Accession Number : AD0754442

Title :   A Technique for Growing Helium Crystals in Preferred Orientations.

Descriptive Note : Technical rept.,

Corporate Author : DUKE UNIV DURHAM N C DEPT OF PHYSICS

Personal Author(s) : Lawson,D. T.

Report Date : JAN 1973

Pagination or Media Count : 31

Abstract : An apparatus has been developed in which hcp 4He single crystals of high quality are grown with a 0.3 probability of obtaining c-axis orientations of 0 or 90 deg with respect to the direction of growth. Methods of influencing the relative distribution of crystals between these two angles have been observed and are believed to depend on the anisotropy in the thermal conductivity of hcp 4He. A simple computer simulation of the nucleation process supports our identification of the orientation angles and our explanation of the observed orientation preferences. Some possible applications of similar techniques were surveyed. (Author)

Descriptors :   (*HELIUM, *CRYSTAL GROWTH), (*SOLIDIFIED GASES, HELIUM), THERMAL CONDUCTIVITY, FREEZING, NUCLEATION, SINGLE CRYSTALS, CRYOGENICS

Subject Categories : Crystallography
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE