Ziaul Raza Khan, Munirah, Anver Aziz and Mohd. Shahid Khan
High-quality CdS nanocrystalline thin films were grown by sol-gel spin coating method at different solution temperatures on glass substrates. As-deposited films exhibited nanocrystalline phase with hexagonal wurtzite structure and showed good adhesion and smooth surface morphology. It was clearly observed that the crystallinity of the thin films improved with the increase in solution temperature. Crystallites sizes of the films also increased and were found to be in the range of 10 mm to 17 nm. The influence of the growth mechanism on the band and sub-band gap absorption of the films was investigated using UV-Vis and photothermal deflection spectroscopy (PDS). The band gap values were calculated in the range of 2.52 eV to 2.75 eV. The band gap decreased up to 9 % with the increase in solution temperature from 45 °C to 75 °C. Absorption coefficients estimated by PDS signal showed the significant absorption in low photon energy region of 1.5 eV to 2.0 eV. The dark and illuminated I-V characteristics revealed that the films were highly photosensitive. The results demonstrated the potential applications of sol-gel grown CdS nanocrystalline thin films as photoconductors and optical switches.
Marin Tadic, Matjaz Panjan, Biljana Vucetic Tadic, Jelena Lazovic, Vesna Damnjanovic, Martin Kopani and Lazar Kopanja
, pp. 752, 2018.
 Z. Shaoqiang, T. Dong, Z. Geng, H. Lin, Z. Hua, H. Jun, L. Yi, L. Minxia, H. Yaohua and Z. Wei, “The influence of grain size on the magnetic properties of Fe 3 O 4 nanocrystals synthesized by solvothermal method”, Journal of Sol-Gel Science and Technology , pp. 1–8, 2019.
 J. Mohapatra, F. Zeng, K. Elkins, M. Xing, M. Ghimire, S. Yoon, S. R. Mishra and J. P. Liu, “Size-dependent magnetic and inductive heating properties of Fe 3 O 4 nanoparticles: scaling laws across the superparamagnetic size”, Physical Chemistry Chemical
Zohra Nazir Kayani, Maryam Iqbal, Saira Riaz, Rehana Zia and Shahzad Naseem
 KLEIN C.L., Sol-gel technology for thin films, fibres, performs, electronics, and specialty shapes, Noyes Publications, New Jersey, 1988.
 LOPEZ M.T., AVNIR D., AEGERTER M., Emerging fields in sol-gel science and technology, Kluwer Academic Publishers, London, 2003.
 KAYANI N.Z., AFZAL T., RIAZ S., NASEEM S., J. Alloy.Compd., 606 (2014), 177.
 ANNA K., NINA P., YURI K., MEINHARD M., WERNER Z., AHARON G., Ultrason. Sonochem., 15 (2008), 839.
 LI H., WANG J., LIU H., YANG C., XU H., LI X
In this study, the multi-walled carbon nanotubes were oxidized by m-chlorperbenzoic acid followed by the reaction with titanium n-butoxide and nickel nitrate to prepare Ni distributed CNT/TiO2 composite by a simple sol-gel method. The functional groups formed on the surface of MWCNTs were analyzed by Fourier transform infrared spectroscopy. The prepared Ni distributed CNT/TiO2 composite was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray analysis. The photodegradation of methylene blue, methylene orange and rhodamine B solution under UV irradiation was employed to test the photocatalytic activity of the Ni distributed CNT/TiO2 composite. According to the results, Ni distributed CNT/TiO2 composite showed very excellent photocatalytic activity to decompose MB, MO and Rh.B solutions, due to the electron absorption effect of MWCNTs and electron trapping effect of nickel.
Munirah Munirah, Ziaul Khan, Mohd. Khan and Anver Aziz
This paper describes the growth of Cd doped ZnO thin films on a glass substrate via sol-gel spin coating technique. The effect of Cd doping on ZnO thin films was investigated using X-ray diffraction (XRD), UV-Vis spectroscopy, photoluminescence spectroscopy, I–V characteristics and field emission scanning electron microscopy (FESEM). X-ray diffraction patterns showed that the films have preferred orientation along (002) plane with hexagonal wurtzite structure. The average crystallite sizes decreased from 24 nm to 9 nm, upon increasing of Cd doping. The films transmittance was found to be very high (92 to 95 %) in the visible region of solar spectrum. The optical band gap of ZnO and Cd doped ZnO thin films was calculated using the transmittance spectra and was found to be in the range of 3.30 to 2.77 eV. On increasing Cd concentration in ZnO binary system, the absorption edge of the films showed the red shifting. Photoluminescence spectra of the films showed the characteristic band edge emission centred over 377 to 448 nm. Electrical characterization revealed that the films had semiconducting and light sensitive behaviour.
