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Nanocrystalline metals often display a high strength up to the gigapascal level, yet they suffer from poor plasticity. Previous studies have shown that the development of hetero-sized grains can efficiently overcome the strength-ductility trade-off of nanocrystalline metals. However, whether this strategy can lead to the fabrication of nanocrystalline nanowires exhibiting both high strength and superplasticity is unclear, similar to the atomistic deformation mechanism. In this paper, we show that ultra-small nanocrystalline Au nanowires comprising grains in both the Hall–Petch and inverse Hall–Petch grain-size regions can exhibit extremely high uniform elongation (236%) and high strength (2.34 gigapascals) at room temperature. In situ atomic-scale observations revealed that the plastic deformation underwent two stages. In the first stage, the super-elongation ability originated from the intergrain plasticity of small grains via mechanisms such as grain boundary migration and grain rotation. This intergrain plasticity caused the grains in the heterogeneous-structured nanowires to grow very large. In the second stage, the super-elongation ability originated from intragrain plasticity accompanied by the diffusion of surface atoms. Our results show that the hetero-grain-sized nanocrystalline nanowires, comprising grains with sizes both in the strongest Hall–Petch effect region and the inverse Hall–Petch effect region, were simultaneously ultra-strong and ductile. They displayed neither a strength-ductility trade-off nor plastic instability.

A novel hot extrusion method to fabricate anisotropic nanocrystalline SmCo5 magnet was investigated. The results indicate that the hot-extruded (HE) SmCo5 magnet obtains a strong c-axis texture in perpendicular to the extrusion direction, but the texture strength is clearly different in different regions. The deformation degree plays a key role in the formation of c-axis crystallographic texture and magnetic anisotropy. In surface region of the HE magnet, the deformation degree of grains is the biggest, and the c-axis texture and remanence are the strongest. Furthermore, deformation mechanism of the HE SmCo5 magnet was preliminarily discussed.

In the present work, nanostructured hydroxyapatite (HA)-containing coating was prepared on a Ti surface by ultrasonic mechanical coating and armoring (UMCA). A Ti plate was pre-coated with HA slurry, followed by UMCA, which was achieved by high-frequency ZrO2 ball bombardment. The UMCA process comprised several cycles of pre-coating and ball bombardment, providing high amounts of HA and good coating adhesion. The coating mainly consisted of nano-HA particles (less than 10 nm) and a small amount of Ti. Furthermore, the deformation structures of the Ti surface region were characterized in a nanocrystalline layer with a grain size of 50–200 nm. Additionally, the coating exhibited improved bioactivity and corrosion resistance in Hanks’ balanced salt solution than the Ti surface. Furthermore, the in vitro cytotoxicity test assessed that the HA-containing coating was non-cytotoxic.

Soft magnetic powder cores are attractive due to their loss at medium frequency. However, the performance of electrical equipment is affected by temperature increase by the heat of core losses. In this paper, the magnetic properties of nanocrystalline powder core, amorphous powder core, X-Flux (Fe-Si), Sendust (Fe-Si-Al), and ferrite are measured and compared in the range of 25 °C to 125 °C from 20 kHz to 100 kHz. The discussed magnetic properties include the temperature dependent coercive field, initial permeability, inductance factor, saturation flux density, and core loss. The results show that magnetic properties depend on temperature and frequency. In comparison, the nanocrystalline powder core has the best temperature stability and relatively low core loss among the five materials, so it can be well used at broad temperature and medium frequency.

ZnAl2O4 nanocrystalline particles were prepared using the solution combustion method using a new combustion fuel, Leucine. The prepared samples' structural, microstructural–elemental composition, and optical characteristics were investigated using XRD, SEM-EDS, and UV–Visible spectroscopy. As-synthesized ZnAl2O4 nanoparticles are polycrystalline, with no secondary phases, and crystallized in a cubic - spinel structure. The polycrystalline nature of the prepared sample is due to the exothermicity of fuel and oxidizer, which demonstrate that the fuel utilized (Leucine) provided adequate energy for the production of nanoparticles in their as-synthesized form, as supported by adiabatic temperature through thermodynamic calculations. The thermodynamic calculations also include a universal method to estimate the specific heat capacity at constant pressure. Furthermore, even after 2 h of calcination at 600 °C, ZnAl2O4 exhibits a single phase with no secondary phases, indicating the material stability and single-phase nature. The crystallinity of ZnAl2O4 nanoparticles was observed to increase with increasing annealing temperature. SEM micrographs of as-synthesized samples exhibit the formation of dense particles, voids, and pores in the as-synthesized sample. In addition, tiny aggregates were detected on the surface of more prominent clusters, which reduced as the calcination progressed. In addition, calcined samples exhibit a greater optical reflectance than as-synthesized samples. Tauc's graphs were used to compute the optical energy bandgap. The calculated energy band gap is redshifted to that of the bulk material. The bandgap energy decreases upon calcination, suggesting that the prepared materials have a larger crystallite size or more crystallinity. Correlations were found between the Tad, and the structural and optical properties of the prepared samples. The findings suggest that Leucine could be used as a novel combustion fuel to produce crystalline ZnAl2O4 nanoparticles in their as-synthesis form.

The electrodeposition technique was used to synthesize copper-doped ZrO2 thin film. Different characterization technique such as vibrating sample magnetometry, UV–visible spectroscopy, scanning electron microscope, and X-ray diffractometry were used to study the magnetic, optical, surface morphology, and structural properties of the thin films. The Uniform nanocrystalline grains without cracks, and of various sizes were obtained. The optical studies showed a decrease in energy band gap from 4.1 eV to 3.9 eV. The magnetic studies revealed that the doped samples have unique ferromagnetic ordering, this could be due to the increase in grain size. The 2% and 4% doped samples are saturated around 4.51 × 10−4 emu/g and 4.70 × 10−4 emu/g at coercive field of 274.54 and 274.96 respectively.

The nanocrystalline alloys are gradually used as shielding materials in wireless power transfer (WPT) systems with the development of high-power-density. In this paper, the system properties of WPT using ferrite and four types of nanocrystalline cores are simulated by three-dimensional (3-D) finite element analysis (FEA). Based on this, a novel shielding pad composed of nanocrystalline alloy and ferrite is designed to improve the WPT system properties. The WPT systems are preliminarily compared by 3-D FEA when the different nanocrystalline alloys are used in the novel shielding pad. The experimental WPT system for 85 kHz, 1.5 kW with a 24 cm air gap between the primary and secondary coils is built to validate the simulation. The results show that significantly greater shielding can be realized for the novel pad at the price of a slight decrease of transmission efficiency than conventional ferrite core.

