Equation of state and metallization of CsI
Self-consistent, nonrelativistic augmented-plane-wave (APW) calculations for CsI were carried out to generate the band structure, the static-lattice equation of state (EOS), and the volume dependence of the electronic energy-band gap. The theoretical room-temperature isothermal compression curve agrees well with static and ultrasonic measurements at low pressure. Our calculations do not agree with two recent sets of diamond-anvil-cell measurements above 10 GPa. The calculated band gaps are too small at low pressure, but, at high pressure, are consistent with both the experimental results and the Herzfeld-model prediction. These results suggest that the insulator-to-metal transition occurs in the range 100 +- 10 GPa. A calculation of the shock compression curve of CsI shows that the thermally excited electrons cause a significant softening of the Hugoniot curve. The experimental zero-pressure band gaps of the isoelectronic compounds Xe, CsI, and BaTe are linearly correlated with ln(v/v/sub H/), where v/sub H/ is the specific volume of metallization predicted by the Herzfeld model. Based on this correlation, and on the similarity of the APW calculated EOS's of Xe and CsI, which agree closely with experimental compression measurements, we predict that BaTe will become metallic at approximately 30 GPa.
- Research Organization:
- Department of Geology and Geophysics, University of California, Berkeley, California 94720
- OSTI ID:
- 6825144
- Journal Information:
- Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 29:5; ISSN PRBMD
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360602* -- Other Materials-- Structure & Phase Studies
ALKALI METAL COMPOUNDS
CESIUM COMPOUNDS
CESIUM IODIDES
CRYSTAL STRUCTURE
DENSITY
ELECTRICAL EQUIPMENT
ELECTRICAL INSULATORS
ELEMENTS
ENERGY GAP
EQUATIONS
EQUATIONS OF STATE
EQUIPMENT
HALIDES
HALOGEN COMPOUNDS
INORGANIC PHOSPHORS
IODIDES
IODINE COMPOUNDS
LATTICE PARAMETERS
METALS
MUFFIN-TIN POTENTIAL
PHASE TRANSFORMATIONS
PHOSPHORS
PHYSICAL PROPERTIES
POTENTIALS
PRESSURE DEPENDENCE