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Donetsk National Technical University, created in 1921, became a largest center of training of highly-qualified engineers and researchers. Facts of history of one of basic departments of the university – department of metallurgy and heat-power engineering presented. Its role in the forming and development of the leading Donbass industry – metallurgy – shown.

Resistivity superconducting transition has been for the first time found in single crystal of two-component 0.95(CdSb)–0.05(NiSb) system. End members of the system are not superconductors under normal conditions. Insulating behavior in temperature dependence of the electrical resistivity, which is due to hopping conductivity, precedes the transition. The resistivity superconducting transition is rather broad, since at cooling down the electrical resistivity starts to fall at 10.5 K, whereas zero resistivity is reached only at ~2.3 K. Longitudinal magnetic field gradually depresses superconductivity and shifts the superconducting transition to lower temperatures. Under magnetic field above 0.5 T, superconductivity is totally destroyed. Main features observed in the resistivity superconducting transition, including its unusually big width and insulating electrical behavior above the transition, can be related to inhomogeneity of the single crystal studied. According to XRD and SEM examinations, the single crystal consists of major CdSb phase and minor NiSb phase. The NiSb phase forms inhomogeneities in the CdSb matrix. Micro-sized needle-like NiSb crystals and nano-sized Ni1-xSbx clusters can be considered as typical inhomogeneities.

We describe the results for full-scale experimental test production of high-basicity sinter (basicity 2.0–5.0) at the Enakievo Metallurgical Plant Sinter Shop. As sinter basicity increased from 2.0 to 5.0, the iron content of the sinter decreased from 53.05% to 32.24%, and the ferrous oxide concentration decreased from 17.55% to 9.29%. However, the strength specifications of the sinter were improved: The concentration of 0–5-mm fines decreased from 19.32% to 15.89%, and the yield of +5 mm size class in a drum test increased from 65.9% to 72.3% through optimization of the sintering process parameters. The use of high basicity sinter in blast-furnace smelting reduced the specific consumption of lime in the blast-furnace charge from 233.9 kg/metric ton of cast iron (at sinter basicity 2.0) to 103.5 kg/metric ton (at basicity 4.5) and, correspondingly, the specific feed rate for coke during castiron production decreased from 538.1 kg/metric ton to 476.6 kg/metric ton.

Specific features and regularities of self-assembly and self-organization of multi-walled carbon nanotubes (MWCNT) have been studied for diffusion-limited conditions (method of drops) in water-based (deionized water) colloidalal solutions with aerosil exposed to DC electric fields with magnitudes of 15 to 25 V. Studies of hierarchical structure formation during drop evaporation in uniform electric fields have revealed the formation of 40–120 nm sized linear piecewise formations, 25–45 nm sized fractal structures and 250 nm sized diffuse structures from MWCNT – COOH + aerosil + H2Odw. The structures have been studied using confocal microscopy, X-ray diffraction, Raman scattering, atomic force microscopy, IR spectroscopy and scanning electron microscopy. The sizes of the observed micro- and nanostructures decrease following the hyperbolic law d = 1/U in the approximation d → 2R, their growth rate increasing as U2. We show that intense ultrasonication of functionalized MWCNT – COOH + aerosil + H2Odw in colloidal solutions causes the formation of the so-called “breathing" modes in axis centered single-walled carbon nanotubes. This is confirmed by short-wave Raman scattering excitation and enables the existence of both combined sp2-hybridization types with π- and σ- carbon bonds and the metallic and semiconductor conductivity types in the material thus showing good promise of these structures for nanoelectronics.

Magnetic properties of two-phase granular semiconductor–ferromagnet GaSb–MnSb films obtained by pulsed laser deposition as a function of growth temperature and postgrowth annealing were stu-died.

The method for calculating indicators of blast furnace smelting with replacement of part of coke with additional fuels has been developed on the basis of full and complex compensation and compensating measures. Efficiency of the use of natural gas and pulverized coal in the blast furnace conditions of the Enakievo Metallurgical Plant was calculated and it has been confirmed as rather high. Increase in the consumption of natural gas from the baseline (71.8 m3/t of iron) to 110 m3/t ensures a corresponding increase in productivity of the blast furnace to 107.6 % and a decrease in the consumption of coke to 417.3 kg/t of iron (–38.4 kg/t, –8.42 %). Replacing natural gas with pulverized coal in the amount of 160 kg/t of iron made it possible to completely remove it from the blast. At the same time, coke consumption decreased to 354.59 kg/t of iron (–101.1 kg/t; –22.18 %). Increasing the consumption of pulverized coal fuel up to 200 kg/t of iron with compensation of the blast temperature of1200 °Cand oxygen of the blast of 25 % provides an increase in the productivity of the blast furnace to 105.8 % and reduction of coke consumption to 303.8 kg/t of iron (–151.9 kg/t, –33.33 %). High efficiency of the use of pulverized coal in conditions of the Enakievo Metallurgical Plant is explained by its lower cost compared to natural gas, high carbon content in coal and a significantly lower effecton the theoretical combustion temperature and other technological parameters.

Thin (~50 nm) cadmium arsenide films have been grown by magnetron sputtering on single-crystal silicon and sapphire substrates. Using X-ray diffraction, scanning electron microscopy, atomic force microscopy, and Raman spectroscopy, the composition of the films has been shown to correspond to the Cd3As2 stoichiometry. Along with the α-Cd3As2 phase, the films contained trace levels of the α'-Cd3As2 phase. Annealing at 520 K led to recrystallization and the formation of [112] textured films on single-crystal silicon substrates. In the annealed films, the crystallite size evaluated using the Debye–Scherrer equation was ~30 nm.

The vapor phase growth of Cd3As2—Zn3As2 (in the following (Cd1−x Znx)3As2 solid solutions process is described. The (Cd0,993 Zn0,007)3As2 solid solution single crystals were synthesized. Scanning electron microscopy and electron diffraction data suggest high crystalline quality of studied sample. Its structure and surface morphology, indicating the presence of growth nuclei and cleavage planes, were investigated. Giant anisotropic magnetoresistance and Shubnikov — de Haas oscillations were observed at low temperatures. Obtained results suggests that peculiarities of Dirac semimetal phase persist in (Cd1−x Znx)3As2 solid solution at low zinc content. At the same time, there are indications of some differences with initial Cd3As2 properties.

We observed a temperature-controlled increase in the magnetic anisotropy and its dispersion in thin GaMnSb films with MnSb nanoinclusions obtained by pulsed laser deposition. The data of transmission electron microscopy indicate that in the samples, a transition of the crystalline structure of magnetic MnSb nanoinclusions from hexagonal (spatial group (sp. gr.) P63/mmc) to cubic (sp. gr. F-43m) takes place. Analysis of the temperature dependences of the magnetic moment m(T), measured using a SQUID magnetometer, obtained for both unannealed and annealed samples cooled in a zero magnetic field and a magnetic field of 10 kOe, indicates that this mechanism is not unique. In unannealed samples, the distribution of the magnetic anisotropy of MnSb nanoinclusions, determined from the dependences of m(T), is unimodal. In the annealed samples, the same dependence becomes multimodal. This means that several thermally activated processes occur in the samples during annealing, resulting in several “populations” of nanoinclusions present in the annealed thin films. The contribution to the increase in the magnetic anisotropy during annealing can result in the structural phase transition, the mismatch of the crystal lattices between MnSb and GaSb, an increase in the average volume of MnSb nanoinclusions, and a change in their stoichiometry.

We report a highly anisotropic magnetoresistance of (Cd0.993Zn0.007)3As2 single crystals, which have been synthesized by the vapor-phase growth. Scanning electron microscopy and electron diffraction data confirm the high crystalline quality of obtained samples. Studied samples exhibit specific features such as octahedral nuclei growth and step-like morphology of the surface formed by {112} planes. The giant anisotropic magnetoresistance and Shubnikov-de Haas oscillations have been observed at low temperatures. The results suggest the existence of the Dirac semimetal phase in (Cd1 −xZnx)3As2 solid solution with low zinc content. Thus, the observed magnetoresistance anisotropy is partially attributed to the chiral anomaly.

