Defects and Orientation Dependent Transport in Orthosilicates

原硅酸盐中的缺陷和方向相关输运

• 批准号: 5451553
• 负责人: Professor Dr. Klaus Dieter Becker
• 金额: --
• 依托单位: Institut für Physikalische und Theoretische Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2005
• 资助国家: 德国
• 起止时间: 2004-12-31 至 2010-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5451553?language=en
• 关键词: Defects; Orientation; Dependent; Transport; Orthosilicates

An optical spectroscopy study is proposed into the defect structure and the diffusion of defects in non-cubic orthosilicates of the type A2SiO4 with A = Co, Ni, Mn, which crystallize in the olivine structure. The spectroscopic experiments performed at high temperatures and defined oxygen activities will provide information on electronic defects (holes) and on the chemical diffusion responsible for redox processes in the material. Due to the orthorhombic structure of olivines, the kinetics for oxidation and reduction exhibits a pronounced dependence on crystal orientation. By comparison of chemical diffusion data with tracer diffusion data obtained by the American counterpart, a novel possibility is opened to determine the concentration of cation vacancies from transport data, which can then be compared with the direct data from thermogravimetry to elucidate details of the complex behavior of cation diffusion. The electrical conductivity of the transition metal orthosilicates will be measured as a function of temperature and oxygen activity for the different orientations of the crystals. In the framework of the small-polaron model, electrical conductivity is intimately related to the defect-induced contribution to optical spectra. From a comparison of these data detailed information is available on the microscopic mechanism and geometry of small-polaron hopping.

本文用光谱法研究了非立方晶系A_2SiO_4（A = Co，Ni，Mn）正硅酸盐晶体的缺陷结构和缺陷扩散。在高温和定义的氧活性下进行的光谱实验将提供有关电子缺陷（空穴）和负责材料中氧化还原过程的化学扩散的信息。由于橄榄石的正交结构，氧化和还原的动力学表现出显着的晶体取向的依赖性。通过比较化学扩散数据与示踪剂扩散数据获得的美国同行，一个新的可能性是打开确定的浓度的阳离子空位的传输数据，然后可以比较的直接数据从热重阐明的复杂行为的阳离子扩散的细节。对于晶体的不同取向，将测量过渡金属原硅酸盐的电导率作为温度和氧活度的函数。在小极化子模型的框架下，电导率与缺陷对光谱的贡献密切相关。从这些数据的比较详细的信息是可用的微观机制和几何形状的小极化子跳跃。

项目成果

Point defects and orientation-dependent transport of matter and charge in iron-containing olivines

含铁橄榄石中的点缺陷以及方向相关的物质和电荷传输

• DOI: 10.1016/j.ssi.2011.05.001
• 发表时间: 2011
• 期刊: Solid State Ionics
• 影响因子: 3.2
• 作者: T.-L. Tsai;K.-D. Becker;R. Dieckmann
• 通讯作者: R. Dieckmann