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Spinel type nano ferrite compound MgFe2O4 was synthesized through sol gel technique using metal nitrates as precursors. The phase composition, morphology and elemental analysis of magnesium ferrite (MgFe2O4) were performed by X-ray diffraction, fourier transform infrared, atomic force microscopy, energy dispersive x-ray and scanning electron microscopy, analyses. The sample's X-ray diffraction pattern verifies the existence of single phase material, with the size of its crystallites estimated to be 39.9 nm. Fourier transform infrared examination supported metal-oxygen vibrations corresponding to tetrahedral and octahedral sites, respectively. From scanning electron microscopy image, grain size obtained about 97.7 nm. Raman spectra of the sample shows five Raman active modes (A1g + Eg + 3F2g), which is compatible with the spinel structure. Magnetic measurement study at room temperature shows a hysteresis loop behaviour with a low saturation magnetization value, 27.192 emu g-1 and a small coercivity value. The optical band gap determined using UV-visible transmittance spectra. Additionally, X-ray photoelectron spectroscopy are used to confirm oxidation states and explore the chemical composition of the sample.

The synthesis and luminescence analysis of Tb3+-activated phosphors were reported. Y2SiO5 phosphors were synthesized by a modified solid-state reaction method with a variable doping concentration of Tb3+ ion (0.5–2.5 mol.%). As synthesized, the phosphors were characterized by X-ray diffraction (XRD) analysis. The XRD pattern confirmed the monoclinic structure of the prepared phosphor. Scanning electron microscopy and High-Resolution Transmission Electron Microscopy (HRTEM) studies revealed nearly uniform particle size distribution in the prepared phosphors. The photoluminescence excitation spectra of the Y2SiO5:Tb3+ (0.5–2.5 mol.%) phosphor displayed one broad, intense peak at 258–277 nm. When excited at the 258 nm wavelength, the phosphors showed emission peaks at 553 nm (5D4 → 7F5), 544 nm (5D4 → 7F5) and 489 nm (5D4 → 7F6). The 1931 CIE (x,y) chromaticity coordinates showed the distribution of the spectral region calculated from the photoluminescence emission spectra. The values of x = 0.25 and y = 0.46 were very close to light green emission. Therefore, the prepared phosphor is very useful for light-emitting diode (green component) applications. [ABSTRACT FROM AUTHOR]

Y2Sr3B4O12 phosphors doped with europium ions were synthesized by a modified conventional solid-state reaction method. Characterizations of the prepared samples, viz., X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL), and Commission Internationale de I'Eclairage were studied. The XRD analysis confirmed the formation of mixed phase due to polyborate and has a hexagonal crystalline yttrium orthoborate phosphor. SEM images showed the irregular morphology of the sample. The grain size distribution was broad and the average size was found to range from 2 μm to 100 nm. PL measurements showed excitation and emission characteristics of the prepared phosphor with different concentrations of the doping ion. From the emission spectra, it was clearly observed that the emission intensity of the magnetic dipole was higher than that of electric dipole transition owing to the Eu3+ ions occupying a higher symmetry site in the Y2Sr3B4O12 host. The intensity of PL increased with increasing concentration of the doping ion up to 2.0 mol.%; after that, the PL intensity decreased owing to the concentration-quenching phenomenon. The results indicated that Y2Sr3B4O12:Eu3+ phosphors can be selected as a potential candidate for solar cell/photovoltaic application. [ABSTRACT FROM AUTHOR]

We report on the structure and diffusion behaviour of the various constituent molecules in ionic liquid (IL) mixtures under confinement in nanoporous glasses. X-Ray diffraction measurements indicate that the ions adopt a lamellar arrangement under confinement. Furthermore, using selective deuteration in combination with high resolution neutron spectroscopy reveals how the dynamics and the activation energy of the IL is affected by different confinement conditions (pore sizes 50 Å and 135 Å) and different temperatures (265 and 318 K). With different deuteration schemes we could separate the different motions of acetate and water. The confinement leads to distortions of the domains, which gives more room for diffusion. In the smaller pores, the stronger distortion gives even more room such that the hydrogen bonds between acetate and water seem to be even stronger than in bulk and weaker confinement. The results are discussed in the context of previous measurements on dry samples.

We present the electrospinning preparation and investigation of metal oxides TiO2 (T), ZnO (Z) and TiO2/ZnO (TZ) composite nanofibers. For the fabrication of TZ composite nanofibers, different proportions of TiO2/ZnO solutions (1:1, 1:2, 2:1 and 1:3) are preferred. X-ray diffraction (XRD) pattern of sample ‘T’ exhibited the mixed anatase and rutile phases while the wurtzite phase is examined in the sample ‘Z’. The field-emission scanning electron microscopy (FESEM) study evidenced the preparation of continuous and randomly oriented nanofibers whereas the transmission electron microscopy (TEM) investigation endorsed the cylindrical morphology of the TZ13-sample with mean diameter of 230 nm. The lattice d-spacing is estimated to be 0.289 nm corresponding to the plane (100) of the hexagonal wurtzite ZnO while selected-area electron diffraction (SAED) analysis endorsed the polycrystalline nature of the TZ13 composite nanofibers. Finally, photodegradation of the Eriochrome black T dye was performed and the catalyst TZ13 showed about 85% photodegradation in 90 min as compared to TZ11, TZ12 and TZ21. This boosted photocatalytic activity is ascribed to the synergetic effect of the TiO2/ZnO composite nanofibers with their distinct morphology.

