V centres in plastically deformed SrS

摘要

V centres of several types were studied by electron paramagnetic resonance in SrS polycrystals for the first time. Both isolated cation vacancies and their complexes with other defects are formed in SrS during plastic deformation and are further transformed by ionic processes on annealing. They become paramagnetic when the samples are irradiated by X-rays at 77 K and a hole is captured by a S2- ion situated next to a cation vacancy. Thus, V- centres arise from isolated cation vacancies V-c, V-SH from v(c)-(SH)(-) complexes, and V-2(SH)(+) from (SH)(-)-v(c)-(SH)(-) complexes. The holes captured are released 2(SH) from V centres below room temperature, within a very wide temperature range. The electric fields of dislocations are supposed to modify the activation energies of hole release. Low activation temperatures of ionic processes (compared with ionic conductivity of undamaged SrS) indicate that defects are transported by dislocations in plastically deformed SrS. [References: 18]