Accession Number : AD0646654

Title :   HIGH PRESSURE AND DIELECTRIC INVESTIGATIONS OF THE ALKALINE EARTH FLUORIDES.

Descriptive Note : Final rept. Oct 64-Jun 66,

Corporate Author : BOSTON COLL CHESTNUT HILL MASS

Personal Author(s) : Chen,Joseph H. ; Smith,Henry I.

Report Date : AUG 1966

Pagination or Media Count : 186

Abstract : The interactions between ions in the alkaline earth fluorides were investigated by means of two independent studies: (1) direct evaluation of the repulsive interaction, and (2) dielectric relaxation measurements on doped samples. With respect to (1), the experimental approach was to apply pressure up to about 65 kilobars directly to samples of CaF2, SrF2, and BaF2 using a tetrahedral-anvil press. The change of lattice spacing with pressure was determined by X-ray diffraction. These data were then analysed in terms of the Mie-Gruneisen equation of state to obtain the dependence of the repulsive lattice energy on interionic separation. From this, the magnitude and functional dependence of the repulsive interaction between ions was inferred using the theoretical formalism of the Born model. In the dielectric measurements, loss peaks were observed in samarium and uranium doped calcium fluoride crystals. The measurements covered a range from 1Hz to 300KHz and from 100C to 500C. The relaxation mechanism could be attributed to the rotation of dipoles made up to X393+) impurity ion at a Ca(2+) site and a change compensator F(-) at the nearest interstitial site. Activation energy obtained increased with increasing impurity ion size. (Author)

Descriptors :   (*ALKALINE EARTH COMPOUNDS, INTERACTIONS), (*FLUORIDES, INTERACTIONS), (*CALCIUM FLUORIDES, INTERACTIONS), (*STRONTIUM COMPOUNDS, FLUORIDES), (*BARIUM COMPOUNDS, FLUORIDES), CRYSTAL LATTICES, ATOMIC ENERGY LEVELS, HIGH PRESSURE, EQUATIONS OF STATE, MOLECULAR ASSOCIATION, X RAY DIFFRACTION, QUANTUM STATISTICS, CRYSTAL DEFECTS, SAMARIUM, URANIUM, IMPURITIES, DIELECTRIC PROPERTIES, RELAXATION TIME

Subject Categories : Electricity and Magnetism
      Atomic and Molecular Physics and Spectroscopy
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE