TY - JOUR
T1 - Water and gallium at absolute negative pressures. Loci of maximum density and of melting
AU - Veiga, H. I. M.
AU - Rebelo, L. P. N.
AU - Ponte, M. Nunes da
AU - Szydlowski, J.
N1 - HIMV and JS are grateful to PRAXIS (BD 3958 94 and BCC 16424 98, respectively). This work was financially supported by PRAXIS under Contract *2 2.1 QUI 178 94.
PY - 2001/7/1
Y1 - 2001/7/1
N2 - Several physical properties of liquids as well as those of the coexistence between liquid and solid can be determined at absolute negative pressures. Examples for this include thermal pressure coefficients, loci of temperature of maximum density, melting lines, speed of propagation of low-intensity sound waves, and (p, T, x) conditions of occurrence of liquid/liquid phase separation. Three model temperature-pressure cycles, which allow for the measurement of temperature-pressure conditions of the occurrence of maxima of liquid density, negatively sloped fusion lines, and the upper critical solution temperature (UCST) of liquid solutions in these metastable regimes are described. A new apparatus for measuring negative pressures was developed. The temperature and pressure are determined within an uncertainty of ±0.05°C and ±5 bar, respectively. Water and heavy water have been used as testing systems with respect to the location of their temperatures of maximum density (TMD) loci. Empirical equations of state whose parameters have been fitted to experimental data located in the normal positive pressure region have proven to extrapolate well to the negative pressure regime. Furthermore, an attempt was made to use SAFT in order to provide a more theoretically founded framework. Preliminary results for gallium have shown that a TMD exists 45 K inside the supercooled regime, and that the continuation of its melting line down to -80 bar evolves with a slope of -515 ±25 bar·K-1.
AB - Several physical properties of liquids as well as those of the coexistence between liquid and solid can be determined at absolute negative pressures. Examples for this include thermal pressure coefficients, loci of temperature of maximum density, melting lines, speed of propagation of low-intensity sound waves, and (p, T, x) conditions of occurrence of liquid/liquid phase separation. Three model temperature-pressure cycles, which allow for the measurement of temperature-pressure conditions of the occurrence of maxima of liquid density, negatively sloped fusion lines, and the upper critical solution temperature (UCST) of liquid solutions in these metastable regimes are described. A new apparatus for measuring negative pressures was developed. The temperature and pressure are determined within an uncertainty of ±0.05°C and ±5 bar, respectively. Water and heavy water have been used as testing systems with respect to the location of their temperatures of maximum density (TMD) loci. Empirical equations of state whose parameters have been fitted to experimental data located in the normal positive pressure region have proven to extrapolate well to the negative pressure regime. Furthermore, an attempt was made to use SAFT in order to provide a more theoretically founded framework. Preliminary results for gallium have shown that a TMD exists 45 K inside the supercooled regime, and that the continuation of its melting line down to -80 bar evolves with a slope of -515 ±25 bar·K-1.
KW - Gallium
KW - Liquids under tension
KW - Maximum density loci
KW - Melting line
KW - Metastability
KW - Negative pressures
KW - Water
UR - http://www.scopus.com/inward/record.url?scp=0000891783&partnerID=8YFLogxK
U2 - 10.1023/A:1010612208895
DO - 10.1023/A:1010612208895
M3 - Article
AN - SCOPUS:0000891783
VL - 22
SP - 1159
EP - 1174
JO - International Journal of Thermophysics
JF - International Journal of Thermophysics
SN - 0195-928X
IS - 4
T2 - 14th Symposium on Thermophysical Properties
Y2 - 25 June 2000 through 30 June 2000
ER -