Pressure-Volume-Temperature Relations in Liquid and Solid Tritium

PVT relations in liquid and solid T2 near the melting curve were measured over 20.5 K-22.1 K and 0 MPa-7 MPa (0 bar-70 bar) with a cell that used diaphragms for pressure and volume variation and measurement. Because of ortho-para self conversion, the melting pressure Pm and the liquid molar volume Vlm increased with time. The rates were consistent with a second order reaction similar to that for c the J = odd concentration: [Formula: see text]where k1 = 6-9×l0-2h-1. By extrapolation, the ortho and para forms differed by ΔPm ~6 bar and ΔVlm ~0.5%. Measurements of the volume change on melting and the thermal expansion and compressibility for liquid T2 were consistent with those for H2 and D2. Impurities such as H2, HT, DT, and 3He were removed by a technique using an adsorption column of cold activated alumina. Corrections for 3He growth during an experiment were adequate except near the triple point.