Samarium(III) fluoride (SmF3) is a slightly hygroscopic solid fluoride. At room temperature, it has orthorhombic structure with space group Pnma a/b/c-YF3 type with lattice constants a = 666,9 pm, b = 705,9 pm, c = 440,5 pm. Above 495 C, it has the rhombohedral LaF3 structure (space group P3cl) with