Diffusion of impurities in ionic crystals as studied by nuclear magnetic resonance techniques
Creators
- 1. Bochum Univ. (Germany, F.R.). Abt. fuer Chemie
Description
The method to investigate the diffusion of atomic defects in cubic ionic crystals by measurements of nmr relaxation rates is described very briefly. Examples are given for longitudinal and transversal relaxation of 81Br- and 35Cl-nuclei in LiBr, TlBr, AgCl, AgBr and CuBr. Selfdiffusion coefficients obtained for Cu+ and Ag+ in LiBr at temperatures above 3500C are D(Cu+) = 8 exp(-1.0 eV/kT); D(Ag+) = 1 exp(-1.0 eV/kT) cm2s-1. In TlBr at 4000C the foreign ions K+, Rb+ and Cs+ have the same mean jump frequency. This frequency is about 3 times larger than that of Tl+ and 3 times smaller than that of Br-. Ag+ diffuses at 3000C 10 times faster than even Br-. In AgCl doped with CuCl the frequency of formation of a defect pair is observed. The jump processes connected with formation and recombination of this pair do not contribute considerably to Cu tracer diffusion. In AgBr doped with CuBr and treated with bromine the relaxation measurements show that Cu2+-ions are formed. The jump frequency of Cu2+ can be determined besides that of Cu+ at temperatures about 2000C. (orig.)
Availability note (English)
MF available from INIS under the Report Number.Abstract (German)
Die Methode zur Untersuchung der Diffusion atomarer Defekte in kubischen Ionenkristallen durch Messung von NMR-Relaxationsraten wird kurz beschrieben. Beispiele fuer longitudinale- und transversale Relaxation der 81Br- und 35Cl-Kerne in LiBr, TlBr, AgCl, AgBr und CuBr werden angegeben. Fuer Cu+ und Ag+ in LiBr erhaelt man bei Temperaturen ueber 3500C folgende Selbstdiffusionskoeffizienten: D(Cu+) = 8 exp(-1,0 eV/kT); D(Ag+) = 1 exp(1,0 eV/kT) cm2s-1. In TlBr haben die Fremdionen K+, Rb+ und Cs+ bei 4000C diesselbe mittlere Sprungfrequenz. Diese Frequenz ist etwa 3mal groesser als die fuer Tl+ und 3mal kleiner als die fuer Br-. Ag+ diffundiert bei 3000C sogar 10mal schneller als Br-. In CuCl-dotiertem AgCl wurde die Paardefekt-Bildungsfrequenz beobachtet. Die Sprungprozesse in Verbindung mit der Bildung und Rekombination dieser Paare tragen nicht wesentlich zur Cu-Tracerdiffusion bei. In CuBr-dotiertem und mit Brom behandeltem AgBr zeigen Relaxationsmessungen die Bildung von Cu2+-Ionen. Die Sprungfrequenz der Cu2+- und C+-Ionen kann bei Temperaturen von ungefaehr 2000C bestimmt werden. (orig.)
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Additional details
Publishing Information
- Imprint Pagination
- 22 p.
- Report number
- AED-Conf--76-360-002
Conference
- Title
- 2. europhysical topical conference on lattice defects in ionic crystals.
- Dates
- 30 Aug 1976.
- Place
- Berlin, Germany, F.R.
INIS
- Country of Publication
- Germany
- Country of Input or Organization
- Germany
- INIS RN
- 8311590
- Subject category
- S75: CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY;
- Resource subtype / Literary indicator
- Conference
- Descriptors DEI
- BROMINE 81; CHLORINE 35; COPPER IONS; CRYSTAL DEFECTS; DIFFUSION; DOPED MATERIALS; IONIC CRYSTALS; NUCLEAR MAGNETIC RESONANCE; SILVER BROMIDES; SILVER CHLORIDES
- Descriptors DEC
- ATOMIC IONS; BROMIDES; BROMINE COMPOUNDS; BROMINE ISOTOPES; CHARGED PARTICLES; CHLORIDES; CHLORINE COMPOUNDS; CHLORINE ISOTOPES; CRYSTAL STRUCTURE; CRYSTALS; HALIDES; HALOGEN COMPOUNDS; INTERMEDIATE MASS NUCLEI; IONS; ISOTOPES; LIGHT NUCLEI; MAGNETIC RESONANCE; NUCLEI; ODD-EVEN NUCLEI; RESONANCE; SILVER COMPOUNDS; STABLE ISOTOPES; TRANSITION ELEMENT COMPOUNDS
Optional Information
- Notes
- 5 figs.; 36 refs.