Negative thermal expansion property of Zn2V1.7P0.3O7

A novel negative thermal expansion material of Zn2V1.7P0.3O7 is prepared using a solid-state method. Its phase, microstructure, thermal expansion property, and Raman spectra are analyzed in detail. Experimental results show that Zn2V1.7P0.3O7 exhibits excellent negative expansion characteristics with an expansion coefficient of -4.47 x 10(-6) K-1 in a wide temperature range of RT-673 K. The underlying mechanism of the negative thermal expansion of Zn2V1.7P0.3O7 is as follows. The distorted [ZnO5] trigonal bipyramides and [V2O7] structural units with staggered Cs symmetry (part of which V is replaced by P) in Zn2V1.7P0.3O7 are connected by sharing O-2 and O-3 atoms to form a chain, such that the sample has a layered staggered structure. The lateral vibration of the O-3 atoms and the coupling twist and rotation effect of [ZnO5] and [VO4] polyhedrons intensify, causing angles between Zn-O-3(long)-V and Zn-O-3(short)-V to decrease gradually. The gap between the inner layers of unit cell is gradually reduced, and the volume of Zn2V1.7P0.3O7 shrinks slowly.

Automated summary

A novel negative thermal expansion material Zn2V1.7P0.3O7 with excellent negative expansion characteristics has been prepared and analyzed, showing a gradual volume reduction due to structural changes within the material.