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This paper presents the magnetic core characteristics of three magnetic materials at cryogenic temperature. Amorphous, nanocrystalline, and ferrite ring cores are tested at room temperature as well as 77 K under various operating frequencies. The core characteristics, including saturation flux density, permeability, and power loss are analyzed. The results show the core characteristic differences between the room and cryogenic temperatures as well as the performance differences among different magnetic materials, which will help optimize the high-frequency inductor design for cryogenic applications. Furthermore, the thermal shock test is performed to test the reliability of the cores. One ferrite core inductor and one nanocrystalline core inductor are built and tested in a 9 kW buck converter at cryogenic temperature.

In this work we investigated the influence of the carbonic materials Single Layer Graphene, Nanocrystalline Graphite and Graphene Nano Walls on the flow field in a microchannel using the experimental technique micro-Particle Image Velocimetry. The velocity and vorticity distributions show that the presence in the microchannel of the carbonic materials have an important influence and above 300 mbar inlet pressure the average velocity decreases in the NCG and GNW cases compared with SLG.

Nanocrystalline and nanoporous structures have been identified as a promising hydrogen storage solid material for fuel cell systems. Limited grain sizes and a branched system of grain boundaries are providing favorable conditions for acceleration and facilitation of the hydrogen diffusion and accumulation. In addition, the nanoporous structures have good gravimetric properties. This study reports on the accumulation and release of the large amounts of hydrogen by nanocrystalline Mg-N-H and nanoporous $\left(\mathbf{V}_{0.9} \mathbf{T i}_{0.1}\right)-\mathbf{N}-\mathbf{H}$ thin-film structures. A comparison of the structural changes during the hydrogen absorption and desorption has been carried out. The research revealed the relationship between the electrical resistance of investigated films and the amount of the hydrogen contained in them. It is shown that nano-porous $(\mathrm{V}_{0.9} \text{Ti}_{0.1})-\mathrm{N}-\mathrm{H}$ films have better kinetic properties than nanocrystalline Mg-N-H films, while their gravimetric and thermodynamic properties are broadly similar.

Ceramic samples on the basis of nanocrystalline powders $\mathrm{c}_{\mathrm{u}1-\mathrm{x}} A \mathrm{g}_{\mathrm{x}})_{7}$GeSe5I(x=0,0.25,0.5,0.75,1) were made by cold pressing technique at a pressure of $\sim$0.4 GPa with further annealing during 36 hours at 873 K. The size of ceramic materials crystallites is determined by the method of microstructural analysis. Investigation of electrical properties of ceramics based on (Cu1-xA$\mathrm{g}_{\mathrm{x}})_{7}$GeSe5I mixed crystals were carried out by the method of impedance spectroscopy in the temperature range 293-383K and in the frequency range from 10 Hz to 300 kHz. Analysis of Nyquist plots allowed to determine the ionic and electronic components of electrical conductivity, the temperature dependence of which in Arrhenius coordinates has a linear character, which indicates their thermoactivation mechanism. Compositional behaviour of both components of electrical conductivity (ionic and electronic) and their activation energies were estimated. Their nonlinear character is explained by both the complex process of recrystallization and Cu+$\leftrightarrow$ Ag+ cationic substitution.

The paper presents the results of studies of the magnetoresistance effect and magnetic parameters of three-component film alloys based on the ferromagnetic alloy $\mathrm{Fe}_{\mathrm{x}}\mathrm{Co}1-\mathrm{x}$ and Cu with a thickness of 20-50 nm and at a concentration of cobalt atoms of $10\leq c\mathrm{c}_{0}\leq 90$ aT.%. It is shown that for film alloys $\mathrm{Fe}_{\mathrm{x}}\mathrm{C}_{01-\mathrm{x}}$ in the entire range of studied concentrations and thicknesses at room temperature, the anisotropic nature of magnetoresistance is recorded, while for films $(\mathrm{Fe}_{\mathrm{x}}\mathrm{C}_{01-\mathrm{x}})_{0.5}\mathrm{C}_{\mathrm{u}0.5}$ at $x\gt 0.6$ the magnetoresistance has an isotropic character. The dependences of the values of the coercive force BC and the saturation field BS on the content of Fe x atoms for film alloys $\mathrm{Fe}_{\mathrm{x}}\mathrm{Co}1-\mathrm{x}/\mathrm{S}$ $Ta (\mathrm{Fe}_{\mathrm{x}}\mathrm{c}_{01-\mathrm{x}})_{0.5}\mathrm{C}_{\mathrm{u0.5}}/\mathrm{S}$ with a thickness of 30 nm are analyzed.

High enthalpy of refractory metals borides and carbides points that these compounds can be obtained at low temperature. This can be performed with help of a planetary mill where synthesis processes take place at low temperatures. The carbide and boride formation process at a low temperature yields compounds in nanocrystalline state with the specific surface area up to 7 m2/g. The formation of a particular phase through milling of refractory metals with boron or carbon in a planetary mill depends on the physical-chemical properties of starting powders, enthalpy of the final product formation, and on the intensity of milling process. Depending on these conditions, processes of mechanical alloying in the system Me-boron and Me-carbon run by the following mechanisms: mechanically-induced reaction of self-propagating synthesis (MSS), diffusion-controlled process of interstitial solid solutions decomposition and destruction (amorphization) of the initial metals with subsequent formation of carbide and boride nucleation’s. The compounds obtained during mechanochemical synthesis, independently of the mechanism formation, have a nanostructure.

CuTa alloy is a typical alloy with high melting point, corrosion resistance and excellent ductility, which is expected to be used as a warhead material for weaponry. In present study, molecular dynamics (MD) method is used to reveal the thermal and mechanical responses of copper-tantalum alloys under high velocity impact from the atomic scale. The model of the nanocrystalline polycrystalline CuTa alloy was established by the two different methods. The shock wave propagation process at the particle velocity of 1.3 Km/s was simulated by the “momentum mirror” method, and the polycrystalline copper-tantalum alloy during the impact was analyzed. The change of grain boundaries in the alloy and the generation and annihilation process of dislocations. The MD simulation results show that the propagation of shock waves in the copper-tantalum alloy can be divided into three stages, namely elastic deformation, dislocation emission and double-wave structure transmission. Additionally, the vacancies generated at the same time will cause local stress concentration and temperature rise. These transformations can easily be classified in MD simulation details.

This work demonstrates the feasibility of fabricating resistive nanocrystalline graphite (NCG) on a Si substrate. The NCG film thickness of 9 nm was deposited using metal-free plasma enhanced chemical vapour deposition (PECVD) on a 6-inch p-type silicon wafer. The surface and electrical properties of the resistors produced were investigated. The average grain size of the NCG thin film is 35 nm with 0.8 nm of surface roughness. The electrical characterization of the NCG strips show metal-like behaviour in which the resistance is proportional to the strip lengths. The sheet resistance is found to be 39 kohm/sq which is two orders of magnitude larger than graphene deposited using Chemical Vapour Deposition. This indicates the carrier transport across grain boundaries has a large influence on the overall resistance of the device. However, the nano-sized grains on the NCG material could be used to enhance the sensitivity of the material towards the environment.

Cellulose is a natural biopolymer that shows some attractive properties such as recyclability, biodegradability, renewability, non-toxicity, low density and high functionality. Nanocrystalline Cellulose is (NCC) obtained from acid hydrolysis of cellulose fibres but compared to cellulose fibres, NCC possesses many more advantages, such as higher specific strength and modulus, higher surface area, unique optical properties, etc. This research work extracts cellulose from locally available rice straw variety. The extraction process included dewaxing, delignification, bleaching, acid hydrolysis, centrifugation, dialysis, sonication and freeze drying. It was observed using FTIR analysis that almost all the silica content of fibres was solubilized in the dewaxing step. XRD analysis concluded the decrement of crystallinity with an increment of the temperature and time of the centrifugation. The dialysis conditions and sonication parameters were optimized. Finally, the aqueous suspension was freeze dried to obtain Nanocrystalline cellulose powder. The results of the image analysis showed that almost 50% of Cellulose fibres within the range of 64–98 nm with 70% crystallinity and maximum yield 18.68% of NCC.

Metal oxides (e.g. In 2 O 3 , InZnO) have demonstrated mobility an order of magnitude higher than a-Si, which makes them excellent candidates for display applications [1] . One common practice to achieve higher mobility in metal oxide thin-film transistors (TFTs) is to use high-κ gate dielectrics [2] . We have recently explored this phenomenon with a systematic study which found that the observed ‘mobility enhancement' in metal oxides on high-κ dielectrics is due in large part to the increased gate capacitance, which increases carrier concentration in the channel [4] . However, the interfaces also play a significant role, and in some cases a poor-quality interface offsets the benefits of the higher gate capacitance. In this work, we compare two different metal oxide semiconductors – nanocrystalline In 2 O 3 and sol-gel indium zinc oxide (IZO) – to show that these conclusions are consistent across different semiconductor materials. We continue to investigate the charge transport with high-κ dielectrics by introducing an interfacial SiO x layer between the high-κ dielectric and the IZO channel.

We apply NAnocrystalline Transport path in Ultra-thin dielectrics for Reinforced passivating contact (NATURE contact) to crystalline silicon solar cells for simultaneous achievement of passivation and carrier extraction. The Si nanocrystals are formed in silicon oxide by deposition of hydrogenated amorphous silicon oxide with different oxygen concentration and subsequent annealing. NATURE contact with total layer thickness of 8 nm exhibits reasonably good passivation performance. Furthermore, we demonstrate that NATURE contact can be successfully implemented to the both sides of crystalline silicon solar cells. NATURE contact, which permits flexible structural and chemical design of a passivation contact layer, will open a possibility for various functional devices.

The eddy current loss for nanocrystalline alloys is detrimental at high frequencies due to the low material resistivity. Novel flexible nanocrystalline flake ribbons fabricated from Fe-based nanocrystalline alloys are introduced to solve the problem. In this paper, the manufacturing process of a novel material and the mechanism of reducing eddy current loss are described. The material characterisation and magnetic measurement of nanocrystalline flake ribbons are given. The core losses of nanocrystalline flake ribbons and conventional nanocrystalline ribbons are compared. The experimental results show that the core losses of nanocrystalline flake ribbons decrease by 30% compared to the corresponding nanocrystalline ribbons. Following an optimal design procedure, high frequency (HF) transformers built by the flake ribbons and ferrites are tested in a 1.2 kW DAB converter, and the core losses are reduced by over 50% compared with ferrite transformers.

Nickel oxide metal-semiconductor-metal structure was fabricated on 4H-SiC substrate by radio frequency magnetron sputtering from nickel oxide target and following electrode process. X-ray diffraction and scanning electron microscopy results indicate that the sputtered non-stoichiometric nickel oxide on silicon carbide is nanocrystalline. The current and voltage characteristic of the fabricated device was measured. When triggered by 365 nm incoming light, the current at 1 V and -1 V are 2.28 mA and -2.26 mA, respectively. Meanwhile, the dark current was as small as 26 $\mu$ A at both 1 V and -1 V. Furthermore, the secondary turn on behavior of the NiO x MSM structure was investigated. The results indicate that there are 3.35 eV barriers for electrons flowing from nickel electrodes to nickel oxide. Based on the investigated results, the equivalent circuit for secondary turn on behavior of the fabricated device was set up and simulated. The simulated curve matches the experimental curve well.

