Thermal, vibrational, and thermoelastic properties of Y2Mo3O12 and their relations to negative thermal expansion

Abstract

Y2 Mo3O12, a material that exhibits negative thermal expansion (NTE) from 10 to 1173 K, offers an excellent opportunity to examine relationships between NTE and other physical properties over a wide temperature range. We report experimental heat capacity, thermal conductivity, and elastic properties of Y2Mo3O12, as well as results of an ab initio study of the lattice dynamics, and show how the anomalously high heat capacity and low thermal conductivity are correlated with NTE. We also report the ab initio elastic tensor and experimental velocity of sound of Y2Mo3O12 and use it to calculate the thermal stresses in a simulated polycrystal using finite-element analysis, showing that elastic anisotropy and thermal expansion anisotropy couple to influence the properties of the bulk solid.