Materials

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12 pages, 30702 KiB

Open AccessArticle

High Refractive Index GRIN Lens for IR Optics

by Yan Kang, Jin Wang, Yongkun Zhao, Xudong Zhao, Haizheng Tao and Yinsheng Xu

Materials 2023, 16(7), 2566; https://doi.org/10.3390/ma16072566 - 23 Mar 2023

Cited by 5 | Viewed by 1549

Infrared gradient refractive index (GRIN) material lenses have attracted much attention due to their continuously varying refractive index as a function of spatial coordinates in the medium. Herein, a glass accumulation thermal diffusion method was used to fabricate a high refractive index GRIN [...] Read more.

Infrared gradient refractive index (GRIN) material lenses have attracted much attention due to their continuously varying refractive index as a function of spatial coordinates in the medium. Herein, a glass accumulation thermal diffusion method was used to fabricate a high refractive index GRIN lens. Six Ge_17.2As_17.2Se_xTe_(65−x) (x = 10.5–16) glasses with good thermal stability and high refractive index (n_{@10 μm} > 3.1) were selected for thermal diffusion. The refractive index span (∆n) of 0.12 was achieved in this GRIN lens. After thermal diffusion, the lens still had good transmittance (45%) in the range of 8–12 μm. Thermal imaging confirmed that this lens can be molded into the designed shape. The refractive index profile was indirectly characterized by the structure and composition changes. The structure and composition variation became linear with the increase in temperature from 260 °C to 270 °C for 12 h, indicating that the refractive index changed linearly along the axis. The GRIN lens with a high refractive index could find applications in infrared optical systems and infrared lenses for thermal imaging. Full article

(This article belongs to the Special Issue Advanced Functional Glass: Preparation, Properties, and Applications)

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14 pages, 20352 KiB

Open AccessArticle

Influence of Mixed Na₂O/K₂O on Chemical Durability and Spectral Properties of P₂O₅-Al₂O₃-BaO-K₂O-Na₂O-Nd₂O₃ Phosphate Glasses

by Xiben Ma, Yongchun Xu, Jimeng Cheng, Shiyu Sun, Youkuo Chen, Xin Wang, Wei Chen, Shubin Chen and Lili Hu

Materials 2022, 15(21), 7439; https://doi.org/10.3390/ma15217439 - 23 Oct 2022

Cited by 4 | Viewed by 1259

Abstract

A series of 56P₂O₅-7.5Al₂O₃-5.9BaO-(28.56-x)K₂O-xNa₂O-1.51Nd₂O₃ phosphate glasses with different Na/(Na+K) ratios, which were specially designed for high-power laser application, were prepared by a high-temperature melting method. Except for the [...] Read more.

A series of 56P₂O₅-7.5Al₂O₃-5.9BaO-(28.56-x)K₂O-xNa₂O-1.51Nd₂O₃ phosphate glasses with different Na/(Na+K) ratios, which were specially designed for high-power laser application, were prepared by a high-temperature melting method. Except for the density, refractive index, glass transition temperature, and DC conductivity, the chemical durability and spectral properties, as emphasized by high-power and high-energy laser material, were further measured and analyzed. Regarding the chemical durability, the dissolution rates of these glasses do not show an evident mixed alkali effect with increasing the Na/(Na+K) ratio, although the effect is obvious for the glass transition temperature and DC conductivity. To better understand the nature of the dissolution mechanism, the ionic release concentrations of every element are determined. Both Na and K undergo ion exchange, but the ion exchange rate of K is much larger than that of Na. In terms of the spectral properties, the J–O parameters, emission cross-section, radiation lifetime, fluorescence lifetime, effective bandwidth, fluorescence branching ratio, and quantum efficiency are determined from absorption and emission spectra. The trend of Ω₂ deviating from linearity indicates that the coordination environment symmetry of Nd³⁺ ions and the covalence of Nd-O also present an evident mixed alkali effect. The most important finding is that the emission cross-section and fluorescence lifetime of Nd³⁺ ions at 1053 nm were not affected by the change in the Na/K ratio. According to the above experimental results, the optimized value of the Na/K ratio was determined, based on which the 56P₂O₅-7.5Al₂O₃-5.9BaO-(28.56-x)K₂O-xNa₂O-1.51Nd₂O₃ glass maintains a high emission cross-section with good chemical durability. Full article

(This article belongs to the Special Issue Advanced Functional Glass: Preparation, Properties, and Applications)

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18 pages, 2949 KiB

Open AccessArticle

Investigation of the Efficiency of Shielding Gamma and Electron Radiation Using Glasses Based on TeO₂-WO₃-Bi₂O₃-MoO₃-SiO to Protect Electronic Circuits from the Negative Effects of Ionizing Radiation

by Artem Kozlovskiy, Dmitriy I. Shlimas, Maxim V. Zdorovets, Elena Popova, Edgars Elsts and Anatoli I. Popov

Materials 2022, 15(17), 6071; https://doi.org/10.3390/ma15176071 - 1 Sep 2022

Cited by 10 | Viewed by 1785

Abstract

This article considers the effect of MoO₃ and SiO additives in telluride glasses on the shielding characteristics and protection of electronic microcircuits operating under conditions of increased radiation background or cosmic radiation. MoO₃ and SiO dopants were chosen because their properties, [...] Read more.

This article considers the effect of MoO₃ and SiO additives in telluride glasses on the shielding characteristics and protection of electronic microcircuits operating under conditions of increased radiation background or cosmic radiation. MoO₃ and SiO dopants were chosen because their properties, including their insulating characteristics, make it possible to avoid breakdown processes caused by radiation damage. The relevance of the study consists in the proposed method of using protective glasses to protect the most important components of electronic circuits from the negative effects of ionizing radiation, which can cause failures or lead to destabilization of the electronics. Evaluation of the shielding efficiency of gamma and electron radiation was carried out using a standard method for determining the change in the threshold voltage (∆U) value of microcircuits placed behind the shield and subjected to irradiation with various doses. It was established that an increase in the content of MoO₃ and SiO in the glass structure led to an increase of up to 90% in the gamma radiation shielding efficiency, while maintaining the stability of microcircuit performance under prolonged exposure to ionizing radiation. The results obtained allow us to conclude that the use of protective glasses based on TeO₂–WO₃–Bi₂O₃–MoO₃–SiO is highly promising for creating local protection for the main components of microcircuits and semiconductor devices operating under conditions of increased background radiation or cosmic radiation. Full article

(This article belongs to the Special Issue Advanced Functional Glass: Preparation, Properties, and Applications)

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13 pages, 4185 KiB

Open AccessArticle

Silver-Neodymium Codoped Lithium Aluminum Metaphosphate Glasses for Radio-Photoluminescence Dosimeter

by Xiben Ma, Jimeng Cheng, Sijun Fan, Xin Wang, Wei Chen, Shubin Chen and Lili Hu

Materials 2022, 15(16), 5527; https://doi.org/10.3390/ma15165527 - 11 Aug 2022

Cited by 2 | Viewed by 1360

Abstract

Commercial radio-photoluminescence (RPL) glass dosimeters generally use Ag single-doped phosphate glass as a single-wavelength sensor. Now, a novel type of Ag–Nd-codoped phosphate glass has been developed, which can be applied to dual-wavelength or multi-wavelength RPL sensors, and can thus improve the accuracy and [...] Read more.

Commercial radio-photoluminescence (RPL) glass dosimeters generally use Ag single-doped phosphate glass as a single-wavelength sensor. Now, a novel type of Ag–Nd-codoped phosphate glass has been developed, which can be applied to dual-wavelength or multi-wavelength RPL sensors, and can thus improve the accuracy and stability of RPL dosimeters. An anhydrous 99.5 (0.7LiPO₃–0.3Al (PO₃)₃) −0.25Ag₂O–0.25Nd₂O₃ glass was prepared and irradiated at different doses, and then the absorption, fluorescence, infrared transmission spectra, as well as fluorescence lifetimes were tested and analyzed. The results show that there is an energy transfer between the Ag defect center and Nd³⁺ ions, and the transfer efficiency using 380 nm excitation is greater than that using 310 nm excitation. Aside from the 650 nm fluorescence of the Ag defect center, strong 882 nm and 1054 nm fluorescences of Nd ions are exhibited. It is possible that these fluorescences would allow the developed Ag–Nd-codoped phosphate glass to be applied to new RPL glass sensors and dosimeters. Full article