Manganese pnictides MnP, MnAs, and MnSb are ferromagnetic semimetals and have some unique properties, namely, high Curie points, considerable magnetic anisotropy, and giant magnetocaloric effect. Experimental and theoretical studies showed that these compounds can enter a superconducting state under high external pressures. Manganese pnictides are widely used in design of hybrid structures, such as spin diodes and transistors, in combination with semiconductors. The survey focuses on the design and properties of such the structures.

Protocols for sputtering stoichiometric aluminum antimonide thin films were developed by calculating aluminum and antimony vapor condensation flux densities. Aluminum and antimony were sputtered separately. The high chemical reactivity of nanosized aluminum and antimony films made it possible to reduce the synthesis temperature considerably (far below the melting point of the compound). The synthesis involved thermal annealing. The reaction between aluminum and antimony films started at 470°С. Optimal AlSb formation parameters comprise annealing at 540°С for at least 10 h. Film synthesis steps were studied by X-ray powder diffraction, optical, electron, and atomic force microscopy. The composition was monitored by energy dispersive X-ray spectra. The films were found to have hole conductivity; the 300-K charge density and charge mobility in the films are 1 × 1019 cm–3 and 1 × 102 cm2/(V s), respectively.

Conditions and mechanisms of controlled variation of the magnetic anisotropy of GaMnSb films containing magnetic MnSb nanoinclusions by means of heat treatment have been determined. For this purpose, the temperature and magnetic-field dependences of the magnetic moments of samples before and after thermal annealing were measured using a SQUID magnetometer. It is established that the heat treatment of GaMnSb films leads to a significant increase in the values of characteristics determined by the magnetic anisotropy, including the growth of blocking temperature (from 95 to 390 K) and the magnetic anisotropy field (from 330 to 630 Oe). Results of transmission electron microscopy investigation indicate that a change in the magnetic anisotropy of GaMnSb films as a result of their thermal annealing can be related to a transition of the crystalline structure of magnetic MnSb nanoinclusions from hexagonal (space group P62/mmc) to cubic (space group F-43m).

We have studied the properties of relatively thick (about 120 nm) magnetic composite films grown by pulsed laser deposition using the eutectic compound (GaSb)0.59(MnSb)0.41 as target for sputtering. For the studied films we have observed ferromagnetism and an anomalous Hall effect above room temperature, confirming the presence of spin-polarized carriers. Electron microscopy, atomic and magnetic force microscopy results suggest that the films under study have a homogenous columnar structure in the bulk while MnSb inclusions accumulate near the surface. This is in good agreement with the high mobility values of charge carriers. Based on our data we conclude that the magnetic and magnetotransport properties of the films at room temperature are defined by the MnSb inclusions.

Based on the results of the Shubnikov-de Haas oscillations study in single-crystalline diluted magnetic semiconductors (Cd1−x−yZnxMny)3As2 (CZMA) with х + y = 0.2 and Mn content (у = 0.02, 0.04, 0.06, 0.08) at temperatures T = 4.2 to 30 K and magnetic fields B = 0 to 12 T under hydrostatic pressure p = 0 and 10 kbar, the values of the phase shift β, indicating the existence of the Berry phase in all samples were determined. Thickness of two-dimensional surface topological nanolayers in CZMA (х + y = 0.2) single crystals was defined. The rise in Mn concentration led to an increase in the concentration of charge carriers in the 2D surface layers n 2D and a decrease in its mobility μ 2D. The reduced cyclotron mass m с (0)/m 0, depending on the Fermi wave vector k F , experimentally observed from the Shubnikov-de Haas oscillations, which was in a good agreement with the prediction theory of linear dependence and experimental results in topological insulator single crystals Bi2Se3 indicated that Dirac fermions were present in a diluted magnetic semiconductor CZMA system with х + y = 0.2. The damping of the Shubnikov-de Haas oscillations for pressures p = 0 and 10 kbar in the CZMA sample (х + y = 0.2; y = 0.2) was found to be associated with an amplitude decrease by spin splitting (Zeeman effect). From the analysis of experimental data, the effective Lande factor g = 7.63 and 7.87 and the band gap Δ =35.3 and 9.7 meV at p = 0 and 10 kbar, respectively, were obtained.

