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In the current study magnetic, magneto-optical and microstructural properties of the amorphous Fe 83 Cu 1 Nb 3 Si 5 B 8 alloy were properly investigated depending on the external treatments such as annealing and stress annealing. Kinetic nanocrystallization temperatures of certain ribbon were determined at the range of 500–510 °C. The amorphous ribbons produced in the as-spun state were subjected to tensile stress loading with and without rapid heat treatment of 510 °C during five seconds. Behaviors of certain ribbons were extensively investigated in terms of several factors such as magnetic properties, microstructural evaluation, magneto-optical effects and structural deformation by means of quasi-static hysteresis loops, XRD analyses, TEM micrographs, magneto-optical Kerr imaging and nanoindentation test. Present nanocrystalline Fe 83 Cu 1 Nb 3 Si 5 B 8 alloy have allowed yielding not only ultrafine grain structure of around 7.02 nm but also saturation induction of 1.85 T, coercivity of 5.8 A.m −1 and saturation magnetostriction of 6 ppm. Additionally, based upon determined optimum stress annealing circumstances, toroidal nanocrystalline core was produced using a proposed stress induced winding (SIW) system. SIW system based principally on the gradient of the rotational speed of each mandrel in the standard toroidal core winding machine. Structural deformation of the core was determined by an analysis method performed on the ribbon. Accordingly, induced elastic modulus ( E ), Poisson's ratio ( V ) and residual strain ( e ) in the ribbon under the influence of stress annealing by 200 MPa at 510 °C were found as 7.9 GPa, 0.39 and 0.031, respectively.

In order to understand the effect of Pr3Al11 nanoparticles on crystallite growth kinetics of nanocrystalline Mg, the crystallite growth characteristics in a Mg−Pr3Al11 composite and a pure Mg sample were comparatively investigated in this work. The crystallite growth exponents of nanocrystalline Mg in the Mg−Pr3Al11 composite and pure Mg were determined as n = 5 and n = 4, respectively. Meanwhile, the activation energy for crystallite growth in Mg−Pr3Al11 composite was calculated to be 118.8 kJ/mol, which is higher than 97.1 kJ/mol in pure nanocrystalline Mg. Further studies reveal that the rise of crystallite growth exponent and increase of activation energy in the Mg−Pr3Al11 composite are primarily attributed to the pinning effect of Pr3Al11 nanoparticles at crystallite boundaries of Mg.

Advantages of spectral sensitivity in the infrared range and good stability against light exposure together have made nanocrystalline silicon–germanium alloy (nc-Si1-xGex) as an ideal absorber material at the bottom-cell in multi-junction Si thin film solar cells. Evolution of good quality SiGe thin films with sustained nanocrystallinity, particularly at low growth temperature (TS), is a challenging task in view of very different chemical reaction behaviors controlled via different energy requirements of two frequently used source gases, e.g., SiH4 and GeH4. Growth of nc-SiGe:H thin films have been pursued at TS ∼220 °C, using H2-diluted (by ∼96%) (SiH4 + GeH4) plasma in 13.56 MHz RF-PECVD, by varying the RF power applied to the parallel plate capacitively coupled electrodes of the reactor. At lower RF power Ge-dominated low band gap SiGe network has been produced with Si component in mostly amorphous configuration that leads to a low electrical conductivity. At high RF power Si–Si network becomes highly crystalline; however, Ge content reduces drastically. Breaking of weaker Ge–Ge bonds creates defects via dangling bonds and increased grain boundary defects around Si nanocrystals together produce relatively wider band gap SiGe network with degraded electrical conductivity. The novelty and significance of the present investigation remains in realizing the narrowing of the optical band gap (Eg ∼1.499 eV) even at lower Ge content, through moderate crystallization in the SiGe network and a simultaneous high electrical conductivity of the nc-SiGe:H films (σD ∼2.38 × 10−3 S cm−1) obtained at a high growth rate (∼9.5 nm/min), via optimization of the applied RF power at a moderate level (∼100 W). In such circumstances nanocrystallization of the network plays leading role in narrowing the optical band gap, overriding the effect arising out of the restricted presence of Ge.

Metal oxide semiconductor (MOSC) sensors based on nanocrystalline MoO3, In2O3, and their composites are considered to be very sensitive to detect low concentrations of ethanol, ozone, hydrogen, formaldehyde, and nitrogen dioxide. Here, we firstly introduced In2(MoO4)3 phase, which has excellent negative thermal expansion and high electric conductivity properties, into In2(MoO4)3@In2O3 crystalline nanocomposites. The gas-sensing performance of the In2(MoO4)3@In2O3 nanocomposites was studied upon exposure to the ethanol gas with different concentration from 5 to 300 ppm at the optimum temperature (300 °C). What's more, the device possesses ultra-high response of 110 and selectivity to ethanol. Particularly, it can effectively work in high humidity (RH = 80%) with super long-term stability of as long as 90 days, compared with the pristine In2O3 sensor and previous reports. The presented novel In2(MoO4)3@In2O3 sensor offers great opportunities for future ethanol detection under harsh conditions.

In this work CdTe NCs with different sizes were synthesized through a hot-injection chemical precipitation method. Then they were applied as the co-sensitizers in the photoelectrode of the CdTe and CdS sensitized solar cells. The photoelectrodes were composed of a nanocrystalline TiO2 layer formed of hydrothermally grown TiO2 NCs with dominant size of 25 nm. This layer was sensitized with CdS and CdTe NCs via the successive ionic layer adsorption and reaction (SILAR) and drop casting methods. The average size of utilized CdTe NCs was altered in the range of 2.7–3.4 nm in the experiments. Polysulfide electrolyte and CuS counter electrodes were also applied in conventional structure of these QDSCs. Different photoanodes were fabricated with various sizes of the as prepared CdTe NCs. Then the effect of corresponding bandgap energies and band edge positions on the photovoltaic performance of the CdS/CdTe sensitized solar cells was investigated. According to the results, a maximum efficiency of 3.8% was achieved for the QDSC with CdTe NCs prepared at 5h of refluxing process (3.2 nm). This efficiency was increased about 72% compared to the reference cell which was sensitized with just CdS NCs. The optimization was also addressed based on the energy band diagram of the composing components of the fabricated QDSCs.

Novel fine grained Al matrix composites reinforced by nanocrystalline high-entropy alloy particles (NC-HEAp) were successfully prepared by combining ball milling, hot pressing, hot extrusion and heat treatment. It was found that the average particle size of NC-HEAp significantly decreased after the milling, and NC-HEAp showed a uniform particle distribution in the hot extruded Al matrix composites. The NC-HEAp showed good thermal stability in the processing procedures. Microstructure and tensile tests revealed that the NC-HEAp are good candidates as the reinforcements in Al matrix composites.

