Thermodynamic properties of /sup 4/He. II. The bcc phase and the P--T and V--T phase diagrams below 2K

Journal Article · Thu Apr 01 04:00:00 EST 1976 · J. Low Temp. Phys.; (United States)

DOI:https://doi.org/10.1007/BF00117245· OSTI ID:7352669

Hoffer, J K; Gardner, W R; Waterfield, C G; Phillips, N E

The constant-volume heat capacity of /sup 4/He has been measured at molar volumes from 20.45 to 29.71 cm/sup 3//mole in the temperature range from 0.3 to 4 K. The entropy has been obtained as a function of volume and temperature by extrapolation of the data to 0 K. The P--T equilibrium curves below 2 K were obtained from the volume dependence of the entropy in the two-phase regions. The V--T curves were obtained above 1.25 K by observation of heat capacity discontinuities at the phase boundaries and below 1.25 K from the equilibrium pressure-temperature data and the properties of pure phases. The minimum in the melting pressure occurs at 0.774 K and is 8.04 x 10/sup -3/ atm below the 0 K value. The corresponding maxima in the molar volumes of the solid and liquid were also determined. Both the temperature and volume dependence of the heat capacity are similar to those of bcc /sup 3/He, in the very limited ranges of volume and temperature in which the phase could be studied. An unexpected rise in heat capacity in the 20 mK interval below the melting temerature was observed.

• Research Organization: Univ. of California, Berkeley
• OSTI ID: 7352669
• Journal Information: J. Low Temp. Phys.; (United States), Journal Name: J. Low Temp. Phys.; (United States) Vol. 23:1/2; ISSN JLTPA
• Country of Publication: United States
• Language: English

Related Subjects

640450* -- Fluid Physics-- Superfluidity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BCC LATTICES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CUBIC LATTICES
DIAGRAMS
ENTROPY
EVEN-EVEN NUCLEI
FLUIDS
HELIUM 4
HELIUM ISOTOPES
ISOTOPES
LIGHT NUCLEI
LIQUIDS
NUCLEI
PHASE DIAGRAMS
PHASE STUDIES
PHYSICAL PROPERTIES
SOLIDS
SPECIFIC HEAT
STABLE ISOTOPES
THERMODYNAMIC PROPERTIES