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Proceedings Paper

Ion and electron trapping: release and relaxation processes in fluoride crystals
Author(s): Valters Ziraps; Peteris Kulis; Ivars Tale
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Paper Abstract

The thermally stimulated relaxation (TSR) processes in CaF2, BaF2 and LiBaF3 crystals (X-ray irradiated at LNT or RT) have been investigated by means of the ionic conductivity, thermally stimulated (TS) ionic depolarization current (TSDC), TS current (TSC), TS luminescence (TSL) and thermal bleaching techniques. The ionic TSDC measurements evidence that under DC field fluorides accumulate large ionic space-charge (thermoelectric state is formed) as a result of the migrating anion interstitial and/or vacancy capture on defects. In the ionic conductivity region (290 - 650 K) the thermoelectric state anneals, and several wide and overlapping anionic TSDC peaks are detected. The ionic TSDC stages correlate with the X-ray induced absorption band (F-type and other) thermal bleaching stages. These data evidence that the TSR processes are initiated and controlled by the anion defect thermal detrapping and interaction with the color centers and other localized charges. The anion diffusion-controlled TSR processes take place in fluorides. The TSL, TSC and TSL efficiency (TSL/TSC) data evidence that holes and, probably, the interstitials are detrapped: in CaF2 -- at 125 - 190 K, 260 - 320 K; in LiBaF3 -- at 132 K, 170 K and 220 K. The hole or interstitial diffusion-controlled radiative recombination (TSL) takes place above LNT.

Paper Details

Date Published: 10 April 2001
PDF: 6 pages
Proc. SPIE 4415, Optical Organic and Inorganic Materials, (10 April 2001); doi: 10.1117/12.425502
Show Author Affiliations
Valters Ziraps, Univ. of Latvia (Latvia)
Peteris Kulis, Univ. of Latvia (Latvia)
Ivars Tale, Univ. of Latvia (Latvia)

Published in SPIE Proceedings Vol. 4415:
Optical Organic and Inorganic Materials
Steponas P. Asmontas; Jonas Gradauskas, Editor(s)

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