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

New quinary phases with the CeAl2Ga2 (tI10, I4/mmm) and Y0.5Co3Ge3 (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 Gd1‑xCaxFe2‑yCoyGe2 (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 Ca0.5‑xGdxFe3‑yCoyGe3 (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 Y0.5Co3Ge3-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: GdFe2‑yCoyGe2 (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 Gd0.5Fe3‑yCoyGe3 (y = 0.75-1.5, a = 5.1247(8)-5.1225(7), c = 4.052(1)-4.010(1) Å), Ca0.5Fe3‑yCoyGe3 (y = 0.75-2.25, a = 5.1153(2)-5.1066(2), c = 4.0451(2)-3.9839(3) Å), Ca0.5Fe3Ge3 (a = 5.10167(9), c = 4.06565(7) Å), and Ca0.5Co3Ge3 (a = 5.0899(2), c = 3.9199(1) Å) with Y0.5Co3Ge3-type structure.