Abstract: Modern Electronic Materials 9(2): 77-90 DOI : 10.3897/j.moem.9.2.109923 Authors : Vladimir V. Sleptsov, Lev V. Kozhitov, Anna O. Diteleva, Dmitry Yu. Kukushkin, Alena V. Popkova : Physicochemical fundamentals have been developed for the basic design solutions and fabrication technologies of prospective electrolytic power cells with a reusable cell capacity of 350–500 W·h/kg at the first stage and 1000 W·h/kg at the second stage. Along with conventional chemical current sources and ionistors, there are emerging high-performance supercapacitor structures with thin dielectric in the double electric layer and hybrid capacitors in which energy is accumulated in the double electric layer and due to electrochemical processes. This approach reduces the internal resistance of the electrolytic cells thus decreasing the heat emission during operation and therefore providing for a higher specific energy capacity and operation safety, shorter charging time and an increase in specific power. Prospective anode is a nanostructured electrode material in the form of a carbon matrix filled with a nanostructured chemically active material. Promising carbon matrix fillers are Li and its alloys, Si, Al, Na, Sn, Mg, Zn, Ni, Co, Ag, as well as a range of other materials and their compounds. The effect of carbon material specific surface area, dielectric permeability and chemically active material addition on the specific energy capacity has been studied. Theoretical specific energy capacity of metal/air hybrid capacitors has been calculated. Thin-film technological system has been designed for new generation electrode materials in the form of carbon matrices with highly developed surface containing thin tunneling dielectrics and chemically active materials on dielectric surface. HTML XML PDF PubDate: Thu, 6 Jul 2023 13:14:08 +0300
Abstract: Modern Electronic Materials 9(2): 45-56 DOI : 10.3897/j.moem.9.2.109827 Authors : Aliaksei V. Pashkevich, Alexander K. Fedotov, Eugen N. Poddenezhny, Liudmila A. Bliznyuk, Vladimir V. Khovaylo, Vera V. Fedotova, Andrei A. Kharchenko : The thermal, electrical and thermoelectric properties of ZnO–MexOy ceramics with 1 ≤ x, y ≤ 3, where Me = Al, Co, Fe, Ni, Ti, have been studied. The specimens have been synthesized using the ceramic sintering technology from two or more oxides in an open atmosphere with annealing temperature and time variation. The structural and phase data on the ceramics have shown that post-synthesis addition of MexOy doping powders to wurtzite-structured ZnO powder causes Znx (Mе)yO4 spinel-like second phase precipitation and a 4-fold growth of ceramics porosity. Room temperature heat conductivity studies have testified to predominant lattice contribution. A decrease in the heat conductivity upon doping proves to be caused by phonon scattering intensification due to the following factors: size factor upon zinc ion substitution in the ZnO lattice (wurtzite) by MexOy doping oxide metal ions; defect formation, i.e., point defects, grain boundaries (microstructure refinement); porosity growth (density decline); secondary phase particle nucleation (Znx (Mе)yO4 spinel-like ones). The above listed factors entailed by zinc ion substitution for metal ions (Co, Al, Ti, Ni, Fe) increase the figure-of-merit ZT by four orders of magnitude (due to a decrease in the electrical resistivity and heat conductivity coupled with a moderate thermo-emf decline). The decrease in the electrical resistivity originates from a more homogeneous distribution of doping metal ions in the wurtzite lattice upon longer annealing which increases the number of donor centers. HTML XML PDF PubDate: Wed, 5 Jul 2023 21:43:07 +0300
Abstract: Modern Electronic Materials 9(2): 69-76 DOI : 10.3897/j.moem.9.2.109743 Authors : Aleksandr G. Belov, Vladimir E. Kanevskii, Evgeniya I. Kladova, Stanislav N. Knyazev, Nikita Yu. Komarovskiy, Irina B. Parfent'eva, Evgeniya V. Chernyshova : The optical and electrical properties of zinc-doped Cz p-GaAs have been studied. Reflection spectra of ten p-GaAs specimens have been taken in the mid-IR region. Van der Pau galvanomagnetic, electrical resistivity and Hall coefficient measurements have been carried out for the same specimens (all the measurements were carried out at room temperature). The reflection spectra have been processed using the Kramers–Kronig relations, spectral dependences of the real and imaginary parts of the complex dielectric permeability have been calculated and loss function curves have been plotted. The loss function maximum position has been used to calculate the characteristic wavenumber corresponding to the high-frequency plasmon-phonon mode frequency. Theoretical calculations have been conducted and a calibration curve has been built up for determining heavy hole concentration in p-GaAs at T = 295 K based on known characteristic wavenumber. Further matching of the optical and Hall data has been used for determining the light to heavy hole mobility ratio. This ratio proves to be in the 1.9–2.8 range which is far lower as compared with theoretical predictions in the assumption of the same scattering mechanism for light and heavy holes (at optical phonons). It has been hypothesized that the scattering mechanisms for light and heavy holes differ. HTML XML PDF PubDate: Wed, 5 Jul 2023 09:09:15 +0300
Abstract: Modern Electronic Materials 9(2): 57-68 DOI : 10.3897/j.moem.9.2.109980 Authors : Konstantin V. Feklistov, Aleksey G. Lemzyakov, Alexander A. Shklyaev, Dmitry Yu. Protasov, Alexander S. Deryabin, Evgeny V. Spesivsev, Dmitry V. Gulyaev, Alexey M. Pugachev, Dmitriy G. Esaev : In2O3 : Er films have been synthesized on silicon substrates by RF magnetron sputter deposition. The currents through the synthesized metal/oxide/semiconductor (MOS) structures (Si/In2O3 : Er/In-contact) have been measured for n and p type conductivity silicon substrates and described within the model of majority carrier thermoemission through the barrier, with bias voltage correction to the silicon potential drop. The electron and hole injection barriers between the silicon substrate and the film have been found to be 0.14 and 0.3 eV, respectively, by measuring the temperature dependence of the forward current at a low sub-barrier bias. The resulting low hole injection barrier is accounted for by the presence of defect state density spreading from the valence band edge into the In2O3 : Er band gap to form a hole conduction channel. The presence of defect state density in the In2O3 : Er band gap is confirmed by photoluminescence data in the respective energy range 1.55–3.0 eV. The band structure of the Si/In2O3 : Er heterojunction has been analyzed. The energy gap between the In2O3 : Er conduction band electrons and the band gap conduction channel holes has been estimated to be 1.56 eV. HTML XML PDF PubDate: Wed, 5 Jul 2023 09:09:15 +0300
Abstract: Modern Electronic Materials 9(2): 39-44 DOI : 10.3897/j.moem.9.2.108161 Authors : Maxim V. Silibin, Dmitry A. Kiselev, Sergey I. Latushko, Dmitry V. Zheludkevich, Polina A. Sklyar, Dmitry V. Karpinsky : The crystal structure, piezoelectric and magnetic properties of BiMn1-xFexO3 (x ≤ 0.4) solid solutions synthesized using different solid state reactions from a stoichiometric mixture of simple oxides at high pressures and temperatures have been studied. The structure of the composition undergoes a concentration phase transition from the monoclinic to the orthorhombic structure. The formation of the orthorhombic phase is observed at the concentration x ≈ 0.2 and is accompanied by the destruction of the dz2 orbitals of the Mn3+ ions causing the stabilization of a homogeneous magnetic state. The solid solutions containing 0.2 ≤ x ≤ 0.4 exhibit a non-zero piezoresponse and may have ferroelectric or magnetic domain structures, the ferroelectric switching voltage decreasing with an increase in the iron concentration while the remanent magnetization decreases. The highest piezoresponse signal is observed for the BiMn0.7Fe0.3O3 solid solution. The relationship between the chemical composition, type of crystal structure, piezoelectric and magnetic properties of the BiMn1-xFexO3 solid solutions has been verified. Due to the combination of magnetic and electric dipole ordering these materials show good promise for practical applications. HTML XML PDF PubDate: Mon, 3 Jul 2023 09:01:11 +0300
Abstract: Modern Electronic Materials 9(1): 33-38 DOI : 10.3897/j.moem.9.104830 Authors : Izatullo N. Ganiev, Jamshed H. Jayloev, Ermakhmad J. Kholov, Nargis I. Ganieva : The design of new materials intended for operation under severe conditions faces the task of rendering the materials corrosion resistant. The practical solution of this task is interrelated with the knowledge of corrosion protection of metals and alloys. The use of conducting aluminum alloys for the manufacture of thin wire may encounter specific problems. This is caused by the insufficient strength of these alloys and a small number of kinks before fracture. Aluminum alloys have been developed in recent years which even in a soft state have strength characteristics that allow them to be used as a conductive material. The E-AlMgSi (Aldrey) aluminum alloy is a well-known conducting alloy. This alloy is a heat-strengthened one, possessing good plasticity and high strength. After appropriate heat treatment this alloy acquires high electrical conductivity. Wires made from this alloy are almost exclusively used for air transmission lines. This work presents data on the corrosion behavior of calcium containing E-AlMgSi (Aldrey) aluminum conducting alloy in 0.03, 0.3 and 3.0% NaCl electrolyte medium. The anodic behavior of the alloy has been studied using a potentiostatic technique with a PI-50-1.1 potentiostat at a 2 mV/s potential sweep rate. Calcium doping of the E-AlMgSi (Aldrey) aluminum alloy increases its corrosion resistance by 15–20%. The corrosion, pitting and repassivation potentials of calcium doped alloys shift toward the positive region. An increase in the sodium chloride electrolyte concentration leads to a decrease in these potentials. HTML XML PDF PubDate: Fri, 14 Apr 2023 19:28:49 +030
