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Mixed polyanion glass and glass-ceramic cathodes can have the potential to overcome the disadvantages of achieving high theoretical capacities of promising crystalline network. Three targeted cathode compositions were chosen for the present study (NaFe0.5(VO)0.5PO4, NaMn0.7(VO)0.3PO4 and NaCo0.7(VO)0.3PO4) based on the superior performance over their crystalline counter parts with highest current density ~ 100 mAh/g. XRD results displayed that major crystalline phases (Na2FeP2O7 (COD ID: 4001802), Na2MnP2O7 (ICSD ID: 71229)) which are precipitated with an ordered triclinic, P1 structure. However, Na2CoP2O7 (ICSD ID: 71230) crystalline phase exhibits orthorhombic/P n a 21 structure. The highest conducting glass-ceramic cathode sample NaCo0.7(VO)0.3PO4 (σ = 6.41 × 10−7 S·cm−1) retains its discharge capacity retention as 84.5 mAh g−1 (91%) even after 50 cycles. At a high rate of 10C, NaFe0.5(VO)0.5PO4 cathode sample is achieved to be highest discharge capacity retention 69.7% than NaCo0.7(VO)0.3PO4 (53.76%) which is a significant feature of mixed polyanion family of glass-ceramic cathodes.

Nanocrystalline yttrium aluminium garnet (YAG) powder has been synthesised by sucrose combustion method. A foamy mass obtained by drying a resin prepared by heating yttrium nitrate, aluminium nitrate and sucrose undergoes self-sustained combustion when initiated with a burning splinter and produces YAG precursors containing amorphous oxides of yttrium and aluminium. The YAG phase has been obtained from the precursors during calcination at a relatively low temperature of 900°C without the formation of any intermediate compounds. The YAG powder prepared by planetary ball milling of the combustion product calcined at 900°C contained particles in the size range of 0·06 to 5 μm with a D 50 value of 1·04 μm and had a surface area of 21·5 m2 g−1. The YAG particles are aggregate of crystallites of the size nearly 30 nm.

Nanocrystalline yittria-stabilized zirconia (YSZ) compounds with yittria concentration varying between 8 and 12 mol% have been synthesized by gel combustion method followed by heat treatment at 550°C. The YSZs are found to posses stable face centered cubic structure at room temperature by X-ray diffractometry. The lattice parameter ‘a’ showed an increasing trend with increasing concentration of yittria. The crystallite size estimated by Scherrer method was in the range of 7–10 nm. Band gap studies showed an increasing trend with increasing yittria concentration and are found to be consistent with respective lattice parameters following the tight binding approximation or linear combination of atomic orbitals approximation.

Nanocrystalline 8 mol% yttria stabilized zirconia (YSZ) powder was synthesized using polyvinyl alcohol (PVA) as organic precursor and acidic solutions of yttrium oxynitrite and zirconium nitrate. Complex formation was established using Fourier transform infrared (FTIR) spectroscopy and solid state (13)C nuclear magnetic resonance (NMR) spectroscopy. Thermal stability of the complex was investigated by thermogravimetric analysis (TGA). X-ray diffractometry (XRD) revealed formation of cubic phase YSZ at a temperature as low as 600 degrees C. The lattice parameter and average crystallite size were calculated from the XRD data. Particle size of the YSZ powder was investigated through transmission electron microscopy (TEM). The band gap of the sintered YSZ pellet was measured by UV-Vis-diffused reflectance spectroscopy (DRS). AC electrical conductivity was measured in air at 1 kHz frequency using a programmable RCL meter. The activation energy was calculated from the conductivity data at different temperatures using the standard Arrhenius equation. (C) 2009 Elsevier Ltd and Techna Group S.r.l. .