Synthesis and characterization of multifunctional tin based compounds

Abstract

Conclusions excerpt: The first part of this thesis is focused on synthesis of alkaline earth metal stannates applying four different synthesis routes: gel to crystallite, sol-gel, sol-gel combustion and solid state reaction. The second part of this thesis deals with luminescent properties of Sm3+, Eu3+ and Pr3+ doped alkaline earth metal stannates. Each method showed its own advantages and disadvantages. For instance, the results presented in Chapter 6 demonstrated the potential of novel synthetic approach based on the gel to crystallite conversion (G-C) method to yield phase-pure strontium stannate (SrSnO3), strontium titanate (SrTiO3) and mixed strontium stannate titanate (SrSn1-xTixO3) powders at low crystallization temperature (800 °C). Such temperature is very low as compared to the temperature required for solid state synthesis. The morphological characterization of SrSnO3 by scanning electron microscopy showed the formation of nearly rod, stick or needle-type crystallites. The crystal width and length vary from 500 nm to 3 μm and from 10 to 40 μm, respectively. However, in standard synthesis procedure freshly prepared SnO2·xH2O gel should be repeatedly washed with cold distilled water in order to eliminate chloride ions. During this step the part of the gel is washed out resulting in poor stoichiometry control of the final product. Moreover, XRD analysis revealed that elimination of remaining chloride ions lead to the reduction of tin at higher temperatures. Due to this process, tin oxide is observed as a secondary phase in the synthesis product.