Hydrothermal synthesis of cobalt telluride nanorods for a high performance hybrid asymmetric supercapacitor.

Cobalt telluride nanostructured materials have demonstrated various applications, particularly in energy generation and storage. A high temperature and reducing atmosphere are required for the preparation of cobalt telluride-based materials, which makes this a difficult and expensive process. The development of a facile route for producing the desirable nanostructure of cobalt telluride remains a great challenge. We demonstrated a simple hydrothermal method for preparing cobalt telluride nanorods (CoTe NRs) and telluride nanorods (Te NRs) for supercapacitor applications. The morphology of CoTe NRs and Te NRs was analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The prepared CoTe NR electrode material exhibited a high specific capacity of 170 C g-1 at a current density of 0.5 A g-1 with an exceptional cyclic stability. The asymmetric supercapacitor was assembled using CoTe NRs and orange peel-derived activated carbon (OPAA-700) as a positive and negative electrode, respectively. The fabricated device delivered a high energy density of 40.7 W h kg-1 with a power density of 800 W kg-1 at 1 A g-1 current density. When the current density was increased to 30 A g-1, the fabricated device delivered a high power density of 22.5 kW kg-1 with an energy density of 16.3 W h kg-1. The fabricated asymmetric supercapacitor displayed a good cyclic stability performance for 10 000 cycles at a high current density of 30 A g-1 and retained 85% of its initial capacity for after 10 000 cycles. The prepared materials indicate their applicability for high performance energy storage devices.

dz2 orbital-mediated bound magnetic polarons in ferromagnetic Ce-doped BaTiO3 nanoparticles and their enriched two-photon absorption cross-section.

The enriched ferromagnetism and two-photon absorption (TPA) cross-section of perovskite BaTiO3 nanoparticles are indispensable for magnetic and optical data storage applications. In this work, hydrothermally synthesized Ce-doped BaTiO3 nanoparticles exhibited the maximum room temperature ferromagnetism (4.26 × 10-3 emu g-1) at 4 mol% due to the increase in oxygen vacancies, as evidenced by X-ray photoelectron and electron spin resonance spectroscopy and density functional theory (DFT) calculations. Hence, the oxygen vacancy-constituted bound magnetic polaron (BMP) model was invoked to explain the enhancement in ferromagnetism. The BMP theoretical model indicated an increase in BMP magnetization (M0, 3.0 to 4.8 × 10-3 emu g-1) and true spontaneous moment per BMP (meff, 4 to 9.88 × 10-4 emu) upon Ce doping. DFT calculations showed that BMPs mediate via the Ti dz2 orbitals, leading to ferromagnetism. Besides, it is known that the magnetic moment induced by Ce at the Ba site is higher than Ce at the Ti site in the presence of oxygen vacancies. The open aperture Z-scan technique displayed the highest TPA coefficient, ß (7.08 × 10-10 m W-1), and TPA cross-section, σTPA (455 × 104 GM), at 4 mol% of Ce as a result of the robust TPA-induced excited state absorption. The large σTPA is attributed to the longer excited state lifetime, τ (7.63 ns), of the charge carriers created by oxygen vacancies and Ce ions, which encounter several electronic transitions in the excited sub-states.

Fabrication of MgO nanostructures and its efficient photocatalytic, antibacterial and anticancer performance.