Low-energy nuclear reactions are known to be extremely dependent on the local crystal structure and crystal defects of the deuterated samples. This has a strong influence on both hydrogen diffusion and the effective electron mass. The latter determines the strength of the local electron-screening effect and can change the deuteron–deuteron reaction rates at very low energies by many orders of magnitude. In the present study, zirconium samples were exposed to various conditions and energies of deuteron beams using the unique accelerator system with ultra-high vacuum, installed in the eLBRUS laboratory at the University of Szczecin. Irradiated and virgin samples were investigated by means of the X-ray diffraction (XRD) and positron annihilation spectroscopy (PAS). While the first method delivers information about changes of crystal lattice parameters and possible production of hydrides accompanying the formation of dislocations that are produced during irradiation of the samples, the second one can determine the depth distribution of crystal defects, being especially sensitive to vacancies. The studied Zr samples were also implanted by carbon and oxygen ions in order to simulate the real situation taking place in nuclear reaction experiments and to investigate their influence on the kinetic of produced vacancies. The observed enhancement of the electron-screening effect in the deuteron fusion reaction at very low energies could be explained by formation of a high number of vacancies during the deuteron irradiation of samples. Possible carbon and oxygen impurities can affect this process in various ways by changing the depth distribution of vacancies and their diffusion, but they play only a minor role in the strength of the electron-screening effect. [ABSTRACT FROM AUTHOR]

This work presents the influence of substrate temperature (${T}_{\text{sub}}$) and post-sulfurization on compositional, structural, electrical, and optical properties of dual-ion beam sputtering (DIBS)-grown Cu2(Sn,Ge)(S,Se)3 (CTGSSe) thin films grown on a soda-lime glass (SLG) substrate using a single target. Post-sulfurization of CTGSSe thin films is carried out in a quartz tube chemical vapor deposition (CVD) system. X-ray diffraction (XRD) analysis reveals that the crystal structure of CTGSSe thin films is preferentially tetragonal with (112) and (204) lattice planes at $2\theta $ values of 27.3° and 47.3°, respectively. Field-emission scanning electron microscopy (SEM) has emphasized that the high ${T}_{\text{sub}}$ growth resulted in a larger grain size of 87 nm and better thin-film morphology. Spectroscopic ellipsometry (SE) analysis shows the bandgap values of 1.46–1.62 eV by varying ${T}_{\text{sub}}$ from room temperature (RT) to 300 °C. Furthermore, the bandgap widens from 1.56 to 1.64 eV in the CTGSSe thin films due to post-sulfurization. [ABSTRACT FROM AUTHOR]

Mesoporous nanoparticles have a larger surface area and therefore, suitable for dye‐sensitised solar cells and photocatalytic applications. This Letter presents the analysis of solvothermal derived as‐prepared TiO2 and doped TiO2 nanocrystals by utilising acetone as the solvent. The as‐prepared and doped TiO2 nanoparticles endorsed the presence of anatase phase along with the slightly deviated diffraction peaks with the reduced crystallite size as a result of doping. Surface morphology analyses evidenced the mesoporous microspheres of nanoparticles, whereas the stoichiometry study exhibited the elementary peaks in the as‐prepared and doped samples. The estimated optical bandgaps are found to be 2.68, 2.92, 2.48 and 2.88 eV in accordance with the doped TiO2 with copper, tin, barium and zinc–magnesium as compared to 3.16 eV of TiO2. Doped samples evidenced the enhanced scattering capability, whereas tin and zinc–magnesium co‐doped samples demonstrated the highest diffuse reflectance in a broad wavelength range from 550 to 800 nm. [ABSTRACT FROM AUTHOR]

This Letter reports the synthesis of nanoceramic composite ZnAl2O4TiO2 by using a cost‐effective and straight forward sol–gel route. X‐ray diffraction (XRD) showed the ZnAl2O4 cubic structure along with the mixed anatase‐ and rutile‐phases of TiO2. Rietveld refinement is performed using XRD pattern to study the structural parameters. Raman investigation endorsed the corresponding vibration peaks of TiO2 and ZnO. Field‐emission scanning electron microscopy evidenced the agglomerated spherical nanoparticles. Energy‐dispersive spectroscopy analysis demonstrated the elementary peaks of Zn, Al, and Ti at 4.5, 1.5, and 1 eV, respectively. LCR measurement revealed the decreased dielectric permittivity with the rise in frequency and temperature. This dielectric characteristic is attributed to the dipole movement of the charge carriers. Furthermore, the authors present the investigation of the conductivity and impedance of the prepared dielectric ceramic material. [ABSTRACT FROM AUTHOR]

