Dielectric properties of Li2O-3B2O3 glasses

The frequency and temperature dependence of the dielectric constant and the electrical conductivity of the transparent glasses in the composition Li2O-3B2O3 (LBO) were investigated in the 100 Hz- 10 MHz frequency range. The dielectric constant and the loss in the low frequency regime were electrode material dependent. Dielectric and electrical relaxations were respectively analyzed using the Cole-Cole and electric modulus formalisms. The dielectric relaxation mechanism was discussed in the framework of electrode and charge carrier (hopping of the ions) related polarization using generalized Cole-Cole expression. The frequency dependent electrical conductivity was rationalized using Jonscher's power law. The activation energy associated with the dc conductivity was 0.80 \pm 0.02 eV, which was ascribed to the motion of Li+ ions in the glass matrix. The activation energy associated with dielectric relaxation was almost equal to that of the dc conductivity, indicating that the same species took part in both the processes. Temperature dependent behavior of the frequency exponent (n) suggested that the correlated barrier hopping model was the most apposite to rationalize the electrical transport phenomenon in Li2O-3B2O3 glasses. These glasses on heating at 933 K/10h resulted in the known non-linear optical phase LiB3O5.Comment: 32 pages, 13 figure

The glass transition and crystallization kinetic studies on BaNaB9O15 glasses

Transparent glasses of BaNaB9O15 (BNBO) were fabricated via the conventional melt-quenching technique. The amorphous and the glassy nature of the as-quenched samples were respectively, confirmed by X-ray powder diffraction (XRD) and differential scanning calorimetry (DSC). The glass transition and crystallization parameters were evaluated under non-isothermal conditions using DSC. The correlation between the heating rate dependent glass transition and the crystallization temperatures was discussed and deduced the Kauzmann temperature for BNBO glass-plates and powdered samples. The values of the Kauzmann temperature for the plates and powdered samples were 776 K and 768 K, respectively. Approximation-free method was used to evaluate the crystallization kinetic parameters for the BNBO glass samples. The effect of the sample thickness on the crystallization kinetics of BNBO glasses was also investigated.Comment: 23 pages, 12 figure

Economic Liberalization - A Stumbling Block in the Commercialization of Indigenous Calcium Silicide Technology

Indian ferro alloy industry is passing through one of its worst periods by the process of economic liberalization. Its production in our country is coming down mainly due to inadequate indigenous demand, non-availability of exports and high power cost as compared to other competing countries. The indigenous calcium silicide technology developed at National Metallurgical Laboratory; Jamshedpur could not be commercialized on account of thenew economic liberalization policy of Government of India

Effect of scale-up, design and process parameters on the productivity of ancient iron making process and recovery of iron in the product

Indian iron was famous in ancient times and it was exported to many countriesthroughout the world Though isolated pockets of iron making existed practically all over the country, yet there was no attempt of systematization and wider propagation. Recently an attempt has been made to establish proto-type furnace and scale it up with modifications in its design.The effect of scale -up.design and process parameters on the productivity of ancient iron making process and recovery of iron in the product has been discussed

Magnetite ore of nagaland—its mineralogy and reduction kinetics

The magnetite body near Pokphur in the Kiphere district of Nagaland is geologically quite different and a rare type of occurrence associated with ophiolite. Mineralogical studies reveal the presence of magnetite, chromite and hematite followed by goethite, ilmentite, trevorite, pentlandite and millerrite. Magnetite grains are weathered to various degrees and sometimes fractured. Reduction studies indicate that in gas-solid system considerable reduction of magnetite ore takes place in initial 60 minutes, further the rate of reduction becomes slow. In gas-solid system the percentage reduction of magnetite ore is considerably more compared to solid-solid systems