Investigation of the phase diagrams of the systems R–Ni–Pb (R = Y, La, Ce, Dy) and crystal structures of the compounds R 4Ni 3Pb 4 (R = La, Ce, Pr) and R 5NiPb 3 (R = Y, La, Ce, Pr, Tb, Dy, Ho, Er, Tm, Lu)

Abstract

The isothermal sections of the systems Y–Ni–Pb (at 870 K), La–Ni–Pb (at 670 K), Ce–Ni–Pb (at 670 K) and Dy–Ni–Pb (at 870 K) were constructed using X-ray phase analysis. Five ternary compounds were found in the Y–Ni–Pb system: YNiPb (TiNiSi structure type, space group Pnma, a = 0.71590(4) nm, b = 0.45176(2) nm, c = 0.77610(4) nm), Y 2Ni 2Pb (Mn 2AlB 2 structure type, space group Cmmm, a = 0.4019(1) nm, b = 1.4008(3) nm, c = 0.3679(1) nm), Y 5NiPb 3 (Hf 5CuSn 3 structure type, space group P6 3/ mcm, a = 0.8991(1) nm, c = 0.66393(4) nm), Y 12Ni 6Pb (Sm 12Ni 6In structure type, space group Im3, a = 0.97149(2) nm) and Y 6Ni 2.5Pb 0.5 (Ho 6Co 2Ga structure type, space group Immm, a = 0.9462(1) nm, b = 0.9605(1) nm, c = 0.9891(1) nm). The existence of the compounds La 4Ni 3Pb 4 (La 4Ni 3Pb 4 structure type, space group R3, a = 1.00367(7) nm, c = 0.95558(8) nm), La 5NiPb 3 (Hf 5CuSn 3 structure type, space group P6 3/ mcm, a = 0.94867(4) nm, c = 0.69839(4) nm), La 12Ni 6Pb (Sm 12Ni 6In structure type, space group Im3, a = 1.0233(2) nm) in the La–Ni–Pb system and the compounds Ce 4Ni 3Pb 4 (La 4Ni 3Pb 4 structure type, space group R3, a = 0.9947(1) nm, c = 0.94604(9) nm), Ce 5NiPb 3 (Hf 5CuSn 3 structure type, space group P6 3/ mcm, a = 0.93839(4) nm, c = 0.67922(4) nm) in the Ce–Ni–Pb system was determined. The existence of five ternary compounds DyNiPb (TiNiSi structure type, space group Pnma, a = 0.71485(5) nm, b = 0.45219(3) nm, c = 0.77481(6) nm), Dy 2Ni 2Pb (Mn 2AlB 2 structure type, space group Cmmm, a = 0.4026(1) nm, b = 1.3994(4) nm, c = 0.3651(1) nm), Dy 5NiPb 3 (Hf 5CuSn 3 structure type, space group P6 3/ mcm, a = 0.8956(1) nm, c = 0.65733(7) nm), Dy 12Ni 6Pb (Sm 12Ni 6In structure type, space group Im3, a = 0.9662(1) nm) and Dy 6Ni 2.39Pb 0.55 (Ho 6Co 2Ga structure type, space group Immm, a = 0.93748(3) nm, b = 0.95427(3) nm, c = 0.98823(3) nm) in the Dy–Ni–Pb system was established. Additionally the existence of the compounds Pr 4Ni 3Pb 4 (La 4Ni 3Pb 4 structure type, space group R3, a = 0.9889(1) nm, c = 0.9417(1) nm), Pr 5NiPb 3 (Hf 5CuSn 3 structure type, space group P6 3/ mcm, a = 0.9337(1) nm, c = 0.67927(6) nm), Tb 5NiPb 3 (Hf 5CuSn 3 structure type, space group P6 3/ mcm, a = 0.90448(7) nm, c = 0.66101(3) nm), Ho 5NiPb 3 (Hf 5CuSn 3 structure type, space group P6 3/ mcm, a = 0.89315(6) nm, c = 0.65649(2) nm), Er 5NiPb 3 (Hf 5CuSn 3 structure type, space group P6 3/ mcm, a = 0.89065(7) nm, c = 0.65631(3) nm), Tm 5NiPb 3 (Hf 5CuSn 3 structure type, space group P6 3/ mcm, a = 0.88655(8) nm, c = 0.65302(3) nm), Lu 5NiPb 3 (Hf 5CuSn 3 structure type, space group P6 3/ mcm, a = 0.8775(1) nm, c = 0.65116(6) nm).