A special routine for suppression the grain growth process of yttrium oxide (Y2O3) by confining its nano crystallites in a polycrystalline magnesium oxide (MgO) matrix via the sol-gel method is currently being reported. The binary system of Y2O3-MgO was investigated as a function of the concentration of Y2O3 and calcination temperature. Enhanced isotropic uniform stresses during cooling down caused by the doubled thermal expansion coefficient of the MgO matrix were calculated. Both effects of applied hydrostatic pressure and inhibited grain growth of Y2O3 on the crystallographic phase transitions and morphology were investigated in the unique system of Y2O3-MgO.

It's highly desired to design and fabricate effective α-Fe2O3-based photocatalysts by increasing the surface area, promoting the charge separation and providing catalytic function. Herein, specific surface area-enlarged α-Fe2O3 (SE-FO) nanoparticles have been successfully synthesized by a functional molecule-modulated phase-separated hydrothermal method, with high photocatalytic activities for CO2 conversion and phenol degradation. The photocatalytic activities of SE-FO could be greatly improved by coupling nano-sized BiPO4 via an in-situ introduction method. This is attributed to the coupled BiPO4 as a high-energy platform to accept photogenerated electrons from α-Fe2O3 so as to enhance the charge separation mainly by means of surface photovoltage spectra and fluorescence spectra-related to the amount of produced •OH species. Moreover, the photocatalytic activities are further improved by introducing a proper amount of nanocrystalline CuO via a simple impregnation process. It is confirmed based on the temperature-programmed desorption and electrochemical reduction measurements that the improved photoactivity is attributed to the introduced CuO as the co-catalyst for promoting electron-induced reduction reactions. Remarkably, the optimized α-Fe2O3 nanocomposite exhibits about 3-time photoactivity improvement compared with the pristine α-Fe2O3. This work would provide a feasible route to fabricate high-activity α-Fe2O3-based photocatalysts for CO2 conversion and phenol degradation.

A polycrystalline Ni45.5Co4.5Mn36.6In13.4 alloy was obtained by mechanical alloying during high energy ball milling. As-milled powders after 2.5 h, 5 h, 10 h, 15 h, 20 h, 30 h, 40 h, 50 h, 60 h and 70 of milling were studied in terms of structure, particle size and morphology, martensitic transformation. Selected powders were cold pressed and two-step sintered at 1253 K for 0.5 h and then at 1173 K for 24 h, followed by quenching into the ice-water mixture. The structure was examined by X-ray diffraction and electron microscopy. After 30 h of milling, solid-solution of nanocrystalline NiCoMnIn alloy with disordered body-centered cubic structure was observed. The microstructure of sintered samples revealed precipitates of γ particles inside of the matrix B2 grains, creating ‘subgrains’ of the matrix. The estimated average size of subgrains was around 60-70 μm.

Fuel-blend combustion method using urea and monoethanolamine (MEA) fuels, is employed to tune the defect states and hence luminescence properties of nanocrystalline ZnAl2O4. Prepared nanocrystals flaunt a ravishing blue and intensified near-infrared (NIR) emission with varying intensities. Sample prepared using 80% MEA blended with 20% urea exhibits highest NIR emission, seven-fold intense than that prepared by 100% MEA, attributed to larger amount of deep band gap defects. Presence of multiple defects viz. vacancies of zinc, aluminium and oxygen is probed by means of Rietveld refinement, X-ray absorption near edge spectroscopy and photoluminescence spectroscopy. Band tailing and presence of shallow defect states are indicated by optical band gap and Urbach energy values. Broad range visible to NIR emission envisages application of ZnAl2O4 nanocrystals for bioimaging purposes. Radiative transitions among various defect levels contributing toward the emission have been depicted through a band model diagram.

Nanolayered flaky Fe-based amorphous-nanocrystalline/graphite sheet composites with excellent microwave absorbing properties are fabricated by ball milling the Fe-based amorphous alloy and graphite. The obtained composites consist of Fe-based amorphous-nanocrystalline flakes and graphite sheet coating, which exhibit good impedance matching. The modified magnetic and dielectric properties, especially the large coercivity, high permeability and the interfacial polarization are responsible for the significantly improved microwave absorption properties with minimum reflection loss of −67.95 dB at thin thickness of 1.6 mm and bandwidth of 5.36 GHz. The facile composites with excellent microwave absorbing properties are potential materials for high-performance microwave absorbers.

Fe based metallic glass composite coatings with composition of Fe−2.5Cr−6.7Si−2.5B−0.7C (wt%) were deposited by atmospheric plasma spraying onto mild steel substrate under optimum spraying conditions with selected variation in heat input. The effect of spraying power on the microstructure, phase composition, hardness and corrosion behavior of the coatings were systematically investigated. The corrosion behavior of the coatings was studied by potentiodynamic polarization test in simulated sea water containing 3.5% NaCl solution. The corrosion resistance of the coating decreased with increasing plasma power, which is attributed to the decrease in amorphous content and formation of nanocrystalline phases at elevated plasma power. Nanoindentation was carried out for qualitative investigation of the effect of heat input on the transformation of relative fraction of different phases and subsequently on the nanohardness of the coatings. The values of nanohardness increased to ∼12 GPa at higher plasma power as percentage of amorphous content decreased from 93% to 89% and amount of hard intermetallic nanoparticles increased. However, this resulted in increase in corrosion rate i.e. corrosion current density from 17.4 to 69 μA/cm2. The study revealed that low porosity, high hardness and superior corrosion resistance were observed for the plasma sprayed coatings.

Mg-20 wt% TixCr0.8-xV0.2 (x = 0.25, 0.35, 0.45, 0.55) nanocomposites were synthesized by Reactive Ball Milling (RBM) under 5.0 MPa H2 for 8 h at room temperature. The morphology, crystal structure, and isothermal hydrogen ab-/desorption properties of the as-milled nanocomposites were investigated. X-ray diffraction confirms that the composites were composed of nanocrystalline β-MgH2, γ-MgH2 and Ti-Cr-V0.2Hy (1.91

The refractory high-entropy TaNbHfZr films with various microstructures have been synthesized by magnetron sputtering via tuning different deposition temperature from 25 °C to 700 °C. At 25 °C, a complete amorphous structure with featureless surface morphology is formed. With the increase of deposition temperature, the precipitation of crystallites is observed at 500 °C and a nanocrystalline bcc structure high-entropy TaNbHfZr alloy film with the surface morphology of needle-like islands at 700 °C due to the significantly improved atom diffusion ability. Nanoindentation results also indicate that the hardness and reduced elastic modulus of the films are strongly dependent on their distinct microstructures. For amorphous dominated films, the hardness increases with the elevated temperature accompanied with enhanced modulus. The bcc TaNbHfZr high-entropy alloy film displays superior hardness of ∼15.3 GPa. The strengthening mechanism can be attributed to the distortion induced solid-solution strengthening and the grain boundary strengthening in the nanocrystalline microstructure.

