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Plasmon resonance modulation with an external magnetic field (magnetoplasmonics) represents a promising route for the improvement of the sensitivity of plasmon-based refractometric sensing. To this purpose, an accurate material choice is needed to realize hybrid nanostructures with an improved magnetoplasmonic response. In this work, we prepared core@shell nanostructures made of an 8 nm Au core surrounded by an ultrathin iron oxide shell (

Представлены результаты экспериментального исследования влияния термического отжига на структуру, морфологию поверхности и оптические свойства тонких пленок нитрида алюминия на сапфире. Тонкие пленки нитрида алюминия на сапфире толщиной 200 нм отжигались на воздухе и в атмосфере азота при остаточном давлении газов в вакуумной камере установки ионно-лучевого осаждения не менее 100 Па при температуре 850 °C. Установлено, что при термическом отжиге пленок нитрида алюминия на сапфире в атмосфере азота происходит уменьшение среднеквадратичной шероховатости пленок до 0,8 нм, увеличение коэффициента пропускания в диапазоне длин волн 300 -1100 нм вплоть до 96 %, а также повышение стехиометрии пленок. Показано, что для пленок нитрида алюминия на сапфире, отожжённых на воздухе, происходит окисление нитрида алюминия с образованием аморфного оксида алюминия при температуре 850 °C. Результаты энергодисперсионного анализа показали полное отсутствие азота на поверхности этих пленок. Снижение коэффициента пропускания во всем диапазоне длин волн для пленок AlN, отожжённых на воздухе, делает их не пригодными для применения в оптоэлектронике. Морфология поверхности этих пленок представляет собой массив остроконечных образований с максимальной высотой 190,7 нм и среднеарифметической шероховатостью поверхности 3,7 нм. The results of an experimental study of the effect of thermal annealing on the structure, surface morphology and optical properties of thin films of aluminum nitride on sapphire are presented. Thin films of aluminum nitride on sapphire with a thickness of 200 nm were annealed in air and in a nitrogen atmosphere at a residual gas pressure in the vacuum chamber of the ion-beam deposition unit of no less than 100 Pa at a temperature of 850 °C. It was found that thermal annealing of aluminum nitride films on sapphire in a nitrogen atmosphere leads to a decrease in the root mean square roughness of the films to 0,8 nm, an increase in the transmittance in the wavelength range of 300 -1100 nm up to 96 %, and an increase in the stoichiometry of the films. It is shown that for aluminum nitride films annealed in air on sapphire, aluminum nitride is oxidized to form amorphous aluminum oxide at a temperature of 850 °C. The results of energy dispersive analysis showed the complete absence of nitrogen on the surface of these films. A decrease in the transmittance over the entire wavelength range for films AlN annealed in air makes them unsuitable for use in optoelectronics. The surface morphology of these films is an array of pointed formations with a maximum height 190,7 nm and an arithmetic mean surface roughness 3,7 nm.

1D solid solutions Zn1-xCuxO and composites Zn1-xCuxO / CuO with spherical morphology of aggregates from formate glycolate complexes Zn1-xCux (HCOO)(OCH2CH2O)1/2 (0 ≤ x ≤ 0,15) were obtained. All materials have been tested in the reaction of As(III) photooxidation upon exposure to ultraviolet and visible radiation. It was found that copper is an effective doping impurity in the composition of the solid solution Zn1-xCuxO (0 ≤ x ≤ 0,1). Its presence in the shell of the Zn1-xCuxO / CuO composite negatively affects the photoactivity of the material up to suppression of photocatalysis in the visible light range. The sorption efficiency of materials for arsenic is also shown, regardless of the composition and morphology of the material. According to x-ray photoelectron spectroscopy data, the surface of the samples after sorption contains arsenic mainly in the form of As(III).

Nanoheterostructures based on titanium, molybdenum, tungsten, and vanadium nanooxides with symmetric crystal structures, morphologies and high photocatalytic activity in under illumination by visible light, have been synthesized and studied. Microscopy, optical spectroscopy, and electron-spin resonance techniques were used. The asymmetric separation of photo-generated holes and electrons between different nanooxides in their nanoheterostructures suppresses their recombination. Using the method developed by the authors and based on ESR spectroscopy, the energy levels of the active centers inside the band gaps of the studied samples were found. We have shown, for the first time, that under illumination of nanoheterostructures under asymmetric conditions with adsorbed rhodamine dye at the dye-absorption wavelength (500 nm), photocatalytic reactions are mainly determined by light absorption by the nanostructures themselves, and not by energy transfer from the dye. This important result shows that high photocatalytic activity of materials with symmetric crystal structures is the primary criterion for creating energy-efficient photocatalysts. The results will be useful for the development of energy-efficient catalytic devices based on various combinations of metal nanooxides.

Titania is very famous photocatalyst for decomposition of organic pollutants. Its photocatalytic properties significantly depend on the morphology and chemical composition of the samples. Herein, the TiO2 nanotubes/CuxO nanoheterostructures have been synthesized and the effect of heat treatment performed in molecular atmospheres of air and argon on their photoelectrochemical and photocatalytic properties has been studied. The prepared samples have a higher reaction rate constant compared to TiO2 nanotubes in the decomposition reaction of methylene blue molecules. It is established that in argon treated nanoheterostructures, the copper oxide is present in two phases, CuO and Cu2O, while in air treated ones there is only CuO. In the TiO2 nanotubes/CuxO samples, Cu2+ ions and molecular O2− radicals were detected while in TiO2 nanotubes only carbon dangling bond defects are present. The dynamics of O2− radicals under illumination are discussed. It was shown that the TiO2 nanotubes do not exhibit photocatalytic activity under visible light. The mechanism of the photocatalytic reaction on the surface of the TiO2 nanotubes/CuxO samples was proposed. It is assumed that a photocatalytic decomposition of organic molecules under visible light at the surface of the nanoheterostructures under investigation is realized mainly by the reaction of these molecules with photogenerated O2− radicals. The results obtained are completely original and indicate the high promise of the prepared photocatalysts.

The increasing release and accumulation of harmful nitrogen oxides (NOx with x = 1,2) in industrial and urban environments renders the efficient removal of these atmospheric pollutants an urgent and obligatory issue. In this regard, the advantages yielded by photocatalytic oxidation processes have triggered the search for eco-friendly catalysts featuring an improved efficiency. In this work, we propose the use of heterostructures based on β-Fe2O3, a scarcely investigated iron(III) oxide polymorph, as viable De-NOx photocatalysts with appealing functional performances. The present materials were fabricated in supported form by chemical vapor deposition (CVD) of Fe2O3. A proof-of-principle investigation on the modulation of material performances by heterostructure formation is explored through Fe2O3 functionalization with CuO or WO3 by radio frequency (RF)-sputtering. The obtained results reveal a controllable dispersion of CuO or WO3 in close contact with β-Fe2O3, a crucial issue to profitably exploit their mutual interplay for De-NOx applications. A preliminary analysis in this regard evidenced very encouraging conversion efficiency and selectivity towards nitrate formation, outstanding among non-titania oxide-based De-NOx photocatalysts. The improved photoactivity with respect to bare Fe2O3, CuO and WO3 was related to a higher oxygen defectivity and an enhanced separation of photogenerated charge carriers, enabled by the matched band edges in the target heterostructures.

Inorganic nanoparticles have great potential for application in many fields, including nanomedicine. Within this class of materials, inorganic nanoheterostructures (NHS) look particularly promising as they can be formulated as the combination of different domains; this can lead to nanosystems with different functional properties, which, therefore, can perform different functions at the same time. This review reports on the latest development in the synthesis of advanced NHS for biomedicine and on the tests of their functional properties in in vivo studies. The literature discussed here focuses on the diagnostic and therapeutic applications with special emphasis on cancer. Considering the diagnostics, a description of the NHS for cancer imaging and multimodal imaging is reported; more specifically, NHS for magnetic resonance, computed tomography and luminescence imaging are considered. As for the therapeutics, NHS employed in magnetic hyperthermia or photothermal therapies are reported. Examples of NHS for cancer theranostics are also presented, emphasizing their dual usability in vivo, as imaging and therapeutic tools. Overall, NHS show a great potential for biomedicine application; further studies, however, are necessary regarding the safety associated to their use.

