有关硒基硫系玻璃中程有序结构若干问题的基础研究

Properties of chalcogenide glasses are closely related to the local ordered structure, especially the middle-range order structure, induced by self-organization of structure. The present project aims at basic studies on some questions concerning about the MRO structure of Ge-As-Se selenium based glasses. Some doped atoms (e.g. Bi, Cu, Ag, O) and properties of conductivity, energy-gap light irradiation induced effects, which are sensitive to MRO structure, are taken as the subjects of study, and MRO structure characterization as the center, the evolution of MRO structure with intrinsic ( compositions) and external (foreign fields) factors will be investigated in order to disclose response mechanism of different properties of chalcogenide glasses to the self-organization process of the structure, and to further strengthen understanding on multi-relaxation process of chalcogenide glasses approaching the balanced entropy of sub-cooled liquid. With the modified theoretic models, design and preparation of multi-functional chalcogenide glasses will be realized. The applicant of the present project has the solid foundation in research of glass properties and structures with some novel results and progresses recently. The project belongs to multi-crossed disciplines with some innovation train of thought and is significant for strengthening basic research activities in the field of condensed matter physics.

硫系玻璃的诸多性能均与其结构自组装现象导致的局部结构有序化，尤其是中程有序（MRO）结构相关。本课题提出对玻璃形成区相对较大的Ge-As-Se系统硒基硫系玻璃MRO结构的若干问题开展基础研究，以对MRO结构敏感的外掺原子（如Bi，Cu，Ag，O）和电导率、能隙光辐照效应等性能为对象，以MRO结构表征为中心，探讨MRO结构随内因（不同组成）和外因（外场作用）条件改变的演变过程及规律，揭示硫系玻璃不同性能的响应机制与网络体拓扑自有序化过程的关系，加深对硫系玻璃结构因接近过冷液体平衡熵而表现出的多重弛豫机理的认识，深化和完善相关理论模型，最终实现多功能化硫系玻璃新材料的设计和制备，为硫系玻璃在新一代多功能光子学器件中的应用奠定基础。本项目申请者近年来在硫系玻璃性能与结构研究方面取得了一系列具有创新意义的进展。课题属多学科交叉，具有新颖的研究思路，对加强我国凝聚态物理学领域的基础研究具有重要意义。

研究了Ag对Ge-Ga-Se-AgI系统硫卤玻璃性能与结构的影响，发现引入Ag使玻璃带隙增宽，电导率提高，当GeSe2/Ga2Se3比为2:1时电导率是同类材料的3-6倍。研究了Te对Ge-Se-Bi系统硫系玻璃结构及玻璃形成、析晶性能的影响，发现Te含量（mol%）从5 提高至20时经历从非晶态到析出Bi2Se2Te及Bi2SeTe2晶体的转变，两种晶相均为热电相，析晶及晶型转变过程和玻璃的结构变化相关。对玻璃热电晶相析晶动力学过程的分析得到的参数表明，Te对Se的取代促进了目标Bi2Se2Te晶相的析出，GeSe2晶相受到抑制。研究了Te掺杂和氧杂质对Ge-Bi-Se硫系玻璃近程结构影响的XPS谱，发现样品表面掺入的氧杂质以及玻璃组成中Te对Se的取代对玻璃结构影响较大。特别是氧杂质使Ge-Se-Bi玻璃网络中的Ge-Ge同极键断裂，导致过约束类乙烷结构单元显著减少，同时部分恢复了低约束的Se-Se-Se链，在一定程度上使Ge-Se-Bi玻璃的网络结构恢复到Ge-Se二元系统玻璃的准自组装状态。拓展研究了AgCl-Ag2S-As2S3系统的玻璃形成区。新发现玻璃形成区位于AgCl含量小于60mol%且Ag2S含量小于65mol%的区域，远大于以往报道的形成区（AgCl≤10mol%）。同时还发现玻璃形成区中间存在一个狭窄的孤立析晶带。研究了以同一系统玻璃作为膜材料制备全固态银离子选择性电极的可行性，发现组成中Ag2S与As2S3比例范围在1:1-2:1时为最佳。含AgCl的电极电导率以及对Ag+离子检测性能远高于不含AgCl的电极，其中AgCl含量为55mol%（G55）的电极具有最低的摩尔级低检测限，这与玻璃的高电导率和较弱干扰离子影响有关。同时电极具有高Ag+选择性（Hg2+除外）、电极响应时间在高浓度Ag+溶液中小于5S，可应用于水溶液中Ag+离子痕量测定。