Interaction of components and crystal structure of compounds in the Pr–Cu–Ge system

Keywords

praseodymium, copper, germanium, ternary system, phase equilibria, ternary compound, crystal structure, structure type.

Cite as

Fedyna L. O., Fedorchuk A. O., and Fedyna M. F. Interaction of components and crystal structure of compounds in the Pr–Cu–Ge system. Physicochemical Mechanics of Materials. 2022. 58(5), 095-101.

Abstract

Using X-ray diffractional phase and structural analysis and partially microstructural ana­lysis methods the phase equilibria in the ternary system Pr–Cu–Ge were investigated and the isothermal sections of the phase diagram of the system at 870 K (0–50 at.% of Pr) and 670 K (50–100 at.% of Pr) were constructed. The existence of seven ternary compounds – PrCu₂Ge₂, Pr₂CuGe₆, Pr₂Cu₃Ge₃, PrCu_0.817Ge₂, Pr₆Cu₈Ge₈, PrCu_1.25…0.95Ge_0.75…1.05, PrCu_0.77…0.5 Ge_1.23…1.5 was established at 870 K. Only one ternary germanide ~Pr_0.6Cu_0.22Ge_0.18 with unde­termined crystal structure was found in R rich range at 670 K. All ternary germanides are formed at constant composition except phases with AlB₂ structure type. Appreciable solu­bility of the third component in the compounds of binary systems was not observed. The structure parameters were determined for ternary germanides: Pr₂CuGe₆ (structure type (ST) Ce₂CuGe₆, Pearson symbol (PS) oS18, space group (SG) Amm2, a = 4.19300(4) Å, b =  = 4.05742(4) Å, c = 21.4823(2) Å, R_I = 0.0686, R_P = 0.0993), PrCu_1.25Ge_0.75 (ST AlB₂, PS hP3, SG P6/mmm, a = 4.2922(2) Å, c = 3.9193(3) Å, R_I = 0.0543, R_P = 0.1036), PrCu_0.72Ge_1.28 (ST AlB₂, PS hP3, SG P6/mmm, a = 4.19347(6) Å, c = 4.1817(1) Å, R_I = 0.0504, R_P = 0.0728). Relationships of investigated system Pr–Cu–Ge with previously studied R–Cu–Ge systems, and structure peculiarities of established ternary germanides of Cu and Pr were analyzed.

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