• B Singh

Articles written in Bulletin of Materials Science

• Electron transport in non-crystalline garnet films

Thin films of yttrium iron garnet (yig) and Gd-substitutedyig of different thickness have been prepared by flash evaporation. The surfacedc andac electrical resistivity and thermopower in these films have been studied. The results are explained on the basis of Mott and Davis model in which narrow tails of localised states exist at the extreme valence and conduction bands and a band of localised levels near the middle of the gap. For the temperature range studied, the main conduction mechanism is on account of excitation of carriers into localised states at the band edges and hopping at energies close to the band tails.

• Surface treatment of red mud and its influence on the properties of particulate-filled polyester composites

The red mud surface was treated with organosilane, organotitanate and organozirconate coupling agents respectively. The change in the surface was determined by IR spectroscopy and SEM. The effect of coupling agents concentration on the tensile and flexural strength of red mud-filled polyester resin has been studied. The efficacy of these coupling agents was discussed in relation to dispersion of red mud in unsaturated polyester resin and also by measuring performance of finished castings under both dry and wet conditions. It was found that organotitanate treated red mud-filled polyester composite gives better physico-mechanical properties than the control and other coupling agents treated red mud. Fractography of failed samples was also discussed in terms of their mechanical properties.

• Chromium-doped Y$_{0.50}$Gd$_{0.50}$BO$_3$ as an excellent photocatalytic and magnetic material

Crystalline chromium-doped Y$_{0.50}$Gd$_{0.50}$BO$_3$ with vaterite structure was synthesized by the calcination of gel from the reaction of yttrium borate, gadolinium borate, boric acid and propylene oxide at 900°C for 4 h. Orthoborates containing 10 and 20 mol% chromium-doped samples were successfully obtained and characterized by various techniques. Photoluminescent studies were performed for the doped samples. The optical bandgap of chromium-doped samples falls in the visible region making the material more viable for photocatalytic activities. The sample was used as a photocatalyst for photodegradation of methylene blue dye. Y$_{0.50}$Gd$_{0.50}$BO$_3$ and chromium-doped samples showed good magnetic properties, as they are antiferromagnetic in nature. To the best of our knowledge, the vaterite form of chromiumdoped Y$_{0.50}$Gd$_{0.50}$BO$_3$ has been synthesized for the first time.

• # Bulletin of Materials Science

Volume 45, 2022
All articles
Continuous Article Publishing mode

• # Dr Shanti Swarup Bhatnagar for Science and Technology

Posted on October 12, 2020

Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020