, the Figures have been modified.

 

18. Line 254: The paragraph does not relate to the main text of the work.

Following the reviewer’s instruction, The paragraph has been modified.

 

19. The conclusion should be rewritten and begin with a general result that accomplishes the purpose of the paper noted in the introduction, followed by a paragraph-by-paragraph listing of the main results with numerical values on which the general result is based.

Following the reviewer’s instruction, the conclusion has been modified.

In the revised manuscript, the following description is added.

“In the work, the WO₃: Yb³⁺, Er³⁺ inverse photonic crystals prepared by the template approach was investigated. The reversible and repeatable UCL and absorption modulation were observed undergo alternating heat treatment in N₂/H₂ and air atmospheres, achieving a regulation rates of absorption intensity and UCL intensity up to 61.4% and 95% due to the larger specific surface area and increased contact area for optical adjustment of the WO₃: Yb³⁺, Er³⁺ inverse photonic crystal structure. The tunable UCL and absorption are attributed to the formation of oxygen vacancies and the transformation of W valence states in different heat treatment atmospheres.This indicates the potential application prospects in the fields of photocatalysis, optical information storage and electrochromism, providing guidance for the design and synthesis of new materials for future development.”

 

20. I recommend that authors improve their figs style. Work on the layout on the sheet, bring all fonts and notations to the same form. Make the figs like Picasso's paintings, beautiful, to be admired.

Following the reviewer’s instruction, the Figures have been modified.

 

21. English is very poor. It is recommended to use an English improvement service or ask a native speaker to read their manuscript.

Following the reviewer’s instruction, the language has been revised.

 

In summary, we have addressed the points raised by the reviewers. I assure you that the experiments were done with care, and that the results are accurate and reproducible. We look forward to receiving notification that the manuscript has been accepted for publication in Journal of alloys and compounds, and we look forward to seeing the article in print.

 

Yangke Cun

College of Materials Science and Engineering

Kunming University of Science and Technology

Kunming, 650093, China

1. R. China

E-mail: [email protected]

 

 

 

 

Reviewer 3 Report

Comments and Suggestions for Authors

Manuscript ID: materials-2974323; Title: “Reversible multi-mode optical modification in inverse opal structured WO3: Yb3+, Er3+ photonic crystal”. In this paper, the author focused on the design and fabrication techniques for opal gemstone-structured photonic crystal materials. The optical properties of the prepared WO3:Yb3+, Er3+ photonic crystals are analyzed and explored through advanced optical testing and characterization techniques, providing crucial experimental evidence for comprehending its upconversion luminescence mechanism.

The topic is interesting for the referee. Therefore, I recommend publication only after minor revisions.

1) It would be important for the author to include a graphical image to show the mechanism described on page 2. The author needs to include graphical images.

2) I think that the introduction is not sufficient, and the introduction should be elaborated with state of art. Needs to include an introduction to are Advantages and Disadvantages. and the author needs to include the motivation and necessity of this research.

3) the author has written “The photoluminescence spectra of WO3: x Yb3+, Er3+ (x = 0.5%, 2%, 3%, 4%) photonic crystals excited by a near-infrared 980 nm laser in Figure 4(b)”. I think that the author needs to include how many scans performed for the photoluminescence spectra.

4) In the result and discussion, the author needs to include a comparison of the present work with the previous work. And needs to explain the importance of the present work.

5) My major observation is that all figures in this manuscript are not good/in appearance. This is the major drawback of this manuscript presentation. The author should change all the figure presentations and show them clearly.

6) Please verify each sentence of this paper, Some typo errors.

Comments on the Quality of English Language

Minor editing of English language required

Author Response

Reviewer 3:

1. It would be important for the author to include a graphical image to show the mechanism described on page 2. The author needs to include graphical images.

Following the reviewer’s instruction, the graphical image has been supplemented.

 

Figure 1. The preparation schematic diagram of WO₃: Yb³⁺, Er³⁺ inverse Opal Photonic Crystals.

 

2. I think that the introduction is not sufficient, and the introduction should be elaborated with state of art. Needs to include an introduction to are Advantages and Disadvantages. and the author needs to include the motivation and necessity of this research.

Following the reviewer’s instruction, the introduction has been modified and supplemented.

