Dissolution of impurities in sodium gadolinium molybdate NaGd(MoO₄)₂

Abstract

Impurity defects simulation in sodium-gadolinium molybdate NaGd(MoO4)2 was carried out using a method of interatomic potentials. The dissolution energies of tri-, di- and monovalent impurities were estimated. The dependences of the dissolution energy on the ionic radius of the impurity were plotted. For heterovalent substitutions, the most energetically favorable mechanism for charge compensation has been found, both due to intrinsic crystal defects and according to the conjugate isomorphism scheme. The positions of the most probable localization of defects are determined. The effect of disordering of sodium and gadolinium ions at equivalent positions on positional differences in the energy of defects is estimated. A comparison of the solubility of impurities in NaGd(MoO4)2 and its isostructural CaMoO4 indicates that, although isovalent substitutions are energetically more favorable than heterovalent ones, the mechanism of conjugate isomorphism, which ensures electrical neutrality, can equalize these processes.