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...     

反应扩散法制备的PbMo6S8超导带的超导特性

本文报道反应扩散法制备Chevrel相PbMo₆S₈超导带材的过程以及带材的超导特性。Mo带与H₂S气体反应生成单相的Mo-S化合物(MoS₂或Mo₂S₃,根据反应温度而定),再与Pb的蒸汽反应生成单相的PbMo₆S₈薄层。PbMo₆S₈超导层的临界温度T_c=13.0 关键词：     

污泥低温热解过程中含硫气体释放实验研究

对污水处理厂污泥空干基进行了低温热解实验,研究了N₂、空气和CO₂气氛下六种含硫气体（H₂S、SO₂、CH₃SH、CS₂、C₂H₆S₂和COS）的释放特性,分析了其释放机理。结果表明:污泥低温热解时释放的含硫气体主要以H₂S、SO₂和CH₃SH形态为主,同时伴有少量CS₂、C₂H₆S₂和COS生成。H₂S、SO₂和CH₃SH生成机理以有机硫转化途径为主。FeS₂与CH₄的反应是CS₂生成的可能途径,CH₃SH的存在为C₂H₆S₂的生成提供了条件。CO₂促进了固态有机硫向气态硫的转化,O₂促进了已生成的CH₃SH的分解。     

硫化锂分子的分析势能函数和光谱

应用密度泛函理论的B3LYP方法和6-311++g（d,p）基组,研究Li₂、LiS和Li₂S分子的基态构型.结果表明它们的基电子态分别为X¹Σ_g⁺、X²Π和X¹Σ_g⁺.通过非线性曲线拟合,得到基态LiS和Li₂分子的4参数Murrell-Sorbie分析势能函数,计算它们的光谱参数和力常数.基于多体项展式理论得到了基态Li₂S分子的单重态势能面的分析函数.利用得到的分析势能函数重构基态单重Li₂S分子的旋转图、伸缩图和旋转伸缩图,准确地再现了Li₂S分子的静态特征,如平衡结构,最低能量,合理反应通道.从等值势能面图看出,反应Li+S+Li→Li₂S是一个无阈值反应.S原子攻击Li₂分子的反应通道上,有一个过渡态.Li原子攻击LiS分子通道上也有一个过渡态.     

K,Na掺杂Cu-S纳米晶的水热合成及对结构、性能的影响

利用水热合成技术, 分别以CuCl₂·2H₂O, 硫粉为铜源和硫源, 以KOH或NaOH为矿化剂, 成功合成了Cu₂S纳米晶体和碱金属离子掺杂的KCu₇S₄纳米线和NaCu₅S₃ 微纳米球. 通过X射线衍射(XRD)、电子能谱(EDS)、扫描电镜(SEM)、透射电镜(TEM)和高分辨率透射电镜 (HRTEM) 对产物的结构和形貌进行了表征和分析. 结果显示: KOH含量低于1g或NaOH低于2g时, 产物为斜方辉铜矿Cu₂S; 高碱含量 (不低于3g) 时, K或Na离子成功掺入产物结构中, K掺杂产物为纯净的四方相KCu₇S₄, 单晶结构, 尺寸均匀, 长度可达几十微米的纳米线; Na掺杂未改变产物的形貌, 形成六方晶系结构的NaCu₅S₃. 产物的形成和生长与反应温度、反应时间和矿化剂密切相关. 并讨论了Cu₂S纳米晶及其掺杂纳米晶的形成机理及掺杂机理. 最后研究了碱金属离子掺杂对产物的光学性能的影响, 漫反射光谱显示Cu₂S, KCu₇S₄和NaCu₅S₃纳米晶的光学带隙分别为1.21eV, 0.49eV和0.42eV, K⁺和Na⁺的掺杂, 极大的改变了产物的光学特性. 关键词： 7S₄')" href="#">KCu₇S₄ 5S₃')" href="#">NaCu₅S₃ 水热法 掺杂     

Li-N-H储氢体系热力学性质的第一性原理研究

基于密度泛函理论的第一性原理方法, 系统地研究了Li-N-H储氢过程中各个化合物的晶胞参数、生成焓和化学反应焓. 结果发现优化后的晶格参数与先前的理论和实验研究符合得很好. 通过计算Li₃N, LiH, LiNH₂和Li₂NH在298 K的生成焓分别为-168.7, -81.0, -173.0和-190.8 kJ/mol, 进而计算得到整个储氢反应过程在T=298 K时反应焓为78.5 kJ/mol H₂, 这和他人计算得到T=300 K的结果75.67 kJ/mol H₂非常接近. 最后, 给出了储氢两步反应过程分别在T=298 K时的反应焓, 这些结果都与实验和他人理论计算得到的数据符合较好. 关键词： 第一性原理 热力学性质 Li-N-H 体系 反应焓     

