Phase Transitions in Magnetite and Nickel Sulphide-Selenide Systems

磁铁矿和硫化镍-硒化物体系中的相变

• 批准号: 9222986
• 负责人: Jurgen Honig
• 金额: $ 45.02万
• 依托单位: Purdue Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-05-15 至 1997-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9222986&HistoricalAwards=false
• 关键词: Phase; Transitions; Magnetite; Nickel; Sulphide

This research is focussed on two projects. The first part involves continued studies on magnetites and zinc-ferrites. The main thrust of this research is directed to the investigation of nickel sulphide-selenide systems. This material exhibits properties of a good insulator, a good metal, or a metal-insulator for x values of 0, 2, and 0.5, respectively. This property presumably is driven by electron correlation effects. The systems can be studied by varying the sulphide/selenide ratio while leaving the cation sublattice intact. The following studies are planned: growth of single crystals, followed by adjustments of stoichiometry, electrical measurements, magnetization investigations, specific heat studies, structural research, and optical measurements. The data acquisition is not just of intrinsic interest but is to be used to identify the changeover from the insulating state, through a narrow band correlated state, to the metal-insulated transition regime, and into the region of good metallic behavior, during which the lattice remains basically unaltered. The data thus serve as a test for current theories of electron transport in the various regimes.

这项研究主要集中在两个项目上。 第一部分涉及对磁铁矿和锌铁氧体的继续研究。 这项研究的主要目的是研究硫化镍-硒化物系统。 当 x 值分别为 0、2 和 0.5 时，该材料表现出良好绝缘体、良好金属或金属绝缘体的特性。 该特性可能是由电子相关效应驱动的。 可以通过改变硫化物/硒化物比率同时保持阳离子亚晶格完整来研究该系统。 计划进行以下研究：单晶生长，然后调整化学计量、电学测量、磁化研究、比热研究、结构研究和光学测量。 数据采集​​不仅具有内在意义，而且用于识别从绝缘态通过窄带相关态到金属绝缘过渡态以及进入良好金属行为区域的转变，在此期间，晶格基本保持不变。 因此，这些数据可以作为当前各种状态下电子传输理论的检验。