Effect of calcination temperature on the degree of polymorphic transformation in Y2SiO5 nanopowders synthesized by sol–gel method

Abstract

Due to its excellent chemical and physical stability, Y2SiO5 is a strong candidate material for host matrix for luminescent materials, high dielectric constant insulators, and protective coatings for ceramic matrix composites such as C/SiC, C/C and C/C-SiC. In this work, Y2SiO5 ceramic powders have been synthesized by simple and reliable sol–gel method using tetraethyl orthosilicate (TEOS) and yttrium nitrate hexahydrate Y(NO3)3·6H2O as precursor substances and 0.1g of HCl as a catalyst. Sol–gel derived powders were subjected to different calcination temperatures. The fabricated powders after calcination resulted in the formation of ultra-high purity nanopowders Y2SiO5 (X1 polymorph) merely at 900°C, which is lower than that reported in previous studies. The powders were analyzed by X-ray diffraction (XRD), thermogravimetry–differential scanning calorimetry (TGA–DSC), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) specific surface area analysis method. Widespread inter-polymorphic transformation into X2 form occurred at temperature above 1200°C. Systematic studies have been performed on inter-polymorphic and intra-polymorphic transition behavior and the associated changes in the grain sizes based on the XRD results.