Zr4+ and Ti4+ substitution in gallium garnets

Abstract

A study was undertaken of the formation of solid solutions with the garnet structure in the systems M₃Ga₅O₁₂–M′O₂–CaO (where M = Y³⁺, Nd³⁺ and M′= Zr⁴⁺, Ti⁴⁺). Synthesis of these compounds was performed by the traditional ceramic route as well as through hydroxide coprecipitation. Characterization was mainly carried out by X-ray diffraction, applying automatic structure-refining techniques. The Zr⁴⁺ and Ti⁴⁺ cations were shown to substitute for Ga³⁺ in octahedral sites, although there might be a degree of tetrahedral site distribution in the case of Ti⁴⁺, and the formation limits of the solid solutions for the systems were established. The application of concepts such as ionic size and charge was seen to be fundamental for understanding the behaviour of these garnets.