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The crystal structure, magnetic and transport properties, including resistivity and thermopower, of Ni50Mn18.75Cu6.25Ga25 and Ni49.80Mn34.66In15.54 Heusler alloys were studied in the (10-400) K temperature interval. We show that their physical properties are remarkably different, thereby pointing to different origin of their magnetostructural transition (MST). A Seebeck coefficient (S) was found to pass minimum of about-20µV/K in respect of temperature for both compounds. It was shown that MST observed for both compounds results in jump-like changes in S for Gabased compound and jump in resistivity of about 20 and 200 µΩcm for Ga and In-based compounds, respectively. The combined analyzes of the present results with that from literature show that the density of states at the Fermi level does not change strongly at the MST in the case of Ni-Mn-In alloys as compared to that of Ni-Mn-Ga.

The effect of carbon filler on the electrical resistance and the thermopower of copper oxide-based composites produced by ceramic technology by hot pressing has been studied. It is found that the dependences of the electrical resistivity on the filler concentration are characteristic by S-like curves that are typical of percolation systems; in this case, the resistivity decreases more substantially as the carbon content increases as compared to the decrease in thermopower value, which is accompanied by the existence of the maximum of the factor of thermoelectric power near the percolation threshold. The studies of the temperature dependences of the resistivity and the thermopower at low temperatures show that, in the range 240–300 K, the predominant mechanism of the electrotransfer of all the composites under study is the hopping mechanism. At temperatures lower than 240 K, the composites with a nanocrystalline CuO matrix have a hopping conductivity with a variable hopping distance over localized states of the matrix near the Fermi level, which is related to the conductivity over intergrain CuO boundaries. A schematic model of the band structure of nanocrystalline CuO with carbon filler is proposed on the base of the analysis of the found experimental regularities of the electrotransfer.

The paper presents the results of studies of the structure, electrical and optical properties of ZnO films with Al content from 1 to 5 at.% obtained by the method of ion-beam sputtering of a composite ceramic target in an argon atmosphere. The composite target is a rectangular ZnO ceramic plate with several bands of Al 2 O 3 corundum unevenly distributed over the ZnO surface. In one sputtering cycle, 10 samples were obtained with an aluminum concentration of 1 to 5 at.% as the results of the analysis of the energy dispersion of the second electrons. After deposition, ZnO films were partially crystallized and contained one phase of hexagonal wurtzite with increased parameters a and c. The grain size of the films was estimated using the Scherrer equation and showed a tendency for the grain sizes to change with increasing Al concentration in ZnO films. X-ray diffraction data were confirmed by studying the surface morphology using atomic force microscopy. Measurement of the electrical parameters of the films showed that the smallest resistivity (~ 4 ·10 −3 Ohm · cm) is observed in ZnO films with 1 at.% Al. As the Al concentration in ZnO increases, the resistivity of the films increases, reaching the value ρ = 250 Ohm · cm at 5 at.% Al. A possible model of the effect of Al impurity on the electrical properties of ZnO films is considered. Studies of the optical properties of the samples showed that all films are highly transparent (~ 70 ÷ 90%) in the visible light range. The interference bandwidths provide an estimate of the value of the refractive index of ZnO : Al films. From the light absorption spectra, the values of the band gap of ZnO : Al samples were determined and a slight increase in the band gap of ZnO : Al with an increase in the Al concentration in films was established. The mechanism of this behavior of Al impurity in ZnO is discussed. Possible areas of application for ZnO films with Al impurities are considered.1 Воронежский государственный технический университет, ул. 20-летия Октября, 84, Воронеж, 394006, Россия 2 Воронежский государственный университет, Университетская пл., 1, Воронеж, 394018, Россия В работе представлены результаты исследований структуры, электрических и оптических свойств пленок ZnO с содержанием Al от 1 до 5 ат.%, полученных методом ионно-лучевого распыления составной керамической мишени в атмосфере аргона. Составная мишень представляет собой прямоугольную керамическую пластину ZnO с несколькими полосами корунда Al 2 O 3 , неравномерно распределенными на поверхности ZnO. За один цикл напыления были получены 10 образцов с концентрацией алюминия от 1 до 5 ат.% по данным энергодисперсионного анализа вторичных электронов. Сразу после напыления пленки ZnO были частично кристаллизованы и содержат одну фазу гексагонального вюрцита с увеличенными параметрами а и с. Размер зерна пленок оценивался по формуле Шеррера и показал тенденцию к изменению размеров зерен по мере увеличения концентрации Al в пленках ZnO. Данные