Magnesium oxide (MgO) nanostructures were prepared using microwave-assisted (M 1) and hydrothermal (M 2) methods and characterized by XRD, SEM and FT-IR. It exhibits cubic structure with an average crystallite size of 20 nm (M 1) and 14 nm (M 2) and the lattice strain (WH plot) is 0.0017 (M 1), 0.0037 (M 2). It's spherical and rods like structures are confirmed through SEM and TEM. The vibrational stretching mode of MgO is 439 (M 1) and 449 cm-1 (M 2). The optical bandgap is estimated as 5.93 eV (M 1) and 5.85 eV (M 2) through UV-Vis spectra. The fluorescence spectrum shows emission peaks at 414 and 437 (M 1) and 367 and 385 nm (M 2). The photodegradation studies of MgO nanostructures were assessed by monitoring the decolorization of methylene blue and Congo red dyes in aqueous solution under sunlight irradiation. The antibacterial activities of M 1 and M 2 are investigated against the gram-negative (Escherichia coli, Shigella flexneri, Salmonella typhi, Proteus mirabilis, Aeromonas hydrophila and Vibrio cholera) and gram-positive (Bacillus subtilis and Rhodococcus rhodochrous) bacteria. The zone of inhibition of 24 (M 1) and 25 mm (M 2) indicates high antibacterial activity towards the gram negative bacterium A. hydrophila. Confocal laser scanning microscopic (CLSM) analysis was utilized for understanding the variation in antibacterial activity between different orientations of MgO nanostructures. The cytotoxicity assay confirmed that the prepared nanostructures are non - toxic to normal healthy RBC's. In-vitro anticancer efficiency (IC50) of MgO nanostructures against human lung cancer cell line (A549) was investigated.

Estimation of lattice strain in nanocrystalline RuO2 by Williamson-Hall and size-strain plot methods.

RuO2 nanoparticles (RuO2 NPs) have been successfully synthesized by the hydrothermal method. Structure and the particle size have been determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM). UV-Vis spectra reveal that the optical band gap of RuO2 nanoparticles is red shifted from 3.95 to 3.55eV. BET measurements show a high specific surface area (SSA) of 118-133m(2)/g and pore diameter (10-25nm) has been estimated by Barret-Joyner-Halenda (BJH) method. The crystallite size and lattice strain in the samples have been investigated by Williamson-Hall (W-H) analysis assuming uniform deformation, deformation stress and deformation energy density, and the size-strain plot method. All other relevant physical parameters including stress, strain and energy density have been calculated. The average crystallite size and the lattice strain evaluated from XRD measurements are in good agreement with the results of TEM.

Low power optical limiting studies of copper doped lithium tetraborate nanoparticles.

The copper doped lithium tetraborate (LTB:Cu) nanoparticles were synthesized by sol-gel method and characterized by XRD (tetragonal structure) and by FESEM (sphere-like nanoparticle). UV-Vis studies show that there is no strong absorption in the visible region. In the luminescence spectrum, the emission peak at 370 nm reveals the presence of Cu+ in LTB lattice. The relative powder second harmonic generation efficiency of pure and doped LTB is equal to the standard NLO material, KDP. The nonlinear optical parameters of LTB:Cu nanoparticles say, nonlinear refractive index, nonlinear absorption coefficient and third order nonlinear optical susceptibility were determined to be of the order of 10(-8)cm2/W, 10(-2) cm/W and 10(-5) esu, respectively. The optical power limiting behavior of the samples were studied by Z-scan technique with (532 nm, 50 mW) Nd:YAG laser and the limiting threshold values are found to be 22.7 mW for 0.01 M and 24.9 mW for 0.03 and 0.05 M LTB:Cu nanoparticles.

χ(3) Measurement and optical power limiting behavior of manganese doped lithium tetraborate nanoparticles.

Manganese doped Li2B4O7 nano crystallites were prepared by chemical method and characterized by XRD, FTIR, UV and fluorescence spectra. FESEM reveals that the particles are coagulated and the particle size is in the range of 50-107 nm. Bands appear at 682-769 cm(-1) corresponds to the bending of B-O linkage in borate network. Nonradiative energy transfer process is observed from fluorescence spectrum. UV-Vis studies show the samples are completely transparent in the visible region and having absorption peaks (234 and 276 nm) in UV regime. The measured second harmonic generation values are 0.9 times KDP. The nonlinear optical parameters such as nonlinear refractive index, n2 (10(-8) cm(2)/W), nonlinear absorption, ß (10(-2) cm/W) and nonlinear optical susceptibility, χ(3) (10(-5) esu) are estimated using a Nd:YAG laser (532 nm, 50 mW).

Microwave-assisted synthesis of CdO-ZnO nanocomposite and its antibacterial activity against human pathogens.

