Relative stability, electronic and structural properties in the family of NH4V3O7 polymorphs from first principles calculations

Abstract

The crystal structure, relative stability and electronic properties of nine possible polymorphic modifications of ammonia vanadate NH4V3O7 with different types of coordination polyhedra and structural motifs are studied by means of first principles calculations. The highest stability of NH4V3O7 polymorph with its own type of monoclinic lattice is proven. We predict that, all NH4V3O7 compounds should be magnetic semiconductors, which magnetic properties are governed by spin splitting of V3d-states. The electronic densities-of-states indicate that, these compounds are perspective cathode materials for Li- or Na-ion battery.