Synthesis of nanostructured carbon allotropes using CO2 as a cheap carbon source is challenging and usually limited by high temperature activation. Herein, formation of 3D nanostructured carbon allotropes including nano-graphene and single crystalline nanodiamond films is feasible at room temperature on various single crystal metals (e.g., Bi, Ag, Zn, and Co) that were formed under the dynamic CO2 electrochemical reduction reaction environment at relatively low applied potential (−1.1 to −1.6 V vs. Ag/AgCl). The nanocrystalline carbon was obtained as the major products from CO2 (≥96% selectivity, ∼1 μm thickness) without any liquid products. Upon applying the negative potential, nanoclustering of the self-limiting ultrathin metal oxide layers of metal particles on the highly conductive substrate could lead to formation of negatively charged metal clusters, which were well stabilized by the ternary electrolyte system containing [BMIm]+[BF4]-/propylene carbonate/water. This system allows the reduction of CO2 into single atoms C∗ and the subsequently electrocrystallization of C∗ into carbon allotropes on the crystallographic planes of the single crystal metals formed as the building blocks. The CO2-derived Ag–C/epoxy composites show promising thermal conductivity. The results present a breakthrough advancement in the growth of nanostructured carbon allotropes from CO2 by the viable negative CO2 emission approach.

Dual-emitting manganese ions singly doped 5ZnO-(5–2.5x)Ga2O3-2.5 xAl2O3–90SiO2 glass-ceramic (GCs) samples, containing the alloyed Zn(Ga, Al)2O4 nanocrystals with a size of about 5 nm, were successfully prepared by a sol-gel method under different heat treatment temperatures, demonstrating an excellent white light emission. We found that the formation of the ZnGa2O4 nanocrystals began at 650 °C (absence of Al2O3, x = 0) while that of the ZnAl2O4 crystals required a higher temperature of about 900 °C (presence of Al2O3, x = 2) in SiO2 glasses. A nanostructured Zn(Ga, Al)2O4:Mn2+, Mn4+ in the glass-ceramic was synthesized by Al3+ replacing part of Ga3+. The doping of Al3+ has effectively contributed to the existence of Mn2+, thus realizing the regulation of the valence state of manganese ions. The glass ceramic samples showed red emission arrived from the 2Eg → 4A2g transitions of Mn4+, green emission originated from the 4T1→6A1 transition of Mn2+, and blue emission derived from the self-activation center of ZnGa2O4 nanocrystalline. In particular, the 0.1%Mn doped the 5ZnO-(5–2.5x)Ga2O3-2.5xAl2O3–90SiO2 glass-ceramic samples can provide white color emission depending on the Al doping concentration (x), x = 0.4–0.9 and the annealing temperature, 650–900 °C.

A diamond film was synthesized by chemical vapor deposition, where a hot graphite plate was used to thermally activate methane and hydrogen. The effect of parameters on the diamond films grown, such as pressure ranging from 40 to 100 torr, methane concentration in hydrogen varying from 0.5 to 2 vol %, and substrate temperatures from 1020 to 1140 °C, were studied. Diamond films with nanocrystalline to polycrystalline crystal sizes were obtained. A maximum growth rate of 0.8 μm/h was obtained, and the quality is comparable to diamond films synthesized by the hot metal filament chemical vapor deposition method. In contrast to the hot filament method, this method does not use a metallic filament as thermal activator. Therefore, the diamond films contain no metal contaminants and thus can be used for electronic and biomedical applications. The absence of metal contaminants was confirmed using different methods.

It is challenging to develop a material that combines good mechanical properties and high translucency since these properties are generally not coincident in one material. In this study, we prepared ZrO2-SiO2 nanocrystalline glass-ceramics that combines the above two types of properties. Raw powder with 55 mol%, 65 mol%, and 75 mol% ZrO2 and each with 5 mol% yttrium as a dopant was prepared by sol-gel method, followed by spark plasma sintering to obtain dense glass-ceramics. XRD results demonstrated that the glass-ceramics with 65 mol% and 75 mol% ZrO2 were composed of tetragonal-ZrO2, whereas, that with 55 mol% ZrO2 was composed of cubic-ZrO2. The as-sintered glass-ceramics showed black/brown discoloration, but they obtained high translucency after thermal treatment. X-ray energy-dispersive spectrometry (EDS) results in scanning electron transmission microscopy (STEM) mode demonstrated yttrium dopants were predominately distributed in ZrO2 nanocrystallites. The glass-ceramics with 65 mol% ZrO2 had the highest flexural strength, achieving an average value of 673 MPa. The glass-ceramics with different compositions sintered at different temperatures showed fracture toughness values ranging from 5.25 MPa m1/2 to 6.69 MPa m1/2. The strong and translucent ZrO2-SiO2 nanocrystalline glass-ceramics showing great protentional to be used in many fields.

From the perspective of high-temperature applications, materials with excellent high-temperature mechanical properties are always desirable. The present work demonstrates that the binder-free nanopolycrystalline WC ceramic with an average grain size of 103 nm obtained by high-pressure and high-temperature sintering exhibits excellent mechanical properties at both room temperature and high temperature up to 1000 °C. Specifically, the binder-free nanopolycrystalline WC ceramic still maintains a considerably high Vicker hardness HV of 23.4 GPa at 1000 °C, which is only 22% lower than the room temperature HV. This outstanding thermo-mechanical stability is superior to that of typical technical ceramics, e.g. SiC, Si3N4, Al2O3, etc. Nanocrystalline grains with many dislocations, numerous low-energy, highly stable Σ2 grain boundaries, and a relatively low thermal expansion coefficient, are responsible for the observed outstanding high-temperature mechanical properties.

In this work, we investigated the influence of Chromium (Cr) concentration 1.5 wt%Cr- 3.5 wt%Cr on the properties of zinc oxide (ZnO) thin films deposited by Dip-Coating technique. The structural, morphological and electrical properties of the obtained thin films are investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and by electrical measurements for testing solar cell performances. It was found that the doped films become more amorphous by increasing Cr concentrations. As a result, the surface morphology of ZnO thin films exhibits the formation of different structures of: nanofibers, nanofibrils and nanorods clearly distributed inside ZnO cells. Moreover, it was also observed that the n-type ZnO is inverted to p-type for 1.5 and 2.5 wt%Cr. The most suitable electrical parameters for this study were obtained for 1.5 wt%Cr doped ZnO solar cells and for 2.5 wt%Cr doped ZnO with an efficiency of 24.32% and 22.43%, respectively.

This report demonstrates high temperature sealing tendency of alumino-silicate glasses (ASG) on the system SiO2-MgO-Al2O3-B2O3-K2O-MgF2 doped with silver (Ag) and gold (Au) nanoparticles. Density of the melt-quenched (1550 °C) glasses were in 2.51–2.55 g.cm−3. The glasses were heat-treated at 900 ± 10 °C over which the opaque glass-ceramics were obtained with major crystalline phase (XRD) fluorophlogopite mica [KMg3(AlSi3O10)F2] with secondary phase norbergite (Mg2SiO4.MgF2). FESEM study indicated the development of Rod-like and rock-like crystallite particles (size ∼1–4 µm) randomly dispersed in mother glass–ceramic which was restructured into nanocrystalline morphology (crystallite size ∼100–400 nm) with the aid of Ag- or Au- nanoparticles. The significant change in microstructure influenced the corresponding density (2.51–2.55 g.cm−3) and thermal expansion characteristics. Coefficient of thermal expansion (CTE) for ASG was estimated to be 9.96 ± 0.10×10−6/K (50–800 °C), which increased to 10.46–11.01×10−6/K when doped with Ag- or Au- content. Such wide CTE (11.01 ± 0.11×10−6/K) value matches well with the CTE of ceramic/metallic materials used for high temperature application thus Ag- doped SiO2-MgO-Al2O3-B2O3-K2O-MgF2 glass can be a suitable for high temperature sealing application (like SOFC).

The present work reports the structural, morphological, and optical analysis of rare earth metal ion (Nd3+) doped Titanium Dioxide Nanoparticles. Titanium Dioxide doped with Neodymium ions (1 wt% and 4 wt%) have been studied by X-ray diffraction (XRD) Aanlysis, High Resolution Transmission Electron Microscopy (HR-TEM) analysis, Energy Dispersive X-ray Analysis (EDAX), Ultraviolet–visible (UV–Vis) spectroscopic analysis. The powder X-ray diffraction patterns ensured the nanocrystalline anatase formation of all the samples. The morphology and particle size of the TiO2 host matrix were confirmed by High Resolution Transmission emission electron microscopy (HR-TEM). The particle size trend obtained from HR- TEM images is acceptable with the crystal size obtained from XRD results. Ultraviolet–visible measurements were carried out to investigate the optical properties of our powdered titania. The dye sensitized solar cells were fabricated with these as-synthesized materials as the photoanode and the J-V measurement shows improved high open circuit voltage, short circuit current and high efficiency achieved.

AlN ceramic was successfully wetted and then joined with nonactive Sn9Zn eutectic solder assisted by ultrasonication in air. The effect of ultrasonic time on the formation of joint was studied. Results indicated that the defect-free joint can be obtained at an ultrasonic time of 5 s. Two regions, namely, AlN/Sn (s,_s) and AlN/Zn (s,_s), were found in the bonding interface. Zn and O accumulated in the AlN/Sn (s,_s) interface. An amorphous and nanocrystalline layer of ZnO formed in the hard-wet AlN surface. And Zn (s,_s) directly bonded with AlN. The low temperature and fast bonding of the AlN was attributed to the high pressure and temperature caused by cavitation effect. The shear strength of the joint increased from 10.6 MPa to 30.7 MPa when the ultrasonic treatment time increased from 5 s to 150 s. With the prolongation of ultrasonic time, more AlN ceramic particles entered the solder and acted as the reinforcing phase.

Utilizing eggshells to synthesize a value added product like nanocrystalline hydroxyapatite (HA) has received a lot of attention from researchers since they are composed of CaCO3 with biologically essential trace elements such as Mg, Si, etc. Different biomedical applications need HA with appropriate nanoscale characteristics like crystallinity, particle size, morphology, surface area, mesoporous nature, etc. The same can be achieved by tuning the reaction parameters, choosing a suitable mode of preparation and utilizing organic modifiers. Here, we report the rapid synthesis of eggshell derived HA in the presence different organic modifiers using a custom built microwave reactor employing the previously optimized parameters. The synthesis process is relatively rapid and gets completed in 5 min. The absence of an organic modifier yielded inhomogeneous size nanorods in the range of 40 – 600 nm. Ethylenediaminetetraacetic acid (EDTA) assisted synthesis resulted in a flower like 1.67 ± 0.12 μm sized HA. Whereas polyethylene glycol 6000 (PEG) and cetyltrimethylammonium bromide (CTAB) assisted synthesis produced aggregated nanorods of length 31 ± 8 and 68 ± 20 nm, respectively. While the synthesis with trisodium citrate dihydrate (TSC) resulted in needles of HA with typical length of 32 ± 8 nm. Presence of Na, Mg and Si trace elements are confirmed from the composition analysis. All the samples are found to be mesoporous in nature. The in vitro cell culture experiment carried out using fibroblast NIH 3T3 cell line clearly revealed equal or higher cell viability for the samples synthesized in presence of organic modifiers as compared to sample produced without organic modifier. Thus, from the present study we find that the synthesis of eggshell derived HA using different organic modifiers via a custom built microwave reactor can be a potential approach for the rapid preparation of precursor materials with suitable nanoscale characteristics for developing bone fillers, drug/protein delivery carriers, tissue engineering scaffolds, etc.

Aiming to gain insight on the hydrogen storage properties of Mg-based alloys, partial hydrogenation and hydrogen pressure related de-/hydrogenation kinetics of Mg–Ni–La alloys have been investigated. The results indicate that the phase boundaries, such as Mg/Mg2Ni and Mg/Mg17La2, distributed within the eutectics can act as preferential nucleation sites for β-MgH2 and apparently promote the hydrogenation process. For bulk alloy, it is observed that the hydrogenation region gradually grows from the fine Mg–Ni–La eutectic to primary Mg region with the extension of reaction time. After high-energy ball milling, the nanocrystalline powders with crystallite size of 12∼20 nm exhibit ameliorated hydrogen absorption/desorption performance, which can absorb 2.58 wt% H2 at 368 K within 50 min and begin to desorb hydrogen from ∼508 K. On the other side, variation of hydrogen pressure induced driving force significantly affects the reaction kinetics. As the hydrogenation/dehydrogenation driving forces increase, the hydrogen absorption/desorption kinetics is markedly accelerated. The dehydrogenation mechanisms have also been revealed by fitting different theoretical kinetics models, which demonstrate that the rate-limiting steps change obviously with the variation of driving forces.