The exhaled acetone concentration of diabetic patients is much higher than that of normal persons, which can be used for early warning, large-scale screening, and adjuvant treatment for diabetes. Therefore, a non-invasive exhaled acetone sensor with a low detection limit, high sensitivity, and high reliability is widely studied. Their sensing performance largely depends on the chemical composition of sensing materials, surface modification, the microstructure of the sensing layer. In this paper, Tin oxide (SnO 2 ) nanocrystalline composed inverse opal structure were successfully prepared, using polystyrene microspheres as templates, as a sensing material for an acetone gas sensor. Compared with pure SnO 2 prepared by the hydrothermal method, inverse opal SnO 2 has a much higher response at a low concentration of 500ppb-10ppm, Up to 5.6 response at 1ppm(240°C), which is already suitable for diabetes screening without doping noble metal. The improvement of gas sensitivity is mainly due to the small size of the SnO 2 nanoparticles and the pore structure composed of the nanocrystalline. The relatively high response, fast response and recovery speed, and good stability make it a promising gas sensor material for screening and monitoring of diabetes.

The purpose of this paper is clarifying the deform mechanism of CuTa/Cu and CuTa/Ta nanolaminates during nanoindentation test. Firstly, two kinds of amorphous and nanocrystalline interface model were built. Additionally, the Cu layer thickness in CuTa/Cu are λ between 3 A and 12 A. The Ta layer thickness in CuTa/Ta are μ between 3 A and 12 A. Secondly, nanoindentation test were introduced to get the elastic modulus and hardness of nanolaminates. As the results claimed that different deform mechanisms play the dominant role during the indentation load and unload. More exactly, when the Cu layer is less than 7 A the Cu layer dominate the deform mechanism, the elastic modulus and harness increase with increasing A. As A increasing much more, the CuTa layer will dominate the deform mechanism. In the contrast, the elastic modulus and hardness will decrease with increasing A. Similarly as CuTa/Cu model, CuTa/Ta model has an obviously change in the dominant role of deform mechanism. In the end, the influence of penetrate rate was discussed.

As a new kind of magnetic material, nanocrystalline soft magnetic alloy has attracted much attention due to its excellent comprehensive soft magnetic properties. In this paper, Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 nanocrystalline alloy is taken as the research object, and its three-dimensional model is constructed by micromagnetic simulation software. The influence mechanism of applied magnetic field frequency (kHz level) and DC bias magnetic field on the high-frequency magnetization process of the alloy material is studied from the mesoscopic scale with the complex permeability as the research parameter. Firstly, in the range of kHz frequency, with the increase of magnetic field frequency, the imaginary part of permeability presents a trend of rapid increase, indicating that the energy loss gradually increases. Secondly, with the increase of the DC bias magnetic field, the real part of the initial permeability shows a decreasing trend, indicating that the stored energy of the material decreases gradually.

Compared to traditional contact power transfer by slip ring, the wireless power transfer applied to slip ring has more advantages which could reudce the mechanical wear and improve the reliability. In this paper, the crystalline nanocrystalline is proved to have a higher electromagnetic compatibility in slip ring compared with other various magnetic meterials. Meanwhile, the structure design of non-contact slip ring also is discussed in this paper. And the simulation results show that the thickness and open hole caliber of shiled has weak influence for mutual inductance between primary and secondary coils.

NANOMET is one of the several nanocrystalline soft magnetic alloys [1]. The authors already reported about the prototype motor with NANOMET stator cores [2]. In this paper, the authors reported that NANOMET core motor has low iron loss characteristics which cannot be achieved with 35A360 core motor, while maintaining the torque density comparable to that of 35A360 core motor. In order to reduce the mass production cost of the currently expensive NANOMET stator cores and promote its practical application, we have devised molding of crushed NANOMET into a stator core. This paper describes about crushed NANOMET toroidal core, and presents the evaluation results of the iron loss characteristics.

In inductive power transfer, ferrite cores present several drawbacks such as brittleness, low permeability and saturation point, and sensitivity to temperature variation. Other materials such as nanocrystalline alloys are being considered as substitutes. They offer a higher permeability and saturation point. Also, they are more robust and stable with temperature. This paper reviews the design considerations that should be taken into account when designing nanocrystalline cores for IPT applications. Bespoke designs are required to mitigate the eddy-current losses which arise due to the high conductivity of the material. A WPT3 pad, 11 kW, is designed and compared to and identical pad with ferrite cores. Using nanocrystalline ribbon cores, a higher coupling factor, 11%, was achieved. Also, a 2% improvement in efficiency was measured. This is attributed to the lower hysteresis losses and higher coupling factor. Finally, the saturation limits were tested for both materials. Results confirm that, with nanocrystalline ribbon cores, higher power ratings and power densities can be achieved.

