Preparation of multi-element soluted metal oxynitrides with a perovskite structure using precursors synthesized through a liquid-phase process

Abstract

The synthesis of perovskite-type oxynitride solid solutions has gained significant attention because of their potential applications in advanced materials. This study presents a novel synthetic strategy for obtaining these solid solutions by integrating multiple elements at both the A and B sites within a single crystalline phase. Utilizing liquid-phase processes—specifically sol–gel and polymerizable complex methods—amorphous metal oxide precursors that enhance the nitridation efficiency during ammonolysis are successfully created. The incorporation of alkaline earth metals and lanthanides result in stable, single-phase perovskite structures, such as Ca_0.2Sr_0.2Ba_0.2La_0.2Pr_0.2Ta(O,N)₃, despite substantial differences in the ionic radii of the cations. Effective charge compensation through optimal ratios of O²⁻ and N³⁻ ions is achieved, enabling greater compositional flexibility. The exploration of B-site multi-element perovskite oxynitrides reveals that amorphous precursors facilitate the formation of solid solutions, as exemplified by SrTi_1/3Nb_1/3Ta_1/3(O,N)₃, whereas crystalline precursors lead to phase separation. Remarkably, the incorporation of up to eight metal elements in complex compositions such as Ca_0.2Sr_0.2Ba_0.2La_0.2Pr_0.2Ti_1/3Nb_1/3Ta_1/3(O,N)₃ and Ca_1/3Sr_1/3Ba_1/3Ti_0.2Zr_0.2Hf_0.2Nb_0.2Ta_0.2(O,N)₃ is demonstrated. These findings underscore the importance of precursor preparation methods in achieving the desired structural properties and pave the way for the further exploration of perovskite oxynitrides with diverse elemental combinations, thereby enhancing their functionality in various applications.