Dependence of Scintillators Optical Properties on Intrinsic Structural Defects
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N.V.KILASSEN Institute of Solid State Physics, Russian Academy of Sciences, 142 432, Chernogolovka, Moscow Region, Russia.
ABSTRACT The studies of the dependence of the optical properties of various scintillators on intrinsic structural defects have been reviewed. The greater part of the review is devoted to the defects introduced by plastic deformation. A wide range of variations in the light output, spectral distribution, kinetics and other properties has been observed. These defects can be induced during crystal growth, annealing, processing, etc. The proper regulation of the superstructure of intrinsic defects can ensure the production of high quality scintillators having required properties.
INTRODUCTION In search of the opportunities to improve the properties of scintillators, the specialists usually study the dependencies of scintillation efficiency, resolution, kinetics, radiation hardness, etc. of various materials on chemical composition of the matrix and dopants. [1,2]. Publications, devoted to the influence of intrinsic structural defects, that is nonstoihiometry, dislocations, twins, grain boundaries, etc. on scintillators properties are scarce. However, the immense experience of the Institute of Solid State Physics (Chernogolovka) in the investigations of the dependence of physical properties of various semiconductors and dielectrics on specific features of their real structure shows that the intrinsic defects can modify radically the optical, electrical and mechanical properties of the materials. This paper is a review of the studies carried out in ISSP on the influence of the intrinsic defects on the optical properties of zinc sulfide and selenide, cadmium sulfide and selenide, alkali halides (that is, the materials, whose electron structure is rather close to that of the most popular scintillators) and of the first results on the dependence of the properties of cerium fluoride, lead tungstate and lead fluoride on the disturbances of their crystalline structure. Also the perspective investigations in these fields are discussed. The influence of structural defects on scintillators' properties is quite a practical question, because in every scintillating element these defects are present in large enough amounts. They can be introduced in uncontrollable way during the crystal growth, cooling, annealing, processing, mounting, 247 Mat. Res. Soc. Symp. Proc. Vol. 348. 01994 Materials Research Society
Fig. la (see text).
irradiation, etc., causing the element degradation. It should be mentioned that many
achievements in semiconductors physics and microelectronics have been due to controllable regulation of the superstructure of the crystalline defects. By analogy we
can hope that the understanding of the behavior of intrinsic defects in scintillators will provide new excellent opportunities for regulation of their properties.
STUDIES OF THE INFLUENCE OF INTRINSIC DEFECTS ON ELECTRON STRUCTURE AND OPTICAL PROPERTIES OF WIDE GAP SEMICONDUCTORS AND DIELECTRICS Generally speaking, any crystal lattice d
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