Rajeev Arora, Subhash Chand and Pankaj Sharma
A conducting nanocomposite film of 60 nm nano-SnO2-polyaniline (PANI) and polyvinyl alcohol (PVA) has been synthesized and analyzed in terms of AC conductivity and dielectric behavior. The conducting polymer nanocomposite of PANI/60 nm (SnO2) and polyvinyl alcohol (PVA) has been prepared via in situ polymerization technique. The morphology of the nanocomposite film has been studied by SEM. The film has been characterized in terms of DC conductivity. The dielectric behavior and AC conductivity of the nanocomposite film have been investigated in the frequency range of 2 Hz to 90 KHz. The film has high dielectric constant which may be correlated with polarization. It has been observed that both dielectric loss and dielectric constant decrease with an increase in frequency.
Imran Khan, S. Kalainathan, M.I. Baig, Mohd Shkir, S. Alfaify, H.A. Ghramh and Mohd Anis
Present investigation has been started to perform the comparative study of pure and glycine doped KH2PO4 (KDP) single crystals grown by most commercial slow solvent evaporation technique. The grown crystals were subjected to single crystal X-ray diffraction analysis to determine their structural parameters. The linear optical studies of pure and glycine doped KDP crystal have been undertaken within 200 nm to 1100 nm wavelength range by means of UV-Vis studies. The enhancement in second harmonic generation (SHG) efficiency of glycine doped KDP crystal has been determined using a standard Kurtz-Perry powder test. The dielectric measurements have been carried out to explore the impact of glycine dopant on dielectric constant and dielectric loss of KDP crystal. The surface growth habitat and etch pit density of glycine doped KDP crystal have been evaluated using the results of microscopic etching studies. In light of obtained results the suitability of glycine doped KDP crystal for device applications has been discussed.
K. Ramarao, B. Rajesh Babu, B. Kishore Babu, V. Veeraiah, K. Rajasekhar, B. Ranjith Kumar and B. Swarna Latha
In this work, Ni substituted magnesium spinel ferrites having general formula Mg1–xNixFe2O4 (where x = 0.0, 0.1, 0.15, 0.2, 0.25 and 0.3) were synthesized by standard solid state reaction method. All the samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), DC resistivity measurements. X-ray diffraction analysis confirmed the single spinel phase. The lattice constant decreased with increasing Ni content due to the difference in the ionic radii of Mg2 + and Ni2 + ions. The FT-IR spectra reveled two prominent frequency bands in the wave number range of 400 cm−1 to 600 cm−1, which confirmed the cubic spinel structure of obtained compound and completion of chemical reaction. Magnetic studies revealed that the saturation magnetization increased with the substitution of Ni. The increase in magnetization was explained on the basis of distribution of magnetic and non-magnetic cations among A and B sites of the spinel lattice. A significant influence of cation distribution on DC electrical resistivity and activation energy was observed.
The effect of MgB2 addition on the Eu1Ba2Cu3O7 (EBCO) ceramics was systematically studied. Series of Eu1Ba2Cu3O7 + x(MgB2) samples (x = 0 wt.%, 0.05 wt.%, 0.1 wt.%, 1 wt.%, 3 wt.%) were prepared using traditional solid state method. X-ray powder diffraction measurements were used for phase identification. The lattice parameters and orthorombicity decreased with MgB2 addition. A standard four point measurement method was used to determine transition temperatures Tc of superconducting samples. Tc values of the samples were decreasing with MgB2 concentration. TGA results indicate thermal stability of doped samples.
T. G. Abdullah, S. A. Sami and M. S. Omar
Theoretical formalism based on the orthogonalized plane wave method supplemented by a potential scaling scheme was used to predict the temperature dependence of energy gap of CuSi2P3semiconductor. A computer code in Pascal was used to perform the variation of fundamental energy gap with temperature in the range of 150 K to 800 K. The dependence of energy gap on temperature for lattice dilation contribution, lattice vibration contribution and total temperature effect were performed separately. The results revealed that, as temperature increases, the top of the valence band and the bottom of the conduction band increase, while the energy band gap decreases. Generally, at low temperatures, the energy gap varies slowly and exhibits a nonlinear dependence and approaches linearity as temperature increases. The calculated energy gap of CuSi2P3at T = 300 K is 0.4155 eV. The temperature coefficients in the linear region due to lattice dilation contribution, lattice vibration contribution and total temperature effect were calculated as -1.101 × 10-5eV/K, -1.637 × 10-4eV/K and -1.7523 × 10-4eV/K, respectively. Also, the ratio of temperature coefficient of the energy gap due to LV contribution to its value and LD contribution in the linear region is equal to 14.868. That ratio is compared to those of CuGe2P3 and III-V compounds, where those of the latter show a systematic change with Eg. Moreover, the Eg of all the compounds shows a quadratic dependence on the inverse of mean bond length.
