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Bismuth ferrite (BiFeO 3) nanorods have been prepared from 2-methoyethanol (2-MOE)-assisted sol–gel technique. Structure, dielectric, and magnetic properties of BiFeO3 nanorods are briefly discussed in this paper. Fourier-transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) results suggest that the BiFeO3 peaks calcined at 500∘C exhibit a distorted rhombohedral perovskite structure with the absence of other secondary phases like Bi2Fe4O9. Meanwhile, the BiFeO3 showed excellent photoluminescence (PL) behavior due to the transmission of electrons from conduction band to the valence band. Ferroelectric hysteresis loop of BiFeO3 shows an increase of coercivity from 5.5–6 μ C/cm2 in a frequency range of 6–12 kHz. The magnetization measurement resulted in a well-saturated ferromagnetic behavior, and in addition, the temperature-dependent magnetization was discussed for BiFeO3 nanorod using superconducting quantum interference device (SQUID) method. The zero-field-cooled (ZFC) and field-cooled (FC) curves reveal spin-glass effect owing to size effects, spin exchange, and anisotropy of material assembly. [ABSTRACT FROM AUTHOR]

This work proposes the synthesis of nanocrystalline calcium oxide (CaO) pure and doped with different concentrations of lithium (Li 2 + ) ions by sol–gel process. Calcium nitrate (Ca(NO 3 ) 2 ⋅ 4H2O; 99.99%) and lithium nitrate (LiNO3; 99.99%) were used as precursors. The synthesized powders were characterized by several techniques such as: UV-Vis transmission spectroscopy, Fourier Transform Infra-red spectroscopy (FT-IR) and X-ray diffraction (XRD). The main objective of this paper is to study the influence of lithium (Li 2 + ratio) on the structural and optical properties of synthesized powders. The band gap values decreased with the increasing of Li 2 + ions in CaO lattice; the slight change in the band gap was directly related to the energy transfer between the CaO excited states and the 2s levels of Li 2 + ions. The influence of Li 2 + doping on the physical properties of CaO nanocrystalline will be studied for the first time in this work; no literature has previously published this kind of impurities. [ABSTRACT FROM AUTHOR]

This paper contains the results of the structural and spectroscopic characterizations of undoped and Cadmium-doped cobalt oxide thin films with different Co/Cd molar ratios (3%, 5%, 7% and 9%). The nanosized undoped and cadmium-doped Co3O4 thin layers were prepared using sol–gel process and deposited on glass substrates by dip coating. The changes caused by the incorporation of cadmium at different levels of doping have been highlighted by the techniques UV–Visible (UV–Vis) spectroscopy, Infrared (IR) spectroscopy, X-ray diffraction (XRD) measurements, SEM coupled EDX and impedance spectroscopy. From the UV–Vis spectroscopy analysis, it was found that all the films are two direct bandgap energies. The optical transmittance and the bandgap energy decrease with increase in Cd concentration. The XRD spectra confirm the films were polycrystalline with a cubic spinel structure. The results of the impedance spectroscopy show that the equivalent circuit of the synthesized samples is an RC parallel circuit. [ABSTRACT FROM AUTHOR]

In this paper, ferrogels comprising nanocrystalline Fe3O4 and γ-FeOOH dispersed in polyvinyl alcohol gel matrix were synthesized via a novel route, without using any cross-linking agent. A moderately high-pressure environment instead was used for the synthesis. The ferrogels were found to be stable over a long period of time and were characterized by transmission electron microscopy (TEM), Mössbauer spectroscopy and DC magnetization studies. TEM studies showed that the particles are mostly spherical with an average size of 10 nm. Mössbauer spectra of the as prepared gels at different temperatures showed the presence of superparamagnetic particles in them. The gels were found to be magnetically ordered at 20 K giving characteristic six-finger Mössbauer patterns. Bulk magnetic properties of the gels were studied by DC magnetization measurements. [ABSTRACT FROM AUTHOR]

In this paper, anisotropic SiO2 with different morphologies were synthesized through an emulsion-based one-pot method by adding various silane coupling agents. Silane coupling agents affected the growth of silica nanostructures at the oil/water interfaces. Robust super-repellent film that showed great durability under different harsh conditions were obtained by bonding the self-assembled anisotropic silica nanostructures (ASN) film to substrate by the commercial acrylic adhesive. The film switched from superhydrophobic (157.1 to superhydrophilic (0 after being heat-treated at 500C. Further, silane treatment with addition of acid reduced the time of modification. Meanwhile, silane grafting density was improved and superhydrophobicity of calcinated ASN films was regenerated. Anisotropic silica nanostructures with different morphologies were synthesized by the co-growth of silane coupling agent. Modified silica particles with high aspect ratio were assembled to prepare super-repellent film. Robust super-repellent film that showed great durability under different harsh conditions was obtained by bonding the self-assembled anisotropic silica nanostructure (ASN) films to substrate by commercial adhesive. [ABSTRACT FROM AUTHOR]

In the present paper, the influences of different double layer on wear and scratch performances of commercially pure Titanium (CP-Ti) were investigated. TiO2/SiO2 and SiO2/TiO2 double layer coatings were deposited on CP-Ti by sol-gel dip coating process and calcined at 750C. The phase structure, cross-sectional morphology, composition, wear track morphologies, adhesion properties, hardness and roughness of uncoated and coated samples were characterized with X-ray diffraction, scanning electron microscopy (SEM), nano-indentation technique, scratch tester and 3D profilometer. Also, the tribological performances of all samples were investigated by a pin-on-disc tribo-tester against Al2O3 ball. Results showed that hardness, elastic modulus and adhesion resistance of double layer coated samples were higher than untreated CP-Ti. It was found that these properties of TiO2/SiO2 double layer coatings have higher than SiO2/TiO2 double layer coating. Additionally, the lowest friction coefficient and wear rates were obtained from TiO2/SiO2 double layer coatings. Therefore, it was seen that phase structure, hardness and film adhesion are important factors on the tribological properties of double layer coatings. [ABSTRACT FROM AUTHOR]

In this paper, we prepared the rattle type nanoparticles ZnO@void@SiO2 by two successive coating processes, followed by heat treatment. The carbon layer was formed over ZnO surface with the aid of the hydrothermal treatment of glucose. Then the resulting composite was used to fabricate a silica shell on the surface by sol-gel method. Finally, ZnO particles were released but still trapped inside the silica hollow after calcination, that is, ZnO@void@SiO2. The composites were characterized by scanning and transmission electron microscope, N2 adsorption experiment, X-ray diffraction, Fourier transform infrared spectroscopy and UV-Vis absorption spectra. The rattle type structure was conformed and the sphere-like structure with the average size of 70 nm and hexagonal wurtzite crystal structure were also observed. The measurement results of optical properties showed even though ZnO@C@SiO2 presented no photocatalysis, ZnO@void@SiO2 showed high activity even the ZnO core was encapsulated with the SiO2 hollow. Rattle-type-structured ZnO@void@SiO2 nanoparticles were prepared by a facile chemical route. The carbonized glucose template and a silica layer were successively coated on the surface of ZnO. The void came out after the removal of carbon layer by calcination. ZnO@void@SiO2 nanoparticles were applied to photo-decomposing MB dye in water solution and showed excellent photocatalytic activity. [ABSTRACT FROM AUTHOR]

The multifunctional textiles are interesting areas to be researched on. In this paper, the effect of the fiber nanocoating on the wrinkle recovery, air permeability and anti-Ultraviolet (UV) property of different woven fabrics using sol-gel method has been studied. The sol-gel method has various advantages over other methods. Along with these properties, no change in visual appearance has also been discussed in this paper. The dispersion of nanoparticles of titanium was obtained into silica sol. The characterization of nanocoating was done using Field emission scanning electron micrograph (FESEM) and Fourier transform infrared spectroscopy (FTIR) studies. The fabric wrinkle recovery properties, air permeability and anti-UV performance were analyzed using three different immersion timings into the nanosol. The results revealed that both wrinkle recovery properties and anti-UV performance have increased with respect to immersing time of the nanocoating although a slight decrease in air permeability and whiteness index of the fabric was also observed. [ABSTRACT FROM AUTHOR]

In this paper, strontium hexaferrite nanoparticles were synthesized by the sol-gel auto-combustion method. Effect of annealing temperature on crystal structure, morphology and magnetic properties of nanoparticles was investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). Also, the thermal decomposition of as-synthesized powdered samples has been studied by thermogravimetric analysis (TGA). The XRD patterns confirmed the formation of single phase M-type hexagonal crystal structure for powders annealed above 950C, whereas the presence of hematite (-Fe2O3) as secondary phase was also observed for sample annealed at 900C. Furthermore, the crystallinity along with the crystallite size were augmented with annealing temperature. Comparison of the FT-IR spectra of the samples before and after annealing treatment showed the existence of metal-oxygen stretching modes after annealing. The thermogravimetric analysis confirmed the thermal decomposition of as-burnt powders happened in three-stage degradation process. The TEM images showed the nanoparticles like hexagonal-shaped platelets as the size of nanoparticles increases by increasing the annealing temperature. With increasing annealing temperature, the magnetic saturation and the coercivity were increased to the maximum value of 74.26 emu/g and 5.67 kOe for sample annealed at 1000C and then decreased. [ABSTRACT FROM AUTHOR]

