New Zr6CoAs2-type R6MnBi2 compounds (R = Er, Tm, Zr) and their magnetic properties

A powder X-ray diffraction investigation of new ternary Zr6CoAs2-type R6MnBi2 (R=Zr, Er and Tm) is reported. The compounds Zr6MnBi2 (a=0.7848(2) nm, c=0.3719(1) nm), Er6MnBi2 (a=0.8124(1) nm, c=0.4235(1) nm) and Tm6MnBi2 (a=0.8062(1) nm, c=0.4215(1) nm) crystallize in the hexagonal Zr6CoAs2-type structure (space group P6b2m No. 189). The Zr6CoAs2-type structure is a superstructure of the Fe2P-type structure. The Er6MnBi2 compound has a magnetic transition at 115 K