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The transformation of gibbsite into boehmite upon hydrothermal treatment at 200°C in 1.5 wt % NaOH have been studied by X-ray powder diffraction, IR spectroscopy, Brunauer–Emmett–Teller, differential scanning calorimetry, and scanning electron microscopy. The stages of the process have been determined. The transformation of gibbsite into boehmite in an alkaline medium takes 1 h and is accompanied by the splitting of gibbsite into boehmite plates with an average particle size of ~1 μm. It has been shown that, upon hydrothermal treatment of gibbsite in a 1.5 wt % NaOH solution, lamellar boehmite particles are formed for 24 h. This makes it possible to recommend the synthesized powder boehmite to be used as an additive to oils, in the production of concrete, fire retardants, and as an intermediate phase in the synthesis of α‑Al2O3 powders

The conversion of gibbsite to boehmite via hydrothermal treatment at 200°С in 1.5 wt % HCl is studied by X-ray powder diffraction, IR spectroscopy, Brunauer–Emmett–Teller analysis, scanning (SEM) and transmission (TEM) electron microscopy. The steps of the process are identified. Gibbsite is split in an acidic medium, with its specific surface area increasing up to 150 m2/g, into thin lamellas that have a disordered boehmite structure. Needle-shaped boehmite crystals are formed from thin elongated lamellas of diverse sizes due to the oriented overlaying and cross-linking with the elimination of weakly bound water and structural perfection.

Superluminescent diodes based on AlGaInAs/InP separate-confinement double heterostructures with strain-compensated quantum wells are investigated. The influence of elastic strains in the active region on the output characteristics of the devices is analysed. It is shown that such a design of a superluminescent diode allows an optical power of more than 5 mW, a radiation spectrum width of more than 60 nm, a degree of output radiation polarisation up to 30 dB to be obtained at the output of a single-mode fibre, and has a great potential for further improvement.

Comprehensive physical and technological studies on the creation of mesastripe structures with a channel in the substrate and subsequent burying of the structure with a layer of zinc selenide are carry out. Planarity of heterointerfaces between the substrate and epitaxial layers is studied by electron microscopy. The atomic structure of epitaxial layers GaInAsP/InP is studied by transmission electron microscopy. The profiles of epitaxial layers of the heterostructure are analyzed by secondary ion mass spectroscopy (SIMS). Layers with required composition of In0.78Ga0.22As0.68P0.32 corresponding to a laser wavelength of 1.3 μm are obtained. A technique for creating laser diodes with a channel in the substrate, including etching of mesastripe structure and burying with a layer of zinc selenide, is developed for the first time. This technique makes it possible to create laser diodes both with an optical confinement of laser emission and with a confinement of the current flow along the laser strip. Etching of p–n junction layers between laser strips and burying with zinc selenide on the surface of etched structure are developed for the first time. This technique made it possible to create heterostructures for laser diodes operating in the microwave range up to 10 GHz by liquid phase epitaxy (LPE). The ability to create and operate laser diodes in this design and technology is shown. The current–voltage characteristics, watt–ampere characteristics, and spectral characteristics of laser diodes are investigated. Russian technology for the creation of a microwave laser diode on a heterostructure with a channel in the substrate and repeated burying with zinc selenide is proposed. The prospects of using laser diodes of mesastripe structure with a channel in the substrate and buried with a layer of zinc selenide to create fast-response devices are shown.

The effect of bulk radiative heat transfer during the growth of profiled sapphire crystals from the melt is studied by the numerical simulation method. The peculiarities in the structure of a lightguide flow in the crystal and in the melt, as well as the possibility of radiation instability of the interface, are considered. It is shown that overcooled regions with the size determined by the growth rate appear under the crystallization front. It is found that the use of a conical shaper ensures a more stable growth.

Semiconductor devices of quantum electronics based on InP/GaInAsP heterostructures require the creation of non-defective chips for emitting devices and photodetectors. The production of such chips is impossible without a thorough technological study of the growth processes of epitaxial structures. One of the important problems in relation to the growth of such structures is the growth defects associated with the process of dissociation of indium phosphide on the surface during their growth. The aim of the work was the investigation of the process and mechanism of destruction (dissociation) of the surface of indium phosphide substrates in the range of growth temperatures of structures, as well as the study of methods andtechniques that allow minimize the process of dissociation of surface of indium phosphide.The work provides studies of the growth processes of InP/GaInAsP heterostructures, from the liquid phase, taking into account the degradation processes of the growth surface and the mechanisms for the formation of dissociation defects.The schemes of the dissociation process of the InP on the surface of the substrate and the formation of the defective surface of the substrate were analysed. At the same time, technological methods allowing to minimize the dissociation of the surface compound during the process of liquid-phase epitaxy were shown. The original design of a graphite cassette allowing to minimize the dissociation of the indium phosphide substrate in the process of liquid-phase epitaxy was proposed