This Letter presents the electrodeposition of zinc oxide (ZnO) nanostructures by varying the negative potential and investigation of structural, optical, and morphological characteristics. UV–vis spectroscopy investigation showed the redshift of the absorption peak with the increased negative potential. Using Tauc relation, the optical bandgap values estimated to be 3.09, 2.97, 2.93, 2.91, 2.90, and 2.84 eV corresponding to the samples prepared at potential −0.5, −0.7, −0.9, −1.1, −1.3 and −1.5 V. Fluorescence spectra exhibited the UV emission band at wavelength 392 nm along with a peak at 650 nm corresponds to the second‐order nature of ZnO. Fourier‐transform infrared spectroscopy analysis confirmed the various vibration modes at 403, 493, and 702 cm−1 originated by the ZnO nanostructures. X‐ray diffraction pattern revealed the hexagonal wurtzite phase of ZnO. Scanning electron microscopy investigation evidenced the distinct morphology of ZnO with the increased negative potential; however, the dense and perpendicularly oriented ZnO nanorods are prepared at highest negative potential as compared to rice grain‐like ZnO structure prepared at least negative potential. Furthermore, the prepared nanostructures are used as dye‐sensitised solar cells (DSSCs) photoanodes, while the DSSC‐Z6 showed the increased cell efficiency up to 1.2%, due to the aligned growth of the ZnO nanorods. [ABSTRACT FROM AUTHOR]

Lead (Pb) ions are a major concern to the environment and human health as they are contemplated cumulative poisons. In this study, facile synthesis of magnetic iron oxide–tea waste nanocomposite is reported for adsorptive removal of lead ions from aqueous solutions and easy magnetic separation of the adsorbent afterwards. The samples were characterised by scanning electron microscopy, Fourier transform‐infrared spectroscopy, X‐ray diffraction, and Braunner–Emmet–Teller nitrogen adsorption study. Adsorptive removal of Pb(II) ions from aqueous solution was followed by ultraviolet–visible (UV–Vis) spectrophotometry. About 95% Pb(II) ion removal is achieved with the magnetic tea waste within 10 min. A coefficient of regression R2 ≃ 0.99 and adsorption density of 18.83 mg g−1 was found when Pb(II) ions were removed from aqueous solution using magnetic tea waste. The removal of Pb(II) ions follows the pseudo‐second‐order rate kinetics. External mass transfer principally regulates the rate‐limiting phenomena of adsorption of Pb(II) ions on iron oxide–tea waste surface. The results strongly imply that magnetic tea waste has promising potential as an economic and excellent adsorbent for the removal of Pb(II) from water. [ABSTRACT FROM AUTHOR]

This review includes research papers on different method of preparation of rare earth activated Sr2SiO4 phosphors and its luminescence studies. Here in Sr2SiO4 has attracted great interest due to its special structure features, excellent physical and chemical stability. Besides, it absorbs ultraviolet radiation and emits white light when activated by different rare earth ions. Different synthesis techniques were compared and it is found that sol–gel synthesis technique is best for preparation of rare earth activated Sr2SiO4 phosphors. Literature related to characterization techniques such as X-ray diffraction techniques, scanning electron microscopy, transmission electron microscopy and other studies are also compared. Photoluminescence studies for white light emitting diode of various rare earth phosphors are compared with Sr2SiO4 phosphor reported in this review. Also some luminescence techniques such as thermoluminescence glow curve analysis and some spectroscopic parameters are also compared. The review end with some important conclusion related to rare earth activated Sr2SiO4 phosphors with proper justifications. [ABSTRACT FROM AUTHOR]

This paper reports on the thermoluminescence (TL) properties of Eu doped in two different host matrix phosphors (YO and YBO). The phosphors were prepared by a high temperature solid state reaction method. The method is suitable for a large scale production. The samples were characterized by X-ray diffraction and Rietveld refinement. The different concentration of Eu samples were also examined by TL glow curve analysis for UV, β and γ irradiation. The YO samples showed well resolved broad peaks that covered the temperature range from 50 to 350 °C and the peak temperature was found at 157 °C for the γ irradiation. For the UV irradiated samples a well resolved peak at 121 °C was found for the YO:Eu doped phosphors. The β irradiated samples showed a resolved peak at 182 °C. A different behaviour was observed for the YBO:Eu doped phosphors which showed both higher temperature peaks and lower temperature peaks for UV, β and γ irradiation. Here UV irradiated sample showed the formation of shallow trap (surface trapping) and the γ irradiated sample showed the formation of deep trapping. The estimation of the trap formation was evaluated by the calculation of the trapping parameters. The trapping parameters such as activation energy, order of kinetics and frequency factor were calculated by the peak shape method using the computerized glow curve deconvolution technique. Here most of the peak showed second order of kinetics. The effect of γ, β and UV dose exposure on the TL studies was also examined and it showed a linear response with dose which indicated that the samples might be useful for TL dosimetry. The possible mechanics and information about traps formation are presented in detail. [ABSTRACT FROM AUTHOR]

