Effect of Si doping on structure, thermal expansion and magnetism of antiperovskite manganese nitrides Mn_3Cu_(1-x)Si_xN

摘要

The negative thermal expansion (NTE) performance and correlated structure and magnetism for Si-doped Mn_3Cu_(1-x)Si_xN (x = 0.1-0.5) are investigated. It is found that the NTE behavior appears below room temperature, the absolute value of coefficient of NTE (|α|) tends to be zero and the Curie temperature (T_C) raises rapidly as the increase of Si content. The tendency of T_N temperature depending on Si contents implies that the valence electrons of Si atoms can partially be donated into Mn_(3d)-N_(2p) bond. Another important finding is that positive thermal expansion (PTE), NTE and zero thermal expansion (ZTE) are alternatively appeared by improving the Si content. The present work proposes a novel route to design the low-temperature devices using adjustable NTE or ZTE performance by making use of antiperovskite Mn_3AN materials.