This paper presents an analytical review that addresses physicochemical principles underlying the synthesis of granular structures in semiconductor–ferromagnet systems. Such systems comprise a II–IV–V2, II2–V3, or II–V2 compound as a semiconductor and MnAs as a ferromagnet. We demonstrate that granular magnetic structures are an alternative to superlattices in spintronic devices and can exhibit giant magnetoresistance and tunneling magnetoresistance effects. It is shown that, owing to the high carrier mobility in semiconductors, they are more attractive as matrices of granular materials than are metals or dielectrics. We have formulated the basic principles underlying the synthesis of granular structures with high magnetoresistance based on eutectic systems. Eutectic crystallization involves simultaneous crystallization of all the constituent phases, leading to the formation of an unusual, fine structure. High cooling rates are favorable for metastable crystallization. This causes a synergistic effect, stimulating nanostructuring and favoring the formation of granular structures. We present results on semiconductor–ferromagnet systems and demonstrate the possibility of producing granular magnetic structures with high magnetoresistance in such systems.

We have synthesized polycrystalline indium antimonide samples codoped with Mn (1 at %) and Ni (0.8, 1, or 1.2 at %). The magnetic properties of these materials have been shown to be dominated by Ni2 –хMnSb (0 < х < 1) clusters, whose composition and Curie temperature depend on Ni content. The samples exhibit metallic behavior of conductivity and have a positive magnetoresistance below room temperature.

We have studied the growth of zinc selenide layers on flat and shaped indium phosphide surfaces. The growth rate of zinc selenide has been shown to depend on substrate orientation. It has been shown that the present results can be useful in designing mesa stripe structures for quantum electronic instruments. We have fabricated mesa stripe laser diodes operating on the absorption band of methane and suitable for producing fiber-optic signal transmission systems.

The new compound Аl2(SO4)3 ⋅ 8(CH3)2SO, which cannot be prepared by direct synthesis, has been synthesized from an Аl2(SO4)3 ⋅ 8(CH3)2SO ⋅ 3Н2О glass. The compound has been identified by X-ray diffraction. Based on IR spectra, it has been concluded that the Al3+ ion has mixed coordination to dimethylsulfoxide (DMSO) molecules, and the ligands are linked to each other through the S and O atoms.

This paper presents results of a comparative experimental study aimed at producing GaAs/GaInP and GaAs/AlGaAs quantum wells (QWs) by metalorganic vapor phase epitaxy. The photoluminescence signal of the GaAs/GaInP QWs is shown to have a higher intensity (by a factor of 50–100) and, at the same time, a larger width (by a factor of ~2.5) in comparison with the GaAs/AlGaAs QWs. We analyze different approaches to controlling emission spectra of these QWs.

We have studied the interaction of etchants and etchant mixtures with {100} planes of InP substrates. The results demonstrate that mesa stripes and grooves faceted by a combination of planes differing in polarity—{111}A, {111}B, {110}, {112}A, or {221}A—can be obtained by properly selecting the etchant and the orientation of the mask coating. The mesa stripes have been shown to be faceted by the most close-packed planes and, in the case of polar properties, they are faceted by planes with a low dissolution rate ({111}A for the sphalerite lattice). The most close-packed planes {111}A and {111}B differ in their orientation relative to the (110) and ( $$\bar {1}$$ 10) basal planes.

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.

Buried light edge-emitting diodes (LEDs) with a wide emission spectrum in the wavelength range of 1380–1420 nm were developed. The design of an edge LED with a channel in a substrate and with the crescent active region and blocking layers of InP/GaInAsP/p-n-p-n/ZnSe was presented. Coupling of LED with an optical single-mode fiber and a microlens on the end of an optical fiber was performed. The characteristics of LEDs based on mesa-stripe heterostructures InP/GaInAsP were investigated. The dependences of the output power and the LED emission spectra based on mesa-stripe heterostructures InP/InGaAsP/InP with the crescent active region and p-n-p-n/ZnSe structure blocking the leakage current on the stabilization temperature of the active element and the injection current were studied. The dependence of the output parameters on the emitter stabilization temperature was demonstrated, which enables the creation of devices based on such LEDs both with and without forced cooling. The opportunity to develop buried LEDs with the crescent active region and a low degree of emission spectrum modulation was shown. The possibility of the entry of up to 45% of the LED radiation into a single-mode optical fiber using microlenses produced by chemical etching and fusion of a fiber end in a high-voltage arc of a welding machine was demonstrated.