We determined, using a set of physicochemical methods, including X-ray powder diffraction (XRD), differential thermal analysis, and microstructure studies, that the CdAs2–Cd3As2–MnAs ternary system is bounded by three eutectic-type quasi-binary sections: Cd3As2–MnAs, CdAs2–MnAs, and Cd3As2–CdAs2. For Cd3As2–MnAs and CdAs2–MnAs sections, the eutectic coordinates are, respectively, 75 mol % Cd3As2 + 25 mol % MnAs, T m.eut = 604°C; and 92 mol % CdAs2 + 8 mol % MnAs, T m.eut = 608°C. These are rod eutectics. Manganese solubilities in Cd3As2 and CdAs2 phases are insignificant and, according to XRD and SEM, they do not exceed 1 at %. The binary eutectics of the quasi-binary sections form ternary eutectic Cd3As2 + CdAs2 + MnAs, whose average composition as probed by SEM is 34.5 at % Cd, 63 at % Cd and 2.5 at % As and T m.eut = 600°C. Cadmium and manganese arsenide alloys are ferromagnets with the Curie point at ~320 K. The magnetic and electric properties are due to ferromagnetic MnAs microinclusions.

We report on the characterization and magnetotransport measurements as a function of applied pressure for Mn-doped CdSb magnetic semiconductor. A pressure-induced negative magnetoresistance (MR) is observed in the polycrystalline ingots of p -Cd 1- x Mn x Sb with x = 0.03 and х = 0.06 at hydrostatic pressure up to 7 GPa and room temperatures. We found that a magnitude of negative MR is strongly depends from application of pressure, magnetic field and chemical composition. Only in a low magnetic field of H ∼1 kOe we observed a weak positive MR that changes its sign with increase in pressure or magnetic field. The behavior of negative MR is closely linked with the magnetic inclusions in the studied samples, as it evident from analysis of composition and distribution of elements on the surface.

We demonstrate that measurements of the photo-electromagnetic effect using terahertz laser radiation provide an argument for the existence of highly conductive surface electron states with a spin texture in Dirac semimetals (Cd1−xZnx)3As2. We performed a study on a range of (Cd1−xZnx)3As2 mixed crystals undergoing a transition from the Dirac semimetal phase with an inverse electron energy spectrum to trivial a semiconductor with a direct spectrum in the crystal bulk by varying the composition x. We show that for the Dirac semimetal phase, the photo-electromagnetic effect amplitude is defined by the number of incident radiation quanta, whereas for the trivial semiconductor phase, it depends on the laser pulse power, irrespective of wavelength. We assume that such behavior is attributed to a strong damping of the interelectron interaction in the Dirac semimetal phase compared to the trivial semiconductor, which may be due to the formation of surface electron states with a spin texture in Dirac semimetals.

The features and regularities of self−assembly and self− organization processes in the diffusion−limited conditions (method of drops) of aqueous (deionized water) colloidal solutions of multi−walled carbon nanotubes with aerosil under the influence of constant electric fields with a value varying of direct current voltage from 15 to 25 V have been studied. During droplet evaporation in an electric field, the processes of hierarchical structuring have been studied and the formation of linear piecewise with the sizes of 40—120 nm, fractal structures 25—45 nm and diffusion structures 250 nm from MWCNT — COOH + aerosil + H 2 O DI have been observed. These structures have been analyzed by methods of confocal microscopy, X−ray powder diffraction, Raman scattering, atomic force microscopy, FT−IR spectroscopy and scanning electron microscopy. The size of micro− and nanostructures in hyperbolic dependence of d = 1/U in the approximation d → 2R, and their growth rate increases as U 2 have been observed. Intensive ultrasonic dispersion proves to produce a centrally−axial arrangement located SWCNT after ultrasonic dispersing of functionalized MWCNT — COOH + aerosil + H 2 O DI colloidal solution, as confirmed by excitation of Raman lines in the low−wavelength region, the so−called breathing mode, resulting in the existence of mixed types sp 2 −hybridization with π− and σ−carbon bonds, as well as metallic and semiconducting conductivity, which indicates great practical importance of this structuring for the development of nanoelectronics.