(This article belongs to the Special Issue Advanced Functional Glass: Preparation, Properties, and Applications)

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14 pages, 13734 KiB

Open AccessArticle

Facile Solution Process of VO₂ Film with Mesh Morphology for Enhanced Thermochromic Performance

by Zhao Yu, Zhe Wang, Bin Li, Shouqin Tian, Gen Tang, Aimin Pang, Dawen Zeng and Gopinathan Sankar

Materials 2022, 15(12), 4129; https://doi.org/10.3390/ma15124129 - 10 Jun 2022

Cited by 2 | Viewed by 1261

Abstract

The fabrication and applications of VO₂ film continue to be of considerable interest due to their good thermochromic performance for smart windows. However, low visible transmittance (T_lum) and solar modulation efficiency (∆T_sol) impede the application of [...] Read more.

The fabrication and applications of VO₂ film continue to be of considerable interest due to their good thermochromic performance for smart windows. However, low visible transmittance (T_lum) and solar modulation efficiency (∆T_sol) impede the application of VO₂ film, and they are difficult to improve simultaneously. Here, a facile zinc solution process was employed to control the surface structure of dense VO₂ film and the processed VO₂ film showed enhanced visible transmittance and solar modulation efficiency, which were increased by 7.5% and 9.5%, respectively, compared with unprocessed VO₂ film. This process facilitated the growth of layered basic zinc acetate (LBZA) nanosheets to form mesh morphology on the surface of VO₂ film, where LBZA nanosheets enhance the visible transmittance as an anti-reflection film. The mesh morphology also strengthened the solar modulation efficiency with small caves between nanosheets by multiplying the times of reflection. By increasing the zinc concentration from 0.05 mol/L to 0.20 mol/L, there were more LBZA nanosheets on the surface of the VO₂ film, leading to an increase in the solar/near-infrared modulation efficiency. Therefore, this work revealed the relationship between the solution process, surface structure, and optical properties, and thus can provide a new method to prepare VO₂ composite film with desirable performance for applications in smart windows. Full article

(This article belongs to the Special Issue Advanced Functional Glass: Preparation, Properties, and Applications)

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10 pages, 3497 KiB

Open AccessEditor’s ChoiceArticle

Optimizing Evanescent Efficiency of Chalcogenide Tapered Fiber

by Xudong Zhao, Ni Yao, Xianghua Zhang, Lei Zhang, Guangming Tao, Zijian Li, Quan Liu, Xiujian Zhao and Yinsheng Xu

Materials 2022, 15(11), 3834; https://doi.org/10.3390/ma15113834 - 27 May 2022

Cited by 2 | Viewed by 1653

Abstract

Evanescent wave absorption-based mid-infrared chalcogenide fiber sensors have prominent advantages in multicomponent liquid and gas detection. In this work, a new approach of tapered-fiber geometry optimization was proposed, and the evanescent efficiency was also theoretically calculated to evaluate sensing performance. The influence of [...] Read more.

Evanescent wave absorption-based mid-infrared chalcogenide fiber sensors have prominent advantages in multicomponent liquid and gas detection. In this work, a new approach of tapered-fiber geometry optimization was proposed, and the evanescent efficiency was also theoretically calculated to evaluate sensing performance. The influence of fiber geometry (waist radius (R_w), taper length (L_t), waist deformation) on the mode distribution, light transmittance (T), evanescent proportion (T_O) and evanescent efficiency (τ) is discussed. Remarkably, the calculated results show that the evanescent efficiency can be over 10% via optimizing the waist radius and taper length. Generally, a better sensing performance based on tapered fiber can be achieved if the proportion of the LP₁₁-like mode becomes higher or R_w becomes smaller. Furthermore, the radius of the waist boundary (R_L) was introduced to analyze the waist deformation. Mode proportion is almost unchanged as the R_L increases, while τ is halved. In addition, the larger the micro taper is, the easier the taper process is. Herein, a longer waist can be obtained, resulting in larger sensing area which increases sensitivity greatly. Full article

(This article belongs to the Special Issue Advanced Functional Glass: Preparation, Properties, and Applications)

