Crystal Growth and Structural Characterization of the New Ordered Palladates LnKPdO₃ (Ln = La, Pr, Nd, Sm−Gd) and the Isostructural, Partially Cu-Substituted Palladate PrK(Cu_0.14Pd_0.86)O₃

Single crystals of a new series of lanthanide-containing palladates, LnKPdO3 (Ln = La, Pr, Nd, Sm−Gd), and a partially copper-substituted palladate, PrK(Cu0.14Pd0.86)O3, were grown from potassium hydroxide fluxes. The compounds are all isostructural and crystallize in the C2/m space group with lattice parameters ranging from a = 13.4232(8) to 13.0212(2) Å, b = 3.9840(2) to 3.9096(2) Å, c = 7.4424(4) to 7.3209(9) Å, and β = 105.644(2) to 104.427(2)°. The crystal structure contains ordered slabs of LnO7- and KO7-capped trigonal prisms arranged in a complex network of face-, edge-, and vertex-shared polyhedra which, in turn, share edges with PdO4 square planes.