The phase diagram of freezing helium-3-helium-4 mixtures

Abstract

Freezing and lambda curves of He/sup 3/- He/sup 4/ mixtures were determined over the entire concentration range for pressures up to 50 kg/cm/sup 2/ at 0.5 to 2.0 deg K. Minima were found in the freezing curves, and the onset of phase separation was detected in the 50.5% He/sup 3/ mixture. The explanation of the results in terms of entropy is discussed. A T-X diagram is also presented; closed freezing lines were found at pressures below 25.9 kg/cm/sup 2/. The phase diagram is further complicated by phase separation and transition. (D.L.C.)