Wyniki 1-2 spośród 2 dla zapytania: authorDesc:".S. FEDOTOV"

Electric properties of composite ZnO-based ceramics doped with Fe DOI:10.15199/48.2018.03.39

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Nowadays special attention is paid to the search for new ceramic materials based on wide-gap oxides, as well as to the study of their structure and properties for the purpose of their application in various areas of the radioengineering, electronic and optoelectronic industries [1]. Analysis of the literature indicates that single crystals, polycrystalline films, nanostructured powders and wires based on ZnO have been studied in sufficient detail. At the same time, ZnO-based compositions, obtained by ceramic technologies, have not been studied so well. In particular, there is no many research dedicated to the effects of ZnO ceramics doping with magnetic impurities as well as influence synthesis technology and subsequent heat treatments on the chemical and phase compositions (including the magnetic states of phases and also the type of self-defects and complexes formed on their basis, and the mechanisms of electrical conductivity of ceramics. The aim of this work is to study the structure and electrical properties of ZnO-based ceramics doped with iron using various types of FexOy doping agents. Experimental The conventional ceramic technology was used to obtain the ZnO-based samples .The initial compounds for the preparation of the charge were high-purity powders of ZnO, and FexOy (FeO, Fe2O3, Fe3O4) oxides. For preparation of the investigated samples we used the compound (ZnO)90(FexOy)10, where the mass of the FexOy powders corresponded to 10 wt. %.The initial powders were milled for one hour in agate mortar with the addition of distilled water and then dried at room temperature. After this 3% (by weight) of PVA glue was added to the powder as a binder, then mixture were mixed and compacted into tablets with press. These tablets were subjecte[...]

Synthesis and properties of doped ZnO ceramics DOI:10.15199/48.2016.11.56

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In our work, we studied zinc oxide ceramic samples doped with aluminum and gallium. Structure peculiarities of ceramics depending on their synthesis regime were investigated by the SEM, EDX, XRD, and Raman spectroscopy methods. It was demonstrated that at some technological conditions the formation of indesirable phases of zinc aluminate or gallate may occur preventing an uniform material doping and reducing quality of samples. Single-phase ZnO ceramics were produced when the nanostructured alumina powders were used as a dopant source. The correlations between the synthesis regimes of ZnO ceramics and their electrophysical parameters essential for thermoelectric figure-of-merit (electrical conductivity and Seebeck coefficient) have been established. The best electrophysical characteristics were obtained when the nanostructured alumina produced by combustion in isopropyl alcohol was used as a dopant. Conductivity and Seebeck coefficient of such ceramics are equal to 3·103 S/m and -0.27 mV/K, respectively, corresponding to the power factor of 2.2·10-4 W/(m·K2). Streszczenie. W naszej pracy zbadaliśmy próbki ceramiki tlenku cynku domieszkowanej aluminium oraz galem. Specyfikę struktury ceramiki zależącą od warunków syntezy zbadano metodami SEM, EDX, XRD oraz spektroskopią Ramana. Zaprezentowano, że dla niektórych warunków technologicznych tworzą się niepożądane fazy glinianu cynku lub galusanu zapobiegając jednolitemu domieszkowaniu materiału oraz zmniejszając jakość próbek. Jednofazowa ceramika ZnO została uzyskana w czasie, gdy nanostrukturalny proszek tlenku aluminium był używany jako źródło domieszki. Określono powiązania pomiędzy warunkami otrzymywania ceramiki ZnO oraz jej elektro-fizycznymi parametrami niezbędnymi do termoelektrycznego współczynnika jakości (przewodnictwo elektryczne oraz współczynnik Seebeck`a). Najlepsze elektrofizyczne charakterystyki otrzymano, gdy używano jako domieszkę nanostrukturalny tlenek aluminiu[...]

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