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The influence of molecular phase separation on thermal activation barriers of phase transformations in GexSe80-xPb20 glasses has been investigated using non-isothermal methods. Kinetic parameters of glass transition, crystallization and decomposition were determined using differential scanning calorimetric and thermo-gravimetric measurements. The model free Kissinger and isoconversional Flynn-Wall-Ozawa methods were employed to calculate the activation energies of thermally induced structural transitions. The observed variation in thermal properties with Ge content in place of Se could be interpreted in terms of the formation of tetrahedrally coordinated Ge-Se structural units at expense of Se-Se units. Deviations in the activation energies of crystallization and decomposition with the extent of conversion indicate the mechanistic complexity of the transformations as these involve different nucleation and growth events due to the presence of different phases. GexSe80-xPb20 glass with x = 20 has been found to attain the maximum activation barriers showing high thermal stability and structural rigidity. [ABSTRACT FROM AUTHOR]

In the framework of this study, pure and Li-doped TiO 2 (0.5, 1.5, 2.5 at.%) thin film samples were synthesised via sol–gel spin coating method. The structural, morphological and optical properties were examined by using X-ray diffraction, scanning electron microscopy (SEM) and UV–Vis spectroscopy respectively. XRD pattern reveals the polycrystalline nature of Li-doped TiO 2 thin films with anatase crystal phase. The average crystallite sizes were found to be in the range of 19–23 nm. The energy-dispersive X-ray spectroscopy (EDS) demonstrates the oxidation states of Ti, O and Li in the deposited thin films. The optical band gap of TiO 2 thin films was varied from 3.15 to 3.26 eV on increasing Li doping. For the study of light emission properties of Li-doped TiO 2 thin films, the PL spectra were recorded in the wavelength range of 350–700 nm. The doping of Li on TiO 2 films show improved charge transport properties which can be used in optoelectronics and energy storage devices. [ABSTRACT FROM AUTHOR]

Al-doped ZnO (AZO) thin films have been deposited onto the glass substrate via sol–gel spin coating method with different Al concentrations (0, 2, 4, 6, 8, 10 at.%). The growth orientation and crystalline structure were investigated by studying the X-ray diffraction (XRD) pattern. The XRD results reveal that the thin films show wurtzite phase with preferential orientation along the c-axis (002) plane for lower concentration of Al. The diffraction peak gets weaker corresponding to plane (002) and the diffraction peaks of planes (101) and (100) become stronger with higher concentration of Al content. The field emission scanning electron microscopy (FE-SEM) images confirm that thin films show wrinkle-type structure with a few minor cracks. The transmittance spectra of thin films were recorded by UV–Vis spectrophotometer in the wavelength range 350–800 nm. The optical transmittance of thin films was found to be above 85%. The band-gap energy of AZO films varies from 3.16 eV to 3.27 eV with increasing concentration of Al. The better conductivity and high optical transparency of AZO films make them a more promising alternative to indium-doped tin oxide (ITO) for optoelectronic applications. [ABSTRACT FROM AUTHOR]

In this paper, the design of a triode-type magnetically tunable magnetron injection gun (MT-MIG) is presented for 1-MW 110-, 120-, and 127.5-GHz-frequency gyrotrons with the various operating modes. Some basic equations relevant to the problem available in the literature have been used to obtain the preliminary design. Computer simulation has been performed by using the commercially available code EGUN. The triode-type MT-MIG with the accelerating voltage of 80 kV, the beam current of 40 A, the average transverse-to-axial velocity ratio of the electron beam of 1.26–1.35, and the maximum transverse velocity spread of less than 5% has been designed. Tuning of the MT-MIG is performed by varying the magnetic field. [ABSTRACT FROM AUTHOR]

A 40 A double-anode magnetron injection gun for a 1 MW, 110 GHz gyrotron has been designed. The preliminary design has been obtained by using some trade-off equations. The electron beam analysis has been performed by using the commercially available code EGUN and the in-house developed code MIGANS. The operating mode of the gyrotron is TE22,6 and it is operated in the fundamental harmonic. The electron beam with a low transverse velocity spread ( $$ \delta {\beta_{ \bot \max }} = 2.26\% $$) and the transverse-to-axial velocity ratio of the electron beam (α) = 1.37 is obtained. The simulated results of the MIG obtained with the EGUN code have been validated with another trajectory code TRAK. The results on the design output parameters obtained by both the codes are in good agreement. The sensitivity analysis has been carried out by changing the different gun parameters to decide the fabrication tolerance. [ABSTRACT FROM AUTHOR]

In this study, n-type CdyZn1−yO (y = 0, 0.5, 1, 1.5 at%) thin films were deposited on p-Si and soda lime glass substrates using sol–gel spin coating technique. From the X-ray diffraction patterns, it was observed that all thin films had wurtzite structure with (002) orientation. Scanning electron micrograph results revealed that the morphology varied with higher Cd doping in ZnO. The bandgap was decreased from 3.29 eV (undoped ZnO) to 3.26 eV (y = 1.5 at%) as Cd content increased. The electronic parameters of the CdyZn1−yO (y = 1 at%) thin film heterojunction such as ideality factor (η) and barrier height (ΦB) were obtained using the thermionic emission theory as 2.53 and 0.70 eV, respectively. CdyZn1−yO (y = 1 at%) showed responsivity 0.01 A/W on 3.2 mW/cm2 exposure of UV light (365 nm) at 4 V bias voltage. The heterojunction so formed seems to be an excellent candidate to be used as an optical sensor (UV photodetector) in optoelectronics. [ABSTRACT FROM AUTHOR]

