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Demineralization of coal carried out using EDTA for different time and HF of varying concentration. The residual coal from each treatment was characterized together with virgin coal using Scanning Electron Microscopy and energy dispersive X-ray analysis (EDAX). Micrograph and EDAX analysis of Virgin coal reveal the features lithophiles like aluminium

Single crystal whiskers of gallium telluride (GaTe) have been grown by the physical vapour deposition (PVD) method. Microindentation studies were carried out on the prism faces of the needles to understand their mechanical behaviour. The variation in the microhardnessof GaTe crystals with applied load has been determined at room temperature using Vickers microhardness indenter. The work-hardening exponent has also been computed for different load regions.

The structural defects and microhardness of Bi 2 Te 3-x Se x whiskers (x = 0, 0.2 and 0.4 at % Se) grown by physical vapour deposition (PVD) method have been investigated. Concentric pairs of dislocation loops were observed on the as-grown surfaces of short hexagonal prisms. A systematic study of dislocations in these crystals was carried out by chemical etching technique. The effects of Se doping, annealing and quenching on the mechanical properties have also been studied on the prism faces of Bi 2 Te 3-x Se x whiskers.

The physical vapour deposition (PVD) method has been employed to yield gallium telluride (GaTe) platelets. The morphology and growth mechanism of these platelets were investigated with the aid of scanning electron micrographs. The stoichiometry and homogeneity of the grown samples were confirmed by chemical analysis. The X-ray diffraction (XRD) technique has been used to explore the structure and phase of the compound. On the basis of the Archimedes principle, the density of crystals was estimated to be 5.442 kg mm À3 . The resistivity and conductivity type were determined by the van der Pauw method. UV-vis-NIR studies revealed a direct transition with an energy gap of 1.69 eV. Mechanical properties such as microhardness, toughness, Young's modulus and elastic stiffness constant of GaTe crystals in response to the stress field due to an external load were studied to realize their suitability for radiation detector applications. The present observations provide an insight into the physical properties of the vapour-grown GaTe platelets, which are found to be superior over their melt counterparts.

Different morphologies of indium telluride (In 2 Te 3 ) including novel spherulites were crystallized using the physical vapour deposition (PVD) method, by varying the difference in the growth and source zone temperature (ΔT) of a dual zone horizontal furnace assembled indigenously. Whiskers and kinked needles of In 2 Te 3 were grown at ΔT = 250 K and 300 K respectively, maintaining the growth zone at 500 °C. At high supersaturation (ΔT = 400 K), spherulitic crystals were obtained. The stoichiometric composition of these crystals has been confirmed using energy dispersive analysis by x-rays (EDAX). The structure of β-In 2 Te 3 spherulitic crystals is identified as zinc blende with lattice parameter a = 6.159 Å, from x-ray diffraction (XRD) studies. The scanning electron microscope (SEM) images revealed the radial structure of the grown spherulites. The growth mechanism for the spherulitic crystallization of β-In 2 Te 3 crystals has been discussed based on the theoretical models.

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A horizontal linear gradient two zone furnace was designed and employed to grow single crystals of indium telluride by Physical Vapour Deposition (PVD) method. It was calibrated for various trials including, series and parallel combinations of coils, and set temperatures. Systematic growth runs for chalcogenide crystals were performed by varying the source and growth temperatures. Crystals of different sizes and morphologies were obtained. The morphology and chemical analysis of the grown crystals were investigated by Scanning Electron Microscope (SEM) and Energy Dispersive Analysis using X-rays (EDAX). The hardness of the crystals was estimated using a Vickers microhardness tester.