A study of the structural, Raman scattering and thermodynamic properties of a nanocrystalline ceramic rare earth oxide Yb2O3 and its bulk counterpart is reported. The nanosized sample was obtained by mechanical milling of bulk Yb2O3 (99.998%, high purity powder). The Rietveld analysis of the X-ray diffraction data indicates the presence of nanoparticles with a mean grain size of 12 ± 1 nm after 75 h of milling time. The crystallographic structure within nanoparticles is cubic Ia-3 and the lattice parameter a = 10.455 ± 0.002 A. The nanocrystalline structure is confirmed by the evaluation of transmission electron microscopy images, showing a size distribution with a mean size DTEM = 8 ± 2 nm. Measurements of the specific heat (2 K–300 K) reveal an excess contribution respect to the unmilled (bulk) compound in the high temperature region above 70 K. At lower temperatures the results are consistent with a drastic change of the antiferromagnetic contribution (ordered below TN = 2.2 K) as a result of the magnetic disorder arising from the size reduction process. The specific heat above TN for the bulk and nanocrystalline samples are explained by the interplay among the phonon contribution, crystalline field and the presence of anharmonic effects. In the nanocrystalline state, broadening and shifts of the contribution of phonon modes to the Raman spectra, and a further reinforcement of the anharmonic contribution are found.

Rare earth element Ce3+ substituted spinel cobalt ferrite, CoFe2-xCexO4 for (x = 0.0, 0.05, 0.10, 0.15, 0.20) is synthesized using an economical sol–gel technique. The X-ray diffraction analysis reveals that all samples have spinel symmetry indexed to Fd3m space group. Fullprof Rietveld analysis is performed to find out lattice parameters that increase monotonically due to induced lattice strains in samples. The crystallite size was determined to be 54.9 nm using Williamson-Hall plots. The morphological analysis of samples has been performed using SEM imaging. FTIR spectrum confirms octahedral and tetrahedral site occupancy by metal–oxygen bonds for all samples. The magnetic properties of samples refine with Ce3+ doping at iron site, with magnetization ranging from 23.59 to 57.68 emu/g and retentivity 17.14 to 24.08 emu/g. The Coercive field values drastically increased from 739 to 1912 Gauss. Thus, we have explored the influence of rare earth Ce3+ (1.14 A) substitution at the Fe3+ site (0.55 A) in CoFe2O4 crystal lattice for improvement of its structural and magnetic properties in this paper.

Cu(In,Ga)Se2 (CIGS) is a prevalent material with superior thermo-chemical stability and excellent optoelectronic properties for solar cell applications. In thin film form, CIGS could be a potentially economical and building integrated photovoltaic adaptable substitute to Silicon solar cells, solving humanity's extensive energy demands. To be economically sustainable, CIGS thin film processing must be abridged and affordable. We explored a low-cost, simplified wet chemical nano-ink method to make the CIGS thin film absorber layer comprising precursor thin film preparation by spraying CIGS nano-ink and subsequent post-treatment using Selenium vapor under Nitrogen atmosphere at a temperature of 550 °C. The spray-casted nanocrystalline layers were selenized at a low pressure of 1 Torr or 1 atm Nitrogen utilizing elemental pallets of Selenium as a source of Se vapor. The impact of Selenization pressure on the structure, morphology, composition, and electronic conductivity of selenized CIGS thin films absorber is investigated in this study, as well as the device performance associated with the processing parameters.

SnO2 is an n-type semiconductor and a transparent conducting oxide and has apt properties in a gas sensing material, photovoltaic cells, fuel cells, batteries etc., Nanocrystalline tin oxide (SnO2) powders with different grain sizes were prepared by chemical co-precipitation method. Synthesised nanopowder XRD data were analyzed with different tools. X-ray diffraction (XRD) analysis mainly used to determine the crystal structure of nanomaterials such as ZnO, CuO, CdO and SnO2, etc., Pure SnO2 test conditions were set to be Cu-Kα XRD source, accelerating voltage 40 kV, acceleration currency 40 mA, scan range 20–80° with Ni filter (λ = 0.154056 nm). The pure SnO2 sample was exhibiting different crystalline peaks from the powder XRD study. The diffraction peak of pure tin oxide nanoparticles possesses a tetragonal rutile structure with space group P42/mnm. The FULLPROF Suite program was used for Rietveld–type analysis for pure SnO2powder diffraction data. The resultant data were compared with Nelson-Riley, Williamson-Hall plot, and Debye-Scherer methods. The lattice parameters and particle size of pure SnO2were agreed with the ICDD.No.01-077-0447data. The main advantages of these methods are low angle regions and a small number of peaks needed.

A favourable material for the optoelectronic system, nanocrystalline ceramic oxide CaBiNbO6, has been fruitfully prepared by single step auto ignition combustion method. The modified auto ignition combustion method took a vibrant role in synthesizing the nano structured oxide samples. The XRD revealed that, the sample crystallizes in orthorhombic structure without any secondary phase. The crystallite size calculated from the XRD data using the Scherrer formula is found to be 14 nm. TEM image of the as prepared sample shows a spherical morphology with a narrow particle size of nearly 19 nm. The 97 % of theoretical density of the sample with minimum porosity was attained during the sintering at 900 0C. The optical properties of the sample were studied using Ultraviolet visible absorption and Photoluminescence spectroscopy. The optical studies revealed that the material is wide band gap ceramic oxide and the optical band gap is obtained as 3.59 eV. Photoluminescence studies also revealed that the sample is a photoluminescent material with strong emissions in the visible region. The optical properties of the nano structured CaBiNbO6 makes the sample find various applications in opto-electronic systems.