Li2CO3/K3PO4复合助熔剂对新型Y2O2S：0.09Ti长余辉磷光体发光性能的影响

采用高温还原法合成了一种新型无稀土掺杂Y₂O₂S:0.09Ti长余辉发光材料。基于助熔剂种类对长余辉发光材料特性的重要作用,选择了对余辉衰减初期和后期余辉强度有明显作用的Li₂CO₃和K₃PO₄两种助熔剂,研究了不同配比(以下用x表示,x=Li₂CO₃/(Li₂CO₃+K₃PO₄))的复合助熔剂对Y₂O₂S:0.09Ti磷光体晶体结构和发光性能的作用,以获得具有较好综合发光性能的Y₂O₂S:0.09Ti磷光体。采用PL光谱和余辉测试仪对材料的发光特性进行了表征,用XRD研究了其晶体结构的变化。XRD结果表明,在复合助熔剂范围内(x=0~1.0)均可获得单相性的Y₂O₂S:0.09Ti磷光体。同时发现复合助熔剂比例不同制备的样品中,Y₂O₂S:0.09Ti磷光体晶体择优取向也发生明显的变化,且高比例Li₂CO₃有助于Y₂O₂S:0.09Ti磷光体的晶体形成。复合助熔剂比例x对样品的激发峰与发射谱主峰位置(565nm)基本没有影响;但助熔剂比例x对发射峰强度则有明显影响,随着x增加,该磷光体的发光强度先增后减,在x=0.8时发光强度最大。     

BaO-Li2O-B2O3三元系中BaB2O4-Li2B2O4和BaB2O4-Li2O截面相平衡关系的研究

本文用X射线和差热分析方法对BaO-Li₂O-B₂O₃三元系中的两个截面:BaB₂O₄-Li₂B₂O₄和BaB₂O₄-Li₂O作了研究。在BaB₂O₄-Li₂B₂O₄赝二元系中发现了一个新的化合物4BaB₂O₄·Li₂B₂O₄。化合物在930±3℃由包晶反应形成,并与Li₂B₂O₄形成共晶反应。共晶温度为797±3℃,共晶点组分为79mol％Li₂B₂O₄。在BaB₂O₄-Li₂O截面中也存在化合物4BaB₂O₄·Li₂B₂O₄,其包晶反应温度从930±3℃随Li₂O含量增加下降到908±3℃。在组分60mol％Li₂O处形成另一个新的化合物2BaB₂O₄·3Li₂O。该化合物在630±3℃也是由包晶反应形成,并与Li₂O和Li₂CO₃分别形成共晶反应,共晶温度分别为400±3℃和612±3℃。在BaB₂O₄-Li₂B₂O₄和BaB₂O₄-Li₂O体系中都没有观察到固溶体。用计算机程序分别对化合物4BaB₂O₄·Li₂B₂O₄和2BaB₂O₄·3Li₂O的X射线粉末衍射图案进行了指标化,其结果:4BaB₂O₄·Li₂B₂O₄的空间群为Pmma,a=13.033?,b=14.630?,c=4.247?,每个单胞包含两个化合式单位;2BaB₂O₄·3Li₂O的空间群为Pmmm,a=4.814?,b=9.897?,c=11.523?,每个单胞也含有两个化合式单位。 关键词：     