“In the aforementioned techniques, the photonic crystal materials, featuring an inverse opal structure inspired by the design of opal gemstones, have exhibited distinctive advantages in the realm of optical materials, garnering extensive research attention [14,15]. The inverse opal structure exhibits an ordered three-dimensional macroscopic porous structure with interconnected pores, with three small dark regions corresponding to the voids in the lower layer in each larger air. The structure of photonic crystals is characterized by a periodic arrangement, which gives rise to the presence of photonic bandgaps within this periodicity. By manipulating the lattice parameters and refractive indices of materials, precise control over the optical properties of photonic crystals can be achieved [16,17]. Leveraging the unique structure of photonic crystals to enhance the interaction between light and materials, thereby augmenting the luminescent properties of materials, offering a compelling approach for modulating the optical characteristics of materials, and further expands the applications in fields such as optical storage and photocatalysis. Cheng Zhu et al. investigated the effect of photonic bandgap on the luminescence characteristics of NaYF₄:Yb, Tm@SiO₂ photonic crystal [18]. However, it is difficult to achieve reversible and repeatable regulation of the luminescent properties of photonic crystals.The present reports still exist a potential risk of structural collapse during optical modulation, which will significantly impact the reversibility and repeatability in practical applications [19]. Therefore, the development of lanthanide ions doped photonic crystal with reversible optical performance poses a crucial challenge.”

 

3. the author has written “The photoluminescence spectra of WO₃: x Yb³⁺, Er³⁺(x = 0.5%, 2%, 3%, 4%) photonic crystals excited by a near-infrared 980 nm laser in Figure 4(b)”. I think that the author needs to include how many scans performed for the photoluminescence spectra.

Following the reviewer’s instruction, the photoluminescence statistical chart has been supplemented in Figure 5(c).

 

Figure 5. (a) Absorption spectra of WO₃ and WO₃: xmol%Yb³⁺,1 mol%Er³⁺ (x = 0.5%, 2%, 3%, 4%); (b) The UCL spectra of WO₃: x mol%Yb³⁺, 1 mol%Er³⁺ (x = 0.5%, 2%, 3%, 4%) excited at 980 nm; (c) The UCL stability (inset) and logarithmic plot of UCL intensity of WO₃: 3 mol%Yb³⁺, 1 mol%Er³⁺; (d) Diagram of the UCL mechanism of the WO₃: Yb³⁺, Er³⁺ inverse photonic crystal.

 

4. In the result and discussion, the author needs to include a comparison of the present work with the previous work. And needs to explain the importance of the present work.

Following the reviewer’s instruction, The conclusion has been modified.

In the revised manuscript, the following description is added.

“In the work, the WO₃: Yb³⁺, Er³⁺ inverse photonic crystals prepared by the template approach was investigated. The reversible and repeatable UCL and absorption modulation were observed undergo alternating heat treatment in N₂/H₂ and air atmospheres, achieving a regulation rates of absorption intensity and UCL intensity up to 61.4% and 95% due to the larger specific surface area and increased contact area for optical adjustment of the WO₃: Yb³⁺, Er³⁺ inverse photonic crystal structure. The tunable UCL and absorption are attributed to the formation of oxygen vacancies and the transformation of W valence states in different heat treatment atmospheres. This indicates the potential application prospects in the fields of photocatalysis, optical information storage and electrochromism, providing guidance for the design and synthesis of new materials for future development.”

 

5. My major observation is that all figures in this manuscript are not good/in appearance. This is the major drawback of this manuscript presentation. The author should change all the figure presentations and show them clearly.

Following the reviewer’s instruction, the figures have been modified.

 

6. Please verify each sentence of this paper, Some typo .

Following the reviewer’s instruction, the errors have been modified.

 

In summary, we have addressed the points raised by the reviewers. I assure you that the experiments were done with care, and that the results are accurate and reproducible. We look forward to receiving notification that the manuscript has been accepted for publication in Journal of alloys and compounds, and we look forward to seeing the article in print.

 

Yangke Cun

College of Materials Science and Engineering

Kunming University of Science and Technology

Kunming, 650093, China

1. R. China

E-mail: [email protected]

 

 

 

Reviewer 4 Report

Comments and Suggestions for Authors

the study focuses of tungsten oxide with Yb and Er ion doping as photonic crystals with an inverse opal structure. This is an intersting study that merits publication. However authors should address the following points:

1. The applications of these materials include energy storage and optical emission. The real-world scenarios in which these materials can be applied merits further examination and discussion. In particular there is lacking a comparison with similar methdods and materials and the implications for the sustainable use of dielectric components in real world situations.