This work reports on an experimental investigation of the influence of vertical stacking of quantum dots, the thickness of GaAs potential barriers, and their isovalent doping with bismuth on the photoluminescence properties of InAs/GaAs heterostructures. The experimental samples were grown by ion-beam deposition. We showed that using three vertically stacked layers of InAs quantum dots separated by thin GaAs barrier layers was accompanied by a red-shift of the photoluminescence peak of InAs/GaAs heterostructures. An increase in the thickness of the GaAs barrier layers was accompanied by a blue shift of the photoluminescence peak. The effect of isovalent Bi doping of the GaAs barrier layers on the structural and optical properties of the InAs/GaAs heterostructures was investigated. It was found that the Bi content up to 4.96 atom % in GaAs decreases the density of InAs quantum dots from 1.53 × 1010 to 0.93 × 1010 cm−2. In addition, the average lateral size of the InAs quantum dots increased from 14 to 20 nm, due to an increase in the surface diffusion of In. It is shown that isovalent doping of GaAs potential barriers by bismuth was accompanied by a red-shift of the photoluminescence peak of InAs quantum dots of 121 meV.

A metal-free C60/CNTs/g-C3N4 nanoheterostructure with excellent visible-light photocatalysis for rhodamine B (Rh B) degradation has been reported. Via a convenient low-temperature solution-phase method, g-C3N4 nanosheets can serve as substrate for dispersion of C60/CNTs. The loading of C60/CNTs onto g-C3N4 nanosheets surfaces significantly enhanced visible-light-driven photocatalytic activity of g-C3N4 catalyst, for oxidation of organic pollutant (Rh B, 100%). Excellent photocatalytic properties of C60/CNTs/g-C3N4 can be predominantly attributed to the intimate interfacial contact among constructing compounds, increased specific surface area and enhanced light adsorption efficiency resulted from C60/CNTs carbon materials. Particularly, the synergistic heterostructure interaction remarkably hinders the electron–hole pairs recombination, giving rise to significantly enhanced photocatalytic performance of C60/CNTs/g-C3N4 in comparison with other counterparts.

A metal-free C 60 /CNTs/g-C 3 N 4 nanoheterostructure with excellent visible-light photocatalysis for rhodamine B (Rh B) degradation has been reported. Via a convenient low-temperature solution-phase method, g-C 3 N 4 nanosheets can serve as substrate for dispersion of C 60 /CNTs. The loading of C 60 /CNTs onto g-C 3 N 4 nanosheets surfaces significantly enhanced visible-light-driven photocatalytic activity of g-C 3 N 4 catalyst, for oxidation of organic pollutant (Rh B, 100%). Excellent photocatalytic properties of C 60 /CNTs/g-C 3 N 4 can be predominantly attributed to the intimate interfacial contact among constructing compounds, increased specific surface area and enhanced light adsorption efficiency resulted from C 60 /CNTs carbon materials. Particularly, the synergistic heterostructure interaction remarkably hinders the electron–hole pairs recombination, giving rise to significantly enhanced photocatalytic performance of C 60 /CNTs/g-C 3 N 4 in comparison with other counterparts.

Gas sensors based on titanium dioxide (TiO2) have attracted much public attention during the past decades due to their excellent potential for applications in environmental pollution remediation, transportation industries, personal safety, biology, and medicine. Numerous efforts have therefore been devoted to improving the sensing performance of TiO2. In those effects, the construct of nanoheterostructures is a promising tactic in gas sensing modification, which shows superior sensing performance to that of the single component-based sensors. In this review, we briefly summarize and highlight the development of TiO2-based heterostructure gas sensing materials with diverse models, including semiconductor/semiconductor nanoheterostructures, noble metal/semiconductor nanoheterostructures, carbon-group-materials/semiconductor nano- heterostructures, and organic/inorganic nanoheterostructures, which have been investigated for effective enhancement of gas sensing properties through the increase of sensitivity, selectivity, and stability, decrease of optimal work temperature and response/recovery time, and minimization of detectable levels.

