Synthesis and characterization of some rare earth based ceramic compounds

Abstract

Ceramics are a class of materials broadly defined as inorganic, nonmetallic solids and are commonly electrical and thermal insulators, brittle and composed of more than one element. Here the term will be restricted to polycrystalline, inorganic, non-metallic materials that acquire their mechanical strength through firing or sintering process. Ceramics comprise crystallites that may vary in structure, perfection and composition as well as in size, shape and the internal stresses to which they are subjected. In view of the above said importance, the present thesis describes the synthesis and characterization of some rare earth based ceramic compounds in seven chapters. This thesis comprises a brief summary of advanced ceramic materials, their peculiar properties, recent trends in the technological development of ceramics and need for basic research on ceramic materials. The synthesis and characterization of superconducting GdBaSr1-xNdxCu3O7-! (where x = 0, 0.1, 0.2, 0.3 and 0.4) compounds have been carried out. From the powder X-ray diffraction studies, it was observed that all the compounds crystallize in orthorhombic structure. Variation in crystallite sizes and composition were studied by SEM and EDX analysis. Variation in crystal structure, surface morphology and composition were also studied by micro- Raman analysis, SEM and EDX analysis. From the thermal analysis, it was observed that all the prepared compounds only undergo endothermic reaction till 900ºC without any more phase transition which reveals the high crystalline nature of the compounds. From the dielectric studies, it was observed that the incorporation of Ca in the BaFe12O19 system results in increase in dielectric constant which substantiates the space charge polarization. The summary and conclusion of the present investigations along with future scope of work is also presented in the thesis. newline