CdO-ZnO nanocomposite was prepared by microwave-assisted method and characterized by X-ray crystallography (XRD), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR). It exhibits hexagonal cubic structure with an average crystallite size of 27 nm. From the UV-Vis spectra, the bandgap is estimated as 2.92 eV. The fluorescence spectrum shows a near band edge emission at 422 nm. In addition the antibacterial activity of CdO-ZnO nanocomposite was carried out in-vitro against two kinds of bacteria: gram negative bacteria (G -ve) i.e. Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and gram positive bacteria (G +ve): Staphylococcus aureus, Proteus vulgaris and Bacillus spp. This study indicates the zone of inhibition of 40 mm has high antibacterial activity towards the gram positive bacterium S. aureus.

Micro-structural, linear and nonlinear optical properties of titania nanoparticles.

TiO(2) (titania) nanoparticles were prepared by sol-gel method using titanium tetrachloride as precursor and calcined at 500°C (SA1) and 800°C (SA2). X-ray diffraction pattern of SA1 has mixed phases of anatase (17%) and rutile (83%) whereas SA2 has pure rutile (100%) TiO(2). From the X-ray diffraction peak profile analysis, the crystallite size, lattice strain, deformation stress and energy density value of TiO(2)nanoparticles were determined more precisely by Williamson-Hall method, uniform deformation model, uniform stress deformation model, uniform deformation energy density model and size-strain plot method. The calculated average crystallite size from uniform stress deformation model is 21 and 53nm for SA1 and SA2 respectively. From the FTIR spectra Ti-O vibrational frequency is observed at ∼530cm(-1). Using Tauc's relation the direct bandgap of SA1 and SA2 is calculated from UV-vis spectra as 2.75 and 2.95eV respectively. The excitation wavelength dependent photoluminescence has been investigated for 290 and 330nm as excitation wavelengths. It was observed that the band edge emission is decreased with respect to excitation wavelengths. The second harmonic generation efficiency (SHG) observed for centrosymmetric rutile TiO(2) is more comparable with KDP crystal.

4-Hy-droxy-1,2,6-tri-methyl-pyridinium chloride monohydrate.

In the crystal of the title hydrated mol-ecular salt, C8H12NO(+)·Cl(-)·H2O, the water mol-ecule makes two O-H⋯Cl hydrogen bonds, generating [010] zigzag chains of alternating water mol-ecules and chloride ions. The cation is bonded to the chain by an O-H⋯O hydrogen bond and two weak C-H⋯Cl inter-actions. Weak aromatic π-π stacking [centroid-centroid separation = 3.5175 (15) Å] occurs between the chains.

4-Hy-droxy-1,2,6-tri-methyl-pyridinium bromide monohydrate.

The title salt, C8H12NO(+)·Br(-)·H2O, is isomorphous with the chloride analogue [Seethalakshmi et al. (2013). Acta Cryst. E69, o835-o836]. In the solid state, the cations, anions and water mol-ecules are inter-linked by a network of O-H⋯O, O-H⋯Br and C-H⋯Br inter-actions. The water mol-ecule makes two O-H⋯Br hydrogen bonds, generating [010] zigzag chains of alternating water mol-ecules and bromide anions. The cation is involved in two inter-molecular C-H⋯Cl inter-actions in the chloride salt, whereas three inter-molecular C-H⋯Br inter-actions are observed in the title bromide salt. This additional inter-molecular C-H⋯Br inter-action links the adjacent water and bromide zigzag chains via cationic mol-ecules. In addition, weak π-π stacking inter-actions are observed between pyridinium rings [centroid-centroid distance = 3.5664 (13) Å].

Optical studies on electron beam evaporated lithium triborate films.