The energy stored in the crystallographic defects in nanocrystalline Ni-Mo alloy films was determined experimentally by differential scanning calorimetry (DSC) and compared with the calculated values. Two Ni-Mo layers with low (∼0.4 at.%) and high (∼5.3 at.%) Mo contents were processed by electrodeposition. It was revealed that the majority of the heat released during DSC (∼77%) was related to the grain boundaries. It was also found that the increase of Mo content from 0.4 to 5.3 at.% yielded an enhancement of the stored energy with a factor of about two. The measured and the calculated stored energies were compared with the values obtained for ultrafine-grained Ni-Mo alloys with similar compositions but processed by severe plastic deformation (SPD). It was revealed that in the SPD-processed samples there was a considerable contribution of vacancies to stored energy while their effect in the electrodeposited layers was lower.

The influence of mechanical milling (MM), primarily on microstructure and phase evolution in Al62.5Cu25Fe12.5 (at%) quasicrystalline (IQC) matrix reinforced with varying volume fraction of Sn has been investigated by means of X-ray diffraction (XRD), scanning & transmission electron microscopy (SEM and TEM) and differential scanning calorimetry (DSC) methods. It was observed that with increasing the milling duration, the IQC phase transforms to crystalline B2 phase [Al (Cu, Fe) and Pm3 m, a = 0.29 nm]. In SEM and TEM analysis, it was found that both IQC and Sn particles are refined during MM. The XRD and TEM results confirm the formation nanostructured matrix consisting of nanocrystalline B2 phase along with minor IQC phase reinforced with ultrafine grained Sn particles after 40 h of MM. The STEM-EDS results show a homogenous distribution of elements (Al, Cu, Fe). The Sn particles were immiscible in a matrix consisting of B2 and IQC phase as indicated by XRD and TEM investigations.

Nanocrystalline spinel nickel ferrite NiFe2O4 thin film has been studied and synthesized via the electrodeposition-anodization process. Electrodeposited NiFe2 alloys were obtained from aqueous sulphate bath. The formed alloys were electrochemically oxidized (anodized) in aqueous (1 M KOH) solution, at room temperature, to the corresponding hydroxides and annealed in air at 400 °C for 2 h. The parameters controlling of the electrodeposition of NiFe2 alloys such as the bath temperature, agitation and the current density were optimized. The crystal structure, crystal size and microstructure of the produced ferrites were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD shows that NiFe2O4 had a spinel structure and. The crystallite size of NiFe2O4 phase was 16 nm. SEM micrograph of the formed ferrite particles shows that the distorted rectangular structure and semi square like morphology was noted.

In this paper, a novel solution combustion combined with hydrogen reduction was developed to prepare W-30Cu powders using ammonium metatungstate, copper nitrate and ammonium nitrate as raw materials. The results indicate that the combustion products own nanocrystalline and porous structure with high specific surface areas. The combustion products can be completely reduced in hydrogen gas at 700 °C and the reduced W-Cu composite powder particles have spherical shape with mean particles size of about 80 nm. The reaction mechanism in the system was also identified. Furthermore, the resultant W-Cu powders show good sinterability and the W-Cu sintered samples have fine grain size and good mechanical properties. Relative density, microhardness and thermal conductivity of the sintered W-Cu specimens reach 98.6%, 245.6 HV and 223.55 W/(m·k), respectively.

Recently, due to their high capacity and excellent cycle stability, bimetallic transition-metal oxides have attracted great interest from researchers for use as anode materials in lithium ion batteries. The main disadvantages of bimetallic transition-metal oxides are poor conductivity and easy aggregation during charge and discharge. Here, Co-based metal-organic frameworks (MOFs) are compounded with amorphous titanium oxide by a solvothermal reaction. After the high-temperature alloying of the precursor, carbon-coated CoTiO3 nanocrystallites are synthesized. CoTiO3 nanocrystallites coated by amorphous carbon not only improve the conductivity of the material but also effectively inhibit the aggregation of the CoTiO3 nanocrystallites during charge and discharge. A total of 1400 cycles were cycled at a high current density of 2000 mAg−1, and the reversible capacity was maintained at 610 mAhg−1. In addition, cycling 100 cycles at the current density of 100 mAg−1 reveals the reversible capacity of 630 mAhg−1. Thus, the anode demonstrates excellent lithium storage performance. Then, we characterized the material composition, morphology and specific surface area by means of X-ray diffraction, high resolution transmission electron microscopy and nitrogen adsorption-desorption experiments. These experiments confirmed the unique structure of cobalt-coated CoTiO3 nanocrystallites and excellent lithium storage performance.

Ni-Cr-Y2O3 nanocomposite coating, with Y2O3 nano-particles finely dispersed, was prepared by cathode plasma electrolytic deposition from environmental-friendly nickel-trivalent chromium sulfate electrolyte directly. The coating is dense and uniform with typically molten morphology, possessing a nanocrystalline structure with an average grain size of about 30–50 nm. Owing to the synergy effect of the fine-grained structure of the coating and the reactive-element effect of the addition of Y2O3 nano-particles, a thin, compact, uniform and continuous Cr2O3 oxide scale can be formed during 200 h oxidation at 750 °C. Such Cr2O3 oxide scale provides effective protection to the inner alloy and substrate.

To apply bulk hot-deformed magnets into commercial fields, it is quite necessary to deeply understand the origins and evolution of their inhomogeneous microstructure. In this work, the microstructure of hot-deformed nanocrystalline cylindrical Nd-Fe-B magnets with a dimension of ∼24.8 mm in diameter and ∼7.0 mm in height along the radial direction was investigated in order to correlate them with the inhomogeneous magnetic properties. The remanence was 1.42 T, 1.37 T, and 1.30 T for the samples taken from the center (sample P3), subcenter (sample P2), and edge (sample P1) of the hot-deformed magnet, respectively. Scanning electron microscopy images showed from the P3 to P1 the interval of strip-shaped Nd-rich layers increased. Meanwhile, the perpendicularity between the pressure direction and the Nd-rich layers deteriorated for the samples from the P3 to P1. Well oriented platelet-shaped grains with c-axis parallel to the pressure direction were observed in the P3 sample, and the orientation gradually deteriorated with the position changing from the center to the edge. It was also found that large Nd-rich phase aggregation areas occurred in the edge sample. The maximum value of Henkel plot decreased gradually for the samples from the P3 to P1, which was caused by the thickened grain boundary observed by transmission electron microscopy. The openness of recoil loops increased gradually from the center to the edge due to the aggregation of the Nd-rich phase. The inhomogeneous microstructure shows distinct effects on magnetic properties, therefore changing the magnetization behavior along the radial direction of hot-deformed magnets.

