Developing Structure-Property Relations in Metal-Insulator Transition Materials*

Materials which undergo a metal-insulator transition- a rapid change in resistivity upon temperature, pressure, or composition- have potential for the next generation of electronic switching devices. The underlying mechanisms which drive metal-insulator transitions are of interest both fundamentally in the field of condensed-matter physics and practically for the design of high-performance electronic materials. We develop a link between crystal structure and macroscopic electronic properties to realize new metal-insulator transition materials. We start by examining the AB₄Q₈ defect spinel system, where A is Al, Ga, Ge, B is Ti, V, Nb, Mo, Ta, and Q is S/Se. These materials, with molecular-orbital-like clusters, start at a cubic F-43m structure at room temperature and then distort to R3m or Imm2 at low temperatures.¹ Detailed analysis of the local structure, through pair-distribution function analysis, and the average structure, through high-resolution diffraction, can provide insights into subtle links between structure and electronic behavior.
Reference:
1) D. Johrendt, Z. Anorg. Allg. Chem. 624 (1998) 952