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.

Manganese monoarsenide samples have been prepared by the sealed-ampule technique and characterized by X-ray diffraction, differential thermal analysis, and scanning electron microscopy. The hexagonal- to-orthorhombic phase transition of MnAs has been studied using differential scanning calorimetry (DSC) and magnetic measurements. The enthalpy and temperature range of the transition have been determined to be ΔH =–5.6 J/g and 312.5–319 K, respectively. The enthalpy and temperature range of the transition are influenced by the quality of the samples. The samples containing inclusions of the metastable, orthorhombic phase have a lower enthalpy and broader temperature range of the magnetostructural transformation of manganese monoarsenide. It has been demonstrated that DSC is an effective tool for assessing the quality of MnAs samples. Temperature dependences of specific magnetization and magnetic permeability for MnAs lend support to the DSC results. From these data, the Curie temperature of MnAs has been determined to be 40°C, in good agreement with previously reported data.

Long crystals of NiFeGaCo alloy with shape memory effect, including magnetically controlled ones, were obtained by the methods of Czochralski and Stepanov. A strong influence on the properties of crystals of dendritic formations, especially noticeable in the initial part of the crystal, has been revealed. In order to optimize the growth experiments, the heat transfer process in the thermal growth zone was simulated. It is shown that the formation of dendrites is due to a change in heat transfer during growth, which leads to an increase in the axial temperature gradient near the crystallization front as the crystal grows. This fits into the framework of the classical concepts of the transition from dendritic growth to normal growth.

A process has been developed for the liquid phase epitaxy of mesa stripe buried crescent InP/InGaAsP/InP heterostructures with a p–n–p–n/ZnSe leakage current-blocking structure. The salient feature of the process is a discontinuous mesa stripe which alternates with the structure of blocking layers. This technology allows one to fabricate linear edge-emitting diodes, mounted with the mesa stripe down or up, with an emission wavelength λ = 1.3–1.5 μm, high reproducibility, the possibility of coupling more than 50 μW of optical power into single-mode fiber at a current of 100 mA, an emission bandwidth of about 60 nm, and essentially negligible Fabry–Perot modulation.

A simple and cost- and power-efficient microwave signal optoelectronic delay line using a long-wavelength vertical cavity surface emitting laser is demonstrated and investigated by computer simulation and experimental inspection. Comparison with similar products of well-known global manufacturers, using a direct intensity modulation of distributed-feedback laser, showed comparable parameters with the better small-signal transmission characteristics for time delays up to 125 µs.

A technique for measuring the crystal cross-sectional area with a weight sensor based on the difference between its readings at the extreme rod positions in the stepwise and continuous modes of modulation of the pulling rate is proposed for the low-thermal gradient Czochralski method. A change in the crystallization rate at harmonic oscillations of the pulling rate is estimated with the aim of conserving the quality of the growing crystal for this measurement method.

This paper presents a technological study aimed at producing buried heterostructures for single-mode semiconductor lasers operating in the wavelength range 1651–1662 nm. We have fabricated laser diodes operating at a wavelength corresponding to an absorption band of methane. The effect of temperature on the optical emission spectrum of the laser diodes has been examined. The results demonstrate the possibility of tuning their emission spectrum in the range from 1651 to 1662 nm and producing smart fiber-optic systems for the remote monitoring of the methane concentration.

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.

The paper considers the experimentally observed instability of capillary shaping during the growth of thick-walled sapphire tubes by the Stepanov method. The explanation of this phenomenon is based on the theoretical model of radiative-conductive heat transfer in a crystal. An algorithm is developed for the asymptotic expansion of the problem based on the presence of two small parameters. It is shown that the spatial density of the radiation is inhomogeneous along the cross section of the tube and is maximum near its inner walls. This leads to their overheating and the meniscus separation from the inner edges of the shaper.

A method for stepped etching of optical glass fibers using various compositions of etching agents based on a 40% hydrofluoric acid (HF) and aqueous solutions of ammonium fluoride (NH4F) has been considered. Compositions, etching rates, the dependence of etching rate on temperature, and tyeh dependence of etching forms on composition have been determined. The potential use of the method for stepped etching of optical glass fibers in the manufacture of microelectronic devices has been demonstrated.

