CRYSTAL CHEMISTRY OF THE NEW RARE-EARTH SODIUM BORATES Na3Ln(BO3)2(Ln equals La, Nd).

Article abstract of DOI:10.1016/0022-4596(81)90262-0

The ternary borate systems Na//2O-Ln//2O//3-B//2O//3 (Ln equals La, Nd) have been investigated in view of obtaining high-neodymium-concentration materials with weak concentration quenching. A ternary phase of composition Na//3Ln (BO//3)//2 (Ln equals La, Nd) has been found. It crystallzes in the monoclinic space group P2//1/c. The structure has been determined for Na//3Nd(BO//3)//2. A full-matrix least-square refinement led to R equals 0. 040. The structure is formed by isolated BO//3 triangles held together by the neodymium and sodium ions. The rare-earth atoms have a complex eightfold coordination in a covalent BO//3 matrix.