Single-step hydrothermal synthesis of strontium titanate nanoparticles from crystalline anatase titanium dioxide

Abstract

In the present study, strontium titanate (SrTiO3) nanoparticles were successfully synthesized by a single-step direct hydrothermal process under the strong alkaline condition using crystalline anatase titanium dioxide (TiO2) and strontium hydroxide octahydrate (Sr(OH)2·8H2O) as the starting materials at 220°C. The X-ray diffraction (XRD) patterns identified the products were highly crystalline and well matched with standard SrTiO3 data. The crystalline structure, lattice parameters, and atomic position were refined by Highscore Plus and Maud program. The results of Rietveld refinement showed high purity of products. The thermal field emission scanning electron microscope and energy dispersive spectrometer (FE-SEM-EDS) displayed the samples prepared were perovskite phase cubic SrTiO3 nanoparticles having regular morphology and small particle with a size distribution of 32–45nm. The fine morphologies and structures of SrTiO3 nanoparticles were investigated by field emission transmission electron microscope (FE-TEM). The results showed the important roles played by reaction duration and mole ratio of Sr and Ti (Sr/Ti) to the grain size of SrTiO3 nanoparticles. The particle sizes increased with prolonging reaction duration and reducing Sr/Ti. Compared to SrTiO3 synthesized by solid state reaction, the as-synthesized SrTiO3 nanoparticles had large specific surface areas (up to 32.98m2/g), which would exhibit potential applications in photocatalysis. The reaction mechanism of the process was illustrated using the dissolution–precipitation mechanism finally.