As a continuation of our studies aimed at creating semiconductor lasers based on buried InP/GaInAsP heterostructures, we consider the design and fabrication aspects of 1310-nm laser diodes for operation at elevated temperatures. We report the key features of the fabrication process and parameters of the laser emitters at temperatures of up to 120°C, and present their power-current and spectral characteristics.

It is lead numerical modeling of processes of heat exchange at growth of crystals of sapphire from a melt by Stepanov and Czochralski methods. The influences of volumetric radiating overcooling of a melt and of growth speed on the form of front of crystallization and distribution of temperature near to it is studied. It is shown, that the account of absorption of thermal radiation in a melt can lead to formation of volumetric supercooled areas near to crystallization front and to appreciable change of its shape.

InGaAsP/InP nanoheterostructures have been grown by liquid phase epitaxy and their structural perfection has been studied. The nanoheterostructures have been used to fabricate buried mesa laser diodes on a p-InP substrate that emit in the spectral range 1310–1550 nm. The design of the buried mesa stripe diode with the use of a semi-insulating II–VI compound has made it possible to create laser diodes operating at a wavelength of 1310 nm with a telecommunication signal transfer rate of 5.5 GHz. The results are technologically attractive and reproducible. We analyze potentialities for further increasing the optical signal transfer rate.

Modern notions about surgical techniques for the treatment of deep purulent processes in the zone of hip implant are presented. In 13 cases surgical sanitation without implant removal was performed. In case of implant loosening treatment tactics was determined by the possibility of total revision arthroplasty. In 76 patients with periprosthetic infection surgical sanitation was aimed at inflammation arrest and restoration of extremity weight bearing after compelled implant removal. In 44 patients resection arthroplasty with formation of neoarthrosis by Girdlestone was performed. In 17 cases a two-step surgical intervention with implantation of antibiotic impregnated cement spacer followed by revision arthroplasty was used. Clinical, microbiologic and immunologic criteria of favourable treatment outcome with minimum risk of inflammatory process relapse were determined.

Conditions that ensure reproducible growth of 〈110〉-oriented perfect Bi12SiO20 (BSO) crystals by the low-thermal-gradient Czochralski technique, whereby the entire crystallization front is occupied by the (110) crystal face, have been determined with the aid of numerical simulations. Using the established regime, BSO crystals have been obtained with a diameter of 85 mm, a length of 200 mm, and a mass of 10 kg. The density of dislocations in the crystals does not exceed 10 cm−2, and the refractive index inhomogeneity is below 10−3.

This paper examines an approach to the remote sensing of explosion-safe methane concentrations using optical fiber and demonstrates that considerable potential is offered by a system for the remote sensing of methane using a laser diode emitting at 1655 nm. We describe a novel procedure for the growth of epitaxial buried InGaAsP/InP heterostructures for 1655-nm lasers. Single-mode 1655-nm laser diodes have been produced and their parameters have been studied. It is shown that the diodes can be employed in real systems for remote monitoring of methane.

As a continuation of our studies aimed at designing InP/GaInAsP heterostructures based on semi-conductor solid solutions, we consider the design and fabrication aspects of laser emitters with a high average-power bandwidth product. We describe in detail experimental studies of the microwave parameters of laser emitters and present their power-current curves, spectral response, and frequency modulation characteristics at frequencies of up to 10 GHz.

The ways in which a block structure is formed in shaped sapphire single crystals grown from melt by the Stepanov method are considered. The measured temperature distributions and results of a mathematical modeling of the heat exchange in the growth zones, as well as the calculated thermoelastic fields and measured residual stresses, are reported. The possibility of effectively controlling the thermal fields and growth of block-free crystals by choosing optimal screening is shown for single crystals in the form of tubes and basal-plane-faceted ribbons.

A process is described for liquid phase epitaxy of mesa stripe buried crescent InP/InGaAsP/InP heterostructures with a p-n-p-n/ZnSe leakage current blocking structure. The process enables the fabrication of 1.3-μm light-emitting diodes with a low threshold current, stable fundamental transverse mode operation, and high output power. When mounted with the mesa stripe up, the diodes offer an emission power above 30 mW.