Two new experimental devices, which allow obtaining both gradient multilayer composites and coatings of each of their layers separately are presented. Using them, a wide range of compositions of multicomponent carbide coatings is obtained. Among them there are three groups- (a) coatings with high Cr content (b) coatings with high Ti and C content (c) coatings with high mixing entropy and composition closer to equimolar. Group (a) is characterized by BCC lattice and elongated surface structures. Group (b) has an FCC lattice, and at a content of C>51 at. % there is a porous structure on the surface, which adversely affects the microhardness of the coatings. For group (c) mainly amorphous/nanocrystalline or FCC structure, slight surface roughness, and good microhardness values were found. Multilayer composites demonstrate the best mechanical properties - high adhesion and good microhardness (23-28 GPa).

Nanocrystalline powders of new mixed manganites-chromites $R\mathrm{M}\mathrm{n}{}_{1-x}\mathrm{C}\mathrm{r}_{x}\mathrm{O}_{3}$(R=Pr, Sm, Er, x=0.5, 0.9) and manganites-gallates $R\mathrm{M}\mathrm{n}_{1-x}\mathrm{G}\mathrm{a}_{X}\mathrm{O}_{3}(R=\mathrm{P}\mathrm{r}$, Sm, Eu; $x=0.25,0.5,0.9)$ with orthorhombic perovskite structure were obtained by sol-gel citrate route. Crystal structure parameters and microstructural parameters of the materials were established depending on the synthesis conditions. Based on the results obtained formation of continuous solid solutions RMn1- ${}_{x}\mathrm{C}\mathrm{r}_{x}\mathrm{O}_{3}$ in the $R\mathrm{M}\mathrm{n}\mathrm{O}_{3-}R\mathrm{C}\mathrm{r}\mathrm{O}_{3}$ systems and limited solid solutions in the $R\mathrm{M}\mathrm{n}\mathrm{O}_{3-}R\mathrm{G}\mathrm{a}\mathrm{O}_{3}$ systems were predicted.

Ceramic samples based on $(c_{u1-x}Ag_{x})_{7}SiS_{5}I$ nanocrystalline powders were manufactured by pressing them at $\sim 400$ MPa pressure and subsequent annealing at 973 K during 36 hours. Investigations of electrical conductivity of ceramics based on $(c_{u1-x}Ag_{x})_{7}SiS_{5}I$ solid solutions were carried out by the method of impedance spectroscopy in the frequency range from 10 Hz to $2\times 10^{6}$ Hz and in the temperature range 292-383 K. It is established that with increasing the content of silver atoms in ceramic samples based on $(c_{u1-x}Ag_{x})_{7}SiS_{5}I$, the ionic component of electrical conductivity increases nonlinearly, while electronic component decreases nonlinearly, and their ratio increases nonlinearly and for $Ag_{7}SiS_{5}I$ exceeds 60000.

This research focuses on the establishment of the relationship between composition-structure-properties of nanocomposite Ti-Zr-C coatings. The coatings have been deposited by the dual-target magnetron sputtering on Si substrates and explored with the atomic force microscopy, scanning electron microscopy with energy dispersive spectroscopy, X-ray diffraction and nanoindentation. It has been found that the coatings have a nanocrystalline microstructure, are sufficiently textured, and represent a solid solution of the fcc-phase. The atomic concentration of elements in the initial target affects the structure and composition of the resulting coatings. It is shown that Ti-Zr-C coating with the lowest surface roughness (0.8 nm), the stoichiometric composition by carbon (50 at. % C) and the coarsest crystalline structure (15 nm) has the maximum values of the hardness of $\sim 35$ GPa and Young's modulus of $\sim 310$ GPa.

