Anomalous lattice compressibility of hexagonal Eu2O3

Monoclinic Eu2O3 was investigated in a Mao-Bell type diamond anvil cell using angle dispersive x-ray diffraction up to a pressure of 26 GPa. Pressure induced structural phase transition from monoclinic to hexagonal phase was observed at 4.3 GPa with 2% volume collapse. Birch –Murnaghan equation of s...

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Bibliographic Details
Published in:Materials chemistry and physics 2017-07, Vol.195, p.88-93
Main Authors: Irshad, K.A., Chandra Shekar, N.V.
Format: Article
Language:English
Subjects:
Bulk modulus
Compressibility
Crystal structure
Diamonds
Diffraction
Europium compounds
Hexagonal phase
High pressure
Lattice theory
Monoclinic lattice
Phase transition
Phase transitions
Pressure
Rare earth sesquioxides
Rietveld refinement
Studies
X-ray diffraction
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Summary:Monoclinic Eu2O3 was investigated in a Mao-Bell type diamond anvil cell using angle dispersive x-ray diffraction up to a pressure of 26 GPa. Pressure induced structural phase transition from monoclinic to hexagonal phase was observed at 4.3 GPa with 2% volume collapse. Birch –Murnaghan equation of state fit to the pressure volume data yielded a bulk modulus of 159(9) GPa and 165(6) GPa for the monoclinic and hexagonal phases respectively. Equation of state fitting to the structural parameters yielded an axial compressibility of βa > βc > βb for the parent monoclinic phase, showing the least compressibility along b axis. Contrary to the available reports, an anomalous lattice compressibility behavior is observed for the high pressure hexagonal phase, characterized by pronounced hardening of a axis above 15 GPa. The observed incompressible nature of the hexagonal a axis in the pressure range 15–25 GPa is found to be compensated by doubling the compressibility along the c axis. •Structural phase transition in Eu2O3 from monoclinic to hexagonal phase.•Anomalous lattice compressibility in the hexagonal phase has reported first time.•Quantitative analysis of lattice compressibility.
ISSN:0254-0584
1879-3312
DOI:10.1016/j.matchemphys.2017.04.012