Pressure—Volume—Temperature Relations in Solid Parahydrogen

Abstract

Effect of free volume and temperature on the structural relaxation in polymethylphenylsiloxane: A positron lifetime and pressure-volume-temperature study Experimental data are presented for the molar volume of solid parahydrogen at five different temperatures over the range 11.49° to 19.97°K and at pressures from 0 to 350 atm. In making the density measurements, it was found that there is a fairly well-defined region of temperature and pressure in which solid hydrogen is viscoelastic. At higher pressures the solid is rather hard and rigid.A diagram is included which gives an idea of the PVT relations for solid parahydrogen up to a pressure of about 400 atm. The accuracy with which the points on this diagram are known ranges from ±0.2% along the melting line to ±5% at points far from the melting line. A striking feature is the shape of the isobars in the neighborhood of the melting line; at pressures above about 150 atm, each isobar passes through a maximum at a molar volume which is greater than the corresponding molar volume along the melting line. It appears that the thermal coefficient of expansion of solid parahydrogen is negative in a narrow range of temperature and pressure.

Experimental determination of the equation of state of solid hydrogen and deuterium at high pressures

“…Isochores of solid hydrogen, corrected to correspond to the para species. Data points on the melting line and in the liquid phase have been omitted, as well as points below 8 K. The solid lines are fits with the Mie-Grfineisen theory.carefully monitored, could be interpreted as an isochoric increase in pressure with decreasing temperature, similar to the result of Cook et al16 In the present work, measurements in H2 show a drop in pressure at lower temperatures, but this is due to short-range ordering of the EQ moments as seen earlier by Jarvis et al22 …”

“…(9) we find oo (15) where (16) with V given in cm3/mole and F in degrees kelvin. A sufficient number of points is given in Table I or Fig.…”

The case of the phantom phases in solid hydrogen

“…Then in July of that year two papers appeared with almost identical titles. Roder, 7 in a paper entitled, "A New Phase Transition in Solid Hydrogen?," cited the Cook et al 5 data along with more recent evidence supporting a structure change, while Manzhelii et al, 8 in "Possible Phase Transition in Solid Parahydrogen," gave preliminary expansion and compressibility measurements that also suggested a phase transition. The year closed with Durana and McTague 9 reporting Raman studies at helium temperatures indicative of an hcp-fcc transition in p-H2 at -0.8 kbar (80 MPa).…”

Raman Spectrum of Solid Orthodeuterium to 150 kbar at 5 K

“…Some years ago Cook et at. 9 observed an anomaly in isobars of solid H 2 near the melting line. This led Roder 10 to speculate that a phase transition had taken place.…”