NOVEL PEROVSKITE-BASED OXIDES: SYNTHESIS, STRUCTURAL CHARACTERIZATION, DIELECTRIC AND MAGNETIC PROPERTIES by PIKA JHA

The perovskite structure is one of the most versatile structures for tailoring the properties of materials. The range of properties of perovskites varies from superconductivity to ferroelectricity, magnetoresistance to magnetocapacitance, and laser host properties to name a few. In particular, the perovskite oxides have been explored for their dielectric and magnetic properties. Traditionally, titanium based oxides are known to show good dielectric properties. This thesis deals with synthesis of titanium-based oxides, in order to obtain new oxides with improved dielectric, properties. ••■01.1■1•••■••••• ,...Chapter 1 provides a brief introduction to synthetic strategies, the perovskite structure and dielectric and magnetic properties. In addition, a brief survey of the research activity that has taken place in the area of perovskite oxides, particularly, in the area of ordered structures and dielectric and magnetic properties, has been presented. In chapter 2 we have discussed two new families of perovskite-based oxides, namely, (Lm2isBa2/5Calf5)(Zn2isTi3/5)03 and (Ln1i3Balf3Cair3)(Zni5Tiv3)03 (Ln = rareearth). We have discussed the synthesis and structural characterization of the oxides. Detailed structural analysis of the oxide (Ln2,5Ba2t5Cal,5)(Zn2,5Ti3,5)03 (Ln = Nd) has been carried out using powder X-ray and neutron diffraction. It is found from Rietveld refinement of powder neutron data that the oxide crystallizes in cubic symmetry with space group Pm 3 m and lattice parameter — 3.95 A. Electron diffraction confirmed the cubic structure. Powder X-ray diffraction patterns of other rare••earth containing oxides