Inspired by the hierarchical structure of the pearl shell and its related multi-scale toughening mechanism, based on the combination of powder metallurgy technology and spark plasma sintering, a layered graphene and carbon nanotubes hybrid reinforced Cu matrix composite material was successfully prepared. Compared with other conventional Cu matrix composite materials, the compressive elongation of the bionic materials is significantly improved, and all of them are above 20%, which is attributed to the effective crack deflection and the pull-out of the reinforcing phase. In terms of overall strength and toughness, (0.8 wt% MWCNTs+0.2 wt% GNPs)/Cu has the best performance. Its tensile strength, compressive strength and compressive elongation are 103.63 MPa, 202.32 MPa and 33.49% respectively. The large grain size in the laminates is conducive to the movement of dislocations, while the interlayer interface and nanocrystalline grains hinder the movement of dislocations in the direction perpendicular to the laminates.

Catalytic activity of TiO2, 2%Re–TiO2 and 10%Re–TiO2 in the conversion of carbohydrates into levulinic acid under autoclave conditions was evaluated. These materials were prepared by aerogel method, for the first time to the best of our knowledge, and characterized by XPS, SEM-EDX, DRIFTS, DR UV-vis, Raman, N2 adsorption/desorption isotherms, TGA and XRD. Further, the surface acidity was probed by NH3-TPD and pyridine-FT-IR where it was observed that increasing the amount of rhenium doped into TiO2 led to an increase in the total number of acid sites (Lewis + Brønsted) but with an overall lower strength. The presence of both Brønsted and Lewis acid sites led to the hypothesis that these materials may be well suited for conversion of carbohydrates into levulinic acid. Indeed a levulinic acid yield of 57% was reached over 10%Re–TiO2 for a low mass ratio catalyst to glucose (1 : 5). Moreover, the 10%Re–TiO2 catalyst was reused in the conversion of glucose for four catalytic cycles without a significant loss of the catalytic activity.

In this work, a series of few-layered WS2 nanosheets were fabricated through an ultrasonic stripping method assisted by a hydrothermal process, then the WS2/CdLa2S4 composites were prepared by growing CdLa2S4 nanocrystallines in situ on the surface of few-layered WS2 nanosheets through an ultrasonic stripping method followed by a hydrothermal process. Investigation shows that the prepared WS2/CdLa2S4 composite shows an excellent photocatalytic activity toward hydrogen evolution from water with visible light response. The optimized content of few-layer of WS2 nanosheet was estimated to be around 5 wt% of CdLa2S4 nanocrystalline and the corresponding hydrogen evolution rate is about 6 times higher than that of single phase of CdLa2S4 nanocrystalline. Furthermore, the WS2/CdLa2S4 composites still keep high photocatalytic activity after 4 times circles. Combining few-layered WS2 nanosheets as a co-catalyst with CdLa2S4 nanocrystallines not only facilitate the efficient separation of photogenerated carriers, but also promote more active sites for hydrogen evolution. Considering its excellent photocatalytic activity toward H2 evolution with visible light response and photochemistry stability, the obtained WS2/CaLa2S4 composite photocatalyst has promising application for practical photocatalytic H2 production from H2O drived by solar energy.

Nanocrystalline films of pure ZnO and Al-ZnO with a molar ratio Al:Zn = 1:99 and 3:97 were obtained by solid-phase pyrolysis. By XRD analysis the films have a wurtzite structure, the size of the crystallites is about 21 nm. The obtained films are almost transparent in the near UV range (the absorption coefficient is less than 16 %) and are transparent in the visible wavelength range. Electrophysical measurements have shown that the addition of minor amounts of aluminum to the ZnO film leads to a decrease in electrical conductivity by 2–3 orders of magnitude and the activation energy of electrical conductivity. The film with a molar ratio Al:Zn = 1:99 has the lowest activation energy of conductivity (0.23 eV).

The research of thermal expansion of nano- and microcrystalline TiB2 in the temperature range of 298–1473 K was carried out by the high-temperature X-ray diffraction method. The grain size effect on the temperature dependence of a and c parameters of TiB2 hexagonal unit cell was established. For nanocrystalline TiB2 with the 5–7 nm coherent scattering region, we found the linear dependence of the metric of the cell on temperature. The thermal expansion coefficient (TEC) of nanocrystalline TiB2 does not depend on temperature and equals 3.58‧10−6 K−1 and 9.92‧10−6 K−1 for the a and c axis respectively. For the microcrystalline TiB2, we detected the nonlinear temperature dependence of unit cell parameter a, which points to the effect of temperature on the coefficient of thermal expansion along a basal plane. The TECa rises from 6.02·10−6 to 9.94·10−6 К−1 in the range of 300–1473 K, while the TECc weakly depends on temperature and remains constant ∼8.38·10−6 К−1, leading to isotropic thermal expansion of microcrystalline TiB2 at 1273–1473 K. The equations which describe the changes of unit cell parameters and coefficients of thermal expansion of nano- and microcrystalline TiB2 as temperature functions are determined.

Mn-doped perovskite nanocrystals have promised new optoelectronic applications due to their unique material properties. In the present study, Mn-doped perovskite nanocrystalline films were prepared in situ in a polymer matrix. The Mn-doped perovskite nanocrystals (PNCs) had good crystallinity and uniform size/spatial distributions in the polymer film. Bright dual-color emission and the long lifetime of the excited state of the dopant were observed from the host exciton and the Mn2+ dopant, respectively. Furthermore, magnetism was observed in the optimal Mn2+ concentration, implying that magnetic coupling was achieved in the Mn-doped perovskite lattice. The Mn-doped perovskite films also showed superior stability against moisture. To demonstrate the practicality of this composite film, a white light emitting device was fabricated by combining a single composite film with a blue light emitting diode; the device showed a high-quality white light emission, and the Commission Internationale De L'Eclairage (CIE) chromaticity coordinate of the white light emitting diode (WLED) (0.361, 0.326) was close to the optimal white color index. In this single-layer WLED, self-absorption among the luminous multilayers in traditional white light emitting diodes can be avoided. The study findings revealed that Mn-doped perovskite nanocrystalline films have many exciting properties, which bodes well for the fundamental study and design of high-performance optoelectronic devices.

