O M Prakash
Articles written in Bulletin of Materials Science
Volume 14 Issue 3 June 1991 pp 709-712 International Conference On Superconductivity—II
57Fe Mössbauer investigations at 300K have been carried out on V,Mn substituted YBa2Cu3O7−
Volume 14 Issue 3 June 1991 pp 871-876 International Conference On Superconductivity—II
Results of the XRD, XPS, XANES, iodometric titration and transport studies on freshly prepared Ce, Zr and Ti substituted 1-2-3 samples are reported here. It is argued that at least 2% of Ce, Zr and Ti ions go into the 1-2-3 lattice. It is found that Zr, Ti ions exist in 4+ valence state, Ce is in predominantly 4+ (mixed valence) state and valence of Cu remains unaffected on substitution.
Volume 14 Issue 4 August 1991 pp 1145-1150 International Conference On Superconductivity—III
Processing studies on varied shape-forming and densification of bulk ceramic superconductor, YBa1·5Ca0·5Cu3O7\t-\gd, are reported in this paper. Polyvinyl butyral-polyethylene glycol-trichloroethylene has been found to be the best binder-plasticizer-solvent system in plastic shape-forming. The effect of initial particle morphology on final densification has been the most sensitive single parameter as compared to compaction pressure and final sintering durations at ∼930°C. 1-2-3 powders of mean particle size ∼ 1·94 µm have yielded sintered densities ∼92% T.D. albeit with lower oxygen intake O6·7.
Volume 14 Issue 4 August 1991 pp 1151-1155 International Conference On Superconductivity—III
Volume 21 Issue 5 October 1998 pp 399-402 Materials Preparation
Due to a lack of proper understanding about the formation mechanism of oxygen related donors during the transition temperature range (465–540°C) which exhibits the transition of TDs to NDs, an attempt has been made to study their behaviour in the present context. We have found the formation and diffusion of molecule like oxygen at low temperature annealing of silicon and observed that second order kinetics of oxygen diffusion holds good. A relatively low value of 0·6 eV has been estimated to be the activation energy for the diffusion of oxygen in silicon which is supposed to be due to the hydrogen passivation.
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