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This work focussed on the optical, magnetic and photocatalytic properties of sol-gel-synthesized FeO-doped ZnO nanospheres and was compared with pristine ZnO nanospheres. The crystalline phase of FeO-doped ZnO nanospheres was studied with X-ray diffraction analysis and was well matched with standard pattern. Surface morphology was studied with HR-SEM images and EDAX spectrum. Furthermore, elemental mapping analysis was carried out to confirm the presence of FeO phase in FeO-doped ZnO nanospheres. FT-Raman spectral studies show that a strong intense peak at 670 cm indicates the presence of FeO in FeO-doped ZnO nanospheres. The mean crystallite size of FeO-doped ZnO nanospheres was 34 nm as calculated by Debye-Scherrer's formula which confirmed with HR-TEM image. The SAED pattern shows the presence of (100), (101), (102) and (202) of ZnO phase and (400) of FeO phase, confirming the crystalline nature of FeO-doped ZnO nanospheres. The vibrating sample magnetometer (VSM) result shows that FeO-doped ZnO nanospheres possess superparamagnetic nature and the composite nanospheres are magnetically separable. The optical properties have been studied by diffuse reflectance spectroscopy and time-resolved photoluminescence spectra. Implantation of FeO in ZnO nanospheres modifies the UV absorption edge, and it displays near-band gap emission and deep-level emission. The photocatalytic activity of FeO-doped ZnO nanospheres studied against rhodamine B dye is found higher than that of pristine ZnO nanospheres which shows that FeO-doped ZnO nanospheres are a promising photocatalyst. [ABSTRACT FROM AUTHOR]

Abstract: Gallium nitride (GaN) nanocrystals were synthesized by nitridation of Ga-EDTA (ethylene diamine tetra acetic acid) complexes at different temperatures starting from 600 to 900°C. X-ray diffraction analysis, Fourier transform infrared spectroscopy and Raman studies revealed that the compound synthesized at 900°C consists of single-phase GaN nanocrystals with wurtzite structure. The change in morphology of the GaN crystals at different temperatures was observed using scanning electron microscopy. The transmission electron microscopy showed the average size of the crystalline particles to be ∼20nm. The room temperature photoluminescence exhibits band-edge emission of GaN at 3.46eV for all the samples. The present study demonstrates that the nitridation of Ga-EDTA complex method has significant potential for the synthesis of GaN nanocrystals as a simple and inexpensive method. [Copyright &y& Elsevier]

In the present investigation we report the synthesis of a series of transparent glasses of composition 20Li 2 O 20PbO 45B 2 O 3 (15− x ) P 2 O 5 : x V 2 O 5 with eight values of x ranging from 0 to 2.5 mol%, and their characterization. X-ray diffraction (XRD) spectra reflected the amorphous nature of the glasses. Optical absorption, electron paramagnetic resonance (EPR) spectra and FTIR study of vanadyl ions in the present glass network have been analyzed. The optical absorption and EPR investigations have revealed that vanadium ions do exist in both V 4+ and V 5+ states and the redox ratio (V 4+ /V 5+ ) is observed to increase with the increase in concentration of V 2 O 5 . Dielectric properties viz., dielectric constant ε ′( ω ), loss tan δ , electrical moduli M ′( ω ), M ″( ω ), a.c. conductivity σ ac over an extensive scale of frequency and temperature have been investigated as a function of V 2 O 5 concentration. The dispersion of dielectric constant ε ′( ω ) with temperature has been interpreted by space charge polarization model. The dielectric loss and electrical moduli variation with frequency and temperature exhibited relaxation effects. These effects are ascribed to V 4+ ions. The a.c. conductivity of the prepared glasses is perceived to escalate with the hike in V 2 O 5 concentration whereas the activation energy for conduction exhibits a reverse trend. The conductivity mechanism is explained on the basis of polaronic transfer between V 4+ and V 5+ ions. The low temperature a.c. conductivity mechanism is elucidated by the quantum mechanical tunneling model. The growth in the values of dielectric parameters with raise in the concentration of V 2 O 5 is due to V 4+ ions which act as modifiers. The investigation of these results has indicated that at higher concentrations of V 2 O 5 , the VO 2+ ions in the glasses were present in octahedral sites with tetragonal compression and belong to C 4v symmetry. [ABSTRACT FROM AUTHOR]

The crystal structure development of jojoba-like esters incorporating either 1-decenoic acid and/or 1-decenol, namely octadec-9-enyl dec-9-enoate (JLE-281), and its isomer dec-9-enyl oleate (JLE-282) was investigated to reveal the effect of symmetry about the ester group on crystallization of aliphatic fatty monoesters. The phase transformation path was investigated with temperature-time resolved X-ray diffraction during stepped isothermal crystallization, and while cooling from the melt at a fixed rate. Startling differences in phase behavior were uncovered between the isomers. When stepped isothermals were used, selective extinctions occurred at a transition temperature for JLE-281 but not for JLE-282. The extinctions, which are due to dramatic changes in the electronic density of certain families of planes, indicate a phase transition attributed to a brusque rearrangement of the oxygen atoms in the crystal subcell. The phase transition did not occur when the JLEs were cooled continuously. The crucial role played by the position of the alkyl chain and its orientation relative to the easy rotation site of the C-O bond in the phase trajectories of the JLEs was particularly highlighted. [ABSTRACT FROM AUTHOR]

Abstract: A robust, well-defined and reproducible method to accurately measure the oil binding capacity (OBC) of structuring fats was developed. The method was validated using two oil/fat model systems, i.e., fully hydrogenated canola oil (FHCO) in canola oil (CO) (FHCO/CO) and fully hydrogenated soybean oil (FHSO) in CO (FHSO/CO). The mixtures were crystallized from the melt down to three different temperatures (15, 25 and 35°C) at constant rates of cooling and the OBC was measured after different periods of storage time. The critical concentration of hard fat at which the solid fat network is stable and effectively binds oil has been also measured for mixtures crystallized at temperatures close to room temperature, i.e., 25°C. Crystal structure, melting behavior, microstructure, and solid fat content of these binary systems have been investigated in relation to the OBC of the solid fat network using X-ray diffraction (XRD), differential scanning calorimetry (DSC), polarized light microscopy (PLM), and wide-line pulsed nuclear magnetic resonance (pNMR) techniques. The two model systems exhibited similar trends in OBC over time, a behavior attributed to their similar TAG composition and polymorphism. However, relatively smaller OBC values were achieved by the CO/FHSO compared to CO/FHCO samples, largely due to differences in their solid network structure. Four successive decreasing linear segments, identifying successive mechanisms of oil migration/binding, were observed in the experimental OBC versus fat weight fraction curves. The critical concentration of hard fat, at which the solid fat network is effective in binding oil, was also determined and found to be ∼6wt% for both systems. [ABSTRACT FROM AUTHOR]