In this study, the optimized fabrication and evolution of the microstructure and magnetic transition behavior of the melt-extraction LaFe11.2Si1.8 microwires have been studied. After the optimization of extraction technique (heating power 22 KW, feeding rate 30–50 μm/s, rotation velocity 1700 r/min), the content of La(Fe,Si)13 phase in the as-extracted microwires was 54 wt% due to the high solidification velocity, which was increased to 85 wt% via annealing at 1373 K for 20 min. The amount of La(Fe,Si)13 phase was increased and the composition of La(Fe,Si)13 phase became more homogenized through peritectic reaction and short-distance diffusion in the microwires during annealing process. The coexistence of the nanocrystalline and amorphous structures contributed to the broad magnetic transition temperature range of the as-extracted and annealed microwires. The annealed microwires exhibited a second-order magnetic transformation behavior and showed a maximum magnetic entropy change |ΔSM|max of 6.2 J/kg·K and working temperature interval of 36.0 K under a magnetic field of 20 kOe.

Melt-spun Mn50Bi50-xSbx alloys with x ≤ 5 were prepared at different solidification rates and characterized both in the as-spun state and after annealing. In the as-spun alloys, the Sb substitution leads to the formation of a metastable phase, similar to the binary “quenched high-temperature phase” but without the superstructure of the latter and exhibiting a different – increasing – temperature dependence of coercivity. The new nanocrystalline metastable phase is not only itself characterized by a high room-temperature coercivity (in excess of 20 kOe), but upon annealing it transforms into a high-coercivity (up to 13.5 kOe) “low-temperature” α phase. However, the advantage of obtaining a high coercivity without the otherwise required milling made possible by the Sb substitution is undermined by the absence of a local crystallographic texture in the melt-spun alloys. The best combination of the isotropic hard magnetic properties realized for the Mn55Bi43.5Sb1.5 composition is a remanence of 35.5 emu/g and a coercivity of 8.1 kOe. The annealed Sb-free Mn50Bi50 alloys did possess a local crystallographic alignment and, for high solidification rates, a moderate coercivity up to 5.6 kOe; however, they had an inadequate “rectangularity” in the demagnetization curve. The orthorhombic compound known as MnBi0.9Sb0.1 and described earlier as antiferromagnetic was obtained in the annealed ribbons with x ≈ 5. The compound was found to order ferromagnetically between 200 K and ≈250 K and to exhibit a significant coercivity, 14.3 kOe at 50 K. It is suggested that the MnBi0.9Sb0.1 may actually be a Sb-stabilized “new phase” observed earlier as metastable in the Bi–MnBi eutectic alloys.

Nanocrystalline NiTi microwires exhibit stable superelastic effect and are highly potential as elastocaloric materials. Here, nanocrystalline Ni50.5Ti49.5 microwires of diameter 109 μm were prepared by multi-step cold-drawn and the elastocaloric effect (eCE) by taking the advantage of B2↔R and B2↔B19′ transformations have been investigated. Both transitions in the nanocrystalline microwires displayed comparable or even superior caloric effect compared to other elastocaloric and magnetocaloric materials. The B2↔B19′ transformation exhibited larger stress-induced entropy change (ΔS = ∼65 J/kg·K) within a wider operation temperature window (ΔTwin = ∼90 K) compared to B2↔R transition (ΔS = ∼18 J/kg·K with ΔTwin = 12 K). However, the hysteresis for B2↔R transition (ΔThys 50 K) thanks to the smaller transition strain in the latter case. As a result, eCE produced by B2↔R tranistion possessed a more stable cyclic stability. Therefore, both B2↔R and B2↔B19′ transitions in the present microwires are promising candidates in the micro-sized refrigeration field.

Nanocrystalline (NC) AgCu alloys have been attracted significant attention because of excellent electrical and mechanical properties. The microstructural evolution and deformation mechanisms are still challenging issues, and it is hard to observe directly by experimental methods. Accordingly, in this paper, atomic simulations are performed to investigate the tensile behavior of dual-phase equiaxial NC AgCu alloy (DPEA) at different strain rate (104-107 s−1), solute atomic concentration (5–20%) and temperature (300–600 K) using embedded atom method (EAM) potential. Relevant stress-strain curves and yield stress have been obtained. Result analysis reveals dislocation motion, atomic diffusion and grain boundary (GB) sliding are dominating deformation mechanisms. With the increase of strain rate and deformation, main deformation mechanisms are discovered to change from dislocation motion to GB sliding. Furthermore, the increase of solute atomic concentration (SAC) and temperature will promote the atomic diffusion and GB sliding. This work explains evolution process on deformation mechanisms of DPEA. It provides a qualitative analysis to design excellent mechanism property of DPEA by means of optimizing material structure parameters.

Nuclear forward scattering (NFS) is a suitable experimental technique to study the crystallization processes within amorphous alloys. It enables simultaneous investigation of both the structural arrangement and the associated hyperfine interactions. The presence of nanocrystals buried in amorphous matrix is usually manifested via their ferromagnetic exchange interactions. In weakly magnetic metallic glasses the onset of the phase transformation from amorphous to nanocrystalline state is not accompanied by occurrence of well distinguished magnetic hyperfine interactions due to the presence of newly formed nanocrystals. Here, we present evaluation of NFS time spectra acquired in-situ during the crystallization of weakly magnetic metallic glass with a composition of Fe75Mo8Cu1B16. We determine the onset of crystallization from the change in spectral line-widths of the NFS time spectra calculated in energy domain. Additional discussion of the crystallization process based on the evolution of hyperfine magnetic fields is presented, too.

Nanocrystalline of ZnAl2O4 spinel was synthesized by employing the microwave combustion method. Different new spinel compositions of formula Zn1-xFexAl2O4, (0.0 ≤ x ≤ 1.0) were prepared by substitution of Zn ions with Fe ions. The as-synthesized resultant material ZnAl2O4 with spinel structure as well as Zn1-xFexAl2O4 compositions were characterized by Energy Dispersive X-ray and X-ray diffraction. Morphology and particle size evaluation of the nanoparticles were characterized by transmission electron microscopy images. The optical absorption spectra and the magnetization were measured at room temperature for each Fe ratio. The substitution effect of Fe ions on the optical and magnetic properties of the original spinel was studied. The optical absorbance showed that the optical band gap decreased with increasing Fe ratio.

