Effect of Crystal Quality on HCP-BCC Phase Transition in Solid 4He

Abstract

The kinetics of HCP-BCC structure phase transition is studied by precise pressure measurement technique in 4He crystals of different quality. An anomalous pressure behavior in bad quality crystals under constant volume conditions is detected just after HCP-BCC structure phase transition. A sharp pressure drop of 0.2 bar was observed at constant temperature. The subsequent pressure kinetics is a non-monotonic temperature function. The effect observed can be explained if we suppose that microscopic liquid droplets appear on the HCP-BCC interphase region in bad quality crystals. After the interphase region disappearance, these droplets are crystallized with pressure reduction. It is shown that this effect is absent in high quality thermal-treated crystals.Comment: 4 pages, 4 figure

Path integral Monte Carlo study of quantum-hard sphere solids

“…4,33,34 Moreover, bcc also appears under certain conditions as the structure of solid phases composed of light atoms as the helium isotopes. [35][36][37][38][39] In this connection, the bcc lattice of He isotopes is being subject of active research, 38,41 and so is the hcp-bcc equilibrium in 4 He in its own right. [38][39] Furthermore, based on previous experience 9,10,14,15,25 it seems clear that work on the QHS system could give more insights into the study of highly complex real systems.…”

Observation of mass transport through solidH4e

“…Furthermore, crystals grown this way may pass through the bcc region of the phase diagram, which is also believed to adversely effect the crystal quality. 46 Our cell allows us to grow crystals using a slightly modified blocked capillary technique. The 1 K heat sink on line 3 allows us to form a solid helium plug in that capillary.…”

NMR Study of Disordered Inclusions in the Quenched Solid Helium

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