A novel negative thermal expansion material of Zr0.70V1.33Mo0.67O6.73

Abstract

A novel negative thermal expansion (NTE) material of Zr_0.70V_1.33Mo_0.67O_6.73 was synthesized. Its microstructure, crystal structure and thermal expansion properties were studied in detail. Structure analysis shows that Zr_0.70V_1.33Mo_0.67O_6.73 possesses a cubic crystal structure with the space group Pa (no. 205) at room temperature (RT). The experimental results show that Zr_0.70V_1.33Mo_0.67O_6.73 exhibits a stable isotropic negative thermal expansion property and maintains a cubic structure from 103 to 773 K without any phase transition. The average linear coefficients of thermal expansion (CTEs) are calculated to be −3.75 × 10⁻⁶ K⁻¹ (163–673 K) and −4.50 × 10⁻⁶ K⁻¹ (RT–773 K). The intrinsic linear CTEs are calculated to be −3.84 × 10⁻⁶ K⁻¹ (103–473 K) and −4.22 × 10⁻⁶ K⁻¹ (RT–673 K). And the phase transition temperature of ZrV₂O₇ has been reduced below RT, this may be attributed to the incorporation of the cubic ZrMo₂O₈ structure and partially occupied Zr atoms (4a). The NTE property of Zr_0.70V_1.33Mo_0.67O_6.73 can be attributed to the quasi-rigid unit modes (QRUMs).