An alloy gap is used in the place of air gap to mitigate the concentrated gap loss of nanocrystalline core of an LCL filter inductor in a high frequency converter. A finite element analysis (FEA) model has been developed to examine the performance of the proposed method and validated by experiments. Based on FEA results, the maximum eddy current loss density can be reduced by around 89% and 69% for two different winding placements, respectively. The total eddy current loss of the air-gapped inductor can be reduced by 29% and 27% with gap winding placement and side winding placement respectively by applying an alloy gap. As a result, the hotspot temperature can be reduced corresponding to a lower and more uniform loss distribution.

Magnetic nanomaterials have become widely used as functional material components in power electronics. For example, the powder cores of FeCuNbSiB have better high frequency characteristic in MHz frequency band in comparison with other iron-based materials. The microwave properties of the soft magnetics have potential for microwave application. The study of the specific susceptibility dependent on temperature, the X-ray structural analysis, the ferromagnetic resonance spectrums in the field of super high frequency, and the mechanical vibrations in the soft magnetic materials can provide us with the deeper understanding of the distribution of magnetization, collective spin excitations etc. In this work the dependence of the specific susceptibility on the temperature, the Cu K a X-ray diffraction patterns, the ferromagnetic resonance spectrums in the electromagnetic field of frequency 9.4 GHz, and the mechanical vibrations of low frequency for the amorphous and nanocrystalline micro-ribbons of Fe73.5Cu1Nb3Si13.5B9 are discussed.

Irradiation (“SOLO” setup, High-Current Electronics Institute SB RAS) of hypereutectic Al- (22–24) Si composition silumin samples with an intense pulsed electron beam was carried out. The formation of a multiphase submicron nanocrystalline structure is revealed. It was found that after modification, the hardness of silumin surface layer increases by more than 2 times. Tensile tests were carried out for flat proportional silumin samples in the initial and after irradiation states. An increase in the ductility of irradiated samples was demonstrated.

Nanocrystalline nickel manganite (NiMn $_{2} O_{4}$) was obtained by sol-gel combustion using glycine as fuel, followed by calcination at 800°C. X-ray diffraction (XRD) analysis confirmed the formation of a pure cubic spinel structure with a crystallite size of 54.5 nm. Scanning electron microscopy (SEM) of the obtained nickel manganite powder showed porous nanocrystalline morphology. The material constant (B) of the obtained nickel manganite powder applied as paste and dried at 100°C was determined as 4812 K in the temperature range 20-50°C, confirming potential application in flexible temperature sensors.

The experiment were carried out by preparing highly N-deficient nanocrystalline non-stoichiometric TiN x (0.3 x and AlN were investigated. The highly N-deficient structure induced interfacial reaction between TiN 0.3 and AlN, reaction formed complex interfacial structure. The interfacial reaction zone consisted of a continuous stoichiometric TiN layer and a multi-phase region close to TiN 0.3 which with re-formed AlN grains distributed in TiN x matrix. The re-formed AlN grains presented coherent interface with TiN x at grain boundary according to core-shell structure. The decomposed AlN released N and Al free atoms at high temperatures by the effect of N vacancies. N atoms diffused into TiN 0.3 and substituted at N vacancies gave rise to the formation of TiN and TiN x region, Al atoms diffused across the TiN region to produce AlN. The interfacial reaction was controlled by N vacancy content and temperature, reaction will proceed at high N vacancy content and the system will stay equilibrium at low N vacancy content. The interfacial reaction led to a significant microstructural evolution and mechanical property increase. Second phase particles strengthening, core-shell structure strengthening, coherent interface strengthening mechanisms, and the complex interfacial structure enhanced mechanical properties of TiN 0.3 /AlN composites.

