C C Desai
Articles written in Bulletin of Materials Science
Volume 3 Issue 4 December 1981 pp 447-454
Optical and scanning electron microscopic observations have been made of tin-iodide whiskers crystals grown by the gel-method. Most of the whiskers have been found to be of two types: (i) hollow and (ii) solid whiskers. The observations indicate that the formation of hollow whiskers is possible with or without the presence of impurities. By using electron micro probe, the overgrowth of tin-tetra iodide crystals on tin-iodide whisker crystals have been identified. A growth mechanism for tin-iodide whiskers have been suggested. The implications are discussed.
Volume 4 Issue 4 July 1982 pp 443-454 Articles
One-to-one correspondence of dislocation etch pits have been established on the matched cleavage faces and on the opposite sides of thin flakes of calcium fluoride crystals. By selecting 022 and 022 reflections and MoKα1 radiation, stereopair projection x-rays topographs were studied and critically compared with optical micrographs. The dislocation etch pits and dislocation out crop images show a close resemblance. The orientation of the Burgers vectors of the dislocation lines has been identified and these lines lie parallel to the <110> directions. The growth history of the stratigraphical pattern has been studied using x-ray topographic technique.
Volume 5 Issue 5 December 1983 pp 453-457
The variation in the microhardness of tin-di-iodide (SnI2) and tin-tetra-iodide (SnI4) crystals has been determined using Vicker’s microhardness indentor. It is observed that the microhardness of the crystals depends on the applied load and is independent of the duration of loading. Vickers Hardness Numerals (
Volume 9 Issue 2 June 1987 pp 89-96
Ammonium hydrogen tartrate single crystals have been prepared by the reaction of NH4Cl and tartaric acid in silica gel. The morphology of some as-grown symmetrical crystals has been studied by optical microscopy. The growth morphology studies indicate that the grown crystals are needle-shaped, orthorhombic disphenoidal and tetrahedral disphenoidal. The growth mechanism has been assessed.
Volume 9 Issue 3 August 1987 pp 203-205
Ferroelectric single crystals such as lead hydrogen phosphate (LHP) and dihydrated lead nitrate phosphate (LNP) have been derived from the diffusion of lead nitrate into the set gel containing orthophosphoric acid. By employing Faraday’s Gouy balance technique, the magnetic susceptibilities of LHP and LNP have been determined. It has been observed that (i) the gram and molar susceptibilities are independent of magnetic field, (ii)
Volume 9 Issue 5 December 1987 pp 343-348
Ferroelectric crystals of lead nitrate phosphate (LNP) have been grown employing the controlled reaction between lead nitrate and orthophosphoric acid. The microhardness of LNP crystals has been determined. The effect of annealing and quenching on the mechanical properties of these crystals has been studied.
Volume 10 Issue 3 May 1988 pp 187-197
The growth of orthorhombic disphenoidal and long needle habit single crystals of ammonium hydrogen tartrate (AHT) in silica gels under the influence of an externally applied uniform field is described. The properties resulting from different growth parameters are reported. Variation in the electrical conductivities of AHT is illustrated. Two distinct electrical conductivity processes are reported. The polarization effect contributing to the dielectric constants is studied. The mechanism of dielectric behaviour which is different in lower and higher temperature ranges is discussed.
Volume 11 Issue 1 September 1988 pp 21-30
Lead nitrate phosphate (LNP) single crystals were grown in silica hydrogel at an ambient temperature employing various nucleation control methods. The effect of concentration of feed solution, gel density, gel pH, ageing of gels and temperature on reduction of nucleation centres is reported. Kinetic studies of the nucleation and growth of LNP crystals and dentrites were studied. The crystals are characterized by X-ray diffraction, density measurements, magnetic susceptibility, mechanical strength measurements and dissolution behaviour.
Volume 11 Issue 1 September 1988 pp 31-37
Rubidium hydrogen tartrate single crystals were grown in silica hydrogel. Controlled reaction was employed between tartaric acid and rubidium chloride solutions by slow diffusion process in the gel medium. Colourless transparent crystals were grown at room temperature. The average density of crystals measured pyknometrically was 2·263 g cm−3. Thermal stability of the materials was studied. Chemical etching was employed to determine the perfection of these crystals.
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