Crystal Structure and Thermal Expansion of Ge-Doped Mn3CuN

The Ge doped Mn3CuN powder was synthesized using gas-solid reaction method with manganese, copper, germanium powders and N-2 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 Mn-3(Cu0.5Ge0.5)N powder can be prepared via the gas-solid method at 850 degrees C. The crystal structures of Mn-3(Cu0.5Ge0.5)N and Mn3CuN both have the antiperovskite structures. The intrinsic and macro thermal expansion coefficient of Mn-3(Cu0.5Ge0.5)N powder is -16.8x10(-6)K(-1) and -17x10(-6)K(-1), respectively. The temperature range with negative thermal expansion is from -80 degrees C to 50 degrees C.