Nanoheterostructures based on metal oxide semiconductors have emerged as promising materials for the conversion of sunlight into chemical energy. In the present study, ZnO-based nanocomposites have been developed by a hybrid vapor phase route, consisting in the chemical vapor deposition of ZnO systems on fluorine-doped tin oxide substrates, followed by the functionalization with Fe2O3 or WO3via radio frequency-sputtering. The target systems are subjected to thermal treatment in air both prior and after sputtering, and their properties, including structure, chemical composition, morphology, and optical absorption, are investigated by a variety of characterization methods. The obtained results evidence the formation of highly porous ZnO nanocrystal arrays, conformally covered by an ultrathin Fe2O3 or WO3 overlayer. Photocurrent density measurements for solar-triggered water splitting reveal in both cases a performance improvement with respect to bare zinc oxide, that is mainly traced back to an enhanced separation of photogenerated charge carriers thanks to the intimate contact between the two oxides. This achievement can be regarded as a valuable result in view of future optimization of similar nanoheterostructured photoanodes.

Представлены результаты проектирования и натурных испытаний электрических характеристик монолитно-интегральной схемы (МИС) коммутируемого по входу малошумящего усилителя на основе pHEMT арсенид-галлиевой технологии собственного производства для применения в составе бортовых навигационных приёмников сигналов глобальных навигационных спутниковых систем космических аппаратов всех типов орбит для их автономного координатно-временного обеспечения The presents of design and experimental tests results of electrical characteristics of monolithic integrated circuit of the input switch-off low-noise amplifier based on pHEMT GaAs-technology of own production for use in the on-board navigation receivers of global navigation satellite systems signals for autonomous coordinate and time support of all types orbits spacecraft

Gold-iron oxide composites were obtained by in situ reduction of an Au(III) precursor by an organic reductant (either potassium citrate or tiopronin) in a dispersion of preformed iron oxide ultrasmall magnetic (USM) nanoparticles. X-ray diffraction,transmission electron microscopy,chemical analysis and mid-infrared spectroscopy show the successful deposition of gold domains on the preformed magnetic nanoparticles,and the occurrence of either citrate or tiopronin as surface coating. The potential of the USM@Au nanoheterostructures as heat mediators for therapy through magnetic fluid hyperthermia was determined by calorimetric measurements under sample irradiation by an alternating magnetic field with intensity and frequency within the safe values for biomedical use. The USM@Au composites showed to be active heat mediators for magnetic fluid hyperthermia,leading to a rapid increase in temperature under exposure to an alternating magnetic field even under the very mild experimental conditions adopted,and their potential was assessed by determining their specific absorption rate (SAR) and compared with the pure iron oxide nanoparticles. Calorimetric investigation of the synthesized nanostructures enabled us to point out the effect of different experimental conditions on the SAR value,which is to date the parameter used for the assessment of the hyperthermic efficiency., This work was partially funded by the Regione Autonoma della Sardegna under the R&D project ‘Chitostrip’ and by Fondazione CARIPLO (project BaTMAN, no. 2013-0752).

Представлены результаты экспериментальных исследований электрических характеристик радиационностойких монолитно-интегральных схем двухпозиционного коммутатора и малошумящего усилителя, разработанного и изготовленного на основе арсенид-галлиевой технологии собственного производства для применения в составе бортовых многоканальных навигационных приёмников сигналов глобальных навигационных спутниковых систем космических аппаратов всех типов орбит для их автономного координатно-временного обеспечения The presents of electrical characteristics experimental researches results of the radiation-hardened on-off switch and low-noise amplifier (LNA) monolithic integrated circuits (MIC) of the designed and manufactured based on arsenide-gallium technology of own production for use in the multi-channel on-board navigation receivers of global navigation satellite systems (GNSS) signals for autonomous coordinate and time support of all types orbits spacecraft

Zeolite–sepiolite inorganic nanoheterostructures have been hydrothermally synthesized by adding a dispersion of colloidal sepiolite to a solution able to produce a nanocrystalline zeolite (silicalite). The obtained product could be recovered in good yield by simple filtration only when the relative sepiolite concentration exceeded a threshold of 1.8 wt% in the synthesis mixture (amounting to 1:3 sepiolite:zeolite wt. ratio in the recovered product). The resulting heterostructures were characterized by XRD, FTIR, thermal (TG–DTA) and chemical analyses, N2 adsorption, TEM, SEM, 29Si NMR, and methylene blue adsorption. The intimate zeolite–sepiolite interaction at the surface produced a good dispersion of zeolite particles and prevented their sintering upon calcination to remove the organic structure-directing agent. Experiments in conditions yielding microcrystalline silicalite support the idea that the sepiolite surface acts as nucleation sites for the zeolite crystallization. The textural properties of the nanozeolite–sepiolite heterostructure are not a linear combination of their components’., Financial support from the Spanish CICYT, MAT2012-31759, is acknowledged. C. Belver acknowledges MINECO for a "Ramon y Cajal" contract.