In the present study attempt was made to synthesize iron nanoparticles in the presence of alumina (Al-nZVI) by sodium borohydride reduction process. The composite adsorbent has been characterized using various analytical techniques such as scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and transmission electron microscopy which showed that iron nanoparticles were partially dispersed on alumina surface, with their diameter being in the range 40-100 nm. The batch adsorption experiments were carried out to study the effect of different parameters. The maximum removal of fluoride was obtained at optimal condition of pH 5.0 and dose = 1.8 g/L and was observed to be 94% with contact time of 60 min at 40 °C and initial concentration of 2 mg/L. The adsorption data fitted that pseudo second order kinetics and followed Langmuir isotherm model with maximum adsorption capacity of 10.06 mg/g. Thermodynamic study revealed exothermic nature of adsorption. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Electrospinning fabrication of TiO 2 nanofibers via process parameters are presented. • XRD study showed the presence of mixed anatase and rutile phases. • TG/DTA investigation performed to study the characteristic peaks of TiO 2 /PVP mat. • FTIR investigation endorsed the characteristic peak of Ti O Ti bond. • The optimal process parameters led to preparation of thin TiO 2 nanofibers. Abstract This paper reports the electrospinning fabrication and characterization of TiO 2 nanofibers. Various electrospinning process parameters such as applied voltage, distance tip-collector, solution flow rate and polymer (PVP) concentration are studied. The prepared nanofibers were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), thermogravimetric-differential thermal analysis (TG-DTA) and Fourier transform infrared spectroscopy (FTIR). XRD pattern of TiO 2 nanofibers evidenced the presence of mixed phases of anatase and rutile. TG/DTA investigation showed the characteristic peaks corresponding to the heating behavior of TiO 2 -PVP mat. FTIR investigation endorsed a vibration peak at 660 cm−1 associated with the characteristic Ti O Ti bond. With the optimized process parameters, TiO 2 nanofibers diameter was found to be reduced to 74 nm as compared to the first sample prepared with the diameter of 343 nm. Furthermore, these nanofibers were employed as the photoanode material for the preparation of dye-sensitized solar cell (DSSC) and photovoltaic study is evaluated. [ABSTRACT FROM AUTHOR]

SrAl2O4Eu2+ green-light emitting powder phosphor was prepared within a few minutes at furnace temperature as low as 550 °C by using combustion method. The prepared powder was characterized by X-ray diffraction, scanning electron microscopy and Fourier-transform infrared spectrometry. Several ESR lines are exhibited by the phosphor, and some are seen in the low field region apart from lines in the g ~ 2.0 region. Crystal fields that were relatively strong arose from distortions close to the Eu2+ ion lead to lines in the low field region. The photoluminescence of Eu2+-activated SrAl2O4 shows a green-emission dominant peak around 514 nm, which can be attributed to the 4f65d1 → 4f7 transition of Eu2+ ions from the synthesized phosphor particles at an excitation wavelength of 345 nm. [ABSTRACT FROM AUTHOR]

CeO:M (Eu, Er and Dy) phosphors were synthesized by modified solid-state reaction technique at variable concentrations of Eu, Er and Dy. This technique is suitable for large-scale production and it is less time-consuming. The prepared samples were characterized by X-ray diffraction (XRD) technique, scanning electron microscopy (SEM), and Photoluminescence (PL) decay curve analysis. XRD patterns of the prepared samples confirm the cubic fluorite crystal structure of all phosphors. Crystallite size was calculated by using well known Scherer's formula. SEM images express good surface morphology with nanoflower like shape. Comparative studies of photoluminescence decay curves of CeO:M (Eu, Er and Dy) with different concentrations of dopant have been done. Decay constants for all prepared phosphors were calculated by curve fitting technique. Samples were excited under UV radiation for few nanoseconds at room temperature. The PL decay curves were measured for D→F transition of CeO:Eu,S→I transition of CeO:Er and F→H transition of CeO:Dy phosphors. Decay curve for CeO:Eu (1.5 mol%) phosphor shows optimum concentration with higher intensity of photoluminescence signals and comparatively higher decay constants. [ABSTRACT FROM AUTHOR]

Luminescence behaviour was displayed by dysprosium (Dy) doped BaTiO phosphor which was synthesized via solid state reaction method. The method is suitable for large scale production and useful for production of micron size phosphor. The sample was characterized by X-ray diffraction technique and crystallite size was calculated using Scherer's formula. Effects of optimized concentration of Dy on its thermoluminescence glow curve analysis were carried out for γ irradiation. For fixed concentration of dysprosium ions the TL glow curve was recorded using 6.7 °C s heating rate. Also for variable γ dose 1-2.5 kGy and optimized concentration of dysprosium ion i.e. 4 mol% were carried out. It is found that TL glow curve shows linear response with γ dose. Kinetic parameters were calculated using computerized glow curve deconvolution technique. Photoluminescence study of Dy doped BaTiO phosphor was carried out and it is found that the PL emission spectra in visible region had blue, green and red emission wavelength. CIE coordinate shows color rendering index and correlated color temperature for white light emission of Dy doped BaTiO phosphor. It may be used for visible light emission in display device applications and TL dosimetric applications. [ABSTRACT FROM AUTHOR]

