20GeS2·80Sb2S3硫系玻璃的析晶行为及动力学机理研究

实现玻璃微晶化过程控制的基础是要充分认识其析晶行为及动力学机理. 利用示差扫描量热法和析晶热处理等手段, 研究发现 20GeS₂·80Sb₂S₃硫系玻璃属于表面析晶, 在268℃(T_g+30℃)下热处理60 h, 可以获得表面约40 μm的Sb₂S₃晶层复合玻璃陶瓷样品. 在此基础上, 利用非等温法从理论上分析该玻璃的析晶动力学机理. 计算得到其析晶活化能E_c为(223.6±24.1)kJ·mol^-1, 在热处理温度(268℃)下的析晶速率常数K为1.23×10^-4 s^-1, 属于较难析晶的玻璃组成; 玻璃的晶体生长指数m和晶体生长维数n均为2, 表明其Sb₂S₃相的析晶行为是二维生长过程, 与析晶实验结果完全相符. 由此可知, 对于Sb₂S₃晶体复合的硫系玻璃陶瓷样品可通过玻璃粉末压片烧结、带铸法或丝网印刷法制备获得, 为今后功能硫系玻璃的开发提供实验依据和理论指导. 关键词： 硫系玻璃 微晶化 析晶动力学 析晶行为     

GeS2-Ga2S3-CsI硫系玻璃的析晶行为及其组成依赖研究

硫系玻璃晶化过程中析出晶相的控制是硫系玻璃陶瓷制备中的一个重要环节. 在制得的65GeS₂·25Ga₂S₃·10CsI(GGC25)和70GeS₂·20Ga₂S₃·10CsI(GGC20)玻璃和玻璃陶瓷基础上, 利用可见—近红外透过光谱, SEM, XRD, Raman光谱等测试技术表征了其透过性能、晶粒尺寸、晶相类型等信息. 研究发现在这两组玻璃样品中少量的组分差别就能导致其显著的析晶行为改变: GGC20玻璃在热处理过程中析出的是GeS₂晶体; GGC25样品则拥有两步析晶过程, 其率先析出Ga₂S₃, 而后才有GeS₂晶体出现. 此外, 研究讨论了这种析晶行为与组成的依赖关系及其与玻璃网络结构之间联系, 可为今后硫系玻璃的可控晶化研究提供实验依据和理论指导.     

GeSe2-Sb2Se3-CsCl玻璃的光学性质与析晶动力学研究

采用熔融淬冷法制备了20GeSe₂-（80-x）Sb₂Se₃-xCsCl（x=2,4,8,10 mol%）硫卤玻璃系统,测试了样品在可见至中远红外区域的透过光谱,研究了硫卤玻璃中CsCl对玻璃短波吸收限的影响;并测试了典型的20GeSe₂-76Sb₂Se₃-4CsCl样品在不同升温速率下的DTA曲线,利用非等温方法研究了其析晶动力学; 关键词： 硫卤玻璃 非等温过程 析晶动力学     

Ga2S3-Sb2S3-Ag2S硫系玻璃和光纤的制备及性能研究

本工作确定了一种新型的Ga₂S₃-Sb₂S₃-Ag₂S硫系玻璃体系的玻璃形成区,研究了玻璃的热稳定性和光学性能、稀土离子掺杂玻璃的中红外发光特性以及玻璃的成纤性能,评估了该玻璃在中红外波段的应用潜力.实验结果表明,Ga₂S₃-Sb₂S₃-Ag₂S体系的玻璃形成区为～10%—30%Ga₂S₃,～60%—80%Sb₂S₃和～0—15%Ag₂S(均为摩尔分数);该玻璃具有较宽的红外透过范围(～0.8—13.5μm)、较高的线性折射率(～2.564—2.713@10μm)和较大的三阶非线性折射率(～9.7×10^-14—15.7×10^-14 cm²/W@1.55μm);使用1.32μm激光抽运,稀土离子Dy...     