2. How does the information developed here relate to industry and performance of devices and the cost of producing components. Electrochromic applications and their usage should be discussed in some extent to shed light on the utility of the methods and compositions involved in the study presented here.

3. The modification of tungsten oxide is extensively reported. Authors should examine related studies and examine related modification methods applied to powders and thin films. The key differences between this study and those related studies with other lanthanide dopants. 

4. The rare earth doping discussed here is more appropriately termed Lanthanide doping - terminology should be corrected. 

5. Discuss oxygen redox activity in this situation - what do DFT studies say about the oxidation state of oxygen - it is not always 2-

Comments on the Quality of English Language

The subject / object / verbs need to be brought into better agreement thorughout the document. Check sentences for correctness and agreement.

The input of a native speaker would be a big help here 

Author Response

Reviewer 4:

1. The applications of these materials include energy storage and optical emission. The real-world scenarios in which these materials can be applied merits further examination and discussion. In particular there is lacking a comparison with similar methdods and materials and the implications for the sustainable use of dielectric components in real world situations.

Following the reviewer’s instruction, The applications of WO₃: Yb³⁺, Er³⁺ inverse photonic crystals have further analyzed.

In the revised manuscript, the following description is added.

“Compared to powder materials, the WO₃: Yb³⁺, Er³⁺ inverse photonic crystals have a larger comparative area, which increases the contact area during heat treatment in N₂/H₂ reducing atmosphere and air atmosphere, resulting in a higher optical modulation rate that is beneficial for applications such as photocatalysis, optical information storage and electrochromism.”

 

2. How does the information developed here relate to industry and performance of devices and the cost of producing components. Electrochromic applications and their usage should be discussed in some extent to shed light on the utility of the methods and compositions involved in the study presented here.

Following the reviewer’s instruction, The electrochromic applicationss of WO₃: Yb³⁺, Er³⁺ inverse photonic crystals have further analyzed and discussed.

In the revised manuscript, the following description is added.

“The WO₃: Yb³⁺, Er³⁺ inverse photonic crystals also provide possibilities for electrochromism, as the principle of electrochromism is also the change in W valence state caused by ion insertion.”

 

3. The modification of tungsten oxide is extensively reported. Authors should examine related studies and examine related modification methods applied to powders and thin films. The key differences between this study and those related studies with other lanthanide dopants. 

Following the reviewer’s instruction, The advantages of photonic crystals are demonstrated by comparing the relevant modification methods of powders and thin films.

“Compared to powder materials, the WO₃: Yb³⁺, Er³⁺ inverse photonic crystals have a larger comparative area, which increases the contact area during heat treatment in N₂/H₂ reducing atmosphere and air atmosphere, resulting in a higher optical modulation rate that is beneficial for applications such as photocatalysis, optical information storage and electrochromism.”

 

4. The rare earth doping discussed here is more appropriately termed Lanthanide doping - terminology should be corrected. 

Following the reviewer’s instruction, The rare earth should be corrected to Lanthanide.

 

5. Discuss oxygen redox activity in this situation - what do DFT studies say about the oxidation state of oxygen - it is not always 2

Following the reviewer’s instruction, The DFT analysis has been supplemented.

In the revised manuscript, the following description is added.

“DFT calculations indicate that the formation of oxygen vacancies in WO₃ leads to the formation of localized energy levels in the forbidden band, with more W atoms transitioning to lower valence states. The transition of localized energy levels above the Fermi level facilitates a wide range of photoresponse in the vis NIR region [27].”

27. Lu Y, Jia X, Ma Z, Li Y, Yue S, Liu X, Zhang J. W⁵⁺-W⁵⁺pair induced LSPR of W₁₈O₄₉to sensitize ZnIn₂S₄ for full-spectrum solar-light-driven photocatalytic hydrogen evolution. Advanced Functional Materials 2022, 32, 2203638.

 

In summary, we have addressed the points raised by the reviewers. I assure you that the experiments were done with care, and that the results are accurate and reproducible. We look forward to receiving notification that the manuscript has been accepted for publication in Journal of alloys and compounds, and we look forward to seeing the article in print.

 

Yangke Cun

College of Materials Science and Engineering

Kunming University of Science and Technology

Kunming, 650093, China

1. R. China

E-mail: [email protected]

 

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Line 10. Larger than what??

You should be more precise…. Yes, among the two kinds of photonic crystals, inverse opal photonic has a larger specific structure. So, I suggest re-write your sentence to provide better understanding to your readers.

Introduction

Line 25. Inorganic = inorganic

 PREVIOUS COMMENTS

1.