У роботі представлені результати досліджень літієвих феритів, заміщених іонами алюмінію методами ядерного магнітного резонансу (NMR), мессбауерівської спектроскопії та за допомогою вібраційного магнетометра зразків при кімнатній температурі. Результуючий магнітний момент системи залежить як від вмісту заміщуючого елементу, так і від селективного входження в А чи В підгратку. Катіони AL3+ і Li+ переважно займають октаедричні (В) позиції, тоді як Fe3+ розподілений по обох позиціях. Впровадження Al3+ в Впозиції понижує інтенсивність IFNMR амплітуди ехо. Більше того, збільшення вмісту алюмінію зменшує значення магнітного надобмінного поля і спричиняє швидке зростання парамагнітної компоненти (дублет на мессбауерівських спектрах). Зменшення намагніченості насичення призводить до зменшення інтенсивності сигналу. Наші результати показали, що NMR і мессбауерівська спектроскопія є доповняльними методиками для опису магнітних властивостей Li-Al феритів в широкому околі частот. Дослідження деградації метилену синього у водному середовищі показали, що синтезований ферит здатний витупати як фотокаталізатор, що працює у видимому діапазоні освітлення. Показано, що оптична ширина забороненої зони і коефіцієнт деградації знаходяться в оберненій залежності. The paper presents the study of lithium ferrites substituted by aluminum ions by the methods of nuclear magnetic resonance (NMR), Mössbauer spectroscopy, and using a vibrating magnetometer of samples at room temperature. The resulting magnetic moment of the system depends both on the content of the substituting element and on the selective injection into the A or B sublattice. Al3+ and Li+ cations occupy octahedral (B) sites, while Fe3+ is distributed in both ones. Implementation of Al3+ in the B-position reduces the intensity of the IFNMR echo amplitude. Moreover, an increase in the aluminum content reduces the value of the magnetic superexchange field and causes rapid growth of the paramagnetic component (doublet in Mössbauer spectra). A decrease in saturation magnetization leads to a decrease in signal intensity. Our results showed that NMR and Mössbauer spectroscopy are complementary techniques for describing the magnetic properties of Li-Al ferrites in a wide range of frequencies. Studies of the degradation of methylene blue in an aqueous medium have shown that the synthesized ferrite can act as a photocatalyst operating in the visible light range. It is shown that the optical band gap and the degradation coefficient are inversely related.

A novel class of nanocrystalline/amorphous Gd3Ni/Gd65Ni35 composite microwires were created directly from melt-extraction through controlled solidification. X-ray diffraction (XRD), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) confirmed the formation of a biphase nanocrystalline/amorphous structure in these wires. Magnetic and magnetocaloric experiments indicate a large magnetic entropy change (-ΔSM ~9.64 J/kg K), large refrigerant capacity (RC ~742.1 J/kg), and large maximum adiabatic temperature change ( Δ T a d max ~5 K) around the Curie temperature of ~120 K for a field change of 5 T. These values are ~1.5 times larger relative to its bulk counterpart and are superior to other candidate materials being considered for active magnetic refrigeration in the liquid nitrogen temperature range.

The Li2O–Al2O3–SiO2 (LAS) glass ceramics are prepared by one-step thermoelectric treatment. The influence of thermoelectric treatments on LAS glass-ceramics were studied. The crystal phase composition and microstructure of the LAS glass-ceramics were investigated by DSC, SEM, XRD and FTIR. Moreover, the thermal expansion performance and light transmittance of LAS nanocrystalline glass were characterized. The results show that low-expansion transparent LAS nanocrystalline glass can be produced in a short time by thermoelectric treatment. The free energy of nucleation and the degree of polymerization of the glass network are reduced by the electric field. The key is that the electric field polarizes Ti and Zr ions at the crystallization temperature, so that the crystal nuclei repel the same poles. This allows uniform crystal distribution, promotes crystallization and reduces one-step crystallization of crystal agglomeration. This proves that the rapid preparation of nanocrystalline glass by the one-step method is feasible, and provides a reference for the future one-step processing of glass-ceramics.

The effect of cavities on recrystallization growth of amorphous SiC induced by a high fluence He implantation was investigated. 300 keV He ions were used to implant the 6H-SiC (0001) wafer to a fluence of 4.4 × 1017/cm2 at room temperature. A buried amorphous layer with a width of approximately 468 nm was formed. Moreover, many spherical bubbles with diameters over 25 nm were observed by transmission electron microscopy. Recrystallization of the buried amorphous layer was visible after 900 °C annealing for 30 min. Some irregular cavities were found in the damaged layer. The recrystallization started from the amorphous/crystalline interface, and the formed cavities retarded the epitaxial growth. Nanocrystalline SiC was formed in the cavity layer. Extended defects were also characterized by transmission electron microscopy. The research results will give an insight into the recrystallization process in amorphous SiC.

This study was conducted to implement fish collagen hydrolysate as a substrate for synthesizing a nanophasic hydroxyapatite (HA) coating that would display superior osteoinductivity than HA derived from collagen (C/HA) and to comprehend the contribution of secondary structure on HA synthesis. Collagen type I was isolated from mullet skin and fragmented to obtain collagen hydrolysate (MCH). CD, FTIR, XRD, DLS and MS studies revealed that the MCH peptides oriented in polyproline-II conformation and coiled to form a mimic-helix with a packing distance of 0.885 nm. Multiple helices self-assembled into a quasi-fibrillar network with a diameter of 931 nm. The MCH was suspended in HA-nucleating solution to form MCH/HA nanocomposite crystals, which exhibited HA-specific planes in XRD with crystal orientation towards the quasi-fibrillar axis and a % crystallinity of 96.04. MCH/HA crystals were plate-shaped with an average size of 55.4 nm and a Ca/P ratio of 1.77 with moderate resilience (9.9 GPa) and high wettability. Consequently, osteoblasts cultured on MCH/HA coated-Ti surface proliferated faster and expressed 1.2–2 times higher levels of osteogenic differentiation markers when compared to C/HA-coated and uncoated surfaces. The study identified MCH/HA to be a superior coating material, by virtue of the unique quasi-fibrillar architecture of MCH.

The effects of pH of the reaction solution and the concentration of phosphoric acid on the crystal growth behavior of LaPO4 crystallites were investigated and the mechanical properties of rare-earth phosphates were compared. As a result, the concentration of phosphoric acid of 10% was beneficial to the crystal growth of LaPO4 nanocrystalline. When the pH value of the reaction solution was 2, the size of LaPO4 crystallites increased gradually with the increasing reaction temperature, and the smallest crystallite size of 43.27 nm was obtained after heat-treatment at 1000 °C. Simultaneously, the activation energy for crystal growth of LaPO4 nanocrystalline was relatively lower (26.82 kJ mol−1). With the decreasing radii of rare-earth ions, the hardness, Young's modulus and fracture toughness of the bulk rare-earth phosphates exhibited a reduced tendency, resulted from the increase of porosity under the same preparation process.

