A new zero thermal expansion materials FeMoVO7

• 1、University of Science and Technology Beijing Department of Physical Chemistry, Beijing 100083
• 2、University of Science and Technology Beijing State Key Laboratory for Advanced Metals and Materials, Beijing 100083
• 3、 Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing 100083

Abstract：Zero thermal expansion (ZTE) material is a rare special material with almost constant volume when temperature changes, which is of great significance for the dimensional stability of precision instruments. Recently, we have discovered a novel wide temperature range ZTE material FeMoVO7, which exhibits negative thermal expansion along the c-axis in the temperature range of 123-473 K, ac=-3.98 × 10-6 K-1, and exhibits volumetric ZTE in the temperature range of 123-373 K, av=1.81 × 10-6 K-1。 Through comprehensive analysis of X-ray diffraction and Raman spectroscopy, it was determined that the two vibration modes corresponding to the Raman frequency shifts of 57.67 cm-1 and 195.73 cm-1 dominate the NTE of the c-axis. And the ZTE of FeMoVO7 originates from the combined effect of lattice contraction generated by low-frequency phonons and lattice expansion generated by anharmonic interactions.

Keywords： Thermal expansion framework structure low frequency phonons transverse vibration