I appreciate the inverse opal definition, however, maybe you could smoot it. I mean… Line 41-43 are informative and intriguing. Maybe something like:

… [], because their three-dimensional macroscopic porous …

2.

Your answer was:

Structural modification can disrupt the local symmetry of the crystal field and improve rare earth luminescence. By adjusting the concentration of doped rare earth ions, the energy transfer of rare earth ions can be adjusted to enhance luminescence.

I completely agree with this, STRUCTURAL MODIFICATION means that you modify the local symmetry, which could be achieved by co-doping a matrix or modifying the molar concentration of specific ions. However, the use of a core-shell structure does not necessarily mean that.

However, the text presented on lines 33 – 36 was not modified, and this part could be confusing. Here you just changed rare earths by Lanthanides. Please, review it.

Consider that core-shell structures are not changing the local crystal symmetry. And as you are talking about inverse-photonic crystals this could be confusing.

Or maybe you can use a word like more complex photonic structures like cs…

3. The design of your experiment is not explained in detail. For a moment I thought that you do not want to give more details but at line 107 you are giving the molar concentrations of Yb and Er, so, why are you not including them in the experimental section?

 

Line 183. Replace Figure 5(c)for Figure 5(d)

 

Line 207. … were sinterized AGAIN??? It is not clear.

 

Consider to be more careful in your next submission since THIS IS NOT for Journal of alloys and compounds. 

Comments on the Quality of English Language

... doped Inorganic 

... represents is a pioneering 

...doping Lanthanide ...

Lanthanide all the time with capital letter

....level, The ... 

 

Author Response

April 27^th, 2023

Prof. Wenna Dai:

 

Re: “Reversible multi-mode optical modification in inverse opal structured WO₃: Yb³⁺, Er³⁺ photonic crystal” by Bokun Zhu¹, Keling Ruan¹, Cherkasova Tatiana² and Yangke Cun^1,*

 

Dear Prof. Dai:

 

We have carefully considered the reviewers’ comments, and revised the manuscript accordingly.

 

Reviewer 1:

1. Line 10. Larger than what?You should be more precise…. Yes, among the two kinds of photonic crystals, inverse opal photonic has a larger specific structure. So, I suggest re-write your sentence to provide better understanding to your readers.

Thanks for the reviewer’s suggestion, in the revised manuscript, the following description has been revisd in Line 11-13: Compared to the common powder materials, the reverse opal structure has a larger specific surface area and an increased contact area for optical regulation, which is expected to achieve higher regulation rates.

 

2. Introduction. Line 25. Inorganic = inorganic

Thanks for the reviewer’s suggestion, in the revised manuscript, the following description has been revisd in Line 25: inorganic

 

3. I appreciate the inverse opal definition, however, maybe you could smoot it. I mean… Line 41-43 are informative and intriguing. Maybe something like:

… [], because their three-dimensional macroscopic porous …

Thanks for the reviewer’s suggestion, in the revised manuscript, the following description has been revisd in Line 40-43: In the aforementioned techniques, the photonic crystal materials have demonstrated distinctive advantages as optical materials because of their well-ordered three-dimensional macroscopic porous structure with interconnected pores, wherein each larger air void correspons to three small dark regions in the lower layer.

 

4. Your answer was:

Structural modification can disrupt the local symmetry of the crystal field and improve rare earth luminescence. By adjusting the concentration of doped rare earth ions, the energy transfer of rare earth ions can be adjusted to enhance luminescence.

I completely agree with this, STRUCTURAL MODIFICATION means that you modify the local symmetry, which could be achieved by co-doping a matrix or modifying the molar concentration of specific ions. However, the use of a core-shell structure does not necessarily mean that.

However, the text presented on lines 33 – 36 was not modified, and this part could be confusing. Here you just changed rare earths by Lanthanides. Please, review it.

Consider that core-shell structures are not changing the local crystal symmetry. And as you are talking about inverse-photonic crystals this could be confusing.

Or maybe you can use a word like more complex photonic structures like cs…

Thanks for the reviewer’s suggestion, in the revised manuscript, the following description has been revisd in Line 33-39: For instance, co-doping a matrix or modifying the concentration of specific ions to disrupt the local symmetry of the crystal field to improve rare earth luminescence [6], adjusting the concerntration of doping rare earth ions to adjust the energy transfer of rare earth ions [7, 8]. Additionally, using more comlex photonic structures like constructing core-shell structures to govern energy transfer [9, 10], using photonic crystals with photonic band gaps for selective luminescence enhancement [11], using the coupling of surface plasmons and photonic crystal effects to enhance luminescence [12, 13].