In this paper, we have studied the effect of nanocrystalline TiO2 functional layer on the performance of Si photodetectors. It was found that the electron affinity of the deposited TiO2 films is much lower (3.2 eV) than the conventional films of the value 3.9 eV. In addition, the band gap of these newly developed films was found to be 3.6 eV which makes the films transparent for band to band optical absorption. However, a very high absorption co efficient of the value 4.6 × 105 cm−1 and excitonic dissociation facilitate charge generation and transfer mechanisms in such films. It was found that the photodetector parameters like internal gain, response time, responsivity, detectivity, sensitivity and noise can be improved by inserting functional TiO2 layer to make either anisotype or isotype heterojunction with Si photodetectors. The major phenomena for such enhancements were found to be decrease in tunneling length and increased charge generation/transfer due to TiO2 nanocrystals. By this modified design, TiO2/p-Si hybrid device offer high responsivity of the value 23.07 A/W and detectivity of 4.5 × 1012 Jones for red light (620 nm) at an incident power of 1 mW/cm2. Furthermore, it was confirmed that faster devices with rise time of only 30 μs in broadband region from 425 to 620 nm can be made out of TiO2/n-Si configuration which allows slower diffusion of charge carriers. This study will provide a pathway to design ultramodern, highly responsive/sensitive and broadband Si photodetectors.

Phase purity plays an important role in determining the properties of the material and its subsequent applications which depends on the synthesis conditions and dopant concentrations. Phase pure zinc selenide and nickel doped zinc selenide nanoparticles were synthesized by hydrothermal method using sodium selenite as precursor. Calculated crystallite size for various compositions showed a decrease with dopant concentration with the values around 10 nm and less. Morphological analysis showed the formation of spherical particles which is distinct in the micron scale image. SAED pattern showed the formation of nanocrystalline particles with particles size varying between 10 and 20 nm. Quantum confinement effect due to reduced size was corroborated with increased band gap values as measured from diffuse reflectance spectra. Photoluminescence spectra showed the presence of dominant near band-edge emission along with certain defect level emissions for all the samples. Nonlinear optical studies carried out using a continuous wave laser showed an increase in nonlinear refractive index and susceptibility values with dopant concentration signifying the role of defects and the structural modifications occurring due to doping. The nonlinear optical properties exhibited by this material has been utilized for device applications like optical limiting and the results show enhancement in limiting efficiency with dopant concentrations.

Li-Mo-O phase class materials are suitable negative electrode materials for Li-ion batteries. They exhibit better performance at the nanoscale level. This current work deals with the synthesis of nanocrystalline Li2MoO4 material, synthesized by the solution combustion technique using citric acid as the chelating agent. X-ray diffraction and electron microscopy with energy dispersive X-ray analysis were employed to study the structure and morphology of the prepared material. Fourier transform infrared spectroscopy was utilized to study the molecular structure and chemical bonds present in the material. Magnetic characteristics of the Li2MoO4 were explored using the vibrational sample magnetometer. Frequency-and temperature-dependent electrical properties were explored using broadband dielectric spectroscopy. The results revealed the presence of two different relaxations, one corresponding to the free dipoles of LiO4 and MoO4 molecules and the other corresponding to the relaxation of pinned dipoles formed by the association of free carriers with defects. A novel model combining these relaxations was used to fit the electrical data. Activation energies for relaxation and DC conduction were calculated, and the corresponding results were discussed.

Nanocrystalline CoCrFeNi and CoCrFeMnNi high entropy alloys have been processed by mechanical alloying followed by spark plasma sintering. Grain growth kinetics has been estimated for both the alloys by subjecting them to heat treatment in the temperature range 1073–1373 K. These alloys possess a thermally stable single phase FCC structure along with Cr7C3 contamination. Electron back scattered diffraction (EBSD) has been used to determine grain size of all the heat treated samples. Both CoCrFeNi and CoCrFeMnNi alloys exhibit a grain growth exponent, n = 3, suggesting long-range diffusion-controlled grain growth in these alloys. Activation energies for grain growth are 134 and 197 kJ/mol for CoCrFeNi and CoCrFeMnNi, respectively, which are significantly lower than the activation energy of lattice diffusion in these alloys. Hardness is measured for CoCrFeMnNi alloy as function of grain size and is found to follow the Hall-Petch type relation. The strength coefficient (slope of Hall-Petch relation) is calculated as 1.92 GPa, which is nearly three times that of the value reported in literature for coarse grained CoCrFeMnNi. Presence of carbides enhances the hardness of these HEAs. The maximum contribution to strengthening comes from the FCC-carbide phase boundaries.

This paper studied the thermal stability of the nanocrystalline-amorphous (NC-A) composite layer on pure titanium induced by ultrasonic shot peening (USP). The results showed that there were approximately two layers of transitional atoms between the nanograins and amorphous phase in the NC-A composite layer. Both the crystallization temperature of the amorphous phase and the recrystallization temperature of the nanograins in the NC-A composite layer were lower than 200 °C. The nanograins in the NC-A composite layer had a certain thermal stability and the thermal stability of the α-phase Ti in the NC-A composite layer was apparently higher than the original specimen.

Alloying a fourth element and multilayer architecture are efficient methods to tailor the structure and properties of aluminum-containing transition metal nitrides coatings. Here, we combine Si-addition and multilayer structure to improve the properties of TiAlN coating. Incorporation of Si into TiAlN leads to a nanocomposite structure with TiAlN nanocrystalline encapsulated by amorphous SiNx, and thereby an increased hardness from 29.1 ± 1.0 GPa for Ti0.52Al0.48N to 33.1 ± 1.2 GPa for Ti0.53Al0.38Si0.09N. In order to avoid the formation of undesired wurtzite (w) AlN in Ti0.53Al0.38Si0.09N, the c-Ti0.52Al0.48N template layer (∼5.2 nm) is used to stabilize Ti0.53Al0.38Si0.09N layer (∼7.5 nm) in its metastable cubic structure based on epitaxial growth. The Ti0.52Al0.48N/Ti0.53Al0.38Si0.09N multilayer with an overall cubic structure shows a hardness value of 35.6 ± 0.7 GPa. All coatings exhibit an age-hardening ability due to the spinodal decomposition. A peak hardness value of 36.7 ± 0.8 and 38.2 ± 0.5 GPa is achieved by Ti0.53Al0.38Si0.09N and Ti0.52Al0.48N/Ti0.53Al0.38Si0.09N, respectively, upon annealing at 1000 °C. In contrast, Ti0.52Al0.48N coating exhibits a maximum hardness increase to 33.5 ± 0.8 GPa at 800 °C. Furthermore, the Ti0.53Al0.38Si0.09N and Ti0.52Al0.48N/Ti0.53Al0.38Si0.09N coatings show oxide scales of ∼2.1 and 1.0 μm at 1000 °C for 10 h after exposure to air atmosphere, respectively, whereas the Ti0.52Al0.48N coating has already been completely oxidized at 850 °C.

