Structural studies of hydrated rare earth nitrates within the stereoatomic model of crystal structures.

Abstract

All crystal structures containing nitrate ions, water molecules and one of the rare earth (RE) metal atoms (La-Lu, Y, Sc) were extracted from the Inorganic Crystal Structure Database. The composition of the identified compounds is analyzed in terms of the number of coordinated and uncoordinated water molecules and nitrate ions. Among the resulting compounds, several isotypic and morphotropic series are observed. The structures were analyzed within the stereoatomic model of crystal structures. Coordination numbers of RE metals are calculated using the method of intersecting spheres. The variation of RE-O distances is analyzed over the entire series of metal atoms. Coordination modes of both nitrate ions and water molecules are established. Combinatorial topological types of Voronoi-Dirichlet polyhedra of rare earth metal atoms as coordination centers in the studied compounds are calculated.