Polycrystalline ceramics with chemical formula BaBiTiO, Pb BiTiO and SrBiTiO have been synthesized using co-precipitation route. In the present study optimization of calcination and sintering temperature is carried out and the relationship between sintering temperature and morphology, dielectric, and ferroelectric properties of the as-prepared samples is extensively investigated. Pellets of these samples were sintered at a range of temperatures 850, 950 and 1050 °C for 2 h. The phase formation of compounds calcined at different temperatures was studied using X-ray diffraction and scanning electron microscopy was used to examine the surface morphology. Crystallite and grain size was seen to increases with an increase in the calcination and sintering temperature respectively. The dielectric and ferroelectric properties of the ceramics were found to improve at a higher sintering temperature. [ABSTRACT FROM AUTHOR]

The NaYF 4 phosphors codoped with Er 3+ -Yb 3+ have been synthesized by hydrothermal method using oleic acid as a chelating agent. The crystal structure and surface morphology has been identified with the help of powder X-ray diffraction (PXRD) and field emission scanning microscopy (FE-SEM) technique, respectively. The presence of different functional groups in the developed phosphors have been analyzed by using the Fourier transform infrared spectroscopy (FTIR) technique. The optical non-linear behavior of the prepared phosphors has been performed by using the excitation at 980 nm from a CW diode laser. The effect of Li + ions tri-doping on the structural and luminescence behavior of the Er 3+ -Yb 3+ codoped NaYF 4 phosphors has been discussed suitably. The effect of variation of pump power density on the UC emission intensity of different bands has been investigated. The optical temperature sensing behavior based on the green UC emissions of the Er 3+ -Yb 3+ -Li + tri-doped NaYF 4 phosphors under the excitation at very low pump power density (∼0.32 W/cm 2 ) has been studied. The results obtained from the present study indicate that the Er 3+ -Yb 3+ -Li + tri-doped NaYF 4 phosphors may be of particular interest in developing the NIR to visible upconverters, green display devices and temperature sensors. [ABSTRACT FROM AUTHOR]

This paper reports the synthesis of pure and Cr-doped TiO 2 nanoparticles with different doping concentrations by using a cost-effective solvothermal method. The as-synthesized nanoparticles were characterized by using X-ray diffraction, transmission electron microscopy and UV–Vis spectroscopy to study their structural and optical properties. The XRD pattern showed the prepared material is pure anatase of the crystalline phase. Using TEM measurement, the average particles size is found to be about 11–13 nm while selective area electron diffraction (SAED) patterns have confirmed the polycrystalline nature of the nanoparticles. The size of the crystallite is observed to be decreased with an increase in dopant (Cr) concentration. UV–Vis absorption spectra showed enhanced absorption in the visible range in accordance with the doping concentration of Cr with a red shift in the absorption edge. The band gap energy of doped nanoparticles decreases in accordance with an increase in dopant concentration due to the reduced particles size. This presented work would be useful to tune the optical properties of doped and undoped metal oxide TiO 2 for its optoelectronic applications. [ABSTRACT FROM AUTHOR]

The scale-up synthesis of nZVI (zero-valent iron nanoparticles) was optimized by response surface modeling (RSM). The synthesized nZVI was employed for synergistic degradation of metronidazole (MNZ) or methyl orange (MO) in the presence of sodium borohydride (NaBH 4 ). Key parameters such as initial MNZ or MO concentration, nZVI concentration, and NaBH 4 concentration for MNZ or MO removal process was optimized using central composite design (CCD). Under the optimized conditions (nZVI concentration: 150 mg/L; NaBH 4 :0.1 M; interaction time: 25 min for MNZ and 30 min for MO; and MNZ or MO initial concentration: 40 mg/L), the removal was synergistically increased to 100% (MNZ) and 98.07 ± 1.1% (MO). When nZVI was applied without NaBH 4 , the removal of MNZ and MO were 50.62 ± 0.28 and 43.72 ± 0.29%, respectively. In the presence of NaBH 4 alone, the removal of MNZ or MO was 6.5 ± 1.1% and 4.2 ± 0.7%, respectively. Addition of NaBH 4 was found to enhance the remediation ability of nZVI. The MNZ or MO degradation followed pseudo–first–order kinetics. The degradation mechanism was studied by UV–visible spectroscopy, XRD, SEM-EDX, FT-IR, and BET analyses. The applicability of the process was tested with MNZ-spiked or MO-spiked lake water and ground water samples. [ABSTRACT FROM AUTHOR]

