Pressure-volume-temperature relations in liquid and solid4He

PVT relations in liquid and solid⁴He near the melting curve were measured over 0.3-2.0 K with a cell that used diaphragms for pressure and volume variation. The results were largely self-consistent and were essentially in agreement with the most careful previous work. The high values and strong temperature dependence of thermal expansion in the bcc solid resembled that of a liquid, but there was no evidence to substantiate some previous indications of premelting anomalous heat-capacity behavior. The phase diagram was examined carefully, and under equilibrium conditions the measurements led to good correlations. However, it seems improbable thatPVT relations can be connected with heat-capacity data through a simple Grüneisen parameter γ.