Solid state synthesis and physical mechanisms of electrical conductivity variation in polycrystalline, strontium doped indium oxide In 2 O 3 :(SrO) x were investigated for materials with different doping levels at different temperatures (T=20-300 0 C) and ambient atmosphere content including humidity and low pressure. Gas sensing ability of these compounds as well as the sample resistance appeared to increase by 4 and 8 orders of the magnitude, respectively, with the doping level increase from zero up to x=10%. The conductance variation due to doping is explained by two mechanisms: acceptor-like electrical activity of Sr as a point defect and appearance of an additional phase of SrIn 2 O 4 . An unusual property of high level (x=10%) doped samples is a possibility of extraordinarily large and fast oxygen exchange with ambient atmosphere at not very high temperatures (100-200 0 C). This peculiarity is explained by friable structure of crystallite surface. Friable structure provides relatively fast transition of samples from high to low resistive state at the expense of high conductance of the near surface layer of the grains. Microscopic study of the electrodiffusion process at the surface of oxygen deficient samples allowed estimation of the diffusion coefficient of oxygen vacancies in the friable surface layer at room temperature as 3×10 -13 cm 2 /s, which is by one order of the magnitude smaller than that known for amorphous indium oxide films.
We report the results of theoretical and experimental studies of the magnetic after-effect in epitaxial YIG films with multiple easy axes. The transition from the initial metastable domain phase (stripe domains) to the equilibrium domain phase (undulated domains) with a smaller period occurs after switching off the external magnetic field and takes about 10-15 s. It is observed that the velocity of motion of the phase-boundary domain wall is a factor of 3-4 decades less than domain wall velocities in each of the domain phases. To explain this we devised a domain structure model of these films (using experimental results) and calculated the mobility coefficient of the phase-boundary domain wall. It is shown that the phase-boundary domain wall moving under the influence of the difference between two domain phase pressures causes relaxation of a diffusional type in the spin system. The after-effect time is the phase transition time and it is approximately inversely proportional to the difference in domain periods of the two domain structures.
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