Search

This research work bring in a simple circularly polarized slot antenna with Proximity Couple Feed for the utilization in Ultra high frequency (UHF) band Radio-frequency identification (RFID) reader devices. The presented antenna is fed using proximity couple technique with a bent like feeding structure to achieve improved impedance matching and meandering slot etched on ground plane to achieve circular polarization in targeted frequency band. The results obtained from investigation exhibit that the introduced antenna shows a very good return loss (RL)-10-dB bandwidth (BW) 110MHz (865-975) MHz / 12.1% and below 3-decible axial ratio (AR) BW 92(862-954) MHz/ 10.5%. In addition the designed antenna shows maximum gain of 5.89dBic in the targeted frequency band. The proposed slot antenna shows improved results and it has a simple geometry, small in size (120x80x0.8 mm3) which makes it suitable for the use in UHF (860-960MHz) RFID reader applications. [ABSTRACT FROM AUTHOR]

The present study aims at green synthesis of silver oxide nanoparticles (Ag2O NPs). The synthesis of Ag2O NPs was achieved using rhizome extract of plant B. ciliata as a promoter of reduction and stabilization. Characterization of Ag2O NPs were performed using UV–Vis(Ultraviolet–Visible Spectroscopy), XRD (X-ray Diffraction), DLS (Dynamic Light Scattering), FTIR (Fourier Transform Infrared Spectroscopy), SEM (Scanning Electron Microscopy) and EDX (Energy-Dispersive X-ray Analysis). The formation of Ag2O NPs is confirmed by the signatory brown coloured appearance of the solution. UV visible spectrum clearly reveals the formation of nanoparticles and intense surface plasmon resonance band at wavelength of 400-450 nm. FTIR spectrum confirms the distinct interacting groups of nanoparticles are present and are responsible for capping the biomolecules.Studies on XRD showed a high degree of natural crystallinity. The mean particle size investigated using DLS was found in between 10–20 nm. SEM analyses Ag2O NPs aggregate formation with EDX spectrum and spherical-like formation, which confirms the presence of Ag and O in the synthesised NPs. Green synthesis is therefore always a highly recommended low cost and eco-friendly method for large-scale industrial as well as medicinal applications. [ABSTRACT FROM AUTHOR]

The performance of solution-processed organic solar cells is often limited by various recombination pathways. In this scenario ideality factor (nid) act as a signature for identification of different loss mechanisms in these solar cells. A detailed analysis of open circuit voltage (Voc) dependence on illumination intensity as well as electroluminescence (EL) dependence on the injected currents can provide the value of ideality factor. We have carried out this study for identification and quantification of dominant recombination loss mechanism in crystalline Si and organic solar cells. The obtained ideality factor by these two methods support each other which validates the result. On the basis of these studies, it has been concluded that the major energetic loss in bulk heterojunction (BHJ) based organic solar cell arises due to its low radiative efficiency (QLED) and non-radiative recombination loss mechanism at donor/acceptor interface and semiconductor/electrode interfaces. So the performance of the organic solar cells can be improved by optimizing the semiconductor-electrode energy alignment, and surface morphology near contacts [ABSTRACT FROM AUTHOR]

In this paper we discuss and proposed two simple and effective designs of birefringent photonic crystal fibers with modified geometry and the coating of metal with the liquids filled along the direction of propagation of electromagnetic wave. Results revealed the dependency on the parameters of fiber like air hole size and filled liquid. Due to metal-dielectric layer and modified designs the high surface plasmon resonance peak along the transverse axis at wavelengths 1.33 and 1.55μm have been obtained. [ABSTRACT FROM AUTHOR]

Free standing polypyrrole films were synthesized using aqueous-organic interfacial polymerization. The electrical conductivity of these films was found to be higher when hexane(or benzene)-aqueous biphasic system is used. These high conductivity films were utilized as cost effective counter electrode to replace expansive Platinum in the fabrication of quasi-solid dye sensitized solar cells. The efficiency of DSSC was found to be 1.1%, which is close to that of 1.8% prepared using Pt as counter electrode. [ABSTRACT FROM AUTHOR]

Struvite, Ammonium Magnesium Phosphate Hexahydrate [(AMPH) - (NH4)MgPO4.6(H2O)], is one of the fascinating inorganic phosphate minerals. Struvite is one of the components of the urinary stones. Struvite occurs as crystallites in urine and grows as a type of kidney stone. In this study, struvite nano particles were synthesized by wet chemical technique. The aqueous solutions containing dissolved Mg(CH3COO)2.4H2O and (NH4)H2PO4 mixed at the Mg/P molar ratio of 1.00. The synthesized struvite nano particles were characterized by XRD, FT-IR, Thermal Analysis and TEM. From XRD, crystal structure of the nano particle was found to be orthorhombic and crystalline size was found to be within 11 to 26 nm. The FT-IR spectrum for the struvite nano particles confirmed the presence of a water molecule and metal-oxygen stretching vibration, O-H stretching and bending, N-H bending and stretching, P-O bending and stretching vibrations. The Thermal Analysis was carried out from room temperature to 900°C. From TEM analysis, particle size was 23 to 30 nm. All the results were compared with bulk struvite. [ABSTRACT FROM AUTHOR]

Conducting polymer films were synthesized and employed as an alternative to expensive platinum counter electrodes for dye-sensitized solar cells. poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) thin films were spin-coated and polypyrrole films were electrochemically deposited via cyclic voltammetry method on ITO substrates. The morphology of the films were imaged by SEM and AFM. These films show good catalytic activity towards triiodide reduction as compared to Pt/FTO electrodes. Finally the photovoltaic performance of DSSC fabricated using N3 dye were compared with PT/FTO, PEDOT/ITO, and e-PPy counter electrodes. [ABSTRACT FROM AUTHOR]

