Surinder M Sharma
Articles written in Pramana – Journal of Physics
Volume 25 Issue 1 July 1985 pp 75-79 Solid State Physics
An experimental program has been started to study polymorphic phase transitions under pressure in organic solids using the Be gasketing technique developed by us. This allows us to obtain x-ray diffraction patterns of low symmetry organic solids with high resolution, employing CuK
Volume 27 Issue 6 December 1986 pp 835-839 Solid State Physics
X-ray diffraction experiments on
Volume 35 Issue 2 August 1990 pp 177-180
AlPO4 has been compressed to pressures of 16 GPa in a diamond anvil cell and its X-ray diffraction pattern studied by the energy-dispersive technique. The compound is observed to become amorphous at ∼ 12 GPa. This explains the loss of Raman spectrum of AlPO4 reported by Jayaraman and coworkers (1987).
Volume 43 Issue 1 July 1994 pp 1-9
Recent X-ray diffraction studies on α-quartz (SiO2) by Kingma
Volume 49 Issue 3 September 1997 pp 285-291
High pressure behaviour of FePO4 in berlinite form has been investigated up to 10 GPa using vibrational Raman spectroscopy and energy dispersive x-ray diffraction. Combination of these techniques along with studies on pressure quenched samples reveal structural transitions in this material from its room pressure trigonal phase to a disordered and a crystalline phase near 3±0.5 GPa. The latter is the Cmcm phase which is the equilibrium structure at high pressures. These high pressure phases do not revert back to its initial structure after release of pressure. Irreversibility of these transformations indicates that FeO4 tetrahedra do not regain their initial coordination. These high pressure transitions can be rationalized in terms of the three level free energy diagram for such systems.
Volume 50 Issue 3 March 1998 pp 213-220
Infrared absorption and Raman study of
Volume 67 Issue 1 July 2006 pp 141-152
By subjecting materials to high pressures one can significantly reduce interatomic and intermolecular distances. This causes drastic changes in the nature of electronic and vibrational states and also in bonding, bringing about several unusual structural, electronic and magnetic phase transitions. In addition, these studies provide a very useful data about the equation of state of the materials of interest. Several examples from our work are presented which elucidate the richness of physics under these conditions.
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