We report an experimental observation of superconductivity in ${\mathrm{Cd}}_{3}{\mathrm{As}}_{2}$ thin films without application of external pressure. The films under study were synthesized by magnetron sputtering. Surface studies suggest that the observed transport characteristics are related to the polycrystalline continuous part of the investigated films with a homogeneous distribution of elements and the Cd-to-As ratio close to stoichiometric ${\mathrm{Cd}}_{3}{\mathrm{As}}_{2}$. The latter is also supported by Raman spectra of the studied films where two pronounced peaks inherent to ${\mathrm{Cd}}_{3}{\mathrm{As}}_{2}$ were observed. The obtained x-ray diffraction patterns for studied films also correspond to the ${\mathrm{Cd}}_{3}{\mathrm{As}}_{2}$ lattice. The formation of a superconducting phase in the films under study is confirmed by the characteristic behavior of the temperature and the magnetic field dependence of the sample resistivity, as well as by the presence of pronounced zero-resistance plateaus in the $dV/dI$ characteristics. The corresponding ${H}_{c}\text{\ensuremath{-}}{T}_{c}$ plots reveal a clearly pronounced linear behavior within the intermediate temperature range, similar to that observed for bulk ${\mathrm{Cd}}_{3}{\mathrm{As}}_{2}$ and ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ films under pressure, suggesting the possibility of a nontrivial pairing in the films under investigation. We discuss a possible role of the sample inhomogeneities and crystal strains in the observed phenomena.

Eutectic composites in the InSb–MnSb system have been grown by the Bridgman method in vertical geometry using a growth charge of eutectic composition. The composites consisted of a [110]-oriented single-crystal InSb matrix and single-crystal MnSb needles aligned in the growth direction. As the solidification rate was raised from 0.5 to 6 mm/h, the length of the needles increased, whereas their diameter dropped from 20 to 4 µm. Further raising the solidification rate led to spontaneous crystallization. Characteristically, the electrical and magnetic properties of the eutectic composites in the InSb–MnSb system were found to exhibit large anisotropy. The low-temperature resistivity of the composites across the needles is four to five times that along the needles. With increasing temperature, the resistivity ratio drops by up to a factor of 2–3. This can be accounted for in terms of a geometric factor. The electrical conductivity of the composites is determined primarily by the MnSb phase, whose volume along the growth direction was considerably larger. According to magnetic measurements, the eutectic composites in the InSb–MnSb system are ferromagnets with a Curie temperature of ≃ 600 K.

Charge carriers parameters on a 2D-layer surface for (Cd1−x−yZnxMny)3As2 (y = 0.08) (the concentration n 2 D = 1.9 × 1012 cm–2, the effective value of the 2D-layer d 2 D = n 2 D / n 3 D = 14.5 nm, the wave vector k F = 0.1 nm–1, the charge carriers relaxation time due to dispersion τ D = 1.8 × 10–13 s, the velocity of charge carriers on Fermi surface v F = ℏ k F / m c = 2.65 × 105 m s−1, the mean free path l F = v F τ D = 47.7 nm) were determined. It was found that the dependence of the cyclotron mass m с (0)/m0 on Fermi wave vector k F for (Cd1−x−yZnxMny)3As2 (y = 0.08) is in compliance with a theoretical linear dependence, that describes mass-less Dirac fermions.

We studied the effect of high pressure on the border of intrinsic conductivity in CdSb doped with 0.5%Ni, the structure of which is needlelike due to spherical extended NiSb inclusions. The bandgap state has been found to be strongly governed by a structural transition in the composite structure. A pressure-induced phase exhibits an activation behavior only upon heating with a very low energy gap by 0.05 eV at 5.32 GPa, while metallic conductivity appears upon subsequent cooling, which is attributed to the instability of the cadmium antimonide structure. Room-temperature Hall effect measurements confirm that the high-pressure phase is not fully metallized, yielding a hole concentration of 4.08 × 1018 cm−3 at the onset of structural transition and a reduced magnitude by order in this phase.

Zn3As2 + MnAs composite films 0.7–0.9 μm in thickness have been grown on silicon and sapphire substrates by vacuum thermal evaporation. As shown by scanning electron microscopy, the films consisted of spherical grains ranging in size from 5 to 150 nm and had uniform Zn, As, and Mn elemental concentration distributions. The grains were made up of magnetic clusters less than 10 nm in size, as determined by atomic force microscopy, magnetic force microscopy, and small-angle X-ray scattering.

Effect of charge carriers concentration on magnetic parameters of the ferromagnetic MnSb nanoclusters as well as opposite effect of cluster magnetization on spin polarization of holes and magnetoresistance were observed in GaSbMn thin films. Microwave magneto-resistance effect is evidence of the charge carriers spin filtering by ferromagnetic clusters.

The influence of the charge carrier concentration on the magnetic properties of GaSb-MnSb alloys is studied. The ferromagnetism of GaSb-MnSb films is caused by the presence of MnSb granules and manifests itself in both magnetometric measurements and the presence of an anisotropic magnetoresistance and the anomalous Hall effect. Electric conduction is executed by charge carriers (holes) in a GaSb matrix. The magnetization of clusters depends on stoichiometry and the concentration of Mn2+ and Mn3+ ions, which is specified by the film growth conditions. At high film growth temperatures, ferromagnetic clusters containing Mn2+ ions mainly form. At low growth temperatures, an antiferromagnetic phase containing Mn3+ ions forms.

Six equilibrium samples of (1 − x )ZnSnAs 2 + x MnAs ( x = 0, 0.1, … 0.5 mol.%) and one quenched sample of 0.8ZnSnAs 2 + 0.2MnAs were synthesized. The samples were studied with X-ray, DTA, MFM and SEM. The system ZnSnAs 2 –MnAs has eutectic point with coordinates 45 ± 2 mol.% MnAs and 744 ± 10 °C. The eutectic compound contains isolated, practically round shape inclusions of MnAs in the host ZnSnAs 2 . Based on the earlier investigations, we predict negative magnetoresistance effect in this semiconductor–ferromagnet compound with nanogranular structures. The lattice parameters of ZnSnAs 2 without manganese arsenide and ZnSnAs 2 + MnAs are similar, meaning MnAs does not influence the lattice parameters. Therefore one can make conclusion that solubility of the MnAs in ZnSnAs 2 is low. The lattice parameters are a = 5.8509 A, c = 11.7135 A for tetragonal and a = 5.8558 A for cubic symmetry. The density of the ZnSnAs 2 calculated from the HR-XRD is 5.5314 g/cm 3 for tetragonal and 5.5230 g/cm 3 for cubic structure.

We study InSb:Mn polycrystals with different values of the Mn content. In these samples, two ferromagnetic phases have been found: MnSb nanoinclusions with TC ≈ 600 K and an InMnSb magnetic host with TC below 10 K. The magnetic field dependence obtained for the measured Hall resistance exhibits a nonlinear behavior within a wide temperature range. At high temperatures, such a behavior can be attributed to the existence of two types of charge carriers, namely, light and heavy holes. At temperatures below the Curie point of the InMnSb host, the anomalous Hall effect contributing to the nonlinearity of the Hall resistance has been observed. Ferromagnetic MnSb inclusions do not contribute to the anomalous Hall effect. They do not lead to any spin polarization of charge carriers owing to the Schottky barrier, which surrounds these inclusions and prevents their interaction with charge carriers. A method has been proposed for distinguishing the anomalous Hall component in the case where the Hall resistance includes a nonlinear contribution of a different nature.

We performed a study of a range of (Cd 1−x Zn x ) 3 As 2 mixed crystals undergoing a transition from the Dirac semimetal phase to trivial semiconductor at variation of the composition x. We show that for the Dirac semimetal phase, the photoelectromagnetic effect amplitude is defined by the number of incident radiation quanta, whereas for the trivial semiconductor phase, it depends on the power in a laser pulse irrespective of its wavelength. We assume that such behavior is attributed to formation of surface electron states with a spin texture in Dirac semimetals.

