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Our investigations highlight the importance of alkali carbonates addition on influencing the superionic conduction via composite interfaces in doped ceria based nanocomposites Ce0.76Pr0.08Sm0.08Gd0.08O2-δ/(Li0.52Na0.48)2CO3 (CPSG/LNC). X-ray diffraction of composite confirms single-phase cubic CeO2 like structure as major phase with few weak reflections due to (Li0.52Na0.48)2CO3 suggesting that the major part of the carbonates transform into amorphous phase during synthesis. The CPSG/LNC nanocomposites show improved ionic conductivity in the temperature range 200–650 °C with maximum ionic conductivity σ650°C = 6.02 × 10−2 S-cm−1 for composition having 35 wt% of (Li0.52Na0.48)2CO3. The TEM analysis reveals that the amorphous layer of carbonates forms on the nanocrystalline codoped ceria particles to develop a close shell-layer enclosure, stimulating space charge layer as a preferred conduction paths in the composite electrolytes. Dielectric and complex ac-conductivity measurements confirm the existence of low frequency interfacial/space-charge polarization along the grain boundary regions and multi-ion long-range conduction along the interface regions.

Multiferroic particulate composites have been fabricated by taking the morphotropic phase boundary composition of ferroelectric phase Bi(Ni1/2Ti1/2)O3–PbTiO3 and magnetic phase (Ni,Zn)Fe2O4. The ferroelectric phase has coexisting monoclinic and tetragonal perovskite structures with space group Pm and P4mm, respectively whereas the magnetic phase has spinel cubic structure with space group Fd 3 ‾ m. Rietveld structural analysis for the each components of composite reveals that the tetragonality (c/a) of the ferroelectric phase continuously increases with increasing the concentration of magnetic phase and finally transform in rhombohedral (R 3 ‾ c) phase suggesting partial ionic diffusion between ferroelectric and magnetic phases. Composition dependent Mossbauer spectra of (1-x)Bi(Ni1/2Ti1/2)O3–PbTiO3/x(Ni,Zn)Fe2O4 reveals the superparamagnetic like behavior for the ferroelectric rich composition with x = 0.2. The magnetic ordering increases for the composition with x = 0.4 and 0.6 which completely transforms into ferrimagnetic for the composition with x = 0.9. Unlike the ferroelectric or magnetic components that do not exhibit the magnetoelectric response separately, significant value of magnetoelectric coefficient (> 30 mV/Oe-cm) in (1-x)Bi(Ni1/2Ti1/2)O3–PbTiO3/xNi0.6Zn0.4Fe2O4 composite makes it promising for multifunctional applications.

Studies on (1-x)[Bi(Mg3/4W1/4)O3]-xPbTiO3 ceramics across morphotropic phase boundary have been done to investigate the crystal structure and structure-property correlations. Rietveld structure refinement reveals that the structure of the morphotropic phase boundary compositions consists of coexisting ordered tetragonal and cubic phases for 0.55

A cement free high pure alumina castable composition is developed for high temperature applications using synthesized Mg-Al spinel sol as binder. The spinel sol is prepared from nitrate precursors and characterized for its pH, solid content, particle size, FTIR, thermal behavior (DSC-TG), phase formation with temperature (XRD), microstructure (FESEM), etc. High alumina castable formulations with different particle size distributions (PSDS) are conventionally processed using the synthesized sol as sole binder at two different amounts. Castables were characterized for various refractory properties after heat treatment at different temperatures. The hot strength and the corrosion resistance of the best composition are evaluated and the properties are compared with silica sol bonded high alumina castable with similar formulations, processed under similar conditions. Considerable improvement in terms of hot strength, corrosion resistance and thermal shock resistance are obtained for the spinel sol bonded composition.

Development of high pure alumina castable is studied by using synthesized mullite sol as the sole binder. Mullite sol is prepared by wet chemical route and is characterized by its solid content, particle size, thermal analysis, phase development with temperature, microstructure, etc. This sol is used at two different percentages in high alumina castable compositions with two different particle size distribution patterns. Conventional castable processing is done on the compositions and the characterizations are done after heat treatment at three different temperatures. Finally, the best composition is also compared with the commercially available silica sol containing high alumina castable with similar particle size distribution. Considerably improved hot strength, high corrosion resistance and flexural strength (hot modulus of rupture) are obtained for the mullite sol containing composition but with relatively lower thermal shock resistance.