Lithium triborate (LB3) has numerous applications in scintillator for neutron detection, laser weapon and communication. LB3 films have been prepared by electron beam evaporation technique under a pressure of 1×10(-5) mbar on glass substrate at 323 K for 4 min. The crystallographic orientations and the lattice parameters (a=8.55 (2); b=5.09 (2); c=7.39 (2)Å) were determined by powder XRD indicating the (111) preferential orientation of the film. The lower cut off wavelength at 325 nm with 75% transparency was measured from the UV-vis spectrum. The optical constants extinction coefficient (K), reflectance (R), the linear refractive index (1.34) and the optical energy band gap (~4.0 eV) were estimated. The photoluminescence spectrum shows the emission peak in the visible region with low concentration of oxygen defects. LB3 is found to be second harmonic generation (SHG) active using a Q-switched Nd:YAG laser (1064 nm, 9 ns, 10 Hz). The nonlinear refractive index (n(2)~10(-16) cm(2)/W) and nonlinear absorption coefficient (ß~10(-2) cm/W) reveal (Z-scan technique) that the material has negative nonlinearity and self-focusing nature.

Dibromidobis(1-ethyl-2,6-dimethyl-pyridinium-4-olate-κO)zinc(II).

In the bioactive title compound, [ZnBr(2)(C(9)H(13)NO)(2)], the Zn(II) atom is coordinated in a distorted tetra-hedral arrangement by two Br(-) anions and the O atoms of two zwitterionic organic ligands. The pyridinium rings are almost planar [maximum deviations = 0.004 (4) and 0.003 (4) Å]. The ethyl groups are approximately perpendicular to the corresponding pyridinium ring planes [N-C-C-C = 88.8 (4)° in each ligand]. The packing of the mol-ecules is controlled by π-π inter-actions, with centroid-centroid distances of 3.625 (3) and 3.711 (2) Å, forming chains approximately parallel to (102). The crystal studied was non-merohedrally twinned (twin relationship between the domains 1 0 0, 0 1 0, -0.4672 -0.1864 -1 and batch scale factor of 7.39%).

Dichloridobis(1-ethyl-2,6-dimethyl-pyridinium-4-olate-κO)zinc(II).

In the title compound, [ZnCl(2)(C(9)H(13)NO)(2)], the Zn(II) ion is coordinated by two Cl(-) anions and two O atoms of two zwitterionic organic ligands in a distorted tetra-hedral arrangement. In the crystal, mol-ecules are linked into sheets parallel to the bc plane by C-H⋯Cl and C-H⋯O hydrogen bonds and weak π-π inter-actions [centroid-centroid distance = 3.669 (1) Å].

Synthesis, spectral, optical and thermal studies of 1-methyl-2,6-dimethyl-4-hydroxypyridinium chloride monohydrate and bromide monohydrate.

Semiorganic 1-methyl-2,6-dimethyl-4-hydroxypyridinium chloride monohydrate (MDMPCl.H(2)O) and bromide monohydrate (MDMPBr.H(2)O) salts have been synthesized. Single crystals of MDMPCl.H(2)O and MDMPBr.H(2)O were grown by the slow evaporation method from aqueous solution at constant temperatures 30 and 32 degrees C respectively. The grown crystals were characterized by elemental analysis, FT-IR and FT-NMR techniques and their molecular structures were elucidated. Thermogravimetric, differential thermal analyses and differential scanning calorimetry reveal the presence of water molecules in the crystal lattices and thermal stabilities. Optical transmittance windows in aqueous solution were found as 300-1100 nm using UV-vis-NIR spectrophotometer.

Crystal growth of phase matchable new organic nonlinear optical material for UV laser generation.

L-histidinium tetrafluorosuccinate (L-HFS), an organic nonlinear optical material has been synthesized and characterized by the elemental analysis, FT-IR, FT-NMR and X-ray diffraction studies. Solubility of L-HFS was found to be higher in water than ethanol. Single crystals with dimensions 10 mm x 6 mm x 3 mm were grown in an aqueous solution by the slow evaporation technique at 30 degrees C. The thermal stability of L-HFS has been analyzed by thermogravimetric and differential thermal analyses (TGA and DTA). The UV-vis spectral study reveals that the material has a wide optical transparency in the entire visible region with the lower cutoff wavelength at 235 nm. The phase matching condition was obtained by Kurtz powder second harmonic generation (SHG) efficiency test. The laser damage threshold of the grown crystal was measured using a Q-Switched Nd:YAG laser (1064 nm).