Researchers are currently focusing on nanocrystalline spinel ferrites (MFe 2 O 4 ) due to their use in various applications such as magneto-optics, ferrofluids, spintronics, magnetic storage media,biomedical and microwave devices, etc. Ferrites are also used as a source for energy, humidity sensors, and a lithium-ion battery anode in addition to the electronic and magnetic usages. The NiFe 2 O 4 nanofibers were prepared using electrospinning. XRD, FTIR studies support the production of NiFe 2 O 4 nanofibers from cubic spinel. AFMresults confirm the formation of NiFe 2 O 4 nanofibers, as well as the parameters of roughness. The impedance measurementsof NiFe 2 O 4 nanofiberelectrical conductivity is 6.39 x 10−6 S cm 1at 300 K,and were performed with different temperatures and frequencies.

A great scientific effort has been dedicated to increase the lasers power and to shift their operating wavelengths from traditional telecommunication range 1.2–1.7µm to longer wavelengths. The breakthroughs in many fields; such a LIDARs, chemical sensors, etc.; are associated with an existence of high-power lasers operating in the infrared range 2 – 5 µm. Although the results in the field of chalcogenide or fluoride glass have opened new horizons, the thermal and chemical stability of such class of materials significantly limit the overall transmitted power and their applicability. Transparent ceramics may face this challenge because of their high thermal and chemical stability, low phonon energy and high transparency in short- and mid-infrared. We present the nanocrystalline ceramic luminophore based on the compound (Ho0.05 Y 0 . 95 )2 Ti 2 O 7 crystallizing in pyrochlore structure. The luminophore was constituted of the partially sintered ceramic nanoparticles of the size around 30 nm and its phonon energy was smaller than 700 cm−1. The luminophore revealing an emission around 2.0 µm and 2.9 µm. The further tailoring of the chemical structure can further contribute to the preparation of novel ceramic luminophores emitting in short- and mid- infrared as a high-thermally and chemically stable alternative to conventional glass fibers.

Close space vapor transport is used to investigate PbI2 deposition and the reaction of PbI 2 with CH 3 NH 3 I to form CH 3 NH 3 PbI 3 (MAPI) on nanocrystalline (CdS) or amorphous (SnO 2 ) electron transport layers (ETL). The crystallographic structure and surface morphology of PbI 2 thin films and the resultant MAPI films after reaction have strong dependence on ETL substrates. Smoother morphology, stronger crystallographic orientation - (001) for PbI 2 and (200) for MAPI films - and larger coherency length are observed for films grown on SnO 2 ETL as compared to CdS. Solar cells fabricated on both types of ETL exhibit better cell performance for the MAPI absorbers that contain a small amount of residual PbI 2 . Despite crystallographic differences, solar cells made on both ETLs performed similarly.

Platinum diselenide (PtSe 2 ) is a promising two-dimensional (2D) material of the noble-metal dichalcogenides (NMDCs), a subgroup of the transition-metal dichalcogenides (TMDCs). It has been shown to exhibit a high negative piezoresistive gauge factor (GF) [1] and a charge carrier mobility of up to 210 cm 2 /Vs while being air-stable for many months [2] . It can be grown at CMOS-compatible temperatures by thermally assisted conversion (TAC) [3] . PtSe 2 can be tuned from a semiconductor to a semimetal by varying the number of layers [4] – [7] . Experimental data of electronic devices based on PtSe 2 show large variations in the electronic properties that cannot be explained by the material thickness alone. Here, we show that the nanocrystalline structure of TAC-grown PtSe 2 films greatly influences the electronic properties of PtSe 2 -based devices.

Cellulose-based composites are considered as perspective materials for novel optoelectronic devices. Due to structure of cellulose it can be incorporate with various additives, in particular oxides, in order to produce composites with improved physico-chemical properties. This paper reports data on preparation and characterization of composites based on micro/nanocrystalline cellulose with ZrO 2 nanopaticles codoped with europium and fluorine ions. Morphology, dielectric and luminescence properties of the composites have been studied and analyzed together with data on properties of the starting components and literature data. It was found that samples consist of tightly packed cellulose plates of 2 – 20 µm in size. The small oxide particles are generally located inside the cellulose plates, while the larger ones and agglomerates are found on the plate's surfaces. Chemical elements analysis has shown that carbon and oxygen with average content about 71 and 29 at. %, respectively, are the main components in the most areas of the plates. Degrees of crystallinity for the samples were estimated from XRD patterns and obtained values are in the 58 - 61 % range. The photoluminescence spectra of composites consist of wide band with maxima near 480 nm related with cellulose host and weak bands of Eu3+ ions luminescence peaks in 580–700 nm spectral region. In case of excitation at 393nm the CIE chromaticity coordinates of composites are moving from (x=0.211, y=0.261) for pure cellulose to (x=0.250, y=0.343) for composite with 10 wt. % of ZrO 2 :Eu,F in composite. Dielectric relaxations were observed for real and imaginary part of dielectric permittivity near – 50°C and ascribed to reorientation of methyl groups on the micro/nanocellulose crystallites surfaces.