Gadolinium-doped Y2O3 nanophosphor was synthesized by a solid-state reaction method, which could be used for large-scale production of phosphors. The structure of the phosphor sample was characterized by powder X-ray diffraction, field emission gun scanning electron microscopy and high-resolution transmission electron microscopy. The particle size was calculated from Scherer's formula. X-ray diffraction showed a grain size of 35-55 nm, in good agreement with the scanning electron microscopy image. The synthesized sample showed good morphology and connectivity, with grains and formation of a nano-sized prepared sample. The diffraction pattern was measured by transmission electron microscopy with a selected area diffraction pattern. The prepared phosphor was also examined by thermoluminescence; to record the glow curve, 1 mg phosphor was irradiated with ultraviolet at 254 nm at a fixed heating rate of 7 °C s−1. The sample showed a well-resolved peak at 99 °C for 1 mol% of Gd3+. A lower temperature peak showed less stability and more fading of the prepared sample. A thermoluminescence glow curve gives information about trapping parameters such as activation energy and trap depth, order of kinetics and frequency. All the kinetics were calculated by the peak shape method. [ABSTRACT FROM AUTHOR]

Cadmium Telluride (CdTe) thin films grown by thermal evaporation on quartz substrates were irradiated with swift (100 MeV) Ni+4 ions at various fluences in the range 1011 - 1013 cm -2. The modification in structure and surface morphology has been analyzed as a function of fluence using XRD and AFM techniques. The XRD showed a reduction in peak intensity and grain size with increasing fluence. The AFM micrographs of irradiated thin films show small spherical nanostructures. In addition to direct imaging, AFM profile data enable to derive the Power Spectral Density (PSD) of the surface roughness. In the present work PSD spectra computed from AFM data were used for studying the surface morphology of films. The PSD curves were fitted with an appropriate analytic function and characteristic parameters were deduced and discussed in order to compare film morphology with varying fluence levels. [ABSTRACT FROM AUTHOR]

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Abstract: Metal nanostructures have unusual physicochemical properties and biological activities compared to their bulk parent materials. Thus in recent years a number of physical, chemical and biological techniques were applied for the development of metal nanoparticles (NP). Here we have synthesized silver and gold nanoparticles (AgNPs and AuNPs) by using leaves extracts of Rosa rugosa. Surface plasmon resonance spectra for silver and gold are obtained at 451 and 578nm with brown yellow and pink-red color, respectively. AgNPs and AuNPs vary in size according to different leaves extract and metal concentration used for the synthesis. Different instrumental techniques were applied to characterize the synthesized AgNPs and AuNPs viz. UV–vis, TEM, XRD, FTIR, Zetasizer and EDX. The synthesized NPs were mostly spherical (in case of AgNPs) with some triangular and hexagonal (especially in case of AuNPs) in shapes with an average size of 12 and 11nm for AgNPs and AuNPs, respectively. [Copyright &y& Elsevier]

Thin film of high purity (99.999 %) Cd1-xZnxTe (where x =0.02, 0.04, 0.06, 0.08) was prepared by high vacuum technique (HVTx10-6 Torr), on glass substrates at different substrate temperatures. The film deposited at lower temperature was annealed for one hour in vacuum of 5x10-3 torr at as-deposited to 300K. Structural investigation has been carried out using the X-ray diffraction technique. Scanning electron microscopy have been used to study the morphological behaviour of the thin films. At the lower deposition temperature the film represents amorphous nature but with increasing value of x the film exhibits polycrystalline nature. The SEM indicate that in amorphous state the surfaces are non uniform but at higher annealing temperature the film surfaces are uniform. Effect of annealing on carrier concentration and Hall mobility has been studied. From the Hall effect study various electrical parameters have been estimated. [ABSTRACT FROM AUTHOR]

ZnTe nanoparticles have been synthesized by chemical synthesis method, which is based on the chemical replacement reaction between the chemical compounds. Structural analysis of ZnTe nanoparticles has been performed by using x-ray diffraction techniques. It has been found that the average particle size is 2.6 nm using uv-vis spectroscopy. DC and AC electrical conductivities of ZnTe nanoparticles have been studied. Conduction mechanism is described in brief. The activation energies have also been determined. The results indicate that ZnTe behaves as a semiconducting material. [ABSTRACT FROM AUTHOR]