The annealing temperature of CdO-ZnO (3:1) particles that were derived by using a sol–gel precipitation method has been optimized in order to improve the photoluminescence (PL) efficiency. The CdO-ZnO particles have been characterized by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), impedance spectroscopy and UV–VIS spectroscopy. The transition point was found near 32°C with DSC for the highest annealing temperature (600°C). The impedance (Z) and phase angle (θ) as functions of frequency were recorded and the CdO:ZnO particles annealed at 450°C has the lowest 8.2–6.8 kΩ impedance. The reflectance spectra in the range of 300–800 nm were recorded and the optical bandgap was found varied from 2.76 to 2.99 eV. The excitation and emission PL spectra were obtained and the sample annealed at 600°C showed an intense blue emission with respect to the other samples. [ABSTRACT FROM AUTHOR]

The present paper reports the synthesis and characterization of poly (o-toluidine) (POT) embedded with barium ferrite and reduced graphene oxide. Barium ferrite nanoparticles (BF) were prepared by citrate precursor technique. Synthesis of reduced graphene oxide (RGO) from graphite powder was carried out by improved Hummer's method. Composite of poly (o-toluidine) with barium ferrite and reduced graphene oxide (POT/BF/RGO) was synthesized by in-situ polymerization method. The formulation shows total shielding effectiveness of 12.07 dB in the X-band (8.4-12.4 GHz) frequency range. Permeability and dielectric parameters have been calculated from the measured scattering parameters (S11, S22, S12, S21) using the Nicolson-Ross-Weir algorithm. The synthesized formulations were characterized using x-ray diffraction (XRD), scanning electron microscope (SEM), Transmission electron microscopy TEM, Ultraviolet-visible spectroscopy (UV-Vis) and vibrating sample magnetometer (VSM). [ABSTRACT FROM AUTHOR]

In sequence to permit electronic gadgets to coexist without maleficent electromagnetic interference (EMI) it is essential to evolve new absorbing and shielding materials with good performance. These technological fields demand not only efficient shields but also materials that meet specific criteria for each engineered design. For example chemical and corrosion resistance, lightweight, flexibility, tunable morphology, processing easiness and inexpensiveness are required. The concerned work present BF/EG composite was appreciated for these applications. The Microwave absorption characteristic were find out in the frequency range 8–12 GHz. Shielding effectiveness of BF/EG composite was obtained 52.4 dB. The material is found to have good microwave absorption materials for EMI shielding applications. [ABSTRACT FROM AUTHOR]

This paper presents a three-dimensional (3-D) simulation of a triode-type magnetron injection gun (MIG) for a 42-GHz 200-kW gyrotron with a transverse-to-axial velocity ratio of the electron beam at 1.22 and a maximum transverse-velocity spread of 3.2%. The operating mode of the gyrotron is TE03, and it is operated in the fundamental harmonic. The MIG has been designed by using some tradeoff equations and the 3-D particle-tracing code (computer simulation technology). The simulated results have been validated with the results obtained using the 3-D code OPERA Vector Fields and the two-dimensional trajectory codes EGUN and TRAK. [ABSTRACT FROM AUTHOR]

The magnetic and electromagnetic wave absorbing properties were investigated in the Ni substituted cobalt ferrites, Co1-xNixFe1.9Mn0.1O4 (0≤ x ≤ 1.0), prepared by solid state technique with the increase in concentration of Ni doping uniformly in grain size and densification have improved, while permeability increased remarkably. Saturation magnetization and coercivity both decreased with Ni concentration in cobalt ferrite. Electromagnetic parameters of ferrite samples were measured in X-band frequency range (8-12 GHz) by vector network analyzer (VNA) and their absorbing properties were calculated according to transmission-line theory. Phase formation of all samples has been confirmed by XRD. Ferromagnetic resonance frequency shift has been observed with concentration of Ni concentration which is an important phenomenon of cobalt ferrite to absorb microwave at higher frequencies in X-band. Based on magnetic and microwave measurements Co1-xNixFe1.9Mn0.1O4 (x = 0.8) may be a good potential candidate for electromagnetic compatibility and for other practical applications at high frequencies. [ABSTRACT FROM AUTHOR]

The article presents a study which designed a triode-type magnetron injection gun of a 42-gigahert, 200-kilowatt gyrotron for an Indian TOKAMAK system by applying the code EGUN. The gyrotron is an instrument that can produce high powers at very high frequencies. The estimations are carried out to calculate the parameters connected to the cathode, the magnetic field, and the modulating anode voltage. The study is accomplished with the validation of the design by utilizing another code TRAK.

The present paper reports the fabrication of dye sensitized solar cell (DSSC), where boron doped ZnO (BZO) and aluminum-boron co-doped ZnO (AZB) thin films were used as front window electrodes. The highly crystalline zinc oxide (ZnO) nanoparticles (NPs) synthesized by the sol-gel route were used as host material for the dye. The efficiencies of the DSSCs formed using the BZO and AZB as window layers were obtained to be 1.56 and 1.84%, respectively. The enhanced efficiency in the case of an AZB window layer based DSSC is attributed to the increase in conductivity induced by co-doping of Al and B and an increase in the number of conducting pathways between the window layer and NPs provided by the nanorods. This facilitates a new approach in the window layer (doped ZnO) for DSSC application. [ABSTRACT FROM AUTHOR]