The aim of the present study was to assess the influence of the milling time (10 h, 15 h and 20 h) on the structure and properties of Ti-10Ta-8Mo (wt.%) and Ti-10Ta-8Mo-3Sn (wt.%) alloys for potential biomedical application. In addition, the influence of the addition of 3 wt% Sn on the structure and properties of the milled and sintered materials was investigated. X-ray diffraction confirmed the partial synthesis and formation of the β phase during the milling process. The transmission electron microscope analysis of the bright and dark field images and the diffraction image proved the nanocrystalline nature of the material after being subjected to 20h milling duration. The scanning electron microscope observation of the sintered samples confirmed the influence of the milling time and presence of Sn on the microstructure of the obtained material. Furthermore, a small addition of Sn led to better size homogenization by establishing a better balance between the cold-welding and agglomeration processes. At the same time yielding different structures of pores for the sintered samples. The dry sliding tests revealed the excellent friction properties and wear rate of the samples previously milled for 15 h, with the addition of Sn.

Mechanically alloyed composite powders with equiatomic Fe–Al stoichiometry and with the addition of 5, 10, 20 and 30 vol% of B were subjected to consolidation. For this purpose, hot-pressing at 800 °C under the pressure of 7.7 GPa for 180 s was applied. A reference FeAl sample was prepared using the same procedure as these from the composite powders. The produced bulk materials were investigated by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy as well as characterised by hardness, density and open porosity measurements. For the compositions containing 5, 10 and 20% of B, it was possible to obtain composites with the nanocrystalline FeAl intermetallic matrix reinforced with homogenously distributed fine boron particles. For the material containing 30% of B, the boron particles were distributed in a two-phase matrix consisting of the dominant nanocrystalline FeAl intermetallic and minor amorphous phases. The density of the composite samples is in the range of 5.31 ÷ 4.57 g/cm3, which is lower than that of the FeAl reference sample, and decreases with the increase of B content. The hardness of the composite samples is in the range of 10.75 ÷ 12.1 GPa, is higher than that of the intermetallic FeAl reference sample (9.84 GPa), and increases with the increase of B content. To the best of our knowledge, the FeAl-B composites with nanocrystalline intermetallic matrix were produced for the first time.

A bulk magnet based on Sm-Fe-V with the ThMn12 crystal structure has been fabricated for the first time by hot-compaction of mechanically milled powders with a density of 92% of the theoretical density. The isotropic magnet exhibits a maximum coercivity of 1.06 T with a magnetization of 0.59 T, a remanent magnetization of 0.42 T and a (BH)max of 28 kJ m−3 at 3 T applied field. The Curie temperature is found to be 330 °C and the temperature coefficients of remanent magnetization and coercivity are 0.14% C−1 and 0.39% C−1, respectively. Minor hysteresis loops indicate a coercivity mechanism similar to that of the nanocrystalline Nd-Fe-B magnets. The isotropic magnet was hot-deformed up to 75% of its height, and the best magnetic properties obtained were μ0M3T = 0.63 T, μ0Mr = 0.45 T, μ0Hc = 0.88 T and (BH)max = 33 kJ m−3. A small texture perpendicular to compaction direction was detected when the amount of vanadium was reduced, and the deformation temperature was increased from 800 to 1000 °C.

Innovative methods for producing soft magnetic materials, such as inductor cores, are highly sought to achieve desirable microstructures, pursuant to excellent magnetic, mechanical and chemical properties. Here, silicone resin and nano-sized LBSCA glass (NG), prepared by a sol-gel method, were introduced to a nanocrystalline FeSiBNbCu ferromagnetic phase to produce soft magnetic composites (SMCs) by applying liquid-phase sintering-related spark plasma sintering (SPS). This novel strategy contributed to form a dense and uniform double-percolating microstructure in the SMCs with the co-doping of 1.0 wt % silicone resin (SR) and 0.6 wt % NG, which not only remarkably improved magnetic flux density (∼1.39 T), effectively permeability (∼237.0 at 1 kHz) and Vickers hardness (∼7.1 GPa), but also lowered coercivity (∼7.9 A/m) and core loss (∼120 W/m3 at 20 mT and 1 kHz, ∼2774.6 kW/m3 at 60 mT and 50 kHz). A group of additives have been designed and doped into the SMC and systematically studied to compare and understand the behaviors behind these outstanding results. The evolution of phase components and microstructure of the SMCs with different additives has been revealed and correlated with their performances.

In this work new tantalum-based nanocrystalline alloys and composites were made and tested under oxygen and nitrogen conditions using TGA. The materials were produced by mechanical alloying process. Niobium, molybdenum and tungsten were used as alloying elements, and TaC, ZrO2, and Y2O3 were used as the ceramic reinforced phase in composites, all in 5, 10, 20, and 40 wt ratio (wt.%). The materials were studied using XRD, SEM, TEM and AFM. For the purpose of thermal gravimetric analysis, the weight gain was measured and turned out to be the lowest for the Ta-W alloys. All nanocrystalline Ta alloys and composites exhibit lower weight gain in comparison to pure microcrystalline Ta. The Ta-5W alloy exhibits the highest activation energy. For other Ta alloys and composites the activation energy is lower in comparison to pure microcrystalline Ta. Annealing of bulk hot-pressed Ta compounds in oxidative and nitrogen atmosphere leads to the formation of an external thick oxide coating which is loosely connected to the surface and of the diffusion nitride layer inside the material surface, respectively. In this work the authors demonstrate that nanocrystalline Ta-based alloys and composites have a better thermal stability against oxidation in comparison to microcrystalline tantalum.

The magnetocaloric effect and magnetoresistance (MR) of nanocrystalline/amorphous Gd65Co15Al10Zr10 alloy were investigated. The as-spun alloy shows a large maximum magnetic entropy change (MEC) of 5.4 Jkg−1K−1 under a field change of 5 T and a refrigerant capacity of 468.9 Jkg-1. It is found that Ar ion irradiation increases the MEC and refrigerant capacity (RC) of the alloy, which is associated with the anisotropic stress and heating effects, increasing the atomic mobility and short-range order around Gd. Moreover, the maximum MEC shows a power-law (linear) relationship with the MR above (below) the Curie temperature for the as-spun ribbon, which alters after irradiation.