Yuqi Chen, Liang Li and Shinji Hirai
Single-phase Eu3S4 was obtained via CS2 gas sulfurization of Eu2O3nanospheres at 773 K for longer than 0.5 h. The primary particle size of Eu3S4became larger than that of Eu2O3during the sulfurization process. Pure synthetic Eu3S4powders were unstable and transformed to EuS at 873 K under vacuum. Eu3S4compacts were sintered in temperature range of 773 K to 1173 K and they transformed to EuS at 1473 K during spark plasma sintering. Specific heat of sintered Eu3S4did not show an anomalous behavior in the range of 2 K to 50 K. The magnetic susceptibility of polycrystalline Eu3S4followed a Curie-Weiss law from 2 K to 300 K. Magnetization of polycrystalline Eu3S4was larger than that of single crystal Eu3S4when the magnetic field was less than 3.5 kOe.
Zohra Nazir Kayani, Mahek Zaheen Butt, Saira Riaz and Shahzad Naseem
NiO nanoparticles were fabricated by sol-gel route using ammonium hydroxide and nickel nitrate as precursors. The NiO nanoparticles were calcinated at 400 °C and 1000 °C. The nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), thermogravimetry analysis/differential thermal analysis (TGA/DTA). The structural properties were evaluated by X-ray diffraction (XRD). XRD confirmed the formation of well-crystallized and high purity NiO phase. The XRD showed that the peaks were sharpened and the crystallite size increased as the calcination temperature increased. The average crystallite size ranged from 12 nm to 20 nm, when calcined at temperatures 400 °C and 1000 °C, respectively. Fourier transform infrared spectroscopy (FT-IR) revealed the chemical composition and confirmed the formation of NiO nanoparticles. The nanoparticles showed paramagnetic behavior.
N. V. Lemesh and P. E. Strizhak
In this work, multi-walled carbon nanotubes (MWCNTs) with significantly different mean diameters were produced by catalytic CVD over Ni and Co-based supported catalysts. Our results indicate that Ni nanoparticles in the Ni/MgO catalyst are responsible for controlling the inner diameters of the carbon nanotubes. Contrary, Co nanoparticles in the Co/MgO catalyst control the outer diameters of MWCNTs. The “base-growth” mechanism and smaller diameters of the MWCNTs grown on the Ni/MgO catalyst are associated with a strong metal-support interaction (SMSI) resulting from NixMg1-xO mixed oxide formation. The concept of the weak metal-support interaction (WMSI) between Co nanoparticles and MgO for the Co/MgO catalyst confirms the “tip-growth” mechanism of the MWCNTs.
S. Reena Devi, S. Suresh, S. Kalaiyarasi, M. Nizammohideen and R. Mohan Kumar
A novel 4-methylpyridinium 3-nitrophthalate (4MP3NP) was synthesized and the crystals were grown by using slow evaporation method. The structural data of the grown crystal was collected by single crystal X-ray diffraction. It revealed that the 4MP3NP crystal belongs to triclinic crystal system with a space group P¯1. Structure of the synthesized compound was established using SHELXL 97 program package. The crystalline nature and composition of the grown crystal was established using high resolution X-ray diffraction and FT-IR analyses. UV-Vis transmittance and photoluminescence studies revealed the optical transmission window and electronic transition mechanism of ions, respectively. The laser damage threshold of the grown crystal was estimated by Nd:YAG laser and these results were mutually related to specific heat capacity of the grown crystal. The third-order nonlinear optical susceptibility of the grown crystal was studied by Z-scan technique.