Mechanical and transport properties of low-temperature negative thermal expansion material Mn3CuN co-doped with Ge and Si

Anti-perovskite manganese nitrides Mn3CuN co-doped with Ge and Si show good negative thermal expansion properties at cryogenic temperatures and thus have great potential for cryogenic applications. In this work, Mn3(Cu0.6SixGe0.4−x)N (x = 0.05, 0.1, 0.15) were prepared by reactive sintering under pressure. Their structures, densities, electrical resistivities, thermal conductivities and mechanical properties were studied at room and cryogenic temperatures. The results show that the values of electrical resistivities and thermal conductivities of Mn3(Cu0.6SixGe0.4−x)N (x = 0.05, 0.1, 0.15) are in the range of 2.5–4.3 × 10−6 Ω m and 1.9–3.6 W(m K)−1, respectively. Compression tests indicate the compressive strength and Young’s modulus are about 700 MPa and 110 GPa, respectively.