X-ray Topographs of Solid Helium
Liquid 3He and 4He differ in stability from
all other materials.
They do not become a solid phase at T=0K, because of their giant
zero-point vibration. This means that 3He
and 4He have almost the same
kinetic energy but have nearly no potential minimum that is required
to stabilize a solid phase. Therefore, liquid 3He
and 4He can transform
into solid phases called "quantum crystal", with the aid of pressure
of about 30 atm. Laue spots 110 for the case of a 3He solid phase,
taken at 0.3K using white X-rays, are shown in the figures.
The subboundaries of solid 3He parallel
to the gradients of temperature
and pressure changes with annealing time, as indicated by arrows.
This change might be understood from the quantum tunneling,
because of lack of the thermal activation process.
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