Abstract: Modern Electronic Materials 9(1): 1-7 DOI : 10.3897/j.moem.9.1.103652 Authors : Nikolay A. Kalanda, Marta V. Yarmolich, Alexander V. Petrov, Olga Yu. Ponomareva, Karine K. Abgaryan, Nguyen Huy Dan : In this article, a consistent study of phase transformations during the crystallization of YBa2Cu3O7-δ compound was carried out using XRD, thermogravimetric and differential thermal analyzes, as well as optical microscopy. When studying the microstructure and elemental composition in the reaction zone in the process of obtaining single crystals by the crucible-less method, the products of chemical reactions were identified depending on the composition of the reacting components and synthesis conditions. It has been established that the use of precursors Y2BaCuO5, YBa4Cu3O9-δ and ВаCu2O2 as initial reagents has made it possible to carry out the direct synthesis of YBa2Cu3O7-δ single crystals without the formation of intermediate phases. The superconductor has been synthesized at 1270 K on single-crystal MgO substrates with the (001) orientation, since their surface is poorly wetted by the melt solution and stimulates the YBa2Cu3O7-δ nucleation process. This ensures the minimum loss of the liquid fraction formed in the sample. The growth conditions for YBa2Cu3O7-δ single crystals have been studied and optimized. It has been experimentally revealed that the use of combined cooling conditions leads to an increase in the size of single crystals and a reduction in the time of their growth without changing the quality and crystal structure. The investigation showed that the largest volume (50 mm3) was achieved for single-phase YBa2Cu3O7-δ single crystals grown at a cooling rate of 0.5 deg/h in the temperature range 1260–1240 K and at a rate of 1.2 deg/h in the range 1240–1210 K. An analysis of the Laue rotation lines obtained in this work indicates the presence of blocks in single crystals cooled in the temperature range 1243–1193 K at a cooling rate of 1.5 deg/h and their absence in crystals cooled at 1.2 deg/h. An assessment of the degree of perfection of the structure by the width of the rocking curves at half-height of the X-ray reflection (006) showed that the width of the rocking curves of 0.36 deg indicates the absence of structural defects, such as twins, blockiness, and shear defects. HTML XML PDF PubDate: Fri, 31 Mar 2023 17:36:18 +030
Abstract: Modern Electronic Materials 9(1): 25-31 DOI : 10.3897/j.moem.9.1.104020 Authors : Evgeniya V. Zabelina, Nina S. Kozlova, Oleg A. Buzanov, Elena D. Krupnova : Single crystal calcium molybdate CaMoO4 is a well-known material. However the interest to CaMoO4 has recently grown due to a number of its important applications including as a working material in cryogenic scintillation bolometers. CaMoO4 single crystals acquire blue color during growth due to the presence of color-center type defect centers which are unacceptable for optical applications. Color can be eliminated through annealing in an oxygen containing atmosphere, following which required optical components can be produced from the single crystals by mechanical treatment (cutting, polishing etc.). Therefore assessment of the mechanical properties of these single crystal materials is an important task for the optimal solution of issues occurring in the fabrication of optical components and their further practical application. There are but scarce data on the mechanical properties of CaMoO4, and the available ones have been reported without allowance for anisotropy. There is a significant scatter of data on the Mohs hardness of the single crystals, ranging from 3.3 to 6 in different publications. In this work we present data on calcium molybdate single crystals in the initial state and after high-temperature anneals of different durations in an oxygen containing atmosphere. We show that long-term annealing leads to decolorization of the crystals. Calcium molybdate single crystals prove to be quite brittle: the brittleness index Zp of the crystals in the initial state is the highest and equals 5, while annealing reduces the brittleness index to 4. The Palmqvist toughness factors S have been calculated The limit indentation destruction loads Flim have been determined and annealing in an oxygen containing atmosphere has been shown to increase Flim by 2.5 times for the Z cut and by 10 times for the X cut. The microhardness of the crystals has been shown to exhibit a II type anisotropy: the microhardness of all the specimens was higher for the Z cut than for the X cut. The microhardness anisotropy coefficients KH of the specimens have been evaluated. The bond ionicity degree I has been calculated on the basis of the experimentally measured microhardness. HTML XML PDF PubDate: Fri, 31 Mar 2023 17:30:03 +030
