Effect of Irradiation on Impurity–Vacancy Dipoles in KBr Crystals Doped with Strontium

Abstract

The concentration of impurity-vacancy dipoles in potassium bromide crystals doped with strontium bromide was measured using the ionic thermocurrent (ITC) technique.The parameters of the dipole relaxation are: fundamental relaxation time 4 x 10-14 8, activation enthalpy 0.66 eV. The effect of 6oCo y-irradiation a t room temperature was to reduce the number of dipoles and t o increase the number of trapped holes and electrons, but t,he number of trapped holes and electrons, measured by optical absorption, was about 30 times smaller than the number of dipoles destroyed. It is proposed that the effect of irradiation is t o increase the rate of aggregation of dipoles, primarily into trimer aggregates, through temporary electron trapping by strontium ions.Mit dcr Ionen-Thermostrom(1TC)-Methode wurde die Konzentration der StorstellenLeerstellendipole in Kaliumbromidkristallen, die mit Strontiumbromid dotiert waren, bestimmt. Die Parameter der Dipolrelaxation sind : Grundrelaxationszeit 4 x 10-14 s, Aktivierungsenthalpie 0,66 eV. Der EinfluD von 6oCo-y-Bestrahlung bei Zimmertemperatur rednziert die Zahl der Dipole und erhoht die Zahl der angehafteten Locher und Elektronen, jedoch war die Zahl der angehafteten Locher und Elelrtronen, die durch optische Absorption gernessen wurde, etwa 30mal geringer sls die Zahl der zerstorten Dipole. Es wird sngenommen, daB der EinfluB der Bestrahlung in der Erhohung der Geschwindigkeit der Aggregation der Dipole, hauptsachlich zu Trimer-Aggregaten, durch zeitweiliges Elektronenanhaften a n Strontiumionen besteht.

Thermal recovery and thermoluminescence of room-temperature X-irradiated NaCl:Pb2+single crystals

“…This can be interpreted in two ways. On the one hand, different authors (Muccillo and Rolfe 1974, Rubio et a1 1982, Garcia et a1 1983 have shown that irradiation induces the aggregation and precipitation of impurities. Therefore it is reasonable to expect the emissions due to aggregatesin samples which have been strongly irradiated.…”

Dependence of thermoluminescence sensitivity on temperature of irradiation in LiF (TLD-100) phosphor

“…In view of the dominant effect of the thermal history, the results reported for peak 5 in table 3 may not be very reliable. The possibility of irradiation itself increasing the rate of aggregation of impurity-vacancy dipoles, reported in some other alkali halides, also deserves some attention (Kao andPerlman 1979, Muccillo andRolfe 1974). The effect of the thermal history on the TL intensity of peaks 7 and 10 is much less than peak 5.…”

Piégeage des interstitiels par des impuretés divalentes dans KBr : Sr

“…Les cristaux ont été recuits à 450 OC pendant une heure sous atmosphère inerte, puis portés rapidement à température ambiante. Ce traitement thermique est suffisant pour disperser les agrégats de dipôles et ainsi environ 90 % des impuretés se retrouvent sous la forme de paires isolées cation divalent-lacune associée [16,17,18].…”