Ga2O3组分对Tm3+掺杂GeO2-Ga2O3-Li2O-BaO-La2O3玻璃的光谱性能影响

制备了Tm³⁺(8.0mol%)掺杂(77-x)GeO₂-xGa₂O₃-8Li₂O-10BaO-5La₂O₃(x=4,8,12,16)系列玻璃.系统地研究了Ga₂O₃从4mol%变化到16mol%时,玻璃的光谱性质与热学性质的变化规律.差热分析表明,随着Ga₂O₃含量的增加,锗酸盐玻璃的热稳定性增加.运用Judd-Ofelt(J_O)理论计算得到了Tm³⁺在不同Ga₂O₃含量的GeO₂-Ga₂O₃-Li₂O-BaO-La₂O₃玻璃中的J-O强度参数(Ω₂,Ω₄,Ω₆)及Tm³⁺各激发能级的自发跃迁概率、荧光分支比以及辐射寿命等光谱参量.在808nm激光二极管的激发下,测试并分析了Ga₂O₃对Tm³⁺荧光光谱特性的影响.随着Ga₂O₃从4mol%增加到16mol%,Tm³⁺在1.8μm处的荧光强度呈现先减弱后增强的特性.当Ga₂O₃含量大约在12mol%时,Tm³⁺在1.8μm处的荧光强度最弱,受激发射截面达到最小.还初步讨论了Ga₂O₃对玻璃结构与光谱参数的影响规律. 关键词： 3+掺杂锗酸盐玻璃')" href="#">Tm³⁺掺杂锗酸盐玻璃 光谱性能 Judd-Ofelt参数 热稳定性     

Ga3S2-和Ga4S3-团簇结构及性质的密度泛函理论研究

采用密度泛函理论（DFT）中的B3LYP方法和BP86方法,对Ga₃S₂^-团簇和Ga₄S₃^-团簇进行结构优化,并计算和分析了最稳定结构的成键性质及振动特性.计算结果表明,Ga₃S₂^-团簇和Ga₄S₃^-团簇的最稳定结构是由"Ga-S-Ga"结构单元和处于端位的"Ga-S"结构单元组成的.键级分析表明上述两结构单元都具有较强的稳定性.此外,通过分析红外振动光谱数据也发现在"Ga-S-Ga"单元和"Ga-S"单元处有红外强峰出现.     

Liquid-phase synthesis of Li2S and Li3PS4 with lithium-based organic solutions

Sulfide solid electrolytes are widely regarded as one of the most promising technical routes to realize all-solid-state batteries (ASSBs) due to their high ionic conductivity and favorable deformability. However, the relatively high price of the crucial starting material, Li₂S, results in high costs of sulfide solid electrolytes, limiting their practical application in ASSBs. To solve this problem, we develop a new synthesis route of Li₂S via liquid-phase synthesis method, employing lithium and biphenyl in 1, 2-dimethoxyethane (DME) ether solvent to form a lithium solution as the lithium precursor. Because of the comparatively strong reducibility of the lithium solution, its reaction with sulfur proceeds effectively even at room temperature. This new synthesis route of Li₂S starts with cheap precursors of lithium, sulfur, biphenyl and DME solvent, and the only remaining byproduct (DME solution of biphenyl) after the collection of Li₂S product can be recycled and reused. Besides, the reaction can proceed effectively at room temperature with mild condition, reducing energy cost to a great extent. The as-synthesized Li₂S owns uniform and extremely small particle size, proved to be feasible in synthesizing sulfide solid electrolytes (such as the solid-state synthesis of Li₆PS₅Cl). Spontaneously, this lithium solution can be directly employed in the synthesis of Li₃PS₄ solid electrolytes via liquid-phase synthesis method, in which the centrifugation and heat treatment processes of Li₂S are not necessary, providing simplified production process. The as-synthesized Li₃PS₄ exhibits typical Li⁺ conductivity of 1.85×10^-4 S·cm^-1 at 30 ℃.     

Er3+/Tm3+共掺杂Ga5Ge20Sb10S65玻璃的发光特性及能量传递

采用高温熔融急冷法制备了系列Er3+/Tm3+共掺杂的Ga5Ge20Sb10S65玻璃,测试了样品的吸收光谱,以及分别在980 nm和800nm LD激发下样品的荧光光谱.运用Judd-Ofelt理论计算了Er3+离子在Ga5Ge20Sb1oS65玻璃中的强度参数Ω(i=2,4,6)、自发辐射跃迁几率A和辐射寿命τ等光...     

Material design of new lithium ionic conductor, thio-LISICON, in the Li2S–P2S5 system

A new lithium ionic conductor of the thio-LISICON (LIthium SuperIonic CONductor) family was found in the binary Li₂S–P₂S₅ system; the new solid solution with the composition range 0.0≤x≤0.27 in Li_3+5xP_1−xS₄ was synthesized at 700 °C and characterized by X-ray diffraction measurements. Its electrical and electrochemical properties were studied by ac impedance and cyclic voltammetry measurements, respectively. The solid solution member at x=0.065 in Li_3+5xP_1−xS₄ showed the highest conductivity value of 1.5×10⁻⁴ S cm⁻¹ at 27 °C with negligible electronic conductivity and the activation energy of 22 kJ mol⁻¹ which is characteristic of high ionic conduction state. The extra lithium ions in Li₃PS₄ created by partial substitution of P⁵⁺ for Li⁺ led to the large increase in ionic conductivity. In the solid solution range examined, the minimum conductivity was obtained for the compositions, Li₃PS₄ (x=0.0 in Li_3+5xP_1−xS₄) and Li₄P_0.8S₄ (x=0.2 in Li_3+5xP_1−xS₄); this conductivity behavior is similar to other thio-LISICON family with the general formula, Li_xM_1−yM_y′S₄ (M=Si, Ge, and M′=P, Al, Zn, Ga, Sb). Conduction mechanism and the material design concepts are discussed based on the conduction behavior and the structure considerations.     

