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Ceria stabilized zirconia powders with ceria concentration varying from 6 to 16 mol% were synthesized using spray drying technique. Powders were characterized for their particle size distribution and specific surface area. The dense sintered ceramics fabricated using these powders were characterized for their microstructure, crystallite size and phase composition. The flexural strength, fracture toughness and microhardness of sintered ceramics were measured. High fracture toughness and flexural strength were obtained for sintered bodies with 12 mol% of CeO 2. Flexural strength and fracture toughness were dependent on CeO 2 concentration, crystallite size and phase composition of sintered bodies. Correlation of data has indicated that the transformable tetragonal phase is the key factor in controlling the fracture toughness and strength of ceramics. It has been demonstrated that the synthesis method is effective to prepare nanocrystalline tetragonal ceria stabilized zirconia powders with improved mechanical properties. Ce-ZrO 2 with 20 wt% alumina was also prepared with flexural strength, 1200 MPa and fracture toughness, 9⋅ ⋅2 MPa√ √m.

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Electron paramagnetic resonance of Mn2+ doped Mg(ClO4)2∙6H2O crystals has been studied from room temperature (300 K) down to liquid nitrogen temperature at X-band. The room temperature results show three inequivalent sites for Mn2+ in the crystal. Hyperfine forbidden transitions are observed when the magnetic field is not oriented along one of the principal axes. Two structural phase transitions have been observed at temperatures of 272 ± 1 and 103 ± 1 K, respectively. The transition occurring at 272 ± 1 K has been observed for the first time. The transition occurring at 103 ± 1 K is the one detected earlier through Mössbauer studies.

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An electron paramagnetic resonance study of Mn2+ doped in Cd(ClO4)2⋅6H2O has been made from 328 K to liquid nitrogen temperature. The site symmetry of Cd2+ is trigonal with a water octahedron distorted parallel to the crystallographic c axis. Mn2+ substitutes for Cd2+ and exhibits a characteristic 30-line hyperfine spectrum at room temperature (298 K) for the magnetic field H along the c axis. The D parameter is small and therefore there is considerable overlapping of lines in the spectrum. The spectrum is axially symmetric. On lowering the temperature, phase transitions are found to occur at 272±1 and 115.5±1 K.