0.94Bi0.5Na0.5TiO3-0.06BaTiO3 ceramics were fabricated by sol-gel technique. The XRD results revealed the formation of a single phase perovskite structured Bi0.5Na0.5TiO3-BaTiO3 at 600 °C. The SEM images showed dense microstructure and the optimum density of the ceramics sintered at 1100 °C was 5.2 g/cm3. The saturation polarization (Ps) was found to be increased with increasing temperature while the remnant polarization (Pr) was found to be increased gradually and then decreased abruptly near 85 °C, which could be attributed to the phase transformation. The coercive electric field (Ec) was found to be decreased gradually with increasing temperature. The maximum value of dielectric constant (ɛ
r) at room temperature was 800 and dielectric loss at 1 MHz was 0.07.
Tenzin Tenkyong, Neena Bachan, J. Raja, P. Naveen Kumar and J. Merline Shyla
Synthesis and characterization of a highly efficient photoconductive nanocomposite comprising of two common metal oxides: copper oxide (CuO) and silicon dioxide (SiO2) are being reported in this paper. The CuO/SiO2 nanocomposite has been synthesized using a cost-effective and facile sol gel route. The structural, chemical and optical properties of the prepared samples have been studied using various characterization techniques. The UV-Vis analysis revealed better absorption in the case of the nanocomposite as compared to its parent materials. X-ray diffraction (XRD) analysis has been employed to determine the structural formation of the nanocomposite and the crystallite size with the use of Scherrer’s formula. The photo conductivity study of the sample showed enhanced photocurrent in the case of nanocomposite as compared to its single components, thus, presenting it as a potential candidate for solar cell applications, especially as photoanode material in the dye-sensitized solar cells (DSSC).
H. Bruncková, Ľ. Medvecký, E. Múdra, A. Kovalčiková, J. Ďurišin, M. Šebek and V. Girman
Samarium niobate SmNbO4 (SNO) and tantalate SmTaO4 (STO) thin films (~100 nm) were prepared by sol-gel/spin-coating process on alumina substrates with PZT interlayer and annealing at 1000°C. The precursors of films were synthesized using Nb or Ta tartrate complexes. The improvement of the crystallinity of monoclinic M′-SmTaO4 phase via heating was observed through the coexistence of small amounts of tetragonal T-SmTa7O19 phase in STO precursor at 1000°C. The XRD results of SNO and STO films confirmed monoclinic M-SmNbO4 and M′-SmTaO4 phases, respectively, with traces of orthorhombic O-SmNbO4 (in SNO). In STO film, the single monoclinic M′-SmTaO4 phase was revealed. The surface morphology and topography of thin films were investigated by SEM and AFM analysis. STO film was smoother with roughness 3.2 nm in comparison with SNO (6.3 nm). In the microstructure of SNO film, small spherical (~50 nm) and larger cuboidal particles (~100 nm) of the SmNbO4 phase were observed. In STO, compact clusters composed of fine spherical SmTaO4 particles (~20-50 nm) were found. Effect of samarium can contribute to the formation different polymorphs of these films for the application to environmental electrolytic thin film devices.
Syed Mansoor Ali, W. A. Farooq, M. R. Baig, M.A. Shar, M. Atif, S. S. Alghamdi, M. S. Algarawi, Naeem Ur-Rehman and Muhammad Hammad Aziz
We have investigated the influence of Ag doping on zinc oxide thin films. Pure and Ag doped, preferentially oriented transparent zinc oxide thin films were prepared by sol gel technique on a glass substrate using diethyl amine as a stabilizer. The X-ray diffraction analysis revealed that the films with hexagonal wurtzite type structure were polycrystalline in nature with a preferred grain orientation in the 101 direction. The crystallite sizes decreased from 34 nm to 27 nm after silver doping. Both photoluminescence and optical transmission measurements showed that the band gap increased after the Ag doping. The structure and optical characterization studies clearly indicated the incorporation of Ag in ZnO. Hence, the observed increase in the optical band gap and decrease in crystallite size can be directly attributed to the effect of Ag ion incorporation into the ZnO lattice.
Dongyun Guo, Yang Ju, Chengju Fu, Zhixiong Huang and Lianmeng Zhang
Zinc oxide (ZnO) is an n-type semiconductor with a wide direct band gap of 3.37 eV and a large exciton binding energy (60 meV). ZnO thin films have been widely applied in high technology such as optoelectronic devices, solar cells, piezoelectric transducers and gas sensors [ 1 – 7 ]. Many techniques have been utilized to prepare ZnO thin films, such as metal organic chemical vapor deposition, pulsed laser deposition, sputtering, hydrothermal, sol-gel method, etc. [ 8 – 18 ]. Due to the low cost and simple equipment, sol-gel method has been