Viscosity-dependent hydrothermal synthesis of multinary titanate perovskites

An innovative viscosity-dependent hydrothermal strategy is developed for the controlled synthesis of multinary titanate perovskites, specifically Na0.5Y0.39Yb0.1Er0.01TiO3. By manipulating the viscosity of the reaction solution using various stable additives in both type and quantity, we identify a critical viscosity threshold of ~100 centipoise, which is essential for producing uniform faceted particles. With sodium hydroxide as an additive, a clear morphological evolution occurs as hydroxide concentration increases, shifting from regular cubes to edge-truncated, half-corner-truncated, and fully corner-truncated cube particles. Furthermore, the inclusion of additional sodium chloride and acetate substantially increases the viscosity, facilitating the formation of uniform faceted particles with reduced sizes ranging from ~2.0 micrometers to 200 nanometers. This method is successfully applied to synthesize other uniform perovskites, including Na0.5Y0.395Yb0.1Tm0.005TiO3, Na0.5Y0.4Eu0.1TiO3, Na0.5Y0.39Yb0.1Ho0.01TiO3, and Na0.5Bi0.5TiO3. Our findings provide valuable insights into viscosity-controlled synthesis for creating multinary perovskites and enhance their potential for designing optical functional materials and advancing various applications in optical temperature sensing, anti-counterfeiting security, and fingerprint recognition.