In this paper, nickel nitrate, copper nitrate, cobalt nitrate, ferric nitrate were used as raw materials, citric acid was used as a complexing agent, and chromium nitrate was used as a modifier to synthesize Ni 0. 2 Cu 0. 2 Co 0. 6 Cr x Fe 2 − x O 4 by sol–gel method. The sample was characterized. X-ray diffraction (XRD) data on the sample showed that the particle size of the sample was 52.14–54.88 nm. The lattice constant varied from 8.3569 Å to 8.3758 Å. The data of Fourier infrared showed that the sample did not change with the structure of the doped sample of Cr ion and remained as the spinel type. It can be seen by SEM that the sample is irregularly spherical. Due to the doping of chromium ions, it appears agglomerated. Analysis of the elements of the sample by EDAX revealed that the sample contained Ni, Cu, Co, Fe, O and a peak corresponding to the Cr element was found in the sample having crion content of 0.025, 0.050, 0.075 and 0.100. The magnetic properties of the samples were characterized using VSM. The data are processed to obtain magnetic parameters such as saturation magnetization and coercivity. [ABSTRACT FROM AUTHOR]

Superhydrophobic cotton fabrics are prepared using silica and titania hybrid sol and hexadecyltrimethoxysilane. The surface morphology of cotton fabrics is characterized by scanning electron microscopy. The water contact angles on the as-prepared superhydrophobic cotton fabrics is 159° when the volume ratio between sodium silicate solution and titania sol is 1:3, and the corresponding cotton fabrics can keep the contact angle of 152° after 10 cycles of home machine washing. Meanwhile the treated cotton fabrics can also keep superhydrophobicity after 60 min of UV light irradiation. These results indicate that the cotton fabrics treated with silica and titania hybrid sol and modified with hexadecyltrimethoxysilane show excellent superhydrophobic stability under washing and UV light irradiation. This paper provides the new notion and beneficial reference for the application of the superhydrophobic cotton fabrics in the future. [ABSTRACT FROM AUTHOR]

In this paper, a series of rare-earth-doped barium hexaferrite powders (Ba0.95Re0.05-Fe12O19 and Ba0.95Re0.05M0.05Fe11.95O19: Re = La, Pr, Sm, Nd, Gd, Dy, Yb; M = Zn2+, Mn2+, Mn2+0.5 Zn2+0.5) were synthesized by the sol–gel self-combustion technology. The phase composition and the magnetic properties of the as-prepared barium hexaferrites were characterized and discussed with X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The results showed that the barium hexaferrites exhibited the magnetoplumbite phase structure with the average diameter of 45 nm. Magnetic properties study revealed that the variation of the saturation magnetization (Ms) was similar with the change of the rare-earth ions radius, but the change of Ms was low. This indicated that the magnetic moments of rare-earth ions could not affect Ms. The magnetocrystalline anisotropy field mainly influenced the anisotropism of hexaferrites, and the coercivity (Hc) of the rare-earth ions doped barium hexaferrites basically decreased with the increasing orbital quantum numbers (except Sm3+ and Gd3+). Further study showed the co-addition of Zn2+ and Mn2+ did not change the trend of Ms and Hc. Thus, it is concluded that the rare-earth ions played an important role for the anisotropy field of barium hexaferrites. [ABSTRACT FROM AUTHOR]

In this paper, low temperature, economical sol–gel combustion method was adopted to synthesize wollastonite ceramic. Calcium nitrate tetrahydrate and tetraethyl orthosilicate were taken as source for Ca and Si, while citric acid and nitric acid were used as chelating/combustion agents. The yielded powder calcined at 600 ∘ C for 4 h was characterized by FTIR, XRD and SEM techniques. Results showed that the citrate combustion method was the most efficient method to prepare wollastonite at low temperature. Moreover, in vitro bioactivity test performed in simulated body fluid (SBF) showed good bioactivity of synthesized wollastonite ceramics. [ABSTRACT FROM AUTHOR]

Li-Co nanoferrites (LiCoFeO4) with x = 0.00, 0.03, 0.06, 0.09, and 0.12, were synthesized by chemical sol-gel method. Two different sintering techniques viz. conventional technique (CT) and microwave technique (MT) were employed to heat treat the synthesized samples with an aim to study the effect of sintering technique on the properties of the nanoferrites. Structural and microstructural properties of the samples were investigated using XRD and scanning electron microscopy (SEM) technique, respectively. The variation of room temperature dielectric constant and dielectric loss were measured as a function of frequency in the range 100 Hz-1 MHz and the normal dispersive behavior was observed. Magnetic properties were investigated using Vibrating Sample Magnetometer (VSM), while Soohoo's method was used to measure Curie temperature. The results obtained have been discussed in the paper. [ABSTRACT FROM AUTHOR]