Niobium carbide composite coatings were prepared on titanium alloy surface by plasma spraying NbC–Al2O3, Nb–SiC and Nb–SiC–Al composite powders, respectively. The phase composition, microstructure and formation mechanism of the three composite coatings were analyzed and their microhardness, toughness and scratch resistance were compared. The phases of the NbC–Al2O3 system did not change during the plasma spraying process, and new phases (Nb2C, NbC and Nb3Si) were formed in the Nb–SiC and Nb–SiC–Al systems. TEM results of the Nb–SiC composite coating indicate that the new phases nanocrystalline Nb2C, submicron NbC and nanocrystalline Nb3Si were formed during the plasma spraying process. Compared with the NbC–Al2O3 composite coating, the microstructure of the Nb–SiC and the Nb–SiC–Al composite coatings were uniform, and the porosity were relatively low, and the hardness was higher. The Nb–SiC–Al composite coating was denser than the Nb–SiC composite coating, the lamellar structure was obvious and the number of pores in the coating was the least, which is attributed to the better molten state of the composite powder by the addition of the Al to the Nb–SiC system. The Nb–SiC–Al composite coating had better toughness and scratch resistance.

In this work, we report a comparative study of Ni-based anode compositions, made of Cu and Co (40 and 80 mol%) and gadolinia-doped ceria (CGO) matrices, for application the dry reforming of methane (DRM) reaction using Solid Oxide Fuel Cells (SOFCs). The new compositions are synthesized by a one-step synthesis route, using citric acid as chelating agent, and characterized at three different stages: i) after synthesis, ii) after reduction, and iii) after DRM. X-ray diffraction (XRD) analysis combined with thermodynamic calculations is used to understand phase evolution along the different stages, revealing that complete solid solutions of NiCo- and NiCu-based alloys are formed after DRM reaction. Transmission Electron Microscopy (TEM) shows the formation of nanocrystalline powders, while surface area (SBET) measurements show higher values in the case of the NiCo-based samples. Moreover, the Co-containing compositions exhibit higher reducibility and stronger metal-ceramic interactions than the Cu-containing samples, according to the Temperature Programmed Reduction (TPR) results. Finally, DRM results demonstrate higher CO2 and CH4 conversions in the case of the Co-containing samples, as well as increased resistance towards carbon deposition, as confirmed by Thermogravimetric and Differential Scanning Calorimetry analyses (TG-DSC). Overall, the Co-based compositions are highly beneficial for their use as anodes for the CO2 reforming of methane in SOFCs.

Lean alloy (low alloyed) is beneficial for long-term sustainable development of metal materials. Creating a nanocrystalline microstructure is a desirable approach to improve biodegradability and mechanical properties of lean biomedical Mg alloy, but it is nearly impossible to realize. In the present study, the bulk nanocrystalline Mg alloy (average grain size: ~70 nm) was successfully obtained by hot rolling process of a lean Mg-2wt.%Zn (Z2) alloy and both high strength ((223 MPa (YS) and 260 MPa (UTS)) and good corrosion resistance (corrosion rate in vivo: 0.2 mm/year) could be achieved. The microstructure evolution during the rolling process was analyzed and discussed. Several factors including large strain, fine grains, strong basal texture, high temperature and Zn segregation conjointly provided the possibility for the activation of pyramidal slip to produce nanocrystals. This finding could provide a new development direction and field of application for lean biomedical Mg alloys., Graphical abstract Image 1, Highlights • The nanograins rounded by Zn atoms segregation are achieved in a lean biodegradable Mg-2wt.%Zn alloy by hot rolling process. • The nanocrystalline Mg–2Zn alloy demonstrates a high strength and good degradation properties. • Microstructures and rolling condition conjointly provided the activation of pyramidal slip to produce nanocrystals in Mg–2Zn alloy.

Europium doped (0.1% and 1%) chloroborate BaO–B2O3–BaCl2 glass and glass-ceramic with embedded BaCl2 nanocrystals have been synthesised, investigated, and compared with the corresponding nanocrystalline powder. The structural analysis of the glass evidenced ionic bonds characteristic to the glass host structure and compositional changes during the melting. X-ray diffraction and transmission electron microscopy revealed the formation of orthorhombic BaCl2 nanocrystals of about tens on nm in size and a smaller amount of BaB2O4 nanocrystals. Structural analysis of the Eu2+-doped BaCl2 nanocrystals has shown a distortion of the crystalline cell assigned to the growth process, affected by defects and ionic impurities. Photoluminescence spectra of the glass-ceramic revealed Eu3+ and Eu2+ luminescent ion species, but only Eu2+ is incorporated within the BaCl2 nanocrystalline phase. Electron paramagnetic resonance measurements in X-band sustain the presence of Eu2+ ions. The EPR parameters (g values and hyperfine constants) resulting from the Q-band EPR spectra simulations recorded on glass-ceramic are similar to those in Eu2+-doped BaCl2 and confirmed the partial incorporation of Eu2+ ions within the BaCl2:Eu2+ nanocrystals in the glass-ceramics.

This work reports the preparation of nanocrystalline Ni-Gd0.1Ce0.9O1.95 (NiO-GDC) anode powders using a novel single-step co-precipitation synthesis method (carboxylate route) based on ammonium tartrate as a low-cost green precipitant. The thermogravimetric analysis (TGA) of the synthesised powder showed the complete calcination/crystallisation of the resultant precipitates to take place at 500 °C. The prepared NiO-GDC powder was coated on a GDC electrolyte disc and co-sintered at 1300 °C. A mixture of La0.6Sr0.4Co0.2Fe0.8O3−δ and GDC was used as the cathode material and subsequently coated onto the anode-electrolyte bilayer, resulting in the fabrication of a NiO-GDC|GDC|La0.6Sr0.4Co0.2Fe0.8O3−δ-GDC cell. The crystallite size of both NiO and CeO2 phases were estimated using the X-ray powder diffraction (XRD) profiles and were calculated to be ~14 nm. Applied H2 temperature-programmed reduction (H2-TPR) analysis indicated a synergetic effect among different anode composites' constituents, where an intense interaction between the dispersed NiO nanocrystalline particles and the GDC crystallite phase had weakened the metal-oxygen bonds in the synthesised anode composites, resulting in a strikingly high catalytic activity at temperatures as low as 300 °C. The electrochemical impedance spectroscopy (EIS) and the electrochemical performance of the fabricated cells were measured over a broad range of operating temperatures (500–750 °C) and H2/Ar-ratios of the anode fuel (e.g. 100%–15%). Quantitative analysis from the EIS data and the application of the distribution of relaxation times (DRT) method allowed for the estimation of the activation energies of the anodic high and intermediate frequency processes that were 0.45 eV and 0.76 eV, respectively. This is the first report of a NiO-GDC synthesis, where a considerable improvement in activation energy is observed at the low-temperature region. Such low activation energies were later associated with the adsorption/desorption process of water molecules at the surface of NiO-GDC composite, indicating a high activity towards hydrogen oxidation.

