Gorelov B. Defect formation under action of external perturbances in low dimensional metaloxide systems

Тhe thesis is devoted to the experimental investigation of defect formation, evolution and transport of defects in two-dimensional metaloxide cuprate systems, such as YBa2Cu3O7 (YBCO) and Bi2Sr2Ca2Cu3O10 (BSCCO), and in one-dimensional molecular chains, created by water molecules in the crystal lattice of metaloxides and crystalline hydrate compounds, under action of external perturbances. The radioactive irradiation with low fluences of fast neutrons, when ф<1.05.1014 сm-2, and with low doses of gamma quanta, when D<300 kGy, the physically adsorbed water molecules, the superhigh-frequency impulsive irratiation with impulse power 104-106 W were used as the perturbances. The principal investigations were made by the lifetime positron spectroscopy, Auger electron analysis and the method of radioactive trasers. It was established that the action of external perturbances has the general peculiarities in the metaloxide cuprate systems. In YBCO the perturbances enhance the subthreshold defect formation of cations in the intermediate layers, the intensity of which reduces when the oxygen content decreases, and the transformation of vacancy clusters, namely the changes of their radius and concentration, the defect transport along c axis in the crystals and the defect accumulation in the thin surface layer, the blocking of the bulk and surface diffusive transitions of metal atoms. The mechanism of defect formation is caused by the decay of the collective excitations. In the molecular chains the gamma irradiation with doses 10-50 kGy stimulates two types of the ionic transport, and when D>150 kGy that suppresses the transport of ion defects. Matrix systems with inclusions of compounds with crystalline water are by absorbers of the electromagnetic emission in the temperature range of 50-82 oC.