We describe a process for separate preparation of high-temperature solutions, which includes a prolonged preannealing (synthesis) at elevated temperatures. This process enables liquid phase epitaxy (LPE) of InGaAsP with highly reproducible physical properties (layer thickness, photoluminescence wavelength, and lattice parameter) and electrical characteristics (current-power curve, dark current, output power, emission wavelength, and threshold and working currents). Using this process, InP/InGaAsP/InP heterostructures can be grown by LPE in a wide temperature range (480–680°C) with highly reproducible parameters, for both photodetectors and light-emitting devices. An original LPE process is proposed which takes advantage of the separate preparation and pouring of high-temperature solutions with the use of graphite equipment.

Osseous-plastic material Perfoost demineralized lyophilized perforated allografs- was elaborated at CITO in 1997. Study of mechanical characteristics showed that Perfoost grafts had high plasticity. Mechanical stiffness allowed to use that material for substitution of marginal bone defects. Study in vitro showed high efficacy of cloning that was indirect evidence that demineralized allografts had osteoinductive properties. Between 19982002 at the Department of bone pathology for children and adolescents 121 patients, aged 118, with primary tumor, tumor-like diseases and systemic inherited skeleton pathology were operated on with Perfoost. Follow up period ranged from 1 years to 4 years 10 months. In vast bone defects demineralized allografts were used in combination with frozen cortical implants and metallosteosynthesis. Restoration of bone tissue was achieved in the period from 8 to 12 months. In patients with fibrous dysplasia who underwent extensive bone resection, the time of bone restoration increased by 16 months. Good and satisfactory results were observed in 98,3% of patients.

The proposed method is based on a novel technique for approximating the angular dependence of the radiated intensity. The entire range of solid angles is divided into N cells, which are symmetric relative to the center of the sphere. In each of the cells the radiation is assigned in the form of the P1 approximation, and a system of differential equations is obtained to determine the set of local zeroth and first moments. In some special cases the proposed approach can be regarded as a generalization of the discrete-ordinates method, which makes it possible to solve the problem of selecting the weights in the quadrature formulas in a natural manner. The effectiveness of the method is demonstrated in two one-dimensional test cases. It is shown that in these cases fairly high accuracy is achieved in the solution of the problem already for N=2.

The model of regular solutions has been used to obtain expressions for calculating the boundaries of the region of spinodal decomposition for five-component solid solutions of III-V compounds. The stability region of the solid solution Alx1Gax2In1−x1−x2PyAs1−y has been estimated.

A description is given of planar stripe lasers with two-channel confinement in an InGaAsP/InP heterostructure with a three-layer waveguide. These lasers operate continuously in the spectral range 1.3 ?m. Typical threshold currents at T = 300 K are 20?30 mA (with the minimum value 16 mA). An output power of 10 mW is obtainable up to 80?C and the maximum temperature at which cw operation is observed exceeds 100?C. The maximum output power at T = 300 K is 42 mW. An analysis is made of the relationship between the geometry of a heterostructure and the efficiency of current confinement in lasers of this type. Planar stripe heterolasers with two-channel confinement are compared with lasers based on a buried mesastripe structure.

An investigation was made of the dynamics of amplitude modulation of 1.3-μm radiation emitted by highly efficient low-threshold stripe heterolasers with lateral confinement due to two parallel epitaxial buried channels in a double heterostructure. The rise time of the transient characteristic was 0.1–0.6 ns, depending on the modulation regime. Single radiation pulses of duration less than 70 ps and regular trains of such pulses of frequency ~ 1 GHz were generated. The amplitude-frequency characteristics were determined under weak modulation conditions.

A study was made of cw tunable emission from a GaInPAs/InP semiconductor laser with an external resonator. Continuously tunable narrow-band emission in the region of 1.3 ..mu.. was obtained and the output power was up to 4 mW. The tuning range was 24 nm at half-maximum of the output power.

The spectral dependence of the optical gain was determined for an injecting double heterostructure with a strip active waveguide made of (InGa)AsP. The gain maximum at room temperature corresponded to the wavelength of 1.28 ..mu... Gain saturation by superradiance in a waveguide of 1.2 mm length was observed when the injection current density was 1.3 x 10/sup 4/ A/cm/sup 2/. The single-trip gain reached 27 dB.

The emission spectra of two single-mode heterojunction lasers based on InP–(InGa)AsP structures were determined with a resolution of 50 MHz under conditions of modulation by a small signal superimposed on a constant injection current. The dependences of the frequency modulation coefficient on the frequency of the modulating signal were determined in the range 102–3×109 Hz. These dependences were influenced considerably by the structure and the mounting of the active element.