Experimental compressions for sodium, potassium, and rubidium metals to 20 kbar from 4. 2 to 300 K
Experimental piston-displacement equations of state are given for sodium, potassium, and rubidium to 20 kbar for temperatures from 4 K to just below the melting line in each case. Except for sodium at high pressures, where the low-temperature bcc-hcp martensitic transition appears to cause problems, these data can be represented by a room-temperature pressure-volume reference function and a thermal pressure which is a function of temperature only. In addition, these three solids appear to obey a reduced equation of state at both 4 K and room temperature, for which V/V/sub 0/ is a common function of P/B/sub 0/. A modification of the second-order Murnaghan equation which is well behaved at large compressions is used to extrapolate these results to 40 kbar for comparison with higher-pressure, room-temperature results. These data are compared with other high-pressure equation-of-state experiments and are extrapolated to P = 0 to obtain thermal expansions and isothermal bulk moduli, which in turn are compared with results from other measurements. These comparisons and those with theoretical calculations show, on the whole, satisfactory agreement. The elementary form for the temperature-dependent equation of state is in agreement with a previous suggestion that the Grueneisen parameter is temperature independent and is a linear function of the volume for temperatures greater than the Debye temperature. The 295-K Grueneisen parameters for these solids, as deduced from the high-pressure results, are 1.24 for sodium and potassium and 1.26 for rubidium.
- Research Organization:
- Ames Laboratory U.S. Department of Energy and Department of Physics, Iowa State University, Ames, Iowa 50011
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 5513342
- Journal Information:
- Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 28:10; ISSN PRBMD
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360102* -- Metals & Alloys-- Structure & Phase Studies
360104 -- Metals & Alloys-- Physical Properties
ALKALI METALS
COMPRESSIBILITY
ELEMENTS
EQUATIONS
EQUATIONS OF STATE
EXPANSION
GRUENEISEN CONSTANT
LOW TEMPERATURE
MECHANICAL PROPERTIES
MEDIUM TEMPERATURE
METALS
POTASSIUM
PRESSURE DEPENDENCE
RUBIDIUM
SODIUM
TEMPERATURE DEPENDENCE
THERMAL EXPANSION
ULTRALOW TEMPERATURE
VERY HIGH PRESSURE
VERY LOW TEMPERATURE