Fe-based nanocrystalline ribbons (e.g. FINEMET) has been applied widely in electric industry due to its excellent soft magnetic properties. However, their preparation involves annealing at high temperature for the formation of α-Fe nanograins, which not only consumes additional energy but results in the embrittlement of the ribbon. In this work, the ductile nanocrystalline ribbons of Fe-Ni-Si-B with good soft magnetic properties have been in-situ prepared just using the melt-spinning method. The nanocrystals have a size less than 45 nm. After the stress relief annealing, the ductility is still available and the magnetic performance is improved. It's worth noting that the industrial grade rather than analytically pure raw materials are used in this work. Therefore, the results have profound implications for academic study and engineering application.

In this paper we investigated the viscosity and density of melts Fe73.5Cu1M3Si13,5B9 where M = Nb, Mo, V, Cr. It is shown that the lowest viscosity and activation energy of viscous flow has a melt with Nb, whose atomic radius is the largest. It is shown that the free volume of the melt is higher during cooling compared to heating, and it indicates irreversible structural changes in the melt. The critical temperature Tk = 1770 K is found, above which the activation energy of the viscous flow changes.

We investigate the electrical transport and dielectric properties of the nanocrystalline BaCo0.9Mn0.1O3-δ under 2H- and 12H-type hexagonal phases. Temperature dependent electrical transport properties under 2H- and 12H-type phases show semiconducting-like behavior above the magnetic transition. The numerical value of electrical resistivity of the 12H-type phase at low temperature is 10-fold higher than the 2H-type counterpart, following the trend of structural stacking sequence. The 12H-type phase exhibits rarely known characteristics of ferromagnetic-insulator. The conduction mechanism under both phases is studied using variable range and small polaron hopping conduction mechanism. The 12H-phase shows large magnetoresistance (∼60%) under an application of 5 T of magnetic field at 50 K. The relation between magnetization and electrical resistivity around the magnetic ordering temperature is studied. The relation has been used to correlate the magnetic entropy change derived by magnetization and electrical resistivity measurements. Temperature dependence and magnetic field induced dielectric permittivity of the 2H- and 12H-type hexagonal phases is studied around the magnetic ordering temperature. Both phases exhibit dielectric suppression by magnetic ordering. The field dependence dielectric behavior shows magnetocapacitance value of ∼4% for 2H-phase and ∼94% for 12H-phase at their magnetic ordering temperature under external magnetic field of 5 T. The existence of intrinsic magneto-dielectric coupling is studied under the framework of Ginzburg-Landau theory for ferroelectromagnet. The origin of extrinsic magneto-dielectric contribution is justified using combinational effect of large negative magnetoresistance and Maxwell-Wagner effect. The magnetic and electrical transport properties of the nanocrystalline BaCo0.9Mn0.1O3-δ compound are also studied using density of states. Nanocrystalline BaCo0.9Mn0.1O3-δ sample shows novel magnetic field-induced effect on the magnetic, electric and dielectric properties around the same temperature window which could be utilized for multi-functional applications.

In this work, milling effect on chemically synthesized nanocrystalline Zinc Cobaltite ( Z n C o 2 O 4 ) has been investigated and we report how the structural and electrical properties vary with the milling span. Phase pure Z n C o 2 O 4 has been successfully synthesized via simple and cost-effective co-precipitation method and then it has been milled for one, four and 8 h respectively. XRD confirms formation of single phase cubic structure for both milled and unmilled nano-powders. Different microstructural parameters has been estimated from Rietveld analysis, which shows particle size reduction from ∼29.64 nm for unmilled sample to ∼18.13 nm for 8 h milled sample. TGA-DSC curve of as prepared sample shows good temperature stability that helps to estimate the appropriate sintering temperature for the samples. TEM analysis also gives values of grain size in agreement with Reitveld analysis. Frequency dependent ac conductivity curve obeys universal Jonscher power law and temperature dependence of frequency exponent is explained by small polaron transaction. Comparable activation energies from hopping mechanism and relaxation process indicates similar transport mechanism. Superimposed scaling spectra obeys TTSP principle. AC conductivity increases with frequency as a result of hopping of the charge carriers. Smaller particles with reduced strain gives enhanced conductivity as well as enhanced value of hopping frequency. This further suggests creation of excess charge carriers in milled samples. Cole-Cole plot shows non-Debye type behaviour of the samples. The dielectric loss factor increases with lowering of particle size since smaller grains contributes to faster charge conduction.

In present investigation, co-precipitation as a simple, low temperature synthesis and low cost route was used to prepare nanocrystal perovskite La (Fe and Mn) O3 for solar cell application. The synthesized powders were characterized by XRD, SEM, PL, DRS, CV, EDS, and FTIR analysis. The photovoltaic behavior of prepared La (Fe and Mn) O3 perovskite as photo anode was also investigated, experimentally and theoretically. The best power conversion efficiency was experimentally obtained by LaFeO3 perovskite (0.07). Two different counter electrodes were applied: Pt electrode and an electrode prepared from a candle soot coated on the surface of FTO glass as a remarkable alternative material and process of noble metal electrode (Au or Ag) deposited by complicated vacuum technologies. In another stage, commercial electrolyte was used to enhance efficiency. These results indicate that there is a possibility to further increase the performance and efficiency of perovskite based cells.

In response to the need of new materials characterized by the spectroscopic properties in the near-infrared window in biological tissues (700–1100 nm), a new type of fluorapatites co-doped with Yb3+ and Tb3+ ions has been synthesized. The nanostructured fluorapatites were prepared using the so-called co-precipitation method and heat-treated in a broad temperature range (600–1100 °C). The structural and morphological properties of the obtained materials were determined by using XRPD (X-ray powder diffraction), TEM (transmission electron microscopy) and SEM (scanning electron microscopy) techniques. The crystallites size was verified and calculated by applying the Rietveld refinement. The primary size of the particles was estimated by TEM analysis and was found to be in the range from 30 nm × 15 nm for the sample annealed at 700 °C to 120 nm × 90 nm for the sample annealed at 1000 °C. Moreover, the formation of defects involving the doping process and their contribution to the charge compensation mechanism has also been discussed. Furthermore, the spectroscopic properties of the obtained materials have been investigated in detail with emission spectra, power dependence relations and luminescence kinetics. The co-doped fluorapatites demonstrated not only Stokes, but also anti-Stokes green luminescence (up-conversion (UC)) depending on the laser power. It was also found that there was weak emission from 5D3 energy level under UV irradiation, not detected under NIR excitation. The cooperative energy transfer (CET) was suggested as the main process responsible for the UC luminescence.

