Crystal Structure and Thermal Expansion of Ge-Doped Mn<sub>3</sub>CuN

Abstract

The Ge doped Mn3CuN powder was synthesized using gas-solid reaction method with manganese, copper, germanium powders and N2 gas as raw material. The phase constitute of the as-prepared powder was characterized using X-ray diffraction (XRD). The intrinsic and macro thermal expansion coefficients of the powder were measured by in-situ X-ray diffraction at different temperatures and TMA, respectively. The crystal structure of the powders was analyzed using Rietveld refinement method. The results show that the pure Mn3(Cu0.5Ge0.5)N powder can be prepared via the gas-solid method at 850 °C. The crystal structures of Mn3(Cu0.5Ge0.5)N and Mn3CuN both have the antiperovskite structures. The intrinsic and macro thermal expansion coefficient of Mn3(Cu0.5Ge0.5)N powder is-16.8×10-6K-1 and-17×10-6K-1, respectively. The temperature range with negative thermal expansion is from-80 °C to 50 °C.