Multicomponent Phases with CeAl2Ga2- and Y0.5Co3Ge3-Type Structures in the Gd–Ca–Fe–Co–Ge System

V. Ya. Gvozdetskyi; R. E. Gladyshevskii; N. V. German

doi:10.15330/pcss.16.1.104-110

Authors

V. Ya. Gvozdetskyi Ivan Franko National University of Lviv
R. E. Gladyshevskii Ivan Franko National University of Lviv
N. V. German Ivan Franko National University of Lviv

DOI:

https://doi.org/10.15330/pcss.16.1.104-110

Keywords:

Gd–Ca–Fe–Co–Ge system, intermetallics, solid solution, crystal structure

Abstract

New quinary phases with the CeAl₂Ga₂ (tI10, I4/mmm) and Y_0.5Co₃Ge₃ (hP8-2, P6/mmm) structure types were found at 500 ºC in the Gd–Ca–Fe–Co–Ge system based on X-ray powder diffraction data. They are Gd_1‑xCa_xFe_2‑yCo_yGe₂ (x = 0.085(7)-0.551(6), y = 0.25-0.75, a = 3.99468(6)-4.00003(8), c = 10.1279(2)-10.3981(5) Å) and Ca_0.5‑xGd_xFe_3‑yCo_yGe₃ (x = 0.031(1)-0.314(8), y = 0.75-2.25, a = 5.1081(1)-5.1218(1), c = 3.9751(1)-4.0451(2) Å). The c-parameter of the tetragonal CeAl₂Ga₂-type (122) phase cell depends much more on the Fe/Co and Gd/Ca ratios, than the a-parameter (which remains nearly the same). The volume of the 122 cell increases with increasing Fe and Ca content. The c-parameter of the hexagonal cell of the Y_0.5Co₃Ge₃-type (0.533) phase also depends more strongly on the Fe/Co content than the a-parameter, but Gd/Ca substitutions have little effect on the cell parameters. The following new quaternary and ternary phases were also discovered: GdFe_2‑yCo_yGe₂ (y = 0.5-1.5, a = 3.99419(5)-3.99750(7), c = 10.3271(2)-10.1173(3) Å) with CeAl₂Ga₂-type structure and Gd_0.5Fe_3‑yCo_yGe₃ (y = 0.75-1.5, a = 5.1247(8)-5.1225(7), c = 4.052(1)-4.010(1) Å), Ca_0.5Fe_3‑yCo_yGe₃ (y = 0.75-2.25, a = 5.1153(2)-5.1066(2), c = 4.0451(2)-3.9839(3) Å), Ca_0.5Fe₃Ge₃ (a = 5.10167(9), c = 4.06565(7) Å), and Ca_0.5Co₃Ge₃ (a = 5.0899(2), c = 3.9199(1) Å) with Y_0.5Co₃Ge₃-type structure.

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