In this paper, potassium sodium niobate (KNN) nanopowders were successfully obtained by sol-gel combustion method. According to thermogravimetric analysis (TGA) results, the produced xerogel was calcined at 500C, 600C, and 700C to obtain KNN powders. The structural and optical properties of the prepared powders were studied using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, transmission electron microscopy (TEM), and UV-vis spectroscopy. The XRD patterns indicated formation of orthorhombic KNN samples. The Scherrer formula and size-strain plot (SSP) method were employed to calculate crystallite size and lattice strain of the KNN powders. The TEM image revealed that the average particle size of the prepared samples is about 30 nm and they have cubic shape. The optical band gap energy of the samples was calculated using UV-vis absorbance spectra of the samples along with Tauc relation. [ABSTRACT FROM AUTHOR]

Hexagonal yttrium manganites, YMnO3, are interesting materials for their multiferroic behavior. Substituting suitable cations either at the Y-site or Mn-site offers great opportunities to produce a variety of manganites and tune their properties. Nanocrystalline yttrium iron manganites with the compositional formula YFeMnO3, = 0.0, 0.10, 0.15, 0.20 and 0.25, were synthesized by sol-gel autocombustion method. The prepared samples were heated at 1100C for 1 h. Another set of samples with compositional formula YFeMnO3, = 0.0, 0.10, 0.15, 0.20 and 0.25, were also synthesized by the same method and heated at 1100C for 1 h. Various characterizations were done on these manganite systems synthesized by substituting iron at different sites. X-ray diffraction (XRD) technique studied the structure of the samples and analysis of XRD patterns confirmed the formation of hexagonal phase in the samples. Structural parameters such as lattice constants, crystallite size, theoretical density, etc. were determined using the XRD data. The unit cell dimensions have been found to agree with the standard data and the Debye-Scherrer crystallite size obtained from XRD data ranges from 42 nm to 77 nm. The room temperature frequency variations of electrical properties such as dielectric constant, dielectric loss and AC conductivity were measured in the range of 100 Hz-2 MHz and the variations showed a dispersive behavior for all the samples. The various measurements and the results obtained were studied and discussed in the paper. [ABSTRACT FROM AUTHOR]

La 0. 8 Sr 0. 2 Fe 1 − x Mn x O 3 (x = 0. 0 , 0.1, 0.3 and 0.5) series samples were prepared by sol–gel method and characterized by powder X-ray diffractometer (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Mössbauer spectroscopy. The effects of Mn doping on the microstructure, morphology and electronic structure of La–Sr ferrite were investigated. The XRD results show that all samples are single phase and have orthorhombic structures with Pbnm space group. The surface morphology and composition of chemical elements of the samples were analyzed by SEM and EDS, and the experimental values were consistent with the expected values. The sample was tested by 5 7 Fe Mössbauer spectroscopy at room temperature, and the results showed that the percentage of doublet increased gradually with the increase of Mn ion doping ratio, and at x = 0. 5 , all the sextet disappeared and only the doublet existed. According to the analysis, it can be seen that the prepared series of samples underwent a transition from antiferromagnetic to paramagnetic. La0.8Sr0.2Fe1–xMnxO3 (x = 0.0, 0.1, 0.3 and 0.5) series samples were prepared by sol–gel method, and the effect of Mn3+ doping on the structural morphology and electronic structure of La–Sr ferrite was studied. Mössbauer spectrum test results show that with the increase in the doping ratio of Mn3+, the percentage of double peaks gradually increases. When x = 0.5, all the sextet disappeared and only the doublet existed. The analysis shows that Mn3+ doping led to the transition of La–Sr ferrite from antiferromagnetic to paramagnetic. [ABSTRACT FROM AUTHOR]

We report a straightforward tool to investigate insulator-metal transition in RCo O 3 (R = Pr, and Nd) nanoparticles prepared by a sol–gel technique. Thermogravimetric analysis (TGA) of the as-prepared gel is performed to get the lowest possible calcination temperature of RCo O 3 nanoparticles. The Rietveld refinement of the powder X-ray diffraction (XRD) patterns for both samples shows that the samples crystallize in the orthorhombic (Pnma) phase at room temperature. The particle size of the sample is determined by scanning electron microscopy. Ac conductivity of the materials is analyzed in the temperature range from 303 K to 673 K and in the frequency range from 42 Hz to 1.1 MHz. The insulator-to-metal transition of PrCo O 3 and NdCo O 3 is analyzed by ac impedance spectroscopy. DC resistivity measurement is also done to cross check the insulator-metal transition in RCo O 3 system. [ABSTRACT FROM AUTHOR]

Superhydrophobic cotton fabrics are prepared using silica and titania hybrid sol and hexadecyltrimethoxysilane. The surface morphology of cotton fabrics is characterized by scanning electron microscopy. The water contact angles on the as-prepared superhydrophobic cotton fabrics is 159° when the volume ratio between sodium silicate solution and titania sol is 1:3, and the corresponding cotton fabrics can keep the contact angle of 152° after 10 cycles of home machine washing. Meanwhile the treated cotton fabrics can also keep superhydrophobicity after 60 min of UV light irradiation. These results indicate that the cotton fabrics treated with silica and titania hybrid sol and modified with hexadecyltrimethoxysilane show excellent superhydrophobic stability under washing and UV light irradiation. This paper provides the new notion and beneficial reference for the application of the superhydrophobic cotton fabrics in the future. [ABSTRACT FROM AUTHOR]

Multiferroic nanocrystalline Bi 1 − x Sr x FeO3 (x = 0 , 0.05, 0.1) samples were synthesized using the sol–gel method and characterized by powder X-ray diffraction, Mössbauer spectroscopy and SQUID system. The small-angle X-ray diffraction analysis showed that the sample underwent phase transition from rhombohedral to pseudo-cubic structure with the enhancement of Sr content. In addition, impurity peaks gradually diminished, indicating that content of impurities of samples reduced. Furthermore, it can be determined that there is only Fe 3 + in all the samples and impurity phase that existed in the samples was Bi 2 5 FeO 4 0 by fitting Mössbauer spectra. It is further confirmed that Bi 1 − x Sr x FeO3 samples were generated by oxygen vacancy equilibrium valence state when Sr 2 + ions replaced Bi 3 + ions. The change of quadrupole splitting indicated that a low concentration of Sr 2 + ions diffused homogeneously in the sample. Magnetization measurement showed that the magnetization of the sample increased gradually with the substitution of Bi 3 + by nonequivalent Sr 2 + ions, which can be ascribed to the decrease of grain size and the increase of oxygen vacancy and specific surface in the samples. [ABSTRACT FROM AUTHOR]

This work reports about annealing time effect on structural and optical properties of pure and Dy 3 + -doped CeO2 nanocrystallites. The nanopowders with an average grain size 13–15 nm are successfully synthesized via a conducive and neoteric Pechini-type sol–gel technique. Surface morphology, composition, band gap and photoluminescence properties of the prepared samples are examined by multifarious characterization techniques like Rietveld refinement, FESEM, HRTEM, FTIR, UV–Vis spectroscopy and PL. The effects of annealing time on structural parameters including lattice parameter, bond distance, bond angle, strain, crystallite size and texture coefficient are computed for all prepared samples which are further ensured by Rietveld refinement. In absorption spectra, blue shift in the band gap of as-prepared samples has been observed due to well-known quantum size effect, however, red shift is noticed in further annealed samples. PL emission peaks are observed in violet, blue and green regions that are devoted to various defect levels and color centers such as F, F + , F + + , etc. It is suggested that defects like oxygen vacancies play vital role in tailoring the band gap of prepared samples and therefore enhance its utility in photonics and oxygen storage appliances. [ABSTRACT FROM AUTHOR]

In this study, a new antimicrobial agent was developed through a synthesis of Fe3O4/SiO2/Ag double nanocomposites using the sol–gel method. The prepared samples were characterized using XRD, SEM, FTIR, UV-Vis, VSM, and antibacterial test. The data analysis results for the Fe3O4/ SiO2/Ag composites showed that Fe3O4, SiO2, and Ag constructed respective spinel cubic, orthorhombic, and amorphous structures in nanometric size. The saturation magnetization of Fe3O4/SiO2/Ag nanocomposites decreased due to the increase in the Ag content. Interestingly, the Fe3O4/SiO2/Ag nanocomposites presented excellent microbial activity. Ag deposition on the Fe3O4/SiO2 surface enhanced the antimicrobial activity of nanocomposites because Ag oxidized to Agþ ion to produce a toxic e®ect in the cells of microorganisms. Furthermore, the Agþ ion created the –S–Ag bond chain and deactivated the microorganism cells. Furthermore, surface plasmon resonance of Ag had an impact on the formation of photo-induced electrons, which produced superoxide radical anions, O2 − generating a collapsing force that causes the death of microorganisms. [ABSTRACT FROM AUTHOR]