新型GeSe2-In2Se3-AgI玻璃性能研究

采用传统熔融-淬冷法制备了一系列新型(100-x)(4GeSe2-In2Se3)-xAgI(x=20,30,40mol%)硫系玻璃样品.利用X射线衍射分析、差热分析、可见-近红外吸收光谱、红外透过光谱、喇曼分析等技术手段研究了该玻璃系统的组成、结构、热稳定性和光学特性等.利用Tauc方程计算出了样品的间接带隙;测试了部分样品在不同升温速率下的差示扫描量热曲线,并采用Kissinger法计算了玻璃样品的析晶活化能.X射线衍射数据表明,该玻璃体系在较宽的组分范围内有良好的非晶特性,成玻范围较宽;差热分析和析晶动力学研究表明,玻璃样品70(4GeSe2-In2Se3)-30AgI具有较好的热稳定性(ΔT=114℃)和较高的活化能(Ea=320.4kJ/mol).随着AgI含量的增加,玻璃的短波吸收限蓝移,并且光学带隙有增大的趋势.此外,红外透过光谱分析表明该玻璃体系具有良好的红外透过性能,其红外截止波长不会随着AgI含量的增加而发生明显变化,皆为16μm左右.     

新型GeSe2-In2Se3-AgI玻璃性能研究

采用传统熔融-淬冷法制备了一系列新型(100-x) (4GeSe₂-In₂Se₃) -xAgI(x=20,30,40 mol%)硫系玻璃样品.利用X射线衍射分析、差热分析、可见-近红外吸收光谱、红外透过光谱、喇曼分析等技术手段研究了该玻璃系统的组成、结构、热稳定性和光学特性等.利用Tauc方程计算出了样品的间接带隙;测试了部分样品在不同升温速率下的差示扫描量热曲线,并采用Kissinger法计算了玻璃样品的析晶活化能.X射线衍射数据表明,该玻璃体系在较宽的组分范围内有良好的非晶特性,成玻范围较宽;差热分析和析晶动力学研究表明,玻璃样品70(4GeSe₂-In₂Se₃)-30AgI具有较好的热稳定性(ΔT=114℃)和较高的活化能(E_a=320.4 kJ/mol).随着AgI含量的增加,玻璃的短波吸收限蓝移,并且光学带隙有增大的趋势.此外,红外透过光谱分析表明该玻璃体系具有良好的红外透过性能,其红外截止波长不会随着AgI含量的增加而发生明显变化,皆为16μm左右.     

Al2O3对氟氧化物玻璃微结构和析晶的影响

采用红外, Raman, X射线衍射测试分析方法, 研究了Al₂O₃对氟氧化物玻璃微结构和析晶的影响.结果表明, Al³⁺主要以[AlO₄]的形式与[SiO₄]以顶角相连的方式构成基本网络骨架, Al₂O₃含量的增加, 使氧化物玻璃基质的网络向单体和二聚体结构转变, 并使氟化物微晶尺寸有一个先变小后增大的趋势, 但不影响微晶结构.     

圆柱形红外硫系玻璃淬冷降温模型与实验分析

出炉温度和冷却速率是大尺寸硫系玻璃制备过程中的关键参数. 在热传导方程理论基础上,运用最小二乘拟合的方法建立计算圆柱形硫系玻璃冷却过程温度分布的理论模型. 利用该模型对硫系玻璃的出炉温度、出炉后温度分布以及冷却速率进行了仿真分析,并将仿真分析结果与实验数据进行了比较. 研究表明:出炉后玻璃棒的温度处于非稳态非均匀分布,其表面降温最快,且速率随时间呈现指数型下降;玻璃棒温度从中心到边缘近似呈抛物线型分布;当以高于析晶温度50-100 ℃,表面热交换系数180 W ·m^-2 K 关键词： 红外硫系玻璃 淬冷降温模型 析晶     