Bulk isocubanite (CuFe2S3) was synthesized via a multistep high-temperature synthesis and was investigated as an anode material for sodium-ion batteries. CuFe2S3 exhibits an excellent electrochemical performance with a capacity retention of 422 mA h g-1 for more than 1000 cycles at a current rate of 0.5 A g-1 (0.85 C). The complex reaction mechanism of the first cycle was investigated via PXRD and X-ray absorption spectroscopy. At the early stages of Na uptake, CuFe2S3 is converted to form crystalline CuFeS2 and nanocrystalline NaFe1.5S2 simultaneously. By increasing the Na content, Cu+ is reduced to nanocrystalline Cu, followed by the reduction of Fe2+ to amorphous Fe0 while reflections of nanocrystalline Na2S appear. During charging up to -5 Na/f.u., the intermediate NaFe1.5S2 appears again, which transforms in the last step of charging to a new unknown phase. This unknown phase together with NaFe1.5S2 plays a key role in the mechanism for the following cycles, evidenced by the PXRD investigation of the second cycle. Even after 400 cycles, the occurrence of nanocrystalline phases made it possible to gain insights into the alteration of the mechanism, which shows that CuxS phases play an important role in the region of constant specific capacity.

The structural and electrical properties of the xP2O5-(40 − x) Bi2O3-60V2O5 (0 ≤ x ≤ 20) glass system have been investigated. The samples were prepared by the conventional melt-quenching technique. X-ray diffraction (XRD) patterns confirmed the amorphous nature of the present glasses. Nanocrystalline grains were found due to the annealing of the glass samples under study. Nanocrystals with an average grain size of 22 nm were implanted in the glass structure and estimated from the XRD patterns of the glass–ceramic samples. DC conductivity of the glass system has been determined in the temperature range 300–500 K. It was found that the general behavior of electrical conductivity was similar for all the glass compositions and found to decrease with increasing phosphate content. The electrical conductivity of the glass–ceramic nanocrystals obtained by annealing at crystallization temperature (Tc) was much higher than the initial glass. The activation energy (W) was enhanced by annealing and was obtained from plots of temperature-dependent DC conductivity, and found to be 0.23–0.31 eV for glasses and 0.19–0.23 eV for the glass–ceramic nanocrystals.

Thin films of Sb-doped CdSe have been deposited on glass substrates by a chemical method at room temperature. The X-ray diffraction pattern confirms the presence of a cubic phase with preferred orientation along the (111) plane. The elemental composition of the thin films has been examined utilizing energy dispersive X-ray analysis. Morphology of the thin films has been investigated using scanning electron microscopy. In the optical absorption study, a decrease in the band gap with increase in Sb doping in CdSe lattice has been observed. Photoluminescence spectra show a redshift in the emission peak with an increase in Sb doping in CdSe. Electrical resistivity measurements are additionally carried out utilizing a two-probe DC method, and two types of conduction mechanisms are observed. Raman analysis shows the formation of CdSe thin films with a nanocrystalline phase. Contact angle measurement establishes the hydrophilic behavior of Sb-doped CdSe thin films with water.

In this work, BiFeO3 powders were synthesized by a sol–gel method. The influence of annealing temperature on the structure and magnetic properties of the samples has been discussed. X-ray diffraction studies showed that the purest phase was formed in the temperature range of 400 °C to 550 °C and the samples annealed at a temperature below 550 °C were of nanocrystalline character. Mössbauer spectroscopy and magnetization measurements were used as complementary methods to investigate the magnetic state of the samples. In particular, the appearance of weak ferromagnetic properties, significant growth of magnetization, and spin-glass-like behavior were observed along with the drop of average grain size. Mössbauer spectra were fitted by the model assuming cycloidal modulation of spins arrangement and properties of the spin cycloid were determined and analyzed. Most importantly, it was proved that the spin cycloid does not disappear even in the case of the samples with a particle size well below the cycloid modulation period λ = 62 nm. Furthermore, the cycloid becomes more anharmonic as the grain size decreases. The possible origination of weak ferromagnetism of the nanocrystalline samples has also been discussed.

Cassava stems were one of the largest agricultural by products in Indonesia, especially in Lampung Province. It is known that cassava stems have a fairly high lignocellulose content, especially cellulose which reaches 39.29%. The high cellulose content in cassava stems has great potential to be used as raw material for Nanocrystalline Cellulose (NCC). The preparation of nanocrystalline cellulose consists of four main stages, namely: pre-hydrolysis, delignification, bleaching, and acid hydrolysis. The pre-hydrolysis stage was carried out by boiling a solution of CH 3 COOH and cassava stem powder for 60 minutes at a temperature of 105 o C. Cassava stem powder was then delignified using a 25% NaOH solution heated to a temperature of 105 o C for 1 hour. The bleaching stage used a 3.5% NaOCl solution at a temperature of 50 o C for 60 minutes and was carried out twice. The last step is acid hydrolysis using 2.5N HCl solution for 15 minutes at a temperature of 105 o C, then the electromagnetic induction treatment is varied with temperature variations of 30 o C, 50 o C, and 70 o C for 60 minutes. The prepared nanocrystalline cellulose were tested for lignocellulose, XRD and PSA. From the test results, the best variation of nanocrystal cellulose preparation was acid hydrolysis treatment with 70 o C electromagnetic induction for 60 minutes, namely an increase in the percentage of cellulose 62.93%, crystallinity 90.68%, and an average particle size of 18.04µm with some particles measuring nanometers. From the results of the research, it was concluded that electromagnetic induction increased crystallinity and decreased the size of nanocrystalline cellulose.