Embedding Brittle Metal-Insulator Transition Effects in an Al-Vo2 Composite

Abstract

A new multi-functional Al-VO2 composite was prepared by ball milling and spark plasma sintering (SPS). Temperature dependences of the electrical conductivity, thermal conductivity, and emissivity properties of the Al-VO2 composites with different volume fractions were studied. The metal-to-insulator transition (MIT) behavior on the composites was systematically evaluated in association with different physical properties. The results suggested that MIT leads to a sensitive electrical conductivity variation even with 10 vol.% VO2. Before and after MIT, the change of electrical conductivity with VO2 content revealed a linear relationship apart from a sharp transition at MIT. As percolation nature, the thermal conductivity of the composite is found to be determined by the formation of conductive chains, in which the key factor is the content of VO2 and the percolation threshold is 20%. The X-ray microtomography confirmed the inherent relationship between the 3D configuration of the composites and the MIT effects.

Keywords: Composites, Microstructure, Thermal conductivity, Electrical conductivity