Thermal depolarization in crystals of potassium chloride containing strontium chloride

Abstract

Thermal depolarization has been measured for crystals of KCl doped with SrCG. Suoh crystals annealed at 623 K for one hour and then quenched display one major relaxation peak characterized by an activation energy of 0.74 eV. But if the annealing time is extended to 15 h a t the same temperature two relaxation processes with activation energies of 0.68 and 0.74 eV are observed. The dependence of the dipole relaxation spectrum on annmling time a t 250 K is measured. It is concluded that the relaxation process with E = = 0.68 eV is associated with Ma+-cation vacancy complexes and that with E = 0.74 eV is associated with dimers formed from two of these complexes.Die thermische Depolarisation wird fur SrCI,-dotierte KC1-Kristalle gemessen. Solche bei 623 K eine. Stunde getemperte und d a m abgeschreckte Kristalle zeigen ein Haupt-Relaxationsmaximum, das durch eine Aktivierungsenergie von 0,74 eV charakterisiert ist.Wenn jedoch die Temperungsdauer auf 15 Stunden bei der gleichen Temperatur ausgedehnt wird, werden zwei Relaxaiiansprozesse mit den Aktivierungsenergien 0,68 und 0,74 eV beobachtet. Die Abhiingigkeit des Dipolrelaxationsspektrums von der Temperungsdauer bei 250 K wird gemeseen. Es wird geschlossen, daI3 der RelaxationsprozeD mit E = 0,68 eV mit Me+-Kationenleerstellen-Komplexen und der mit E = 0,74 eV mit Dimeren verknupft ist, die &us zwei dieser Komplexe gebildet sind.

Ionic thermocurrent in KCl doped with SO-24

“…In the case of KCl such an analysis has been carried out by Benière et al [1] for the anion doping they have used K2SO4 and they found that the migration enthalpy h',-and entropy s',-for the free anion vacancy is 0.85 eV and 3.2 k respectively. In the same experiment the analysis showed that the migration enthalpy hm,+ for the free cation motion is 0.73 eV ; this latter value is comparable to those corresponding to a bound cation vacancy motion [2] obtained by the dielectric loss [3] or ITC (Ionic Thermocurrents) [4] techniques (provided that the ionic radius of the divalent cation dopant is not much smaller than that of K+). Unfortunately, to the best of our knowledge, no value of the migration enthalpy hm'bfor the bound anion vacancy in KCI has been published up to date.…”

Thermally stimulated depolarization currents in doped KDP crystals

“…Experimental J(T) curves can be computer fitted [8] to Equation 1 to yield numerical values of P0, E and t0. In the present work, thermally stimulated depolarization current measurements in the case of gel-grown KDP (KH2PO4) crystals doped with divalent anionic impurities like oxalate (C204): and carbonate (CO3) 2-have been reported.…”