Negative thermal expansion property of β-Cu2V2O7

beta-Cu2V2O7 is prepared by using the solid-state method. We discuss that beta-Cu2V2O7 exhibits large negative thermal expansion property over a wide temperature range and no phase change occurs. The coefficient of thermal expansion is -20.2 x 10(-6) K-1 in temperature range of RT-673 K. The change of cell parameters is obtained from High-temperature XRD. Its phase, microstructure, thermal expansion property, and Raman spectra are analyzed in detail. The underlying mechanism of the negative thermal expansion of beta-Cu2V2O7 involves the coupling effect of the tetrahedron caused by the lateral vibration of the bridge oxygen atom and tensile effect of the tetrahedron. The partial collapse caused by the loss of oxygen atoms is also crucial in this mechanism.