Numerous power electronics topologies rely on magnetic components operating with a DC bias flux, resulting in higher core losses. The losses of nanocrystalline gapped cores as a function of the DC flux density, up to 0.95 T, are reported in this paper for various AC flux density ripple, up to 300 mT peak-to- peak. An unprecedented relative loss level increase has been measured under large DC bias, and the phenomenon has been observed to be more pronounced at lower AC flux density ripple.

Structure evolution of rapidly quenched Al65Ni10Si25 alloy under heating and isothermal annealing was investigated using DTA and X-ray diffraction methods. The process of structure transformation from the as-quenched state into a nanocrystalline state has been studied. The occurrence of hexagonal H-phase was observed within wide temperature and time interval. It was shown that the metastable H-phase has not decomposed after isothermal annealing during 5 hour at temperatures 403 – 463 K.

We report the synthesis, structure and nonlinear optical properties of cadmium sulphide (CdS) nanocrystallines (NCs) synthesized electrochemically both with and without detergent ATLAS G3300. Relevant structural and morphological features are explored by X-ray diffraction and scanning electron microscopy (SEM) techniques. The efficiency of the second harmonic generation (SHG) appears to be strongly dependent on the energy density of the incident fundamental laser radiation and NC sizes., Comment: 2020 IEEE 15th International Conference on Advanced Trends in Radioelectronics, Telecommunications and Computer Engineering (TCSET), Conference Location: Lviv-Slavske, Ukraine, 25-29 February 2020, 5 pages, 8 figures, 3 tables

In this paper, the structural, optical and photoluminescence (PL) features of the spray deposited Ba:SnO2 thin films with varying thickness have been investigated. X-ray diffraction analysis showed that Ba:SnO2 thin films have a polycrystalline tetragonal rutile structure and nanometric dimensions. The preferred directional growth of nanocrystalline was along direction. The crystallite size of the samples was calculated using the Debye-Scherrer equation. With an increase in film thickness, the crystallite size decreased from 11.72 to 5.27 nm, while crystal imperfections, viz. lattice strain, degree of lattice distortion and dislocation density increased. The influence of film thickness on the transmittance and reflectance was investigated by using UV-Vis spectral data. The average visible transmittance of Ba:SnO2 nanocrystalline declined from 85 to 79% at 550 nm with an increase in film thickness. Ba:SnO2 nanocrystalline exhibited a slight red-shift in the absorption edge and the optical band gap was found to decrease in the range 3.94 to 3.64 eV. Near band-edge UV emissions band at ~ 402 nm were observed in the PL spectra which are attributed to the defect levels originating from the oxygen vacancies.

One of the main elements for the development and implementation of bidirectional converters applied to smart grids and micro CD grids is the medium frequency transformer (MFT). This element integrates a high efficiency together with a high power density due to the increase in the design frequency of the transformer, compared to conventional transformers at 60 Hz. This change requires the analysis and development of new methodologies and materials in the design to support the needs of these new transformers applied to DC-DC converters in photovoltaic systems, wind systems, solid-state transformers, and electric vehicles. This article describes the design and construction of an MFT, it’s computer simulation and experimental validation by building a prototype in the laboratory. The MFT has an efficiency of 98.71 % which was obtained for a laboratory prototype with 2.5 kVA, 250 V / 670 V and a frequency of 5 kHz.