Microencapsulated phase change materials (MicroPCM) were prepared via sol–gel method using paraffin as heat storage core and silica as inorganic shell. The morphology feature, chemical structure, thermal properties and thermal stability of MicroPCM were characterized by the field emission scanning electron microscope (FE-SEM), Fourier transform infrared spectroscopy (FTIR), the differential scanning calorimeter (DSC), simultaneous thermal analyzer (STA) and the thermal conductivity meter. The results indicated that MicroPCM were spherical in shape with the shell thickness in the range from 236 nm to 303 nm. The stirring speed and TEOS dosage were key factor on the latent heat and supercool effect of MicroPCM. The maximum latent heat of MicroPCM was 240.2 J ⋅ g − 1 with the heat loss of only 0.2 J ⋅ g − 1 in phase transformation when it was prepared at the stirring speed of 400 r/min and TEOS dosage of 20 ml. MicroPCM was a promising material for thermal energy storage (TES). A series of novel MicroPCM with good thermal properties was prepared by sol–gel method using paraffin as the heat storage core material and silica as the inorganic shell material by controlling the stirring speed and adjusting TEOS dosage. MicroPCM was spherical in shape with the shell thickness in the range between 230 nm and 300 nm. The result indicated that MicroPCM had a high latent heat with a range from 229 to 240.2 J·g–1. [ABSTRACT FROM AUTHOR]

High silica zeolite ZSM-5/glass film was successfully synthesized by an in-situ sol–gel dip-coating process combined with the steam-assisted conversion (SAC) technique with low concentration of the synthesis solution. The resulting zeolite films grown on the glass slide show amphiphilic properties. The growing process and the effect of the concentration of SiO2 in the silica source were examined. The mechanism of the formation of the nanoflake crystals and their wetting behavior was investigated. By simply adding fluorescein in the synthesis solution during the preparation, ZSM-5 films showing luminescence property can be obtained. Furthermore, these ZSM-5 zeolite films are easily modified to exhibit hydrophobic property. Super-amphiphilic high silica zeolite ZSM-5 films were prepared on glass slides by an in-situ sol–gel dip-coating process, combined with the SAC technique with low concentration of the synthesis solution. The obtained crystals on the film display nanoflake morphology. The unique shape of nanoflake crystals greatly improved the wettability, which may enable the film with potential application in separation and antifouling areas. [ABSTRACT FROM AUTHOR]

Water electrolysis is of vital importance to store renewable energy and the development of efficient, inexpensive and stable electrocatalysts for oxygen evolution reaction (OER) is essential, which requires much more understanding of the structural and the element classification. Here, a series of LaNi 0. 8 Fex Cu 0. 2 − x O 3 − δ perovskites have been assessed as potential noble-metal-free OER electrocatalysts prepared by sol–gel method. Moreover, the functional role of Cu and Fe amount on the B-site of perovskites for OER electrocatalytic performance was evaluated. LaNi 0. 8 Fe 0. 2 O 3 − δ materials exhibited the highest intrinsic activities in 0.1 M KOH for OER with an onset potential of 1.56 V, a Tafel slope of 76 mV dec − 1 , slightly lower than that of benchmark perovskite-type electrocatalyst Ba 0. 5 Sr 0. 5 C O 0. 8 Fe 0. 2 O3 (BSCF). The above results demonstrate that Cu element in the B-site of perovskites had little effect on the OER performance, and LaNi 0. 8 Fe 0. 2 O 3 − δ is a potential alternative electrocatalyst for OER application. LaNi0.8FexCu0.2–xO3– δ perovskites have been assessed as potential noble-metal-free OER electrocatalysts prepared by sol–gel method. All results demonstrate that Cu element in the B-site of perovskites had little effect on the OER performance, and LaNi0.8Fe0.2O3– δ is a potential alternative electrocatalyst for OER application. [ABSTRACT FROM AUTHOR]

Sn-doped TiO2 nanomaterials were synthesized by sol–gel method. It was shown the phase compositions and phase transitions change with the introduction of different tin amounts (0.5–20 mol.%). X-ray powder diffraction was used to study the effect of different tin amounts on the anatase–rutile phase transition. It was found that the introduction of ions increases the thermal stability of anatase modifications. The material's photocatalytic activity was studied in reaction with a model pollutant (methylene blue) photodegradation under UV and visible light activation. The best photocatalytic properties were shown for material, which contains 5 mol.% of Sn. [ABSTRACT FROM AUTHOR]

The mesoporous CdS/TiO2 composites were synthesized by a sol–gel method combined with solvothermal method. The material showed the gel block-like structures which were composed of heterogeneous spherical gel particles, the average size of the particles was about 14 nm, with specific surface area as 300.254 m2 g − 1 . The mesoporous CdS/TiO2 composites exhibited a wide absorption band to simulated sunlight whose adsorb wavelength reached to 550 nm, its absorption intensity and catalytic performance of photocatalytic water-producing hydrogenation were also increased with the increase of CdS contents. When the molar ratio of TiO2:CdS was 1:1, the photocatalytic activity reached the highest, and the average hydrogen production rate reached 2167.32 μ mol g − 1 h − 1 . Mesoporous CdS/TiO2 composites were synthesized by a sol–gel method combined with solvothermal method, and the photocatalytic activity was evaluated under visible light irradiation. The prepared material had larger specific surface and higher photogenerated electron hole separation rate. The average hydrogen production rate of the prepared material reached 2167.32 μmol⋅g–1⋅h–1. [ABSTRACT FROM AUTHOR]

This work shows an investigation of tin-doped Mn2O3 thin layers synthesized via sol–gel process and deposited on glass substrates using dip-coating technique. The Sn concentration was changed from 0% to 9%. The obtained samples were characterized by X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR), Ultraviolet–Visible spectroscopy (UV–Vis) and impedance spectroscopy (IS). XRD showed that Mn2O3 was crystallized in the cubic form with directionally preferential orientation structure (222). The formation of Mn2O3 was also confirmed by FTIR spectroscopy. The optical transmittance of the samples is greater than 70% and increases following doping, while the band gap energy decreases with an increase in Sn doping concentration. Complex IS indicates that the resulting circuit is a parallel RpCp where Cp is the capacitance of the layer and Rp its resistance. [ABSTRACT FROM AUTHOR]

Detailed structural and dielectric properties of Lanthanum-doped barium titanate Ba 1 − x Lax Ti (1 − x ∕ 4) O3 ceramic powders BLTx (where x = 0. 0 0 ; 0.10; 0.20; 0.30 and 0.40)/BT, BLT10, BLT20, BLT30 and BLT40, synthesized by the sol gel process, calcined at 900∘C for 3 h and sintered at 1250∘C for 6 h, have been investigated. The phase formation and crystal structure of the samples were checked by X-ray diffraction (XRD) and Raman spectroscopy. The samples crystallize in the pure perovskite structure that transforms from tetragonal to pseudocubic under doping with La; results that have been confirmed by Rietveld Refinement technique. The estimated average crystallite size of the samples was about 23 nm. Dielectric parameters (dielectric permittivity and losses) were determined in the temperature range room temperature (RT) — 280∘C and in the frequency range 500 Hz–2 MHz. La doping gives rise to a strong decrease of the ferro-to-paraelectric transition temperature, and the frequency dependence of the permittivity shows that the samples with x = 0. 0 0 and x = 0. 1 0 reach their resonance frequency. The frequency dependence of impedance and electric modulus properties were studied over a wide frequency range from 1 kHz to 2 MHz at various temperatures to confirm the contributions from grains and grain-boundaries. The complex impedance analysis data have been presented in the Nyquist plot which is used to identify the corresponding equivalent circuit and fundamental circuit parameters; it was found that the grain boundaries resistance is dominant at room temperature. The frequency dependence of the parameters permittivity, losses and AC conductivity reveals that the relaxation process is of the Maxwell–Wagner type of interfacial polarization. [ABSTRACT FROM AUTHOR]

With the use of sol–gel method BaTiO3–SiO2 multilayer structures were fabricated on glass or fused silica substrates employing dipping or spinning procedure. The photonic stop band was observed in the reflection and transmission spectra of the multilayer structure annealed at 4 5 0 ∘ C. It is redshifted with an increase of the thicknesses of BaTiO3 and SiO2 layers. For structures comprising Eu-doped BaTiO3 layers of different thicknesses photoluminescence with the main band at 614 nm was detected. It is characterized with the double-exponential decay with the lifetimes of about 0.5 ms and 1.1 ms which do not depend significantly on the photonic stop band position. [ABSTRACT FROM AUTHOR]

Zinc Oxide thin films were deposited on glass substrates by sol–gel spin coating method. Zinc acetate dihydrate, 2-methoxyethanol and monoethanolamine were used as precursor, solvent and stabilizer, respectively. Zinc acetate dihydrate was used with different molar concentrations of 0.15, 0.25 and 0.5 M. Optical properties of ZnO thin films such as dielectric constants, absorption coefficient, Urbach energy and optical band gap energy were calculated by spectroscopic ellipsometry (SE) method. The effect of zinc acetate concentration on optical properties of ZnO thin films is investigated. ZnO thin film with Zn concentration of 0.25 M had the highest optical band gap. Wemple DiDomenico oscillator model was used for calculation of the energy of effective dispersion oscillator, the dispersion energy, the high frequency dielectric constant, the long wavelength refractive index and the free carrier concentration. [ABSTRACT FROM AUTHOR]

Metal-bioorganic compounds of vanadium pentoxide and bovine serum albumin (BSA) (Fraction V) were obtained by using sol-gel method. Series of the samples (BSA) xV2OH2O, where , 0.01 and 0.001, were originally produced by the synthesis of vanadium pentoxide xerogels and subsequent blending with water-dissolved BSA in appropriate molar ratios. It was evident that the gelation process does not occur for . For the X-ray photoelectron spectroscopy (XPS) studies, the thin layers of these materials were prepared by drying the gel onto the glass and mica substrates. The surface morphology of the samples was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. It follows from the analysis of experimental XPS spectra of (BSA) xV2OH2O that the nitrogen ions in pure albumin and in (BSA)V2OH2O are present in imine, amine and protonated amine groups. The additional protonated amine arises when the concentration of albumin in (BSA) xV2OH2O is low (). Increasing the amount of albumin results in decrease of the number of oxygen ions bonded to vanadium. At the same time (with increase of albumin), the component of oxygen bounded to carbon and nitrogen is increasing. In the samples with greater amount of albumin, the reduction of vanadium ions occurs. This means that the trivalent and tetravalent vanadium ions are present together with pentavalent ones. [ABSTRACT FROM AUTHOR]

In the present work, we synthesized a composite medium consisting of Ag nanorods embedded in CoTiO2 matrix (Ag/CTO) using the sol-gel method. We applied a uniform AC electric field at the beginning of gelation and during drying for manipulating Ag nanorods in the matrix. The structure and morphology characterizations of Ag/CTO nanocomposites were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The permittivity and permeability behaviors of samples were investigated. Results showed that for the sample dried in the existence of the electric field, simultaneous negative permittivity and permeability were realized. These results imply the realization of double negative properties in this sample. Therefore, this work suggests that Ag/CoTiO2 nanocomposites can be introduced as a negative index metamaterials (NIMs). A composite medium consisting of Ag nanorods embedded in Co0.05Ti0.95O2 matrix (Ag/CTO) was synthesized using the sol-gel method. A uniform AC electric field was applied at the beginning of gelation and during drying, for manipulating Ag nanorods in the matrix. The results showed that for the sample dried in the existence of electric field, negative permittivity and permeability were realized. These results imply the realization of double negative properties in this sample. [ABSTRACT FROM AUTHOR]

In this work, ZnO and Cu-doped ZnO nanoparticles , , with a calcination temperature of 500C were synthesized using the sol-gel method. The particles were analyzed using atomic absorption spectroscopy (AAS), X-ray diffraction (XRD) and electron paramagnetic resonance (EPR) at X-band, measurement in a temperature range from 90 K to room temperature. AAS confirmed a good correspondence between the experimental doping concentration and the theoretical value. XRD reveals the presence of ZnO phase in hexagonal wurtzite structure and a nanoparticle size for the samples synthesized. EPR spectroscopy shows the presence of point defects in both samples with -values of for shallow donors and for ionized vacancies. It is important when these materials are required have been used as catalysts, as suggested that it is not necessary prepare them at higher temperature. A simulation of the Cu EPR signal using an anisotropic spin Hamiltonian was performed and showed good coincidence with the experimental spectra. It was shown that Cu ions enter interstitial octahedral sites of orthorhombic symmetry in the wurtzite crystal structure. Temperature dependence of the EPR linewidth and signal intensity shows a paramagnetic behavior of the sample in the measurement range. A Néel temperature K was determined. [ABSTRACT FROM AUTHOR]

LaCoO3 (LCO) epitaxial films were grown on (001) LaAlO3 (LAO) substrates by the simple sol-gel technique. X-ray diffraction (XRD) and the cross-section transmission electron microscope (TEM) measurements indicate that single-phase (001) oriented LCO epitaxial films with biaxial compressive strain and elongated distortion of CoO6 octahedrons were grown on (001) LAO successfully. The epitaxial relationship between the LCO film and the LAO substrate is confirmed to be (001) and [100]. It is also found that LCO grown on LAO has a larger mean Co-O bond length and unit-cell size, compared with those of polycrystalline film. In addition, the magnetic characterization shows that LCO epitaxial film exhibits an obvious ferromagnetic (FM) transition at K, which is different from the nonmagnetic ground state of polycrystalline LCO. Combined with the structural analyses, it reveals that the strain-induced ferromagnetism observed in LCO epitaxial film originates from an increase of the mean Co-O bond length and a suppression of the CoO6 octahedral rotations, which can stabilize higher spin state of Co by a decrease of the gap energy. LaCoO3 epitaxial thin films with good crystalline property were successfully grown on (001) oriented LaAlO3 substrates by the simple sol-gel technique. Different from the nonmagnetic ground state of polycrystalline LaCoO3, an obvious ferromagnetic transition at TC∼85 K was observed in LaCoO3 epitaxial film. The strain-induced ferromagnetism originates from an increase of the Co-O bond length and a suppression of the CoO6 octahedral rotations, which stabilizes higher spin state of Co3+ by a decrease of gap energy. [ABSTRACT FROM AUTHOR]