Journal of Physics: Conference Series
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Phase Stability Behaviour of Rare Earth Orthovanadates under High Pressure To cite this article: Alka B. Garg 2017 J. Phys.: Conf. Ser. 950 032001
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AIRAPT IOP Conf. Series: Journal of Physics: Conf. Series 1234567890 950 (2017) 032001
IOP Publishing doi:10.1088/1742-6596/950/3/032001
Phase Stability Behaviour of Rare Earth Orthovanadates under High Pressure Alka B. Garg* High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Mumbai, India 400085
Rare earth orthovanadates, RVO4 (R3+V5+O42-; R= rare earth element including Y and Sc) belongs to the family of ABO4 type compounds. At ambient pressure and temperature conditions, all the RVO4 compounds crystallize in zircon structure (except LaVO4 which can also be stabilized in monoclinic monazite structure). The basic building blocks of tetragonal zircon structure (space group: I41/amd ; Z=4) are VO4 tetrahedra and RO8 polyhedra which extend parallel to c axis and VO4 chains are joined laterally by edge sharing RO8. The V–O bond distance remains nearly the same for the entire lanthanide series, and the R–VO4 interaction is predominantly ionic. The RVO4 series represents an ideal system for studying the interaction between the sublattice of magnetic ions and the ligands of the host lattice. From technological point of view also these zircon-type orthovanadates have important applications as cathodoluminescence, thermophosphors, scintillators, and laser-host materials. They can also be useful for the development of green technologies through applications like photocatalytic hydrogen production. As is well known that pressure, an important thermodynamic variable can change the inter-atomic distances in the solids by an order of magnitude which dramatically alter the electronic properties, break existing bonds, or forming new chemical bonds which intern leads to variety of pressure-induced phenomena such as metallisation, amorphization, superconductivity and polymerisation. Hence, compression provides a unique possibility to control the structure and properties of materials. Usually the zircon-structured materials are known to transform to a denser (~10%) low symmetry tetragonal scheelite structure (space group I41/a) under pressure. On further compression this scheelite phase becomes unstable and system transforms to low symmetry monoclinic structure. In this talk evolution of equation of states and other structural details for various phases of RVO4 compounds studied using synchrotron based X-ray diffraction and Raman spectroscopic measurements will be presented. *
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