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The shielding properties of a Cu-doped Ni–Zn polycrystalline ferrite in the frequency range 1 MHz to 1 GHz were explored. Samples of composition (Cu0.12Ni0.23Zn0.65)Fe2O4 were prepared by the traditional ceramic route. The complex relative permittivity () and permeability () of the absorber ceramics were measured, and the minimum reflection-loss , matching frequency , matching thickness and bandwidth for were calculated using the theory of the absorbing wall. Effect of the main process parameters (pressing pressure P, sintering temperature T, and sintering time t) on the electromagnetic properties and microwave-absorbing characteristics was deeply investigated. The rise of the three selected process parameters was observed to improve the sintered microstructure of the final specimens (monitored by the relative density and the average grain size G), provided that abnormal grain growth does not occurred. The increase in sintered relative density and average grain growth modifies complex permeability and permittivity in the explored frequency range, enhancing the shielding properties of the material. Se han analizado las propiedades de blindaje de una ferrita policristalina de Ni–Zn dopada con Cu en el rango de frecuencia de 1 MHz-1 GHz. Las muestras de composición (Cu0.12Ni0.23Zn0.65)Fe2O4 se prepararon por la ruta tradicional cerámica, midiendo la permitividad () y la permeabilidad () relativas complejas de las cerámicas absorbentes y se calcularon, utilizando la teoría de la pared absorbente, la pérdida por reflexión mínima , la frecuencia a la que se produce esta mínima , el espesor óptimo de pieza y el ancho de banda para . Se ha llevado a cabo una investigación rigurosa del efecto de los principales parámetros del proceso (presión de prensado P, temperatura de sinterización T y tiempo de sinterización t) sobre las propiedades electromagnéticas y los parámetros característicos de estos absorbedores, observándose que el aumento de los tres parámetros de proceso seleccionados mejoran la microestructura final de las muestras sinterizadas (monitorizadas por la densidad relativa y el tamaño medio de grano G siempre que no se produzca un crecimiento anormal del grano. El aumento de la densidad relativa y el tamaño medio de grano de las piezas sinterizadas modifican la permeabilidad y la permitividad complejas en el rango de frecuencia explorado, mejorando las propiedades de blindaje del material. This study has been supported by Ministerio de Economía y Competitividad (Spain) through grant number (MAT2016-76320-R) and by Universitat Jaume I (Spain), grant numbers (UJIB2017-48 and UJIB2020-13). Complex relative permeability and permittivity determination were carried out at the central facilities (Servei Central d’Instrumentació Científica) of the Universitat Jaume I.

Zn0.97Mn0.03S and Zn0.95Mn0.03Cr0.02S nanostructures were synthesized using co-precipitation method. X-ray diffraction analysis confirmed the ZnS cubic phase with preferred orientation along (1 1 1) direction. The shrinkage in crystallite size from 36 A (Zn0.97Mn0.03S) to 26 A (Zn0.95Mn0.03Cr0.02S) and the influence of Cr as well as Mn substitution on the structure and optical nature were examined. The addition of Cr not only diminished the size and also generated more defect related luminescent centres. The elevation in band gap by Cr addition was explained by Burstein–Moss effect and reduced crystallite size. The tuning of transmittance, energy gap as well size of ZnS nanostructure by Mn/Cr doping promote these materials for modern-electronic applications.

In this paper, CuOx@Ag/CeO2 catalysts were synthesized by simple wet-chemical method and equal volume impregnation method. The obtained catalysts were subjected to soot temperature programmed oxidation (soot-TPO) activity tests and were further characterized by various techniques such as X-ray diffraction (XRD), transmission electron microscopy/high-resolution transmission electron microscopy (TEM/HR-TEM), N2 physisorption, X-ray photoelectron spectroscopy (XPS) and H2- temperature programmed reduction (H2-TPR). The results show that CuOx@Ag/CeO2 synthesized presents well controlled core-shell structures, with nano-cube like Cu2O as the core and Ag decorated polycrystalline CeO2 grafting layers as the shell. Such core-shell structured CuOx@Ag/CeO2 can successfully construct a secondary oxygen delivery channel (CuOx → CeO2 → Ag) to effectively transfer bulk oxygen of the catalyst to the soot, resulting in its excellent soot oxidation activity compared to CuOx@CeO2. The potential benefiting effect by Ag introduction over Cu@Ag/Ce can be concluded as: (i) pumping lattice oxygen and accelerating gaseous O2 dissociation to generate significantly increased active surface oxygen content; (ii) modulating a moderate surface oxygen vacancies concentration to maintain more highly active O2– species.

In the present study, a Bi$_2$WO$_6$/ZnWO$_4$ photocatalyst was successfully constructed by a modified hydrothermal synthesis method with different molar concentrations of Bi$_2$WO$_6$ with respect to ZnWO$_4$. The variation in molar concentrations of Bi$_2$WO$_6$ changed the photocatalytic properties of the Bi$_2$WO$_6$/ZnWO$_4$ catalyst. The synthesized Bi$_2$WO$_6$/ZnWO$_4$ photocatalyst was characterized by various techniques to decipher its structural and spectral properties. The interaction of Bi$^{2+}$ ionic charge carriers and many-body effects cause the band gap to narrow in Bi$_2$WO$_6$/ZnWO$_4$, as shown by PL analysis. The decrease in band gap energies (E$_g$) from 4.7 eV (ZnWO$_4$) to 3.5 eV (30% Bi$_2$WO$_6$/ZnWO$_4$) is beneficial because less energy is required to excite the valence electrons. The maximum degradation of Plasmocorinth B dye was found with 30% Bi$_2$WO$_6$/ZnWO$_4$ under UV irradiation. This increased activity of 30% Bi$_2$WO$_6$/ZnWO$_4$ can be attributed to the (i) synergistic effect in the bicrystalline framework of Bi$_2$WO$_6$ and ZnWO$_4$, (ii) the high close contact between Bi$_2$WO$_6$ and ZnWO$_4$, and (iii) the small crystallite size. The photocatalytic activity of synthesized Bi$_2$WO$_6$/ZnWO$_4$ photocatalyst shows its significant potential in water/ wastewater treatment application.

The process parameters for dry reforming of methane (DRM) over Ni–W/Al2O3–MgO catalyst are optimized using response surface methodology (RSM). The Ni–W bimetallic catalyst is synthesized by co-precipitation method followed by impregnation. The catalysts are characterized by BET, XRD, FESEM, EDX and TEM; to study physicochemical properties, morphology, composition, crystallite size and deposited carbon. The effect of process parameters, i.e., reaction temperature (600oC–800 °C) and feed gas ratio (0.5–1.5) on the CH4, CO2 conversions and syngas ratio are studied. A temperature of 777.29 °C with CH4: CO2 of 1.11 at GHSV of 36,000 cm3gm.cat−1h−1, delivered the CH4 and CO2 conversions of 87.6% and 93.3%, respectively along with H2:CO of 1. The predicted process parameters were verified through actual experimental analysis at the optimized conditions, and results agreed with CCD of the RSM model with insignificant error. The MWCNT formed during DRM avoided catalyst deactivation and delivered stable performance over 12 h of reaction test at the optimized conditions.

In this study, β-blocker metoprolol was degraded by photocatalysis and photo-Fenton catalyzed by doped TiO2. The effect of two main variables was elucidated, content and type of doping cation (Fe or Cu). The catalysts were synthesized by Evaporation-Induced Self-Assembly (EISA) method and their performance was compared with typical Degussa P25. All synthesized materials were found to be mesoporous with a specific surface in the range of 121–242 m2/g, they all exhibited anatase phase, and crystallites in the range of 6–10 nm. The use of X-ray photoelectron spectroscopy (XPS) allowed to establish not only the presence of the expected Ti4+ but also Ti3+ species. Cu2+ and Fe3+ species were also identified in the doped catalysts. It was found that the addition of Cu and Fe diminished the energy band gap of synthesized TiO2, from 3.20 eV to 2.58 and 2.64, respectively. The content of Cu is directly correlated with this effect. In photocatalysis, the doping of TiO2 did not have an effect of metoprolol degradation rate. This was improved, however, approximately 60% by the synthesized TiO2 compared to Degussa P25. On the other hand, the photo-Fenton-like process catalyzed by Cu-TiO2 exhibited the highest degradation (total removal) and mineralization extent (90%), being faster than the photocatalytic process and the UV-H2O2 system. Another difference between both methods, was the amount and type of intermediates generated. These were identified by LC-MS. Photo-Fenton catalyzed by Cu/TiO2 can be considered as an effective process with high oxidative power in the metoprolol degradation.

In this communication, structural, dielectric, spectroscopic and electrical characteristics of cerium-modified strontium manganite perovskite of a composition SrMn0.9Ce0.1O3, (SMCO) prepared by a high-temperature solid-state reaction technique have been reported. The preliminary structural analysis of SrMnO3 exhibits hexagonal (P63/mmc) crystal structure, whereas SMCO, synthesized under identical conditions, shows a tetragonal (I4/mmm) structure. The average crystallite size and lattice strain of SMCO using X-ray data were found to be 74 nm and 0.107%, respectively. The surface morphology, study by the scanning electron microscopy (SEM), shows distinct grains of average size of 19.2 μm. The X-ray photoelectron spectroscopy (XPS) study confirms the oxidation state of Mn and Ce as Mn4+ and Ce4+ and composition of SMCO compound. The grains and the grain boundaries play an important role to explain the conduction mechanism. The bulk resistance (Rb) decreases from 1.020 × 105 Ω at 25 °C to 1.096 × 103 Ω at 500 °C. This behaviour of decrease in resistance with the increase in temperature shows semiconductor (negative temperature coefficient resistance) nature of the material at high temperatures. The variation of the activation energies with temperature suggests that the ac conductivity is thermally activated. The immobile charge carriers at low temperatures and defects and oxygen vacancies at high temperatures are responsible for the thermally activated conduction mechanism. Detailed studies of electrical parameters as a function of frequency at different temperatures using dielectric and impedance spectroscopy of SMCO have provided conduction mechanism and structural properties relationship.

Hydrocalumite derived catalysts prepared by co-precipitation with non-noble metal Nickel(Ni) as main active site were tested in ethanol steam reforming, and the influences of Ni (5,10,15 wt%) content were mainly tested in this research. Meanwhile, the physicochemical properties of the prepared catalysts were analyzed through different characterizations including BET, X-ray diffraction (XRD), H2-temperature programmed reduction (H2-TPR) and CO2-temperature programmed desorption (TPD). As the Ni increased, the specific surface area, crystallite size of Ni, reducibility and basicity of catalysts were changed, which further affected their activities. On this basis, the best performance in this catalytic system was presented when Ni in the catalysts was 15 wt%, the ethanol conversion and hydrogen yield could reach almost 100% and 85% at 650 °C respectively. Thus, this kind of catalyst is effective for ethanol steam reforming.

MnOx-Fe3O4 nanomaterials were fabricated by using the innovative scheme of pyrolyzing manganese-doped iron-based metal organic framework in inert atmosphere and exhibited extraordinary performance of NO reduction by CO (CO-SCR). Multi-technology characterizations were conducted to ascertain the properties of fabricated materials (e.g., TGA, XRD, SEM, FT-IR, XPS, BET, H2-TPR and O2-TPD). Moreover, the interaction between reactants and catalysts was ascertained by in situ FT-IR. Experimental results demonstrated that Mn was an ideal promoter for iron oxides, resulting in decrease of crystallite size, improve reducibility property, enhance the mobility and the amount of lattice O2– species, as well as strength the adsorption ability of active NO and CO to form multiple species (e.g., nitrate and carbonate). The unprecedented enhancement of CO-SCR activity over Mn-Fe nanomaterials follows the Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) reaction pathway.

The strength of polycrystalline metals increases with decreasing grain size, following the classical Hall-Petch relationship. However, this relationship fails when softening occurs at very small grain sizes (typically less than 10 to 20 nm), which limits the development of ultrahigh-strength materials. In this work, using columnar-grained nanocrystalline Cu-Ag ‘samples’, molecular dynamics simulations were performed to investigate the softening mechanism and explore the strengthening strategies (e.g., formation of solid solution or grain boundary (GB) segregation) in extremely fine nanograined metals. Accordingly, the softening of pure metals is induced by atomic sliding in the GB layer, rather than dislocation activities in the grain interior, although both occur during deformation. The solid solution lowers the stacking fault energy and increases the GB energy, which leads to the softening of NC metals. GB segregation stabilizes GB structures, which causes a notable improvement in strength, and this improvement can be further enhanced by optimizing the solute concentration and GB excess. This work deepens the understanding of the softening mechanism due to atomic sliding in the GB layer and the strengthening mechanism arising from tailoring the GB stability of immiscible alloys and provides insights into the design of ultrahigh-strength materials.

Magnesium (Mg) based alloys are promising candidates for many applications, but their untreated surfaces usually have low strength and hardness. In this study, a single point diamond turning (SPDT) technique was applied to refine the grain size and improve the mechanical properties of the surface layers of Mg-Li alloys. By refining grains in the topmost layer to the nanometer scale (∼ 60 nm), the surface hardness was found to be enhanced by approximately 60%. The atomic plastic deformation process during the SPDT was then studied by the real-time atomistic molecular dynamics (MD) simulations. A series of MD simulations with different combinations of parameters, including rake angle, cutting speed and cutting depth, were conducted to understand their influences on the microstructural evolution and associated plastic deformation mechanisms on the surface layer of the workpieces. The MD simulation results suggest that using increased rake angle, cutting speed and cutting depth can help to achieve better grain refinement. These simulation results, which provide atomic-level details of the deformation mechanism, can assist the parameter design for the SPDT techniques to achieve the high-performance heterogeneous nanostructured materials.

Nanocrystalline copper ferrite shows distinct photocatalytic properties, but it suffers from a high recombination rate of photogenerated electrons (e−) and holes (h+) due to its narrow bandgap. Herein, Al3+ doping is shown to reduce the (e−/h+) recombination rate and improve the charge carriers’ availability in doped CuFe2−xAlxO4 (0 ≤ x ≤ 1) nanoparticles produced by a solid-state, mechanochemical process. CuFe2−xAlxO4 (0 ≤ x ≤ 1) nanoparticles exhibit the growth of a nanocrystalline cubic spinel lattice when annealed at 1000 °C. The lattice parameter is reduced by Al3+ doping due to the smaller ionic radius of Al3+ ions substituting bigger Fe3+ ions. However, a higher degree of sintering and greater crystallite size are observed for Al3+ doped samples. The surface morphology and topography also reveal an increase in the particle size, but significantly narrow size distribution and greater homogeneity. The effect of Al3+ doping on the optical properties of CuFe2−xAlxO4 (0 ≤ x ≤ 1) nanoparticles is demonstrated by a decrease in the photoluminescence signal that is attributed to the lower rate of (e−/h+) recombination. Thus, Al3+ doping increases transition time and improves the availability of charge carriers for potential photocatalytic applications.

The thermal conductivity of uranium oxide (UO2) containing pores and grain boundaries is investigated using continuum-level simulations based on the finite-difference method in two and three dimensions. Steady-state heat conduction is solved on microstructures generated from the phase-field model of the porous polycrystal to calculate the effective thermal conductivity of the domain. The effects of porosity, pore size, and grain size on the effective thermal conductivity of UO2 are quantified. Using simulation results, a new empirical model is developed to predict the effective thermal conductivity of porous polycrystalline UO2 fuel as a function of porosity and grain size.

With the rapid increase in the demand for lithium as an energy-critical element, the recovery of Li+ ions from seawater is a worldwide challenging issue. Herein, we propose a new facile and fast selective recovery approach of Li+ using an Al3+-crosslinked poly(N-isopropylacrylamide) (PNIPAAm)/alginate (Alg) (PNP/Alg(Al)) adsorbent. The in situ TEM images indicate that Alg–Al3+ coordination is reorganized via the rearrangement of PNIPAAm and Alg networks, as the temperature increases. The reorganization eventually leads to the formation of polycrystalline structure. The in situ FTIR results exhibit that PNP/Alg(Al) composite has peculiar phase transitions, which includes a retrogressive phase change from hydrophobic to hydrophilic. The synergetic effect of the strong repulsion force of Al3+ ions and the attractive force of negatively charged polymeric chains enables the efficient adsorption of Li+ ions with a low affinity from Li-spiked seawater. 7.3% of Li+ ions are recovered from Li-spiked seawater although the concentration of Li-spiked seawater is very high. In addition, Li+ ions can be extracted from PNP/Alg(Al) composite with the use of a small thermal energy. The proposed thermoresponsive IPN gel provides a strong potential in practical applications for Li+ recovery as an innovative energy-material strategy.

Simple strategy to stably preserve the smaller Ni nanoparticles (NPs) having homogeneous crystallite size of ∼5 nm was proposed using ordered mesoporous supports under dry reforming of methane with CO2 (DRM). The NPs-impregnated ordered mesoporous SBA-15 was effective to preserve the smaller Ni nanoparticles with their lower thermal aggregations and less coke depositions by their spatial confinement effects inside of the ordered mesopore structures compared to the irregular conventional SiO2 support. Although the highly ordered mesoporous NPs-impregnated Al2O3 was also found to be effective, the acidic natures of the Al2O3 surfaces accelerated coke depositions by preferentially forming inactive phases.

This work examines the properties of polyvinyl alcohol (PVA)/starch film containing glycerol as a plasticizer under exposure to different nitrogen ion fluence. The prepared PVA/starch blend was irradiated with ion fluence from 3 × 1017 to 12 × 1017 ions.cm−2. From FTIR, the ion beam irradiation attack and weakens the C–H bond in PVA/starch blend. From XRD findings, the crystallite size of the blend decreased at 3 × 1017 ions/cm2 while it increased at higher fluence up to 9 × 1017 ion/cm2. This indicates the degradation of the blend at low ion fluence compared to crosslinking at high ion fluence. Also, the optical bandgap of the blend was decreased with an increase in ion fluence. Furthermore, the effect of N+ ions on some optical dispersion parameters is studied. The thermal stability of the PVA/starch blend shows a decrease in thermal stability upon irradiation with 3 × 1017 ions/cm2 compared to higher thermal stability at higher doses up to 9 × 1017 ions/cm2.

Recent studies have shown that many challenges encountered in conventional single crystal growth methods, including high production costs, can be overcome by using the solid-state single-crystal growth (SSCG) approach, which has been recognized as a simple and cost-effective alternative for obtaining single crystals. In this work, Y3Al5O12 (YAG) and Nd3+-doped YAG (Nd:YAG) single crystals were grown via the SSCG method using spark plasma sintering (SPS). The growth of single crystals was initiated at the surface of (110) YAG single-crystal seeds embedded inside YAG and Nd:YAG powder beds, and this growth continued as the surrounding polycrystalline matrix was converted into a single crystal. The application of external pressure during the SPS process has been found beneficial for reducing the porosity of the grown single crystals. Moreover, high Nd3+ doping levels had a positive effect on the conversion kinetics, with a growth rate of almost 50 µm/h, which increased the driving force for single-crystal growth through the solute drag effect. EDS elemental mapping and line scans confirmed the compositional uniformity of the grown single crystals, while EBSD images verified their crystallization in the (110) direction. The obtained results confirm the strong potential of the SSCG technique coupled with SPS for the growth of undoped and highly doped YAG single crystals with excellent quality.

In recent work, pure α-Fe2O3 (F-1) and series of 5% Cu doped Fe2O3 (CF-5) , 10% Cu doped Fe2O3 (CF-10) and 15% Cu doped Fe2O3 (CF-15) nanoparticles by facile chemical coprecipitation method were synthesized to study the effect of concentration of doping for photocatalytic activity. As prepared F-1, CF-5, CF-10, CF-15 nanoparticles were subjected to X-ray diffraction (XRD) and Fourier transform infra-red (FTIR) techniques to analyse the structural and functional groups features. These characterization techniques confirmed the successful doping of Cu 2+ ions in α-Fe2O3. The crystallite size of synthesized samples was calculated by Scherrer formula. Gradually decline in crystallite size from 18 to 15 nm was observed for undoped to doped samples. Scanning electron microscopic (SEM) analysis expressed that doping of Cu reduced the aggregation of particles and enhanced the surface area of nanoparticles. UV–Visible spectroscopic analysis of synthesized samples was used to calculate the bandgap energy of F-1, CF-5, CF-10, CF-15 nanoparticles i.e., 2.0, 1.7, 1.5, 1.4eV respectively. Narrowing bandgap energy of doped hematite supported to perform excellent photocatalytic activity. Maximum degradation of methylene blue was recorded via CF-10 within 140 min. Higher degradation rate of methylene blue by optimal concentration of CF-10 is due to effective electron trapping ability of photocatalyst.

Partial substitution of ZnO for CaO in the wollastonite formula was performed via wet precipitation. The effects of ZnO/CaO replacement on the structure, porosity, morphology, optical, and mechanical properties of the CaO–SiO2 ceramic were examined. Structural results and Fourier transform infrared (FTIR) spectra indicated the existence of mixed phases of wollastonite with hardystonite and willemite with hadystonite composites, depending on the ZnO content. The calculated crystallite size confirmed that the formed composites were in the nanoscale range. The FTIR results verified the mixed phases of the prepared samples. The optical band gap energy (Eg) values of 3.3 and 4.56 eV referred to the willemite phase in samples with high ZnO content. Addition of ZnO increased the bulk density and decreased the porosity of the wollastonite. The reduced porosity controlled the mechanical behavior of the prepared composites. The maximum stress (σu) increased from ∼4.10 to ∼26.68 N/mm2 as the porosity decreased from 52.20% to 40.17% for a ZnO content increased from 0% to 50%. The fracture load increased with the ZnO content. The degradability of samples revealed that the higher the ratio of ZnO to the nominal wollastonite, the more influential it was on the degree of weight loss % and the variation in the pH value. The bioactivity test estimated that all samples surface exposed development of a newly formed apatite layer, consequently evidencing the bioactivity of the prepared ceramic composites. Therefore, such substitution can be used in vital applications.

We report on the influence of Al doping on the structural, morphological and vibrational properties of hematite crystallite synthesized by using the hydrothermal method. The structural property of the pristine and Al doped hematite samples are extensively characterized by the Rietveld profile refinement of X-ray diffraction data. The structural refinement suggests that both the pristine and the doped compounds are stabilized in the hexagonal R 3 c symmetry. Doping with Al induces a compressive strain in the hematite lattice, which is further reflected in the spectroscopic Raman studies. It is also observed that the Al atom has a significant influence on the growth mechanism of hematite crystallites. Temperature dependent Raman study performed in the Al doped hematite sample brings out anomalous behaviour of phonon modes and line widths around the temperature region of 150 K. These anomalies observed around the temperature region of 150 K are suggestive of the presence of spin-phonon coupling associated with the Morin transition in the Al doped hematite. Our detailed structural and Raman spectroscopic analyses suggest that the Al doped hematite can be a potential magnetodielectric candidate.

Thin film of WO3 has been deposited on conductive fluorine tin oxide substrate using the hydrothermal technique. The film's microstructural, morphological and optical properties have been identified using X-ray diffraction, atomic force microscope, and spectrophotometer. The obtained results have confirmed the nanocrystalline structure of the as-received WO3 thin film with crystallite size ≈63.4 nm. Analysis of the absorption coefficient using Tauc's model shows the possibility of direct and/or indirect allowed transition with energy gaps 3.95 and/or 3.45 eV, respectively. The refractive index has been determined by different methods showing the average value (2.2 and 2.3 corresponding to the direct and indirect transitions, respectively). The nonlinear refractive index and third-order nonlinear optical susceptibility have been determined, showing the high polarizability of WO3/FTO with radiation to be promising for different optical devices and applications.

The synthesis of silver doped cobalt oxide nanoparticles by microwave-assisted method and their structural, optical, antibacterial activities are presented in this study. The doping concentrations were chosen as 5, 10, 15, and 20 wt percentages. The sample was undergone powder X-ray diffraction studies and the result shows the good crystalline nature of the sample. Also, the average crystallite size increases from 13.95 nm, 21.26 nm, 26.13 nm, and 28.35 nm with different doping concentrations. The transmission electron microscopy image shows cubic and spherical morphology. The optical properties were tested by UV–vis–NIR absorption spectrum. It indicates the decrease of band gap value. From the antibacterial activity studies, the 20 wt % Ag doped nanoparticles exhibit better activity.

BaTiO3 ceramics doped with double perovskite Sr2KMoO6 (BT-SKM) are fabricated via solid-state reaction technology. The effects of SKM dopants on the structure, band gap and electrical/magnetic properties of BT are systematically studied. XRD and Raman spectra analysis show polycrystalline perovskite structure of the samples, which confirms the structural changes. With the addition of SKM dopants, the grain size of the samples decreases significantly. The band gaps of doped BT samples reduce, and the minimum band gap of BT-SCM is 1.77 eV, which is apparently reduced compared with the band gap of pure BT of 3.22 eV. However, the ferroelectric properties are weakened in samples doped with SKM. This ascribes to the introduction of more oxygen vacancies by dopants, which impedes the switching of domains, resulting in deterioration of ferroelectric properties. Furthermore, ferromagnetism of BT-SNM is observed, which may be attributed to the long-range exchange interaction between Ni2+ ions and oxygen vacancies. These results reveal the potential applications of these perovskite oxides in photovoltaic and memory devices.

Recently, the anomalous photovoltaic effect of ferroelectric materials has attracted considerable attention in the construction of efficient solar cells owing to the above-bandgap photovoltage of these materials. In this study, we investigate the anomalous photovoltaic effect of relaxor-based ferroelectric Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIMN-PT) ceramics with large remnant polarization and a narrow optical bandgap. Excellent photovoltaic performance with an ultrahigh open-circuit voltage of 23 V (575 V/cm) is achieved, which is higher than the open-circuit voltages of all reported polycrystalline materials with similar thickness. The phase structure, microstructure morphology, domain structure, ferroelectric and optical characteristics are analyzed, which could provide clues to the origin of the ultrahigh open-circuit voltage of PIMN-PT ceramics. The results suggest that the relaxor-based ferroelectric PIMN-PT system is a potential candidate for photovoltaic solar energy conversion devices.

SnSe-based thermoelectric materials are being explored since they have potential high thermoelectric figure of merit. We synthesized polycrystalline AlxSn1-xSe (x = 0.01, 0.02, 0.03 and 0.04) by hot-pressing method, and combined theoretical estimation with experimental measurement to investigate the influence of Al doping on thermoelectric properties of SnSe. It was found that dopant Al can effectively adjust the band structure of SnSe by introducing intermediate band. Al doping with low content (x = 0.01 and 0.02) can introduce a single intermediate band close to the valence band maximum or conduction band minimum, achieving band engineering optimization. In high temperature region (498 K

The structure, microstructure, thermal and mechanical properties of glasses and glass-ceramics in the LMAS (Li2O, MgO, Al2O3, SiO2) system and the effect of P2O5 and Al2O3 additives have been studied. The transition temperatures of both glasses and glass-ceramics increase with the P2O5 and Al2O3 concentration, but at high temperatures the melt viscosity decreases. The main crystalline phases formed are lithium aluminium silicate, enstatite and β-spodumene, being the growth of β-spodumene favoured by fluorine ions, P2O5 and the heat treatment temperature as well. Raman and FT-IR spectroscopies have shown the formation a silica-rich glass phase which acts as a matrix of the crystallites containing Al2O3 and P2O5 in its composition. The shape and aspect ratio of the crystallites depend on the Al2O3 concentration. For low Al2O3 concentration a variety of tubular, granular and plate-like crystals appear, while for high Al2O3 concentration the main shape of the crystals is spherical or globular. Hv, E and CTE properties are related to the crystalline phases formed during the crystallization treatment, and their variations are in accordance with the increase of the crystal aspect ratio. The CTE values of the GCs decrease as the P2O5 content increases up to 3%, while for the Al2O3 concentration of 16% the minimum CTE value is obtained. Hv and E values of the GCs are higher than those corresponding to their respective parent glasses. According to these values, these glasses and glass-ceramics are not appropriate for machining.

Lately, attention to combustion synthesis has been encouraged owing to being cost-effective, rapid, and produces samples with low crystallite sizes and/or different morphology. So, in this paper, for the first time, ZnO nanoparticles were facilely fabricated utilizing the combustion procedure using L-arginine, L-valine, and L-alanine as organic fuels. Besides, the fabricated ZnO samples were recognized using different tools such as FT-IR, XRD, FE-SEM, HR-TEM, and UV–Vis. The XRD patterns show that the mean crystallite size of ZnO samples, which were fabricated operating L-arginine, L-valine, and L-alanine fuels, is 25.24, 31.11, and 35.65 nm, respectively. The HR-TEM images approved that the ZnO samples, which were fabricated operating L-arginine, L-valine, and L-alanine fuels, are composed of irregular, hexagonal, and sphere shapes with an average diameter of 22.46, 34.57, and 40.29 nm, respectively. The EDX patterns display peaks at 1.0 and 8.6 KeV for Zn. Also, there are peaks at 0.6 KeV for O. The values of the energy gap for the ZnO samples, which were fabricated operating L-arginine, L-valine, and L-alanine fuels, are 3.30, 2.88, and 2.63 eV, respectively. The photocatalytic degradation process is an important water treatment method due to its effectiveness in producing hydroxyl free radicals which able to degrade numerous dyes. So, the fabricated ZnO samples were examined for the photocatalytic degradation of methylene blue dye along with biological activity against some strains of bacteria. Furthermore, the maximum percent of degradation of 50 mL of 10 mg/L methylene blue dye under UV irradiations is 54.69, 41.34, and 30.76% after 90 min exploiting the ZnO samples which were fabricated operating L-arginine, L-valine, and L-alanine fuels, respectively. Also, % degradation of methylene blue dye under UV irradiations in the presence of hydrogen peroxide is 100% after 70 min using the ZnO sample which was fabricated operating L-arginine fuel. Moreover, the fabricated ZnO products show high bactericidal activity against Staphylococcus aureus, Listeria monocytogenes, and Enterococcus faecalis. Additionally, the fabricated ZnO products show moderate bactericidal activity against Bacillus cereus and Salmonella typhimurium.

Solid oxide fuel cells (SOFCs) technology, with fuel flexibility, is one of the most promising power generation technology. However, the high operating temperature of SOFCs has hindered their commercial applications. As a crucial requirement to enhance its performance, SOFCs electrolytes should operate at a low temperature. Carbonate/ceria composites are developed as electrolytes for low operating temperature SOFCs, and a better understanding of the mechanism of its ionic conductivity serves this purpose. In this work, ceria-carbonate composite electrolyte, Na2CO3/samarium doped ceria (NSDC) were synthesized by the co-precipitation method. The synthesized electrolytes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV–Vis spectroscopy. The XRD and SEM results showed that the sintered NSDC nanocomposite comprised a single-phase dense electrolyte structure. The crystallite size of the NSDC nanocomposite was greatly affected by the different pre-firing temperatures and different sintering temperatures. Also, the ionic conductivity of the prepared NSDC nanocomposite electrolytes was strongly dependent on the pre-firing and sintering temperatures. The NSDC nanocomposite electrolytes were pre-fired at 950 ​°C and 650 ​°C and sintered at 1200 ​°C and 900 ​°C respectively, had ionic conductivity in H2 and air high as 0.36 ​S/cm and 0.3 ​S/cm.

Electromagnetic wave (EMW) absorbing materials have excellent potential for various applications in civil engineering and the military. In this study, siliconboron carbonitride (SiBCN) ceramics with excellent EMW absorption capability and oxidation resistance were obtained by adjusting the boron content. The results revealed that the graphite crystallite size in the SiBCN ceramics increased from 3.42 to 3.78 nm, whereas the thickness of the oxide layer decreased from 16.6 to 8.2 μm. The highest electrical conductivity and permittivity for the SiBCN ceramics were obtained when the boron content was 5%. The minimum reflection loss was −35.25 dB at 10.57 GHz and a ceramic thickness of 2.0 mm. At a temperature of 600 °C, the SiBCN ceramic exhibited excellent EMW attenuation ability; particularly, the minimum reflection loss reached −29.18 dB at 9.65 GHz and a ceramic thickness of 2.5 mm. The superior EMW absorption properties of the SiBCN ceramics at high temperatures can be ascribed to the synergistic effect of relaxation and conductivity. The results suggest that boron could enhance the transformation of amorphous carbon into crystalline graphite and increase the number of heterointerfaces and conductive paths. This work provides a method for obtaining SiBCN ceramics with excellent EMW absorption properties.

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 effect of specimen thickness on the rupture properties of cast Ni-based polycrystal superalloy M951 was investigated in this paper. The results of the rupture tests in air under 980 ​°C/90 ​MPa revealed that the rupture life and elongation obviously decreased with decreasing specimen thickness. The thin-wall effect for polycrystal superalloy M951 is associated with several factors. First, the surface oxidation and internal nitridation induce the reduction in the load-bearing section, which accelerates the rupture fracture of thin specimens. Second, the combined effect of oxidation and stress at the surface grain boundary facilitates the premature initiation and propagation of the surface cracks in thin specimen. Third, the through-grain boundaries introduce by specimens machining are detrimental for rupture property. A direct comparison of rupture properties of thin-wall samples with different grain morphologies indicate that thin-wall effect can be diminished by avoiding through-grain boundary introduction.

Piezocatalytic materials have been widely used for catalytic hydrogen evolution and purification of organic contaminants. However, most studies focus on nano-size and/or polycrystalline catalysts, suffering from aggregation and neutralization of internal piezoelectric field caused by polydomains. Here we report a single crystal ZnO of large size and few bulk defects crafted by a hydrothermal method for piezocatalytic hydrogen generation from pure water. It is noteworthy that single-side surface areas of both original as-prepared ZnO and Ga-doped ZnO bulk crystals are larger than 30 cm2. The high quality of ZnO and Ga-doped ZnO bulks are further uncovered by high-resolution transmission electron microscope (HRTEM), photoluminescence (PL) and X-ray diffraction (XRD). Remarkably, an outstanding hydrogen production rate of co-catalyst-free Ga-doped ZnO bulk crystal (i.e., a maximum rate of 5915 μmol h−1 m−2) is observed in pure water triggered by ultrasound in dark, which is over 100 times higher than that of its powder counterpart (i.e., 52.54 μmol h−1 m−2). The piezocatalytic performance of ZnO bulk crystal is systematically studied in terms of varied exposed crystal facet, thickness and conductivity. Different piezocatalytic performances are attributed to magnitude and distribution of piezoelectric potential, revealed by the finite element method (FEM) simulation. The density functional theory (DFT) calculations are employed to investigate the piezocatalytic hydrogen evolution process, indicating a strong H2O adsorption and a low energy barrier for both H2O dissociation and H2 generation on the stressed Zn-terminated (0001) ZnO surface.

Efficient adsorption of Ba ions was achieved using Sn@TiO2 nanocomposite generated by ultrasonication process with subsequent calcination at 300 °C. X-ray diffraction, nitrogen adsorption-desorption isotherm, X-ray photoelectron spectroscopy, Fourier transformer infra-red, and scanning/transmission electron microscopy analyses were performed to probe the structural and textural features of the adsorbent powder. The XPS, FTIR, and EDX analyses confirmed the Sn doping into TiO2 host lattice. Some interesting features, including the increase of crystallite size and lattice parameters, were attained due to the successful Sn incorporation into the TiO2 host, as indicated further by XRD analysis. The sorption results fitted the Langmuir isotherm model and the kinetic data complied with the pseudo-second-order kinetics. The adsorption process improved markedly above the pHzc due to the electrostatic attraction between the negatively charged Sn@TiO2 particles’ surface and the positively charged Ba ions. The achieved high-performance mesoporous Sn@TiO2 nanostructures for the adsorption of Ba2+ could be potentially utilized to remove other toxic metal cations.

Nanostructured HoFeO3 powders were obtained by solution combustion method at various glycine-nitrate ratios (G/N = 0.2, 0.4, …, 1.4). According to X-ray powder diffractometry data, the presence of two modifications of HoFeO3 in the synthesized samples was established: orthorhombic (Pbnm) and hexagonal (P63/mmc). The crystallite size of the obtained compositions varies from 62 ± 6 to 29 ± 3 nm, depending on the G/N ratio. From magnetic structure studies, it is found that HoFeO3 obtained with a stoichiometric amount of glycine in the reaction solution is in the magnetically ordered state and is represented by a sextet with quadrupole splitting (QS) = 0 mm/s, isomeric shift (IS) = 0.36 mm/s and effective field strength (Heff) = 497 kOe. According to the results of vibrational magnetometry, it is found that the orthoferrites obtained have a ferromagnetic structure, the main parameters of which (Ms, Mr and Hc) systematically change with a change in the redox ratio of the reaction mixture and, as a consequence, their phase composition, and reach maximum values at a G/N ratio = 0.6. In the samples obtained with a significant excess and lack of glycine (G/N = 0.2 and 1.4), despite their amorphous nature, hysteresis loops characteristic of the ferromagnetic state of the substance is observed. It is hopeful to obtain a pure hexagonal modification of HoFeO3 via heat treatment on amorphous products of glycine-nitrate combustion.

In this study, we synthesized La1-xMgxFeO3 (x = 0.1, 0.2, and 0.3) powdered ceramics using sol − gel and sintering methods and their structure, magnetic and electrical properties have been investigated. All samples showed the Pbnm single phase, and structural analyses revealed a lattice distortion due to the addition of Mg that increases with increasing Mg content. Transmission electron microscopy revealed a decrease in particle size with increasing Mg content. The M − H hysteresis loops of the samples revealed that the samples with Mg substitution at the La site exhibits weak ferromagnetic behaviour, and the hysteresis loops increases with an increase in Mg content. The magnetisation increases as the Mg content is increased, which is might be related to the lower crystallite and particle sizes, as well as higher Fe4+/Fe3+ ratio, as shown by X-ray diffraction and X-ray photoelectron spectroscopy, respectively. Analysis of the electrical properties showed grain–grain boundary effect in the conduction mechanism and two relaxation mechanisms for low Mg contents (x ≤ 0.2), whereas only the grain effect and one relaxation mechanism were observed at higher Mg contents (x = 0.3). The temperature dependence of direct current conductivity obeys the Arrhenius law. The activation energy for the conduction mechanism decreased with an increase in the Mg content. These results contribute the important knowledge in promising the candidate electrode material in electrochemical application.

ZnTiO3 was supported on quartz microspheres to reduce ZnTiO3 particle aggregation and to enhance the photocatalytic activity of ZnTiO3. The distribution of ilmenite phase ZnTiO3 on quartz microspheres was found to reduce the ZnTiO3 crystallite size from 40.4 nm to 19.9 nm. The commonly large ZnTiO3 particles in pure ZnTiO3 can hardly exist in χZnTiO3/SiO2 composites. The bandgap energy of ZnTiO3 is enlarged after support on quartz microspheres. The bandgap energies of 20ZnTiO3/SiO2, 50ZnTiO3/SiO2, 80ZnTiO3/SiO2 and pure ZnTiO3 were determined to be 3.42, 3.38, 3.08 and 2.93 eV, respectively. The pore volume and the BET surface area of χZnTiO3/SiO2 composites were several times larger than that for both quartz microsphere and ZnTiO3. The hole-electron recombination efficiency is reduced after supporting the ZnTiO3 on quartz microspheres. The photocatalytic activity of χZnTiO3/SiO2 composites is in the sequence 50ZnTiO3/SiO2 > 80ZnTiO3/SiO2 > 20ZnTiO3/SiO2 > ZnTiO3. The RBR X-3B degradation rate constants for ZnTiO3, 20ZnTiO3/SiO2 and 50ZnTiO3/SiO2 were determined to be 0.01016, 0.02271 and 0.02653 min−1, respectively. The RBR X-3B degradation efficiency in the presence of 50ZnTiO3/SiO2 reaches 91.7% after 80 min of reaction.

CdO nanoparticles (CdO NPs) were synthesized utilizing urea-assisted auto-combustion (AC) and microwave combustion (MC) methods. The structural, thermal, optical, morphological, and compositional analysis of the prepared samples were investigated after they were heat treated at 350 °C. The impact of heat treatment and the method of synthesis on their physicochemical properties were investigated. XRD was used to determine the phase, crystallite size, and lattice constant of CdO NPs. The modification of the phase and crystallite size of CdO NPs indicates the impact of the heat treatment and synthesis process. The annealing process raises the crystallite size from 28 nm to 45 nm for the auto combustion approach and from 24 nm to 40 nm for the microwave combustion method. Under heat treatment, the energy band gaps of CdO NPs from auto combustion method and microwave combustion method samples were determined to be 2.09 eV and 1.65 eV, respectively. The surface morphology of CdO NPs was documented by SEM, indicating that the particle's morphology was modified by the synthesis procedure. The nanoscale range of the particles is confirmed by TEM micrographs of annealed CdO NPs, which is closely matched with the crystallite size derived from XRD. TG-DTA was used to examine the thermal characteristics of annealed CdO NPs.

In this paper, we present an improved multi-order parameter model for multi-component model of polycrystalline solidification. We introduce an interpolation function in the phase field dynamical equation to obtain controllable grain boundary energy at large undercooling. The same interpolation function is also employed in the kinetics coefficient to allow for better control of grain boundary migration. Temperature dependent phase field parameters and noise terms are consistently coupled into the dynamics of a binary system in a manner that allows for quantitative simulations in the thin interface limit. The model is applied to multi-phase solidification in Al-Cu alloy, where a parabolic fitting method is employed to model the free energy of Al-Cu phases and two-phase nucleation is demonstrated in directional solidification.

A physicochemical mechanism acting between the reactive plasma and the material surface controls the erosion of polycrystalline ceramics in fluorine containing etching plasmas. In this study, a Y2O3/YOF composite was exposed to a fluorine etching plasma. Relocalization enables the direct correlation of crystalline orientation with material response. Our study reveals an orientation dependent surface fluorination of Y2O3, which controls the etching resistance and morphology formation. Orientations near the low index planes (001), (010) and (100) exhibit the lowest stability due to a homogeneous surface reaction. The presented results help to extend the mechanistic understanding of the plasma-material interaction of Y2O3.

Herein, we report the synthesis of Ba-doped Co–Zn ferrite nanoparticles using the sol-gel auto combustion technique. The single-phase formation of the samples with Fd3m space group was confirmed by X-ray diffraction (XRD). The crystallite size, lattice parameter, and x-ray density, decreases with increasing dopant concentration. Scanning Electron Microscopy (SEM) shows the formation of irregular grains for all the samples. The oxidation states of Ba, Co, Zn, Fe, and O were estimated using X-ray photoelectron spectroscopy (XPS), which confirmed the chemical purity of the samples. Cationic distributions at tetrahedral and octahedral sites were proposed based on XPS studies. Fourier transformation infrared (FTIR) spectra shows the presence of two strong peaks around 430 cm−1 and 580 cm−1 that confirmed the formation of ferrite structure. The M − H curves were acquired to analyze the magnetic ordering in the specimens where the highest saturation magnetization (Ms) value of 43.479 emu/g was witnessed for x = 0.05. The microwave properties shows a decrease in magnetic loss and dielectric loss from 0.486 to 0.319 and 0.178 to 0.168 when Ba concentration was increased. EMI shielding analysis shows an increase in effective shielding ( S E T ) from 11.43 dB to 12.82 dB.