We demonstrate a method for the synthesis of multicomponent nanostructures consisting of CdS and CdSe with rod and tetrapod morphologies. A seeded synthesis strategy is used in which spherical seeds of CdSe are prepared first using a hot-injection technique. By controlling the crystal structure of the seed to be either wurtzite or zinc-blende, the subsequent hot-injection growth of CdS off of the seed results in either a rod-shaped or tetrapod-shaped nanocrystal, respectively. The phase and morphology of the synthesized nanocrystals are confirmed using X-ray diffraction and transmission electron microscopy, demonstrating that the nanocrystals are phase-pure and have a consistent morphology. The extinction coefficient and quantum yield of the synthesized nanocrystals are calculated using UV-Vis absorption spectroscopy and photoluminescence spectroscopy. The rods and tetrapods exhibit extinction coefficients and quantum yields that are higher than that of the bare seeds. This synthesis demonstrates the precise arrangement of materials that can be achieved at the nanoscale by using a seeded synthetic approach.

For three types of colloidal magnetic nanocrystals, we demonstrate that postsynthetic cation exchange enables tuning of the nanocrystal’s magnetic properties and achieving characteristics not obtainable by conventional synthetic routes. While the cation exchange procedure, performed in solution phase approach, was restricted so far to chalcogenide based semiconductor nanocrystals, here ferrite-based nanocrystals were subjected to a Fe2+ to Co2+ cation exchange procedure. This allows tracing of the compositional modifications by systematic and detailed magnetic characterization. In homogeneous magnetite nanocrystals and in gold/magnetite core shell nanocrystals the cation exchange increases the coercivity field, the remanence magnetization, as well as the superparamagnetic blocking temperature. For core/shell nanoheterostructures a selective doping of either the shell or predominantly of the core with Co2+ is demonstrated. By applying the cation exchange to FeO/CoFe2O4 core/shell nanocrystals the Neél temperature of the core material is increased and exchange-bias effects are enhanced so that vertical shifts of the hysteresis loops are obtained which are superior to those in any other system., Nano Letters, 13 (2), ISSN:1530-6984, ISSN:1530-6992

The main states of electron and hole in spherically semiconductor quantum-dot are studied. The wave function of the system is optimized by variation of effective radii of electron and hole orbits. The main state and Coulomb energy as function of quantum-dot radius are calculated.

Riga Technical University supported the preparation of this manuscript from the Scientific Research Project Competition for Young Researchers No. ZP-2016/7. The authors wish to kindly acknowledge the financial support of HZB, Estonian Research Council (PUT1096, PUT735 and IUT2-25) and Estonian Centre of Excellence in Research Project “Advanced materials and high-technology devices for sustain-able energetics, sensorics and nanoelectronics” TK141 (2014–2020.4.01.15-0011)., We have developed magnetically separable and reasonably stable visible light active photocatalysts containing CoFe2O4 and mixture of Ag2O/Ag2CO3 nanoheterostructures. Obtained ternary nanoheterostructures outperform previously reported magnetically separable visible light photocatalysts, showing one of the highest visible light photocatalytic dye degradation activities in water by a magnetically separable photocatalyst. Photocatalytically active part is Ag2O/Ag2CO3 whereas the CoFe2O4 mainly has stabilizing and magnetic separation functions. The Ag2CO3 phase junction on Ag2O nanoparticle surface were obtained by straightforward phase transformation from silver oxide to silver carbonate in air due to ambient CO2. The phase transformation was followed using X-ray diffraction (XRD), and hard X-ray photoelectron spectroscopy (HAXPES) measurements., Riga Technical University No. ZP-2016/7; Estonian Research Council (PUT1096, PUT735 and IUT2-25); Estonian Centre of Excellence in Research TK141 (2014–2020.4.01.15-0011); Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART²