Temperature sensitive thick films based on spinel-type semiconducting ceramics of different chemical composition Cu_{0.1}Ni_{0.1}Co_{1.6}Mn_{1.2}O_{4} (with p^{+}-types of electrical conductivity), Cu_{0.1}Ni_{0.8}Co_{0.2}Mn_{1.9}O_{4} (with p-types of electrical conductivity) and their multilayer p^{+}-p structures were fabricated and studied. These thick-film elements possess good electrophysical characteristics before and after long-term ageing test at 170°C. It is shown that degradation processes connected with diffusion of metallic Ag into film grain boundaries occur in one-layer p- and p^{+}-conductive thick films. The p^{+}-p structures were of high stability, the relative electrical drift was not greater than 1%.
Water-sorption processes near grain boundaries in the MgO-Al₂O₃ ceramics prepared at different temperatures were studied using positron annihilation lifetime spectroscopy. Numerical values of three- and four-component treatment of spectra were used for study of physical- and chemical-sorption processes in the MgO-Al₂O₃ ceramics. To apply mathematical approach in the form of positron-positronium trapping algorithm into three-component treatment of positron annihilation lifetime spectra it was shown that physical-adsorbed water did not modify positron trapping sites near grain boundaries in water-immersed MgO-Al₂O₃ ceramics and localized mainly in nanopores. The chemically-adsorbed water modifies structural extended defects located near grain boundaries that accompanied them by void fragmentation at water desorption.
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