High pressure phase transitions in scheelite structured fluoride: ErLiF{sub 4}
- High Pressure and Synchrotron Radiation Physics Division, Mumbai (India)
- Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)
Our synchrotron based angle dispersive x-ray diffraction studies on scheelite structured ErLiF{sub 4} show that it undergoes two phase transitions, at ~11.5 and ~15.5 GPa to lower symmetry monoclinic phases, before becoming (irreversibly) amorphous at ~28 GPa. The first high pressure phase transformation to the fergusonite structure (space group I2/a) is found to be of thermodynamically second order. The second high pressure phase could be fitted to the P2/c space group, but detailed analysis rules out the wolframite structure (P2/c space group), common to many scheelite compounds under high pressures. We also suggest that despite the ionic character of the LiF{sub 4} tetrahedra, the compressibility of LnLiF{sub 4} (Ln=Eu–Lu) kind of scheelites is more affected by the LnF{sub 8} dodecahedra than the LiF{sub 4} tetrahedra. - Graphical abstract: Volume per formula unit of the scheelite and high pressure phases of ErLiF{sub 4} as a function of pressure. - Highlights: • ErLiF{sub 4} transforms to fergusonite and P2/c phase at high pressure. • Polyhedra of LnF{sub 8} affects compressibility of LnLiF{sub 4} (Ln=Eu–Lu) more than LiF{sub 4}. • Amorphization pressure varies inversely in LnLiF{sub 4} with ionic size of Ln cation. • In ErLiF{sub 4}a/c ratio reduces with pressure in contrast to reported increase in YLiF{sub 4}.
- OSTI ID:
- 22486761
- Journal Information:
- Journal of Solid State Chemistry, Vol. 229; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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