Accession Number : AD0722859

Title :   Off-Center Ions in Crystal Lattices.

Descriptive Note : Final scientific rept. 1 Oct 68-30 Sep 70,

Corporate Author : MILAN UNIV (ITALY) ISTITUTO DI FISICA

Personal Author(s) : Nardelli,G. F.

Report Date : 31 OCT 1970

Pagination or Media Count : 14

Abstract : Results under the contract concern, on one hand the individual dynamical properties of off-center ions as well as their collective behavior in polar crystals; on the other hand, the effects of the electron-phonon interaction, with a view to the Jahn-Teller effect and phononinduced polarizability of a trapped electron. Furthermore, the Dynamical Properties of Interstitials are briefly discussed, in connection with infrared and optical response. Particular attention was paid to the collective behavior of off-center substitutional defects in order to understand the conditions for the appearance of a ferroelectric order in a dilute system of randomly distributed centers in ionic crystals. The report discusses other preliminary results obtained following a new line of research, which is in progress now, i.e. surface dynamics: surface phonons, adsorption and catalytic behavior. (Author)

Descriptors :   (*SOLID STATE PHYSICS, SURFACES), (*CRYSTAL DEFECTS, REPORTS), COLOR CENTERS, FERROELECTRIC CRYSTALS, CATALYSIS, ADSORPTION, PHONONS, IMPURITIES, ITALY

Subject Categories : Physical Chemistry
      Crystallography
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE