Crystal structure of the Re(Mn, Cu)6 (Re=Ce, Pr, Nd, Sm, Gd) and RE(Mn, Ni)3 (RE=Nd, Sm) compounds

A crystalline structure of REE(Mn, Cu)6 compounds is studied by the method of monocrystal and powder using Ce(Mn, Cu)6 compound as an example. For the Cesub(0.143)Mnsub(0.220)Cusub(0.637) monocrystal a=0.65781(6), c=0.50454(6)nm, a diffraction class is 4/mmm. Isostructural compound lattice periods at Mn content of 0.220 a parts are equal to: a=0.65666(6), c=0.50280(6)nm for Pr(Mn, Cu)6; a=0.6560(3), c=0.5013(3)nm for Nd(Mn, Cu)6; a=0.65220(6), c=0.49975(9)nm for Sm(Mn, Cu)6; a=0.6520(1), c=0.4965(1)nm for Gd(Mn, Cu)6. Nd(Mn, Ni)3 and Sm(Mn, Ni)3 structures are studied by the powder method. Diffractograms of these compounds are displayed successfully in the P63/mmc space group at a=0.5183(3), c=1.676(1)nm for Smsub(0.25)Mnsub(0.35)Nisub(0.40) and at a=0.5152(2), c=1.6710(6)nm for Ndsub(0.25)Mnsub(0.25)Nisub(0.50). Refinement of the structure is conducted using Sm(Mn, Ni)3 as an example to confirm the belonging of these compounds to the CeNi3 type, when disposing Sm atoms in positions of Ce atoms and statistical mixture (Mn, Ni) atoms in positions of Ni atoms