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16 pages, 4363 KiB

Open AccessArticle

Fabrication and Optical Characterization of VO₂-Based Thin Films Deposited on Practical Float Glass by Magnetron Sputtering and Professional Annealing

by Xinhong Chu, Qiusheng Xie, Xiaoming Zhang, Bingfeng Guo, Jianqing Liao and Xiujian Zhao

Materials 2022, 15(9), 2990; https://doi.org/10.3390/ma15092990 - 20 Apr 2022

Cited by 2 | Viewed by 1795

Abstract

In this paper, VO₂ thin films with good optical properties are fabricated on practical float glass by magnetron sputtering and a professional annealing method. The near-infrared switching efficiency (NIRSE) of the prepared film reaches 39% (@2000 nm), and its near-infrared energy modulation [...] Read more.

In this paper, VO₂ thin films with good optical properties are fabricated on practical float glass by magnetron sputtering and a professional annealing method. The near-infrared switching efficiency (NIRSE) of the prepared film reaches 39% (@2000 nm), and its near-infrared energy modulation ability (ΔT_ir) reaches 10.9% (780–2500 nm). Further, the highest integral visible transmittance T_lum is 63%. The proposed method exhibits good reproducibility and does not cause any heat damage to the magnetron sputtering machine. The crystalline structure of the VO₂ film is characterized by X-ray diffraction (XRD). The lattice planes (011) and (−211) grow preferentially (JCPDS 65-2358), and a large number of NaV₂O₅ crystals are detected simultaneously. The microstructures are characterized by scanning electron microscopy (SEM), and a large number of long sheet crystals are identified. The phase transition temperature is significantly reduced by an appropriate W doping concentration (T_c = 29 °C), whereas excessive W doping causes distortion of the thermal hysteresis loop and a reduction in the NIRSE. Oxygen vacancies are created by low pressure annealing, due to which the phase transition temperature of VO₂ film decreases by 8 °C. The addition of an intermediate SiO₂ layer can prevent the diffusion of Na⁺ ions and affect the preparation process of the VO₂ thin film. Full article

(This article belongs to the Special Issue Advanced Functional Glass: Preparation, Properties, and Applications)

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12 pages, 4976 KiB

Open AccessArticle

Influence of GeO₂ Content on the Spectral and Radiation-Resistant Properties of Yb/Al/Ge Co-Doped Silica Fiber Core Glasses

by Yiming Zhu, Yan Jiao, Yue Cheng, Chongyun Shao, Chunlei Yu, Ye Dai and Lili Hu

Materials 2022, 15(6), 2235; https://doi.org/10.3390/ma15062235 - 17 Mar 2022

Cited by 1 | Viewed by 1738

Abstract

In this study, Yb/Al/Ge co-doped silica fiber core glasses with different GeO₂ contents (0–6.03 mol%) were prepared using the sol–gel method combined with high-temperature sintering. The absorption, fluorescence, radiation-induced absorption, continuous-wave electron paramagnetic resonance spectra, and fluorescence decay curves were recorded and [...] Read more.

In this study, Yb/Al/Ge co-doped silica fiber core glasses with different GeO₂ contents (0–6.03 mol%) were prepared using the sol–gel method combined with high-temperature sintering. The absorption, fluorescence, radiation-induced absorption, continuous-wave electron paramagnetic resonance spectra, and fluorescence decay curves were recorded and analyzed systematically before and after X-ray irradiation. The effects of GeO₂ content on the valence variations of Yb³⁺/Yb²⁺ ions, spectral properties of Yb³⁺ ions, and radiation resistance of Yb/Al/Ge co-doped silica glasses were systematically studied. The results show that even if the GeO₂ content of the sample is relatively low (0.62 mol%), it can inhibit the generation of Yb²⁺ ions with slight improvement in the spectral properties of Yb³⁺ ions in the pristine samples and effectively improve its radiation resistance. Direct evidence confirms that the generation of trapped-electron centers (Yb²⁺/Si-E’/Al-E’) and trapped-hole centers (Al-OHC) was effectively inhibited by Ge co-doping. This study provides a theoretical reference for the development of high-performance, radiation-r esistant Yb-doped silica fibers. Full article