Crystal growth, thermal and optical studies on a semiorganic nonlinear optical material for blue-green laser generation.

The semiorganic nonlinear optical material l-histidine bromide (l-HB) has been synthesized in aqueous solution and characterized by FT-IR, FT-Raman and FT-NMR spectroscopic techniques. The single crystals with dimensions 9mm x 4mm x 3mm were grown by slow evaporation techniques. The grown crystals were subjected to single crystal X-ray diffraction to determine the unit cell dimensions. The thermal stability of the grown crystal was analyzed by thermogravimetric (TG), differential thermal (DT) and differential scanning calorimetric (DSC) analyses. The UV-vis transmittance spectrum shows that it has a good optical transmittance in the entire visible region with the lower cutoff wavelength at 220 nm. The SHG conversion efficiency and laser damage threshold were measured using a Nd:YAG laser (1064 nm). The optical birefringence was measured in the visible region as a function of temperature in the range 30-150 degrees C by interference technique.

EPR of gamma-irradiated single crystals of 2-amino-5-nitro pyridinium L-tartrate: a NLO material.

Single crystals of a non-linear optical (NLO) material 2-amino-5-nitropyridinum L-tartrate (ANPLT) were grown by solvent evaporation technique and characterized by the measurement of density, FT-IR, FT-Raman and X-ray diffraction techniques. Microhardness study and SHG test were also carried out. The EPR spectra were recorded for gamma-irradiated single crystal of ANPLT. The angular variation studies of the spectra were carried out and the principal values of g- and A-tensors were determined. The site symmetry of the radical formed is axial.

Semiorganic nonlinear optical material for frequency doubling: preparation and properties of sodium p-nitrophenolate dihydrate (SPNP).

Sodium p-nitrophenolate (SPNP), a semiorganic nonlinear optical (NLO) material useful for frequency doubling in the IR region, has been synthesized. The solubility studies have been carried out in the temperature range 30-50 degrees C. Single crystals (size 12 mmx7 mmx4 mm) have been grown by slow evaporation of the saturated aqueous solution (methanol as solvent) at 30 degrees C. The lattice parameters of the grown crystals have been determined by single crystal X-ray diffraction technique. The UV-vis-NIR transmittance spectrum has been recorded in the range 200-1500 nm. The molecular structure was confirmed by FT-IR and FT-NMR. SPNP was thermally stable up to 103 degrees C as determined by TG/DTA curves. By a modified Kurtz and Perry method, the powder SHG efficiency was found to be five times that of KDP and its phase matching property was established. Laser damage threshold of SPNP was determined using a Nd:YAG laser.

Spectral and optical studies of 2-amino-5-nitropyridinium dihydrogen phosphate: a semiorganic nonlinear optical material.

2-Amino-5-nitropyridinium dihydrogen phosphate (2A5NPDP) was synthesized and the molecular structure was elucidated by FT-IR, FT-Raman and FT-NMR. The proton and carbon configurations of 2A5NPDP was confirmed through FT-NMR technique. UV-vis-NIR spectrum was recorded and the optical transmittance region was identified as 350 nm. Single crystals were grown from ethanol by slow evaporation technique at 35 degrees C and the unit cell constants were determined. Bulk and powder second harmonic generation (SHG) measurements were carried out using Nd:YAG laser (lambda=1064 nm) and its phase matching condition was determined.

Structural and thermal characterization of a semiorganic NLO material: L-alanine cadmium chloride.

L-Alaninium cadmium chloride (LACC), a semiorganic nonlinear optical material has been synthesized and its single crystal grown and characterized for its thermal, structural, linear and second order nonlinear optical properties. Powder SHG study shows that LACC is 1.5 times efficient as KDP. Its optical transparency goes down to 200 nm comparable to the typical borate crystals like potassium pentaborate.