Liquid phase catalytic hydroxylation of phenol was carried out over ternary hydrotalcites containing copper, nickel and aluminum using hydrogen peroxide as oxidant. The influence of various reaction parameters, namely, substrate:catalyst ratio, substrate:oxidant ratio, nature of oxidant, solvent, pH, time-on-stream, reaction temperature and calcination temperature on the activity and selectivity for the “sought for” reaction, were studied. The catalysts were synthesized by the coprecipitation technique using metal nitrates and a NaOH/Na2CO3 mixture. Hydroxylation of phenol over these catalysts resulted mainly in the formation of catechol and hydroquinone. Among the catalysts studied, CuNiAl3-5 ((Cu+Ni)/Al=3.0; Cu/Ni=5.0) and CuNiAl2-1 ((Cu+Ni)/Al=2.0; Cu/Ni=1.0) showed maximum activity with a catechol:hydroquinone ratio close to 1.6. An increase in the substrate:catalyst ratio enhanced the conversion of phenol over these catalysts. With respect to the influence of reaction temperature, the conversion increased up to 65 °C and decreased when the temperature was further increased. Oxidants other than H2O2 and solvents other than water have not showed measurable conversion of phenol. Time-on-stream studies indicated that around 90% of conversion of phenol was achieved in 10 min and longer reaction time did not significantly enhance the conversion. Among the calcined samples studied, that calcined at 800 °C showed a maximum activity for phenol hydroxylation; however, the activities of calcined catalysts were lower than those of fresh hydrotalcites. The observed variation in the activity may be attributed to the copper concentration, especially those present on the surface. A reaction pathway involving hydroxy radical is proposed for the formation of dihydroxybenzenes. [Copyright &y& Elsevier]

This paper reports the preparation of Eu 3+ doped Gadolinium oxyorthosilicate (Gd 2 SiO 5 :Eu 3+ ) phosphor with different concentration of Eu 3+ (0.1–2.5 mol%) using the modified solid state reaction method. The synthesis procedure of the Gd 2 SiO 5 :Eu 3+ phosphor using inorganic materials such as Gd 2 O 3 , silicon dioxide (SiO 2 ), europium oxide (Eu 2 O 3 ) and boric acid (H 3 BO 3 ) as flux is discussed in detail. The prepared phosphor samples were characterized by using X-Ray Diffraction (XRD), Field Emission Gun Scanning Electron Microscopy (FEGSEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Photoluminescence (PL) and Thermoluminescence (TL). The Commission Internationale de l′Eclairage(CIE) coordinates were also calculated. The PL emission was observed in the 350–630 nm range for the Gd 2 SiO 5 :Eu 3+ phosphor. PL excitation peaks were observed at 266, 275, 312 and 395 nm while the emission peaks were observed at 380, 416, 437, 545, 579, 589, 607, 615 and 628 nm. The emission peak at 615 nm was the most intense peak for all the different Eu 3+ concentration samples. From the XRD data, using the Scherrer's formula, the average crystallite size of the Gd 2 SiO 5 :Eu 3+ phosphor was calculated to be 33 nm. TL was carried out for the phosphor after both UV and gamma irradiation. The TL response of the Gd 2 SiO 5 :Eu 3+ phosphor for the two different radiations was compared and studied in detail. It was found that the present phosphor can acts as a single host for red emission (1.5 mol%) for display devices and light emitting diode (LED) and white light emission for Eu 3+ (0.1 mol%) and it might be used as a TL dosimetric material for gamma dose detection. [ABSTRACT FROM AUTHOR]

Abstract In recent years, the development of electrically active materials for orthopedic implant applications attracted attention owing to the fact that inherent electricity of bone mediates it's various metabolic processes. In this perspective, the present work investigates the effect of incorporation of varying amounts of piezoelectric biocompatible Na 0.5 K 0.5 NbO 3 (NKN) on dielectric and electrical properties of hydroxyapatite (HA) over a wide range of temperature (30–500 °C) and frequency (1 Hz – 1 MHz). The composites HA-x NKN (x = 10–30 wt%) were synthesized by solid state ceramic method and optimally sintered at 1075 °C for 2 h. X-Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) patterns confirmed the formation of phase pure HA and NKN in the composite system. The dielectric response of the samples has been compared with that of the existing theoretical models. The dielectric measurement suggests that the space charge as well as dipolar polarization is the dominant polarization mechanisms. The complex plane impedance and modulus spectroscopic analyses were performed to reveal the conduction mechanism. The activation energies for grain and grain boundary resistance for HA- (10–30 wt%) NKN were 1.03, 1.464, 1.28 and 1.34, 1.56, 1.30 eV, respectively. These results suggest that ionic conduction is the dominant conduction mechanism. Hydroxyl ions and oxygen vacancies are observed to be responsible for the conduction in HA-xNKN composite system. Overall, HA- x NKN composite system can be suggested as a potential material for electro-active orthopedic implant application. [ABSTRACT FROM AUTHOR]

A series of Tb3+-doped Li2CaSiO4 phosphors were prepared by high-temperature solid-state reaction method. The structural studies were done using the X-ray diffraction (XRD) technique. The XRD patterns revealed that the sample was monophased and crystallizes in a cubic structure. Scanning electron microscopy (SEM) was used to obtain information about the morphology of the prepared samples. SEM micrographs clearly indicated that the particles crystallized in inhomogeneous morphology, with the particle size ranging from 1 μm to 100 nm. Also, photoluminescence (PL) analysis of the phosphor samples for different concentrations of doping ions with variable excitations were presented. The PL excitation spectrum of Tb3+ ion-doped Li2CaSiO4 has many sharp peaks, mainly at 418 nm (5D3 → 7F5), 436 nm (5D3 → 7F4), 456 nm (5D3 → 7F3), 472 nm (5D3 → 7F2,1,0), 487 nm (5D4 → 7F6), 550 nm (5D4 → 7F5), and 590 nm (5D4 → 7F4), assigned to the transitions of Tb- ion respectively (excited at 237 nm). The 1931 CIE (x, y) chromaticity coordinates showed the distribution of the spectral region calculated from PL emission spectra, and found to be (0.19, 0.22) in a bluish-green region of Tb3+ (0.01 wt (in grams)) Li2CaSiO4 phosphor. Our study shows that as-prepared phosphor may be useful for optical devices, mainly for LEDs, as a bluish-green component. [ABSTRACT FROM AUTHOR]

