Quaternary rare-earth transition-metal phosphides REMnCuP2 (RE = Y, La-Nd, Sm, Gd-Tm, Lu) with CaAl2Si2-type structure and a polymorph of LaMnCuP2 with BaCu2S2-type structure

REMnCuP2 with CaAl2Si2-type structure forms for nearly all RE members, and LaMnCuP2 forms an additional BaCu2S2-type polymorph.291