High-Pressure Synthesis of Novel Hydrides in Mg–TM Systems (TM = Zr, Nb and Mo)

Abstract

New hydrides of Mg–TM–H systems, where TM = Zr, Nb and Mo, have been prepared by using cubic-anvil-type apparatus, and their crystal structure and hydrogen content have been investigated. The high-pressure synthesis was performed at 1073–1173 K under 2–5 GPa. In the Mg–Zr–H system, a new hydride Mg₂Zr₃H_y with a monoclinic structure (a=0.8591(1) nm, b=0.33539(5) nm, c=0.5816(1) nm, β=103.06(3)°) was obtained by exposing a mixture of MgH₂ and ZrH₂ to pressure of 2 to 5 GPa at 1073 K for 2 h. In the Mg–Mo system, a new hydride Mg₃MoH₆ was synthesized by exposing a mixture of MgH₂ and Mo to 5 GPa at 1173 K for 2 h. The hydride was found to have a hexagonal structure (a=0.49958(6) nm, c=0.8840(2) nm). In the Mg–Nb–H system, a new hydride Mg₄NbH_y was also synthesized by exposing a mixture of MgH₂ and Nb to 5 GPa at 1073 K for 2 h.