(This article belongs to the Special Issue Advanced Functional Glass: Preparation, Properties, and Applications)

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12 pages, 5959 KiB

Open AccessArticle

Effect of Se on Structure and Electrical Properties of Ge-As-Te Glass

by Kangning Liu, Yan Kang, Haizheng Tao, Xianghua Zhang and Yinsheng Xu

Materials 2022, 15(5), 1797; https://doi.org/10.3390/ma15051797 - 27 Feb 2022

Cited by 10 | Viewed by 1687

Abstract

The Ge-As-Te glass has a wide infrared transmission window range of 3–18 μm, but its crystallization tendency is severe due to the metallicity of the Te atom, which limits its development in the mid- and far-infrared fields. In this work, the Se element [...] Read more.

The Ge-As-Te glass has a wide infrared transmission window range of 3–18 μm, but its crystallization tendency is severe due to the metallicity of the Te atom, which limits its development in the mid- and far-infrared fields. In this work, the Se element was introduced to stabilize the Ge-As-Te glass. Some glasses with ΔT ≥ 150 °C have excellent thermal stability, indicating these glasses can be prepared in large sizes for industrialization. The Ge-As-Se-Te (GAST) glasses still have a wide infrared transmission window (3–18 μm) and a high linear refractive index (3.2–3.6), indicating that the GAST glass is an ideal material for infrared optics. Raman spectra show that the main structural units for GAST glass are [GeTe₄] tetrahedra, [AsTe₃] pyramids, and [GeTe₄Se_4−x] tetrahedra, and with the decrease of Te content (≤50 mol%), As-As and Ge-Ge homopolar bonds appear in the glass due to the non-stoichiometric ratio. The conductivity σ of the studied GAST glasses decreases with the decrease of the Te content. The highest σ value of 1.55 × 10⁻⁵ S/cm is obtained in the glass with a high Te content. The activation energy E_a of the glass increases with the decrease of the Te content, indicating that the glass with a high Te content is more sensitive to temperature. This work provides a foundation for widening the application of GAST glass materials in the field of infrared optics. Full article

(This article belongs to the Special Issue Advanced Functional Glass: Preparation, Properties, and Applications)

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11 pages, 25763 KiB

Open AccessArticle

Temperature Dependence of Absorption and Energy Transfer Efficiency of Er³⁺/Yb³⁺/P⁵⁺ Co-Doped Silica Fiber Core Glasses

by Yue Cheng, Hehe Dong, Chunlei Yu, Qiubai Yang, Yan Jiao, Shikai Wang, Chongyun Shao, Lili Hu and Ye Dai

Materials 2022, 15(3), 996; https://doi.org/10.3390/ma15030996 - 27 Jan 2022

Cited by 4 | Viewed by 2346

Abstract

A high phosphorus Er³⁺/Yb³⁺ co-doped silica (EYPS) fiber core glass was prepared using the sol-gel method combined with high-temperature sintering. The absorption spectra, emission spectra, and fluorescence decay curves were measured and compared in temperatures ranging from 300 to 480 [...] Read more.

A high phosphorus Er³⁺/Yb³⁺ co-doped silica (EYPS) fiber core glass was prepared using the sol-gel method combined with high-temperature sintering. The absorption spectra, emission spectra, and fluorescence decay curves were measured and compared in temperatures ranging from 300 to 480 K. Compared to 915 and 97x nm, the absorption cross-section at ~940 nm (~0.173 pm²) demonstrates a weaker temperature dependence. Hence, the 940 nm pump mechanism is favorable for achieving a high-power laser output at 1.5 μm. Additionally, the double-exponential fluorescence decay of Yb³⁺ ions and the emission intensity ratio of I_1018nm/I_1534nm were measured to evaluate the energy transfer efficiency from Yb³⁺ ions to Er³⁺ ions. Through the external heating and active quantum defect heating methods, the emission intensity ratios of I_1018nm/I_1534nm increase by 30.6% and 709.1%, respectively, from ~300 to ~480 K. The results indicate that the temperature rises significantly reduce the efficiency of the energy transfer from the Yb³⁺ to the Er³⁺ ions. Full article

(This article belongs to the Special Issue Advanced Functional Glass: Preparation, Properties, and Applications)

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