Growth of submillimeter SrTaO₂N single crystals by an NH₃-assisted SrCl₂ flux method

Perovskite-type oxynitrides have recently been highlighted due to their dielectric and photocatalytic properties. Numerous studies have addressed the synthesis and characterization of their nanocrystals and ceramics. However, few research works have considered single-crystal formation in such systems due to difficulties in melt growth. In this study, we explore the crystal growth of perovskite-type oxynitride SrTaO₂N by an NH₃-assisted SrCl₂ flux method. Submillimeter-sized single crystals with lengths of approximately 300 μm were grown at a temperature of 1200 °C for 10 h with a solute concentration of 1.5 mol%. Subsequently, the crystal growth mechanism of SrTaO₂N in an SrCl₂ flux was studied systematically through experiments with variable holding temperature, holding time, cooling rate, and solute concentration. Our results suggest that SrTaO₂N crystal growth is induced by the evaporation of SrCl₂ flux.