Abstract: Modern Electronic Materials 9(1): 9-14 DOI : 10.3897/j.moem.9.1.103598 Authors : Igor I. Maronchuk, Daria D. Sanikovich, Elena V. Davydova, Nataliya Yu. Tabachkova : Problems of the synthesis of cadmium telluride powders having required purity and grain size distribution for high-efficiency solar cells have been analyzed. A test batch of powders has been synthesized and used for the manufacture and study of thin-film solar cell specimens exhibiting parameters compliant with the best worldwide standards. The phase composition of the powders has been studied using X-ray diffraction. Structural analysis and elemental composition measurements have been carried out using electron microscopy. The effect of free tellurium phase in the powders on the endurance of devices manufactured from the powder has been described. We show that excess tellurium in the film specimens whose atoms are predominantly localized along grain boundaries may cause temporal degradation of the electrical properties of the manufactured solar cells due to changes in the parameters of the crystalline structure of the cadmium telluride phase which are caused in turn by changes in the stoichiometric composition of the material. Structural studies of the film specimens have not revealed differences in the film structure before and after endurance tests. A new cadmium telluride powder process route has been developed, proven and tested taking into account the advantages and drawbacks of the previously used process and experiments confirming the correctness of the technical solutions chosen have been conducted. HTML XML PDF PubDate: Fri, 31 Mar 2023 13:51:06 +030
Abstract: Modern Electronic Materials 9(1): 15-24 DOI : 10.3897/j.moem.9.1.104721 Authors : Dmitriy G. Muratov, Lev V. Kozhitov, Irina V. Zaporotskova, Alena V. Popkova, Vitaly A. Tarala, Evgenij Yu. Korovin, Artem V. Zorin : FeCoCu ternary nanoparticles distributed and stabilized in the carbon matrix of FeCoCu/C metal-carbon nanocomposites have been synthesized using controlled IR pyrolysis of precursors consisting of the “polymer / iron acetylacetate / cobalt and copper acetates” type system obtained by joint dissolution of components followed by solvent removal. The effect of the synthesis temperature on the structure, composition and electromagnetic properties of the nanocomposites has been studied. By XRD was shown that the formation of the FeCoCu ternary nanoparticles occurs due to the interaction of Fe3С with the nanoparticles of the CoCu solid solution. An increase in the synthesis temperature leads to an increase in the size of the metal nanoparticles due to their agglomeration and coalescence as a result of matrix reconstruction. Furthermore, ternary alloy nanoparticles having a variable composition may form depending on the synthesis temperature and the content ratio of the metals. Raman spectroscopy has shown that the crystallinity of the carbon matrix of the nanocomposites increases with the synthesis temperature. The frequency responses of the relative permittivity and permeability of the nanocomposites have been studied at 3–13 GHz. It has been shown that a change in the content ratio of the metals noticeably increases both the dielectric and the magnetic losses. The former loss is caused by the formation of a complex nanostructure of the nanocomposite carbon matrix while the latter one originates from an increase in the size of the nanoparticles and a shift of the natural ferromagnetic resonance frequency to the low-frequency region. The reflection loss has been calculated using a standard method from the experimental data on the frequency responses of the relative permittivity and permeability. It has been shown that the frequency range and the absorption of electromagnetic waves (from –20 to –52 dB) can be controlled by varying the content ratio of the metals in the precursor. The nanocomposites obtained as a result of the experiment deliver better results in comparison with FeCo/C nanocomposites synthesized under similar conditions. HTML XML PDF PubDate: Fri, 31 Mar 2023 10:39:35 +030
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