Self assembled monolayer (SAM) of Octadecyltrichlorosilane (OTS) was deposited on thermally grown SiO2 dielectric of 200 nm thickness and the electrical performance of copper phthalocyanine (CuPc) based OFETs was studied before and after SAM modification of dielectric. The field effect mobility of charge carriers and drain current on/off ratio wwre found to be improved by about one order of magnitude due to improved crystallinity of CuPc film on SAM modified SiO2. The inverse sub-threshold slope was reduced significantly indicating reduction of trap density at the dielectric/semiconductor interface by 50% as a result of SAM treatment. [ABSTRACT FROM AUTHOR]

A photoelectrochemical cell (PEC) is reported using a BODIPY derivative as dye sensitizer and an aqueous solution containing Ferric/ferrous redox couple (F+++/Fe++) as electrolyte. The dye shows good electrochemical and optical properties as evident from cyclic voltammetry and UV-Vis spectroscopy data. The open circuit voltage and short circuit current of the PEC were found to be 181mV and 0.32 μA/cm2, respectively under white light illumination having intensity of 1mW/cm2. [ABSTRACT FROM AUTHOR]

Effects of growth process and after growth thermal treatment on daylight coloration and afterglow of CsI:Tl scintillator have been studied. Induced absorption, photoluminescence, thermo-luminescence and afterglow were used as tools for the identification/analysis of crystal defects. Formation of color centers and their dependence on growth process were established. A possible diffusion mechanism of color centers during the heat treatment of the crystal is proposed. Results of our experiments show that a post growth annealing minimize those number of color centers that are directly responsible for afterglow and daylight coloration. It has been demonstrated that excess of centers associated with Tl+ dimers are also responsible for the large afterglow in this crystal. [ABSTRACT FROM AUTHOR]

Differential thermal analysis (DTA) and X-ray diffraction (XRD) studies were carried out to understand the melting behavior of the NaY(WO4)2, an important functional material used for the laser production. It has been observed that the stoichiometric NaY(WO4)2 composition forms a solution with another phase of the Na2WO4-Y2(WO4)3 pseudo-binary system. This is found to be detrimental for the growth of single crystals of the material. Therefore, molar fraction in the starting charge was suitably altered to successfully restrict the formation of the undesired phase in the melt. A composition is suggested for the favorable crystal growth of this material. [ABSTRACT FROM AUTHOR]

The performance of dye-sensitized solar cells is improved by simple formic acid treatment of TiO2 photoanodes. The treatment increases number of hydroxyl groups at TiO2 surface and thereby result in enhanced dye-loading and device efficiency. The best device showed an open circuit voltage of 0.62V, short-circuit current density 6.34mA/cm2, fill factor of 60%, and a power conversion efficiency of ∼12 % under 20mW/cm2 white light illumination. [ABSTRACT FROM AUTHOR]

Effect of polystyrene (PS) modification of SiO2 dielectric on the performance of copper phthalocyanine (CuPc) based OFETs was studied. Field effect mobility of holes was found to increase by one order for polystyrene modified dielectric as compared to that on unmodified SiO2. This is attributed to well connected grains and increased crystallinity of CuPc film. Significantly reduced hysteresis was found in the devices with PS/SiO2 dielectric due to almost complete absence of hydroxyl groups at the dielectric/semiconductor interface and hence reduced trap sites. [ABSTRACT FROM AUTHOR]

Electrochemical oxidation of tetrakis-5,10,15,20-(4-hydroxyphenyl)porphyrin (THPP) on ITO electrodes was carried out. It leads to a uniform polymeric film (poly-THPP) with a nanostructured morphology. Poly-THPP electrodes as a bilayer organic solar cell and bulk heterojunction solar cells are investigated. The device with Phenyl-C61-butyric acid methyl ester (PCBM) integrated bilayer shows a modest photoactivity. [ABSTRACT FROM AUTHOR]

We demonstrate a dye sensitized solar cell (DSSC) using a new organic dye (i.e. rhodamine 19 perchlorate) sensitized TiO2 electrode. The power conversion efficiency of the cell was found to be 1.1% under white light illumination. The binding modes of the dye to TiO2 electrode as well as the mechanism of the cell are discussed. [ABSTRACT FROM AUTHOR]

Single crystal growth of NaY(WO4)3 was carried out by the Czochralski technique using a starting charge rich in Y2(WO4)3 composition. This off-stoichiometric starting composition used for the growth has been found to yield reasonable size single crystals. The XRD measurements carried out on the powder from different positions of the grown crystal confirmed the presence of desired single phase NaY(WO4)2. Grown crystals were found to have good transparency. [ABSTRACT FROM AUTHOR]

Photoluminescence properties of NaBi(WO4)2 crystals were studied near liquid nitrogen temperatures. The excitation and emission properties were found to be similar to an iso-structural Scheelite PbWO4. A metal-to-metal charge-transfer character (Bi3+→W6+) is found responsible for the emission process. The thermal activation energy for quenching of the luminescence was found to be about 160 meV. [ABSTRACT FROM AUTHOR]

Differential thermal analysis (DTA) and X-ray diffraction (XRD) studies were carried out to understand the melting behavior of the NaY(WO4)2, an important functional material used for the laser production. It has been observed that the stoichiometric NaY(WO4)2 composition forms a solution with another phase of the Na2WO4-Y2(WO4)3 pseudo-binary system. This is found to be detrimental for the growth of single crystals of the material. Therefore, molar fraction in the starting charge was suitably altered to successfully restrict the formation of the undesired phase in the melt. A composition is suggested for the favorable crystal growth of this material. [ABSTRACT FROM AUTHOR]