GeS2-Ga2S3-CsCl玻璃的三阶非线性光学性能研究

用传统的熔融急冷法制备了组分为(100-2x) GeS₂-xGa₂S₃-xCsCl (x= 15, 20, 25 mol%)系列硫卤玻璃, 测试了样品玻璃的吸收光谱. 采用Z-扫描方法测试了样品的三阶非线性光学特性. 分析了激光光子能量与玻璃三阶非线性光学特性的关系,并研究了组分变化对玻璃的三阶非线性性能的影响. 研究结果表明,光子能量的少许改变可以使非线性吸收系数在一个较大的范围内变化,随着光子能量的增大, 玻璃的非线性吸收系数β 增大;当光子能量趋近于0.5E_g时, β值趋近于0,玻璃有最佳的品质因子; 玻璃样品中CsCl含量的增加使得玻璃的光学带隙E_g增大,短波截止边蓝移,非线性吸收系数β 减小. 但是由于结构与带隙对光学非线性的影响相反,非线性折射率γ 值变化不大. 该结果表明样品的光学非线性性能由光学带隙和结构两方面因素共同决定,对今后研究全光开关用硫系玻璃具有一定的指导意义和参考价值.     

基于AZ5214光致保护层的As2S3硫系脊型波导制备

实验研究发现AZ5214光刻胶在一定曝光剂量下显影后会留存一定厚度的底膜,该底膜可以在干法刻蚀过程中避免As-S薄膜与碱性显影液直接接触,减轻薄膜表面损伤,起到保护作用。基于此,采用该底膜作为保护层制备As₂S₃脊型波导,研究结果表明,在AZ5214光刻胶匀胶厚度为2.1μm、紫外曝光剂量为200 mJ/cm²、显影时间为45 s的条件下会留存约为220 nm厚的光致保护层,该条件下保护层均匀性较好,且在刻蚀阶段可以完全去除。实验表明利用此保护层制备的As₂S₃脊型波导具有良好的形貌特征,波导脊宽约为3μm、脊高约为800 nm的As₂S₃脊型波导的传输损耗约为0.74 dB/cm@1 550 nm。     

Structure dependence of ultrafast third-order optical nonlinearity for GeS2-In2S3-CsI chalcohalide glasses

Ultrafast third-order nonlinear optical responses of GeS₂-In₂S₃-CsI chalcohalide glasses have been measured by using the femtosecond time-resolved optical Kerr effect (OKE) technique at a wavelength of 820 nm. The third-order nonlinear susceptibility was estimated to be as large as 5.12×10⁻¹³ esu. The full width at half maximum of the Kerr signal was 120 fs and its response was dominantly assigned to the ultrafast distortion of the electron cloud. The relationship between the structural units and the third-order nonlinear optical responses was analysed by Raman spectra. It is suggested that the covalent bonds of S-Ge or S-In constituting the tetrahedral units [GeS_4/2] or [InS_4−xI_x], respectively, play an important role in the ultrafast third-order nonlinear optical responses of these chalcohalide glasses.     

Structural investigations of GeS2-Ga2S3-CdS chalcogenide glasses using Raman spectroscopy

Raman investigations were carried out for various compositions of chalcogenide glasses in the GeS₂-Ga₂S₃-CdS system. Addition of Ga₂S₃ into GeS₂ results in the formation of metal-metal bonds and edge-shared GaS_4/2 tetrahedra. Ge²⁺ ions may surround [GaS_4/2]¹⁻ tetrahedra acting as charge compensators. Upon the addition of CdS into the GeS₂-Ga₂S₃ system, the number of the metal-metal bonds and edge-shared GaS_4/2 tetrahedra decreases, resulting in the formation of corner-shared tetrahedra with non-bridging sulfurs (NBS). Cd²⁺ ions can be dissolved into the glass network as charge compensators for these NBS and exited few [GaS_4/2]¹⁻ tetrahedra. The high solubility of CdS is ascribed to the dissociation of metal-metal bonds and edge-shared tetrahedra in these Ga-containing glasses.     