Formation Mechanism and Binding Energy for Equilateral Triangle Structure of Li3 Cluster

The formation mechanism for the equilateral triangle structure of Lia cluster is proposed. The curve of the total energy versus the interatomic distance for this structure has been calculated by using the method of Gou＇s Modified Arrangement Channel Quantum Mechanics. The result shows that the curve has a minimal energy of-22.338 60 a.u at R = 5.82 ao. The total energy of Lia when R approaches co has the value of-22.284 09 a.u. This is also the total energy of three lithium atoms dissociated from Lia. The difference value of 0.0545 08 a.u. for the above two energy values is the dissociation energy of Li3 cluster, which is also its binding energy. Therefore the binding energy per lithium atom for Lia is 0.018 169 a.u. = 0.494 eV, which is greater than the binding energy of 0.453 eV per atom for Li2 calculated in a previous work. This means that the Li3 cluster may be formed in the equilateral triangle structure of side length R = 5.82ao stably with a stronger binding from the symmetrical interaction among the three lithium atoms.     

Formation Mechanism and Binding Energy for Body-Centred Regular Octahedral Structure of Li7 Cluster

The formation mechanism for the body-centred regular octahedral structure of Li7 cluster is proposed. The curve of the total energy versus the separation R between the nucleus at the centre and nuclei at the apexes for this structure of Li7 has been calculated by using the method of Gou＇s modified arrangement channel quantum mechanics （MACQM）. The result shows that the curve has a minimal energy of-52.169 73 a.u. at R = 5.06ao. When R approaches infinity, the total energy of seven lithium atoms has the value of-51.996 21 a.u. So the binding energy of Li7 with respect to seven lithium atoms is 0.173 52 a.u. Therefore the binding energy per atom for Li7 is 0.024 79 a.u. or 0.674 eV, which is greater than the binding energy per atom of 0.453 eV for Li2, the binding energy per atom of 0.494 eV for Li3 and the binding energy per atom of 0.632 eV for Li5 calculated previously by us. This means that the Li7 cluster may be formed stably in a body-centred regular octahedral structure with a greater binding energy.     

Formation Mechanism and Binding Energy for Regular Tetrahedral Structure of Li4

The formation mechanism for the regular tetrahedral structure of Li4 cluster is proposed. The curve of the total energy versus the separation R between the two nuclei has been calculated by using the method of Gou＇s modified arrangement channel quantum mechanics （MACQM）. The result shows that the curve has a minimal energy of-29.8279 a.u. at R = 14.50 ao. When R approaches infinity the total energy of four lithium atoms has the value of-29.7121 a.u. So the binding energy of Li4 with respect to four lithium atoms is the difference of 0.1158 a.u.for the above two energy values. Therefore the binding energy per atom for Lh is 0.020 a.u., or 0.7878 eV, which is greater than the binding energy per atom of 0.453 eV for Li2, the binding energy per atom of 0.494 eV for Lia and the binding energy per atom of 0.632 eV for Li5 calculated previously by us. This means that the Li4 cluster may be formed stably in a regular tetrahedral structure of side length R = 14.50 ao with a greater binding energy.     

Optical characterization of amorphous Ga50Se45S5 films

The transmission spectra of thermally evaporated Ga₅₀Se₄₅S₅ films were measured over the wavelength range 300–900 nm. A simple method, suggested by Swanepoel, was used for the determination of the optical constants and thickness of the films. Increasing the thickness of the film beyond 450 nm does not affect the optical constants. The dependence of the absorption coefficient on the photon energy (hν) at the edge of the absorption band is well described by the relation hν=β(hν−E_opt)² with an optical gap equals 2.4 eV. A good fit of the experimental points with Tauc relation indicates that non-direct transition is the most probable mechanism responsible for the photon absorption inside the investigated film.