The Effect of Strontium Doping on LaFeO₃ Thin Films Deposited by the PLD Method

Round 1

Reviewer 1 Report

answer to this.

The paper presents findings on strontium doping on the perovskite oxides LaFeO3 thin films deposited by PLD (pulsed laser deposition) method.

Overall, I find the flow smooth and sounds scientific. When going into details I find there is need to elaborate on some statements as suggested:

1. Line 38: “wide-gapped”

?? What is the meaning of this expression? It sounds strange.

2. Lines 172-173: “The substitution of La³⁺ by Sr²⁺ created the vacancies.

?? The vacancies can interact with oxygen vacancies and decrease their mobility.”

What would be the author's vision of vacations? From what I understand here there are more types of vacancies?  Could the author explain what kind of vacancies are created in addition to the oxygen vacancies?

3. Lines 173-174: “As oxygen vacancies play an important role in structure mobility, we observe smaller crystalline size and also particle size.”

?? The expression “structure mobility” is something that puzzles me. Could the author bring clarifications on this?

4. Lines 286-287-288: “When La³⁺ ions are replaced by Sr²⁺ ions, hole are produced due to the ionization of [Sr^x_La]: ??_?^?_?→??′+ℎ^* “

?? I suggest holes instead of hole. Also, I do not see any explanations for the symbols used in these equations.

5. Lines 289-290: “c) compound compensation”

?? Could the author bring clarifications on this expression in physical-chemistry meaning?

6. Some typos are detected and English language should be improved.

Author Response

1. line 38 is changing.

This perovskite is as famous antiferromagnetic materials with high Néel temperature T_N=740 °C. The electrical properties of LaFeO₃ are derived from the ordering antiferroelectric and ferroelectric dipole moments.

2. and 3 This fragment has been changed.

Doping has caused a decrease in the size of crystallites from 36 nm for LaFeO₃ to 18 nm for the La_0.8Sr_0.2FeO₃ thin films (Table 1). In nanocrystalline materials such as thin films. interaction between defects (dopants) and grain boundary (GB) plays a key role in determining the structure stability. The interaction between the dopants and surface/grain boundaries may decrease surface energy/grain boundary energy. This leading the stabilization of the surfaces/grain boundaries [20]. In this case. under the same preparation conditions are more surfaces/grain boundaries are observed. It can therefore be concluded that the grain size can decrease with the dopants.

4. and 5. I change hol to hols. For explain the compound compensation I changed this part of article.

All processes occur in Sr²⁺ doped La_1-xSr_xFeO₃ can be described as follows:

1. electroneutrality formed Fe⁴⁺.

(La_1-x³⁺Sr_x²⁺)(Fe_1-x³⁺Fe_x⁴⁺)O₃

1. oxygen vacancies compensation.  - oxygen vacancies.

(La_1-x³⁺Sr_x²⁺)(Fe(O_3-x/2o_x/2)

1. compound compensation (both electroneutrality and oxygen vacancies compensation) which occur in substituted perovskites oxides

(La_1-x³⁺Sr_x²⁺)(Fe_1-y³⁺Fe_y⁴⁺)(O_3-(x-y)/2o_(x-y)/2) [29].

Considering the above we expected the increasing of the sensitivity with the dopants.

English is improved.

 

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript deals with Sr doped LaFeO₃ thin films. The authors have conducted detailed characterizations. Although the topic is interesting due to various applications of these materials.However, certain changes are require before its approval.

Besides the fact that authors conducted detailed characterizations, the manuscript misses detailed scientific discussion. Therefore, it is require to modify the manuscript accordingly.

Section Introduction: line 38: it should be "at" room temperature

Section Introduction: Line 39: "is also one of the few single phase multi iron materials with both anti-ferromagnetic and ferroelectric properties at the same time" It is not clear. Kindly corret it

 

Section Introduction: Line 83: "PED[17], PLD[2] " It is important to write first time complete name of method. Afterwars the authors can use abbreviations.

Figure 1 and 2: The authors should briefly explain and compare the peaks position with those available in literature.

 

Results and discussion: Authors are suggested to make more comparison with state of art, where require.

 

Table 1: Authors are suggested to use internation standard while writing a number i.e. to use a dot (6.3) instead of a comma (6,3). same pattern should use in whol manuscript.

Figure 3: Authors should explain briefly why there is crack in SEM image of thin film at x:0.2

Fiigure 12: It is difficult to distinguish that which is figure "(a)" and which is "(b)". Kindly label properly.

Author Response

Thanks for your comments

I changed in line 38 "in" to "at".

I changed line 39 "This perovskite is as famous antiferromagnetic materials with high Néel temperature T_N=740 °C. The electrical properties of LaFeO₃ are derived from the ordering antiferroelectric and ferroelectric dipole moments [10]. "

Line 83 I explain symbols: "Thin films LaFeO₃ can be deposited by different method such as: Pulsed Electron Deposition (PED) [17], Pulsed Laser Deposition (PLD) [2] and magnetron sputtering (MS) [13]."

I explained the position of the peaks on the XRD Fig 1. and 2.

3.1 "All peaks in targets follow the patterns LaFeO₃ (01-088-0641), La_0.9Sr_0.1FeO₃ (04-007-6515), La_0.8Sr_0.2FeO₃ (04-007-6516). The peaks in doped targets are shifted to the right in relations to the peaks in LaFeO₃ target. This is due to the substitution of La by Sr and changing of cell parameters. The same effect was observed by M. Kumar et all. [18] in perovskite LaFeO₃ and La_0.9Sr_0.1FeO₃. The peaks (101), (121), (220), (202), (141), (042, (242) and (204) in targets are in the same position 2Q as in presented by M. Kumar et all [18]."

3.2 "Peak positions are consistent with the literature data [18]. As for XRD analysis in targets the peaks in doped thin films are shifted to the right in relations to the peaks in LaFeO₃ target. This is due to the substitution of La by Sr and changing of cell parameters."

In chapter Results and Discussion I add more literature about position of the XRD peaks, stress in thin films deposited by PLD method. In interpretation of the XPS results and grain size.

I replaced commas with dots.

The cracks visible on Fig. 3c may be caused by too high a cooling rate after the PLD process. Cracks are also one of the characteristics of the PLD method. In the deposited thin films tensile stress may appear to GPa [21]. They relaxation during the cooling process can produced the cracks in thin films.

Descriptions of Figures have been corrected.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The manuscript has been improved as requested.

Therefore can be accepted.

 

Nevertheless, still English language style, typo etc need to edit.