Abstract
Abstract Several types of hole V centres have been observed by the EPR method in plastically deformed CaS polycrystals after the X-irradiation at 77 K. Dominating V−, VSH, and V2(SH)+ centres are formed when a hole is trapped by a sulphur anion near the isolated cation vacancy or near the cation vacancy associated with one or two (SH)− groups. Holes are released from the V−, VSH, and V2(SH)+ centres at 120–285, 160–210, and 110–160 K, respectively. Hole release in the case of V− centres takes place in an unusually wide temperature range. The possible mechanisms responsible for this process are discussed. The isolated cation vacancies are easily transformed into associates with one or two (SH)− groups by heating the samples up to 450–670 K. These associates disappear completely after the samples are heated above 800 K.
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