Abstract: Recent work has described the preparation and characterization of copper oxalate nanocrystals (CONs). It was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and electron diffraction pattern (ED). The catalytic activity of CONs on the thermal decomposition of ammonium perchlorate (AP) and composite solid propellants (CSPs) has been done by thermogravimetry (TG), differential scanning calorimetry (DSC) and ignition delay measurements. Burning rate of CSPs was also found to be enhanced in presence of copper oxalate nanocrystals. Kinetics of thermal decomposition of AP with and without CONs has also been investigated. The model free (isoconversional) and model-fitting kinetic approaches have been applied to data for isothermal TG decomposition. [Copyright &y& Elsevier]

Abstract: The comparative catalytic activity studies of biologically and industrially important compounds such as Xanthenes and bis (indolyl) methanes were evaluated over propylsulfonic acid functionalized SBA-15/SO3H. The material was characterized via standard characterization techniques such as Powder X-ray diffraction, FTIR, Temperature programmed desorption studies of NH3. The catalytic performance of SBA/SO3H under environmentally benign conditions results in high yield of xanthenes compared to bis (indolyl) methanes and finally the mechanism for both the reactions were proposed. [ABSTRACT FROM AUTHOR]

Abstract: Bimetallic nanoalloys (BMNAs) of 3d-series (Ni–Cu, Ni–Co and Ni–Zn) were prepared by hydrazine reduction of respective metal chloride in ethylene glycol at 60°C. These were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and particle size was found to be in the order of 34, 43 and 30nm, respectively. The thermolysis of ammonium perchlorate (AP) and AP-HTPB composite solid propellants was found to be catalyzed with BMNAs and burning rate was found to be enhanced considerably. TG and ignition delay studies demonstrated that higher temperature decomposition (HTD) of AP is enhanced enormously by these additives and Ni–Co nanoalloy is the best catalyst. [Copyright &y& Elsevier]

Abstract: Nanosized ZrO2 and WO3–ZrO2 particles were prepared by solution combustion synthesis using urea as fuel. These materials were characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy and transmission electron microscopy. XRD study indicates the presence of a mixture of tetragonal and monoclinic phases in the synthesized ZrO2 particles. The tetragonal phase content is enhanced in the WO3–ZrO2 nanocomposite oxide. IR study indicates the presence of well-dispersed WO x species grafted on to the surface of the tetragonal ZrO2. TEM analysis of the sample shows the presence of uniform particles with size in the range of 10–25nm. The catalytic activity of the WO3–ZrO2 nanocomposite catalyst was evaluated for the synthesis of coumarins by Pechmann condensation of phenols with β-ketoesters. It was observed that the composite oxide catalyst was highly active for the reaction. Grafting of WO3 species on the surface of ZrO2 has a beneficial effect on the catalytic activity of the WO3–ZrO2 nanocomposite catalyst. [Copyright &y& Elsevier]

Hydroxylation of phenol was carried out over a series of CoNiAl ternary hydrotalcites (HTs) having a (Co+Ni)/Al atomic ratio close to 2.6 and a Co:Ni atomic ratios ranging from 1:0 to 0:1 using H2O2 as oxidant and water as solvent. Both end members of this series, namely CoAl-HT and NiAl-HT, showed negligible conversion of phenol, while cooperative catalytic behavior was noted when both elements were present together. However, activity of the catalysts varied with Co/Ni atomic composition, wherein the activity decreased with a decrease in the concentration of cobalt. A variation in the activity with the crystallinity of the materials was noted wherein a highly ordered material showed maximum activity and dropped with a decrease in the orderliness of the layered structure. Temperature-programmed reduction (TPR) of the fresh samples substantiated the activity trend by exhibiting a decrease in the reduction maximum with a decrease in the concentration of cobalt. Probably an optimal configuration of sites involving cobalt, nickel, and Brønsted basic hydroxyl groups is necessary for promoting the reaction. Among the catalysts studied, catalyst with a Co/Ni atomic ratio of 1:5 showed maximum conversion of phenol (14.2%, substrate:oxidant=2:1, 65 °C) with a catechol/hydroquinone ratio of 3.8. Heating of these samples even at slightly elevated temperatures (>120 °C in air for 5 h) led to complete loss in the activity necessitating the requirement of a well-ordered network. Prior to catalytic studies, the samples were characterized by various physicochemical techniques for structure–activity relationships. [Copyright &y& Elsevier]