In the present work, we are focused on the influence of Tb/Y substitution on structural and magnetic properties of (Fe80Nb6B14)0.88Tb0.12-xYx (x = 0.02, 0.04, 0.06, 0.08, 0.1 and 0.12) nanocrystalline bulk alloys. The samples were prepared in the form of rods using the vacuum suction technique. The base alloy (x = 0) is characterized by an ultra-high coercivity and the Tb/Y substitution leads to an increase in magnetic saturation from 38 emu/g to 112 emu/g and the decrease in coercivity from 5.88 T to 0.05 T. However, optima of magnetic remanence and |BH|max parameter were observed. It was shown that the changes in magnetic properties are related to a partial replacement of Tb by Y in the unit cell of the Tb/Y2Fe14B phase. In the paper, the optimization of hard magnetic properties as well as its relation to phase composition and microstructure are widely discussed.

Nanocrystalline samples of LaCr1-xCoxO3 (0 ≤ x ≤ 0.3), synthesized through the sol-gel process are characterized to investigate the effect of cobalt doping on various physical properties. The orthorhombic structure of the samples is verified by the XRD patterns. Lattice parameters are estimated using PowderX software and are found to follow the Vegard's law. Williamson Hall analysis is employed to compute the crystallite size and lattice strain. Crystallite sizes exhibit a decrease whereas lattice strain shows an overall increasing trend with the increase in Co concentration. The random dispersal of grains is recognized through scanning electron micrographs and the EDX analysis approves the purity of the samples. TEM analysis provides the particle size in the range of 10–30 nm. The presence of characteristic band in FTIR spectra confirms the formation of LaCr1-xCoxO3 (0 ≤ x ≤ 0.3) samples. UV/Visible analysis is used to calculate the energy band gap and other optical parameters and cobalt doping decreases the band gap considerably. Thermal analysis reveals the occurrence of structural transition for all the samples. Imaginary part of dielectric permittivity and loss tangent decrease with increase in the frequency and finally becomes constant at higher frequencies. The AC conductivity data obey the Jonscher's universal dynamic law and it is established that small polaron hopping is involved in the conduction mechanism. Electrical modulus increases with the rise in frequency indicating the short range mobility of charge carriers. Nyquist plots exhibit only one incomplete and distorted semi-circular plots for all the samples specifying that the relaxation process deviate from the ideal Debye type behaviour. Also, both the grains and charge carriers hopping give rise to the conduction phenomenon in these orthochromites.

Nanocrystalline ZnO were synthesized using refluxed sol-gel method by varying the co-solvent volume ratio of methanol to water (MeOH:Water) from 0:1 to 1:0 with step of 0.2, respectively. It is known that solvent type and ratio significantly affect the morphology, structural and luminescence properties of ZnO. All the produced ZnO samples have nanoneedle, rod, sheet, spherical and nanoplate like mixed morphology and pure highly crystalline hexagonal wurtzite structure. The crystallite size varies from 22.2 to 26.7 nm with an increase in the amount of methanol in a co-solvent from 0:1 to 1:0 and the average lattice parameters are calculated as a = b = 3.246 A and c = 5.202 A. The room temperature PL measurement results showed that both near band gap emission (NBE) at around 380 nm and deep level emission (DLE) in the yellow-green region centered at 530 nm are displayed with an excitation NeCu laser source of wavelength 248.6 nm. The ratio of the intensity of NBE to DLE decreases as the amount of the methanol increases in the solvent. The NBE emission band of the prepared ZnO samples were blue shifted and the emission energy center increased from 3.237 to 3.263 eV as methanol amount increased in the co-solvent. The free and donor-bound excitonic emissions were also studied using low temperature PL measurements and quantum the quenching effects are observed from the results. Primary and secondary longitudinal (LO) phonon replica of the bound excitons also observed during low temperature PL measurements. The optical band gaps of the produced samples determined from UV–Vis reflectance measurements decreased as methanol volume increased in the co-solvent.

The incorporation of TiN and Y2O3 nanoparticles together into Ni-W matrix have been investigated by pulse electrodeposition in present study. The microstructural, surface properties and corrosion resistance of Ni-W/TiN-Y2O3 nanocrystalline coating have been studied. It illustrated that the electrodeposited coatings have dense and nodular structure without defects. Results confirmed that TiN and Y2O3 particles were uniformly embedded in the composites. The embedded particles could improve the hardness and anti-corrosion properties of the obtained coating. The crystallite size calculated based on the preferred orientation (111) plane was of 14–17 nm, illustrating the formation of nanocrystalline structure. The mean Ra value was about 84.6 nm. Electrochemical impedance tests revealed that the preferred combination of operating parameters for optimum corrosion resistance was 70%, 1000 Hz, 40 min and 4 A dm−2. However, the best hardness and anti-wear properties were obtained at parameters of 50%, 500 Hz, 6 Adm−2 and 60 min. The extreme values of hardness and corrosion resistance were not realized simultaneously. The operating parameters should be kept in a certain balance to avoid the formation of inferior properties in any aspects of the coating; then the other performance advantages could be brought into full play. The preferred combination of operating parameters was optimized to be duty cycle of 70%, frequency of 1000 Hz, duration time of 40 min and average current density of 4 Adm−2, which enabled the electrodeposited coating optimum corrosion resistance and high mechanical properties.

Microwave-assisted solution synthesis was employed for the preparation of Cr2O3 nanoparticles using Cr(acac)3 and ethylene glycol. The optimum conditions for the completion of the reaction forming a green precipitate (yield-95%) were: irradiation for 40–60 min at 220 °C solution temperature. The as-prepared sample was barely crystalline; annealing in air at above 300 °C formed nanocrystalline Cr2O3, as shown by X-ray diffraction (XRD). High-resolution transmission electron microscopy (HRTEM) of the “700 °C sample” confirmed the well-crystallised Cr2O3 formation with ∼37 nm average size. The as-prepared powder (bluish-green) showed high near-infrared (NIR) reflectance, whereas the annealed samples showed bright-green reflectance, whose International Commission on Illumination L*a*b* (CIE L*a*b*) values shifted towards the green region. The higher Dq/B value (3.76), suggested that Cr3+ lies in a strong crystal field. Stainless steel blocks covered with the as-prepared (intermediate) material reduced heating under sunlight by 5 °C, indicating its suitability as an easily prepared tile coating for roof-top applications. The annealed samples are found suitable as an anti-dazzling coating for automobile windscreens and rear-view mirrors.