K2CaPrO4 is Caswellsilverite-derived structured and crystallizes in the monoclinic P2/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form distorted KO6 octahedra that share corners with six equivalent Ca(1)O6 octahedra, edges with two equivalent K(1)O6 octahedra, edges with two equivalent Ca(1)O6 octahedra, edges with four equivalent K(2)O6 octahedra, and edges with four equivalent Pr(1)O6 octahedra. The corner-sharing octahedral tilt angles are 12°. In the second K site, K(2) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form distorted KO6 octahedra that share corners with six equivalent Pr(1)O6 octahedra, edges with two equivalent K(2)O6 octahedra, edges with two equivalent Pr(1)O6 octahedra, edges with four equivalent K(1)O6 octahedra, and edges with four equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 11-12°. Ca(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form CaO6 octahedra that share corners with six equivalent K(1)O6 octahedra, edges with two equivalent K(1)O6 octahedra, edges with two equivalent Ca(1)O6 octahedra, edges with four equivalent K(2)O6 octahedra, and edges with four equivalent Pr(1)O6 octahedra. The corner-sharing octahedral tilt angles are 12°. Pr(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form PrO6 octahedra that share corners with six equivalent K(2)O6 octahedra, edges with two equivalent K(2)O6 octahedra, edges with two equivalent Pr(1)O6 octahedra, edges with four equivalent K(1)O6 octahedra, and edges with four equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 11-12°. There are two inequivalent O sites. In the first O site, O(1) is bonded to one K(2), two equivalent K(1), two equivalent Ca(1), and one Pr(1) atom to form OK3Ca2Pr octahedra that share corners with six equivalent O(1)K3Ca2Pr octahedra, edges with four equivalent O(1)K3Ca2Pr octahedra, and edges with eight equivalent O(2)K3CaPr2 octahedra. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded to one K(1), two equivalent K(2), one Ca(1), and two equivalent Pr(1) atoms to form OK3CaPr2 octahedra that share corners with six equivalent O(2)K3CaPr2 octahedra, edges with four equivalent O(2)K3CaPr2 octahedra, and edges with eight equivalent O(1)K3Ca2Pr octahedra. The corner-sharing octahedra are not tilted.
K2CaPrO4 is Caswellsilverite-derived structured and crystallizes in the monoclinic P2/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form distorted KO6 octahedra that share corners with six equivalent Ca(1)O6 octahedra, edges with two equivalent K(1)O6 octahedra, edges with two equivalent Ca(1)O6 octahedra, edges with four equivalent K(2)O6 octahedra, and edges with four equivalent Pr(1)O6 octahedra. The corner-sharing octahedral tilt angles are 12°. Both K(1)-O(2) bond lengths are 2.80 Å. All K(1)-O(1) bond lengths are 2.84 Å. In the second K site, K(2) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form distorted KO6 octahedra that share corners with six equivalent Pr(1)O6 octahedra, edges with two equivalent K(2)O6 octahedra, edges with two equivalent Pr(1)O6 octahedra, edges with four equivalent K(1)O6 octahedra, and edges with four equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 11-12°. Both K(2)-O(1) bond lengths are 2.83 Å. All K(2)-O(2) bond lengths are 2.85 Å. Ca(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form CaO6 octahedra that share corners with six equivalent K(1)O6 octahedra, edges with two equivalent K(1)O6 octahedra, edges with two equivalent Ca(1)O6 octahedra, edges with four equivalent K(2)O6 octahedra, and edges with four equivalent Pr(1)O6 octahedra. The corner-sharing octahedral tilt angles are 12°. Both Ca(1)-O(2) bond lengths are 2.40 Å. All Ca(1)-O(1) bond lengths are 2.45 Å. Pr(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form PrO6 octahedra that share corners with six equivalent K(2)O6 octahedra, edges with two equivalent K(2)O6 octahedra, edges with two equivalent Pr(1)O6 octahedra, edges with four equivalent K(1)O6 octahedra, and edges with four equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 11-12°. Both Pr(1)-O(1) bond lengths are 2.36 Å. All Pr(1)-O(2) bond lengths are 2.44 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to one K(2), two equivalent K(1), two equivalent Ca(1), and one Pr(1) atom to form OK3Ca2Pr octahedra that share corners with six equivalent O(1)K3Ca2Pr octahedra, edges with four equivalent O(1)K3Ca2Pr octahedra, and edges with eight equivalent O(2)K3CaPr2 octahedra. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded to one K(1), two equivalent K(2), one Ca(1), and two equivalent Pr(1) atoms to form OK3CaPr2 octahedra that share corners with six equivalent O(2)K3CaPr2 octahedra, edges with four equivalent O(2)K3CaPr2 octahedra, and edges with eight equivalent O(1)K3Ca2Pr octahedra. The corner-sharing octahedra are not tilted.