Doctor of Natural Science (Dr.rer.nat.)

The main focus of the research work accomplished was to prepare new ternary alkali-oxometallates of the first-row (3d) transition-metal elements containing, providing highly defined materials showing interesting structural and physical properties. ‘Azide nitrate Route’ was employed successfully for the complete synthesis, and overall 11 modifications of alkali oxometallates were characterized alongwith in depth study of their structural property relationships. Out of these, nine compounds were unknown. For all the compounds the crystal structure has been determined from single crystal data (07) and rest from powder data using state of the art techniques (High resolution synchrotron, neutron and advance D8-Bruker diffractometers). The "azide/nitrate route" has proven to be an efficient approach in present work for the solid state synthesis of new magnetic oxides covering the whole dimensionality, starting from 3-dimensional oxoferrates, two dimensional oxochromate and oxocobaltate respectively, and also new intrinsically doped one dimensional cuprates. We observed and illustrated, how by changing the dimensionality of a magnetic lattice, influence dramatically the thermodynamic properties by concerted study of the specific heat and magnetic susceptibility behaviour of the magnetic system particularly at low temperature. Later in order to construct a model for the spin interactions in these alkali oxometallates, the intrinsic magnetic properties of total 10 compounds have also been measured. The resulting magnetic properties were later justifiably analysed by employing various theoretical models. Thermal analysis (DSC, low and high temperature specific heat) bulk and electrical conductivity measurements, Moessbauer spectroscopy, High-resolution synchrotron powder diffractometry, neutron diffraction experiments were performed to study the structure property relation in detail and to validate the authenticity of results received.