In this paper, we present synthesis, structural optical, and magnetic analysis, of the Yttrium Aluminium Borate (YAB) nanomaterials. YAB materials were synthesized by the Sol-gel method. The structural analysis, carried out by using X-ray diffraction (XRD) and shows that the crystal structure of YAB is of nanometric size ranging between 16 nm and 26 nm at annealing temperature above 800 °C. Photoluminescence property shows that YAB gives intense blue light emission in the visible region. Further energy band gap were investigated using Tauc plot which was found to be decreased from 1.782 eV to 1.748 eV respectively with increasing annealing temperature from 800 °C to 900 °C, keeping annealing time constant for 2 hrs. Energy band gap is a function of crystallite size and it is very close to energy band gap of GaAs nanomaterial used in the Light Emitting Diode (LED) application, having band energy gap 1.441 eV. Vibrating Sample Magnetometer (VSM) measurement shows the diamagnetic nature of the prepared sample. Coercivity increases while Magnetization and retentivity decrease for YAB nanomaterial for the temperature above 800 °C Celsius. The prepared YAB nanomaterials may be a potential candidate for LED and other related applications.

ZnO nanorods combined with different concentrations of reduced graphene oxide were synthesized using the hydrothermal method. Structural properties of these nanocomposites were studied by X-ray diffraction analysis. Morphological studies on the shape and size of nanorods were carried out by scanning electron microscopy. X-ray diffraction results revealed highly-crystalline nanorods with a hexagonal wurtzite structure. The morphology of as prepared samples is characterized presence of one-dimensional rod-like nanostructures. Crystallite size, stress and lattice strain were determined by Scherrer equation and Williamson–Hall method. The average particle size of samples calculated from microstructural and morphological analyses are highly interrelated. Microraman spectra exhibited both characteristic bands of ZnO and reduced graphene oxide in the low frequency (300–500 cm−1) and high frequency (1300–1600 cm−1) ranges, respectively, furthermore confirming the efficiency of the hydrothermal synthesis of ZnO/reduced graphene oxide nanocomposites. The band gap of the nanocomposite is lower (2.96 eV).compared to that of ZnO (3.10 eV), as determined from the analysis of UV absorbance spectra.

The polycrystalline ceramic (Sm0.75Bi0.25FeO3)0.5 (BaTiO3)0.5 (SF-BT) is synthesized by high temperature solid state reaction method at an optimized temperature 1250 °C. The sample is investigated for its multifunctionality by analyzing its structural and electrical properties. The room temperature XRD pattern confirms the single phase compound in the tetragonal symmetry. The symmetry of the compound have been verified by commercially available software POWD. Complex impedance studies confirm the grain contribution to the electrical properties in the material. It reveals semiconducting behaviour of the material and transport phenomena is due to short range mobility of charge carriers. The relaxation mechanism in the sample is due to the short-range mobility of charge carriers.

This paper describes the synthesis of La-doped SnO2 nanoparticles for resistive-type relative humidity sensors. The structural characterization of synthesized SnO2 nanoparticles was analyzed using X-ray Diffraction (XRD), that exhibited the formation of the tetragonal rutile structure of pristine and La-doped SnO2 nanoparticles with a decrease in crystallite size in presence of different doping levels. Further increase in doping concentration (at 5 M%) revealed the formation of the La2O3 phase due to the excess amount of lanthanum. The UV–Vis spectroscopy indicates the doping of lanthanum (La) improves the optical property of pristine SnO2. The morphological characterization demonstrates the spherical-shaped nanoparticles. The synthesized nanoparticles were tested for relative humidity (RH) sensing application over the range of 10–100% RH at room temperature. The doping of 3 M% La-doped SnO2 shows good sensitivity (95%) than pristine SnO2 nanoparticles. The fabricated 3 M% La-doped SnO2 sensor not only showed better sensitivity and linear range over 10–100%RH, but also exhibited rapid response (8sec) and recovery (13sec) time than the pristine and the others La-doped levels of SnO2 nanoparticles. This better humidity sensing response of 3 M% La-doped nanoparticles was achieved due to high carrier density and small crystallite size. This indicates 3 M% La-doped nanoparticles is a promising material for room temperature humidity sensing.

Mn-Ni co-doped ZnO thin films (Zn0.98Mn0.01Ni0.01O) were synthesized on glass via sol–gel spin coating approach. The effect of substrate rotation speed was investigated on structural, optical, topographical, and vibrational characteristics of thin films. XRD, SEM, Raman spectroscopy, ultraviolet–visible spectroscopy, and photoluminescence spectroscopy were utilized for the characterization of the films. The size of crystallite has decreased by raising the rotation speed of substrate. The surface of all thin films shows uniformly distributed grains of size ranging 22.41 nm to 19.74 nm. Raman spectra show characteristic hexagonal wurtzite structure peak of ZnO at 429 cm−1 corresponding to E2(High) optical phonon mode. The energy gap changed from 3.275 eV to 3.256 eV with rising substrate rotation speed. The photoluminescence spectra showed UV, violet, green, yellow, and red emission for all thin films. The ultraviolet peak was red-shifted on increasing substrate rotation speed. So, optical properties can be tailored by changing the rotation speed of substrate and utilized in optoelectronic devices.

In this study a series of CoFe2O4 NPs have been synthesized successfully in presence of various surfactant viz. cationic, anionic and non-ionic.CoFe2O4 NPs was prepared in aqueous medium by Co-precipitation technique using Cobalt nitrate (Co2+) and Ferric nitrate (Fe3+) as the precursor and CTAB, SDS and Tween-20 were used as the templating agent. The structural as well as the magnetic properties were investigated by XRD, FT-IR, FESEM and VSM analysis. The XRD study of the NPs confirms that the phases corresponding to the cubic spinel structure of the CoFe2O4 NPs were retained even after the addition of templating agent. The crystallite size has been restricted to within 6–9 nm respectively.