Phase transitions in delafossite CuLaO{sub 2} at high pressures

Structural stability of a transparent conducting oxide CuLaO{sub 2} at high pressures is investigated using in-situ Raman spectroscopy, electrical resistance, and x-ray diffraction techniques. The present Raman investigations indicate a sequence of structural phase transitions at 1.8 GPa and 7 GPa....

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Bibliographic Details
Published in:Journal of applied physics 2014-04, Vol.115 (13)
Main Authors: Salke, Nilesh P., Rao, Rekha, Gupta, M. K., Mittal, R., Garg, Alka B., Achary, S. N., Tyagi, A. K.
Format: Article
Language:English
Subjects:
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
COPPER COMPOUNDS
ELECTRIC CONDUCTIVITY
EQUATIONS OF STATE
LANTHANUM OXIDES
PHASE STABILITY
PHASE TRANSFORMATIONS
PHONONS
POWDERS
PRESSURE DEPENDENCE
PRESSURE RANGE GIGA PA
RAMAN SPECTROSCOPY
TEMPERATURE DEPENDENCE
X-RAY DIFFRACTION
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Summary:Structural stability of a transparent conducting oxide CuLaO{sub 2} at high pressures is investigated using in-situ Raman spectroscopy, electrical resistance, and x-ray diffraction techniques. The present Raman investigations indicate a sequence of structural phase transitions at 1.8 GPa and 7 GPa. The compound remains in the first high pressure phase when pressure is released. Electrical resistance measurements carried out at high pressures confirm the second phase transition. These observations are further supported by powder x-ray diffraction at high pressures which also showed that a-axis is more compressible than c-axis in this compound. Fitting the pressure dependence of unit cell volume to 3{sup rd} order Birch-Murnaghan equation of state, zero pressure bulk modulus of CuLaO{sub 2} is determined to be 154(25) GPa. The vibrational properties in the ambient delafossite phase of CuLaO{sub 2} are investigated using ab-initio calculations of phonon frequencies to complement the Raman spectroscopic measurements. Temperature dependence of the Raman modes of CuLaO{sub 2} is investigated to estimate the anharmonicity of Raman modes.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4870577