References:

6. Song P, Qiao B, Song D, Cao J, Shen Z, Xu Z, Zhao S, Wageh S, Al-Ghamdi A. Modifying the crystal field of CsPbCl₃: Mn²⁺nanocrystals by co-doping to enhance its red emission by a hundredfold. ACS Applied Materials & Interfaces 2020, 12, 30711-30719.
7. Suo H, Guo C, Li T. Broad-scope thermometry based on dual-color modulation up-conversion phosphor Ba₅Gd₈Zn₄O₂₁: Er³⁺/Yb³⁺. Journal of Physical Chemistry C2016, 120, 2914-2924.
8. Yang Z, Hu Y, Chen L, Wang X. Color tuning of Ba₂ZnSi₂O₇: Ce³⁺, Tb³⁺phosphor via energy transfer. Journal of Luminescence 2014, 153, 412-416.
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5. The design of your experiment is not explained in detail. For a moment I thought that you do not want to give more details but at line 107 you are giving the molar concentrations of Yb and Er, so, why are you not including them in the experimental section?

Thanks for the reviewer’s suggestion, in the revised manuscript, the following description has been added in “sample preperation” part: The precursor sol WO₃: x mol% Yb³⁺, 1 mol% Er³⁺ (x = 0.5, 1, 2, 3, 4) were prepared using (NH₄)₆H₂W₁₂O₄₀·xH₂O), Yb₂O₃, Er₂O₃, and HNO₃ as raw materials. The stoichiometric Yb₂O₃ and Er₂O₃ were weighted for the different doping concentration of Yb³⁺ and Er³⁺ ions and then dissolved in hot nitric acid to form Er(NO₃)₃ and Yb(NO₃)₃, which are then dissolved in anhydrous ethanol. The (NH₄)₆H₂W₁₂O₄₀·xH₂O) was dissolved in deionized water and then added dropwise to an alcohol solution of lanthanide nitrates to obtain a precursor solution.

 

6. Line 183. Replace Figure 5(c)for Figure 5(d)

 Thanks for the reviewer’s suggestion, in the revised manuscript, the following description has been revisd in Line 182: Figure (d)

 

7. Line 207. … were sinterized AGAIN??? It is not clear.

The synthetic WO₃: Yb³⁺, Er³⁺ was obtained by sintering at 480℃ for 3h, and for the reversible optical modulation research, we put the WO₃: Yb³⁺, Er³⁺ sample in to the heat trate furnace again at 600℃ for 3 h. To avoid ambiguity here, we have deleted “again” in the revised manuscript in Line 205-207: To further explore the potential applications of WO₃: Yb³⁺, Er³⁺ in the field of optics, the obtained WO₃: Yb³⁺, Er³⁺ inverse photonic crystal materials were sintered at 600°C for 3 h in an N₂/H₂ atmosphere in a tubular furnace.

 

 

In summary, we have addressed the points raised by the reviewers. I assure you that the experiments were done with care, and that the results are accurate and reproducible. We look forward to receiving notification that the manuscript has been accepted for publication in MPDI Materials, and we look forward to seeing the article in print.

 

Yangke Cun

College of Materials Science and Engineering

Kunming University of Science and Technology

Kunming, 650093, China

1. R. China

E-mail: [email protected]

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have worked hard on the paper and I recommend it for publication.

Author Response

April 27^th, 2023

Prof. Wenna Dai:

 

Re: “Reversible multi-mode optical modification in inverse opal structured WO₃: Yb³⁺, Er³⁺ photonic crystal” by Bokun Zhu¹, Keling Ruan¹, Cherkasova Tatiana² and Yangke Cun^1,*

 

Dear Prof. Dai:

 

We have carefully considered the reviewers’ comments, and revised the manuscript accordingly.

 

Thanks for the reviewer 2’s suggestion, Thank you for your help.

 

In summary, we have addressed the points raised by the reviewers. I assure you that the experiments were done with care, and that the results are accurate and reproducible. We look forward to receiving notification that the manuscript has been accepted for publication in MDPI materials, and we look forward to seeing the article in print.

 

Yangke Cun

College of Materials Science and Engineering

Kunming University of Science and Technology

Kunming, 650093, China

1. R. China

E-mail: [email protected]

Author Response File: Author Response.pdf