Second-harmonic generation in transparent surface crystallized GeS2-Ga2S3-CdS chalcogenide glasses

Transparent surface crystallized glasses containing CdGa₂S₄ nonlinear optical crystal were prepared by the 70GeS₂ · 15Ga₂S₃ · 15CdS (GGC15) chalcogenide glass. Average diameters of crystallites are about 150 nm and 600 nm for heating at 405 °C for 48 and 108 h (named GGC15-48 and GGC15-108), respectively, and the thickness of the surface crystallized layer was approximately 15 μm. By using the Maker fringe measurement, prominent second-harmonic generation was observed from these crystallized glasses, and the χ⁽²⁾ of the GGC15-48 sample is calculated to be as well as 38.85 pm/V, and the value is 13.7 pm/V for the GGC15-108. They are promising to be applied in photoelectric and all-optical field in the future.     

Mechanism of electron beam poled SHG in 0.95GeS2·0.05In2S3 chalcogenide glasses

Utilizing the Maker fringe method, SHG was observed in the 0.95GeS₂·0.05In₂S₃ chalcogenide glass irradiated by the electron beam and the intensity of SH increases with the enhancement of beam current from 15 to 25 nA. According to Raman spectra of the as-prepared and the irradiated one, no distinct micro-structural transformation was found. In this work, the built-in charge model was founded to interpret the poling mechanism of electron beam irradiation, the emission of the secondary electrons and Auger electrons results in the formation of positive region and the absorbed electrons form negative region. The positive region was situated near the poling surface, and the negative region was much deeper than the positive region. Between the two opposite charged regions, a strong space-charge electrostatic field, E_dc, is created, which leads to the nonzero χ⁽²⁾ in the 0.95GeS₂·0.05In₂S₃ glass. The emission of backscattered electrons does no contribution to the formation of E_dc.     

Study on the structure dependent ultrafast third-order optical nonlinearity of GeS2–In2S3 chalcogenide glasses

The results of the femtosecond time-resolved optical Kerr at 820 nm in GeS₂–In₂S₃ chalcogenide glasses indicate that the response time in GeS₂–In₂S₃ glasses is subpicosecond, which is predominantly due to the distortion of the electron cloud. The value of χ⁽³⁾ in 0.95GeS₂–0.05In₂S₃ glass is also as large as 2.7 × 10⁻¹³ esu, and it reduces with the addition of In₂S₃, which may be ascribed to the microstructure evolution of GeS₂–In₂S₃ glasses. It is deduced that the intrinsic [Ge(In)S₄] tetrahedral structure units that possess the high hyperpolarizability may do great contribution to the enhancement of third-order optical nonlinearity while [S₃Ge–GeS₃] ethane-like molecular units make no considerable contribution to that in femtosecond time scale. These GeS₂–In₂S₃ and GeS₂–In₂S₃-based chalcogenide glasses would be expected to be the promising materials for all-optical switching devices.     

Si1Sb2Te3 phase change material for chalcogenide random access memory

This paper investigated phase change Si1Sb2Te3 material for application of chalcogenide random access memory. Current-voltage performance was conducted to determine threshold current of phase change from amorphous phase to polycrystalline phase. The film holds a threshold current about 0.155 mA, which is smaller than the value 0.31 mA of Ge2Sb2Te5 film. Amorphous Si1Sb2Te3 changes to face-centred-cubic structure at ~ 180℃ and changes to hexagonal structure at ~ 270℃. Annealing temperature dependent electric resistivity of Si1Sb2Te3 film was studied by four-point probe method. Data retention of the films was characterized as well.     

掺杂As2S8非晶态薄膜波导的光阻断效应

实验研究了未掺杂和低浓度掺锡和掺磷的As₂S₈薄膜波导的光阻断效应,提供了三种样品的光阻断响应曲线、室温退激实验数据和光谱测试数据. 结果表明,掺锡样品可以明显提升毫秒级响应的快过程恢复作用,同时还具有减少残留传输损耗的效果,掺磷的效果则相反. 结合实验结果给出了分析讨论. 关键词： 光波导技术 硫属化合物玻璃 光阻断效应 掺杂