Eutectic GaSb + MnSb films ranging in thickness from 80 to 130 nm have been grown on sapphire substrates by pulsed laser deposition using mechanical droplet separation. The films were similar in composition to the ablation target, consisting of the eutectic GaSb-MnSb alloy. According to atomic force and electron microscopy data, the films were homogeneous, with p-type conductivity. Their electrical properties depended significantly on deposition conditions. The best films had a resistivity of 7 × 10−3 Ω cm, carrier concentration of 8.1 × 1019 cm−3, and carrier mobility of 102 cm2/(V s). Characteristically, the films had a negative magnetoresistance. Their magnetization curves showed saturation in a magnetic field of ∼1 × 10−1 T. According to the magnetic-field dependences, the coercive force in the films was within 3 × 10−2 T; that is, the films were soft magnets with a small domain size.

Diluted magnetic semiconductor InSb:Mn exhibits a ferromagnetic behavior up to T ∼ 600 K due to presence of nanosize MnSb precipitates [Kochura et al., J. Appl. Phys. 113, 083905 (2013)]. Transport properties of InSb:Mn, including the resistivity, the magnetoresistance (MR), and the Hall effect, are investigated between T ∼ 1.6 and 300 K in magnetic fields B up to 15 T. The resistivity, ρ(T), displays an upturn with lowering the temperature below T ∼ 10–20 K attributable to the Kondo effect, where the universal Kondo behavior is observed. The Hall resistivity, ρH, demonstrates a nonlinear dependence on B up to T ∼ 300 K, suggesting an anomalous contribution due to the effect of the MnSb nanoprecipitates. The relative MR, Δρ(B)/ρ(0), is positive (pMR) above T ∼ 10 K and transforms into a negative one (nMR) with lowering temperature. The Hall effect and pMR are interpreted simultaneously with the two-band model, addressed to presence of the two types of holes with quite different concentrations and mobilities. The dependences of nMR on B and T follow those of the Khosla–Fischer model, taking into account damping of the spin-dependent scattering of charge carriers in magnetic field.

It is proposed that the completeness of combustion of pulverized-coal fuel injected into the hearth of blast furnaces be determined by petrographic analysis of the content of unburned coal particles in the top dust and slag and chemical analysis of the dust and slag.

This paper focuses on looking for factors that influence the income of deep coal mining operations in Ukraine. The method of discriminate analysis was employed for assessing economic success of the operations. It could be concluded that mining-geological conditions are the most significant cause of influence; the human factor is of lesser importance.

The paper presents the analysis of main reasons and consequences of the decrease of the efficiency for suppression of single phase-to-ground faults causing dangerous technological failures and faults in distribution networks. Advantages and disadvantages of main systems for partial or full compensation of a ground fault current used for minimizing losses are described. Comparative calculations on the emergency tripping probability due to the development of a single phase-to-ground fault into phase-to-phase short circuit in compensated and ungrounded networks are given. Based on the experience of manufacture and operation, technical requirements to arc suppression devices and their compensation automation systems are developed.

The article analyses factors influencing the Ukrainian coal market. Based on the analysis the preconditions of further development of coal industry in Ukraine are formulated.

AIIBiνC2V semiconductors doped with Mn are perspective materials for spintronic. Structural, chemical and magnetic properties of these materials have been analyzed. The combinations of these compounds with the traditional semiconductors are perspective to create "system on chip" devices. The coexistence of ferromagnetic and paramagnetic phases was observed. The ferromagnetic phase is likely due to the presence of MnAs nanoclusters (3-5 nm). Paramagnetic properties appear due to Mn complexes (dimmer and trimmer).

It has been demonstrated by a combination of physical and chemical methods that InSb and MnSb form an eutectic (6.5 mol % MnSb, Tm = 513°C). A composition consisting of a [110] oriented InSb single crystal matrix and faceted single-crystal MnSb inclusions has been grown by the Bridgman method. The composition shows pronounced electrical conductivity anisotropy. The electrical conductivity along needle-like MnSb inclusions is 5 times higher than the electrical conductivity in the perpendicular direction. The composition possesses magnetic properties and has a Curie temperature of ∼600 K. The material is of interest as a substrate for ferromagnet/semiconductor heterostructures.

This review describes the principles of semiconductor spintronics, represents the physicochemical properties of materials based on manganese-alloyed AIIBIVC 2 V compounds, considers the results from theoretical simulation of magnetic properties of AIIBIVC 2 V alloyed with 3d metals, summarizes the basic approaches to explanation of ferromagnetism with Curie points above room temperature arising in AIIBIVC 2 V :Mn, and indicates promising ways to synthesize and study magnetic semiconductors based on chalcopyrites AIIBIVC 2 V in order to produce a suitable material for spintronic devices.

The results of studying phase equilibria of ternary AIIBIVCV systems have been reported. Physicochemical foundations have been developed for the synthesis of new ferromagnets with Curie temperatures above room temperature structurally compatible with basic semiconducting materials. Methods of synthesis and physicochemical properties of manganese-doped AIIBIVC 2 V ferromagnets have been described. The results of theoretical simulation of magnetic properties have been considered and basic approaches to the explanation of the emergence of ferromagnetism in AIIBIVC 2 V doped with 3d metals have been surveyed. The most promising ways to produce and study dilute magnetic semiconductors as spintronics materials have been presented.

Hybrid nanostructured InSb - MnSb films were obtained by the pulsed laser deposition using the mechanical droplet separation. Films structure was characterized by different methods (electron diffraction, scanning electron microscopy, atomic and magnetic force microscopy). The negative magnetoresistance (nMR) takes place below 100 K. This temperature is several times more than the temperature at which the nMR occurs in homogenous In1-xMnxSb films. At low temperatures the spin-dependent scattering of the holes by the localized Mn2+ moments prevails. When the temperature rises, the low nMR is observed due to the weak spin-dependent scattering on magnetic inclusions.

Single crystals of a diluted magnetic semiconductor (Cd1-x-yZnxMny)3As2(CZMA) (x+y= 0.4;y=0.04 and 0.08) obtained by Bridgman method were used. The Shubnikov-de Haas (SdH) effect was observed within studying of the dependence of the resistivity on the magnetic field in CZMA solid solutions. The values of the cyclotron massmc, Hall and Shubnikov carrier concentrations were calculated.

A new p -type dilute magnetic semiconductor was synthesized on the basis of manganese-doped ZnSiAs 2 chalcopyrite. As the manganese percentage in ZnSiAs 2 increased, the Curie temperature increased from 325 to 337 K for compositions containing 1 and 2 wt % manganese. The ferromagnetic properties of the new dilute magnetic semiconductor were due to nanoclusters that were generated by concurrent substitution of manganese for elements in the cationic sublattice of chalcopyrite.

The quasi-binary join Si-ZnAs2 of the system Zn-Si-As was studied by physicochemical methods. The congruently melting compound ZnSiAs2 and eutectics Si + ZnSiAs2 and ZnSiAs2 + ZnAs2 are formed along this join. The composition of the eutectic Si + ZnSiAs2 is 90 mol % ZnAs2 and 10 mol % Si; T m = 630°C. The composition of the eutectic ZnSiAs2 + Si is 55 mol % Si and 45 mol % ZnAs2. The component solubilities in ZnSiAs2 do not exceed 1 mol %.

Single crystals of the solid solutions CdGeAs2:Mn(x) and Cd0.964Zn0.036GeAs2:Mn(x) have been grown by the vertical Bridgman method. An X-ray diffraction study has demonstrated that Cd0.964Zn0.036GeAs2 (I), Cd0.964Zn0.036GeAs2:Mn (1.5 wt%) (II), and Cd0.964Zn0.036GeAs2:Mn (2.18 wt %) (III) retain the CdGeAs2 structure (tetragonal system, space group I\(\bar 4\)2d). The unit cell parameters of the solid solutions are as follows: a = b = 5.934(1) A, c = 11.219(2) A for I; a = b = 5.919(1) A, c = 11.204(2) A for II; and a = b = 5.918(1) A, c = 11.208(2) A for III. Many of Mn atoms in II and III occupy interstitial sites in the crystal lattice. Selected electrical and magnetic properties of single crystals of CdGeAs2:Mn(x) are discussed.