Advanced Materials Research Vol. 667

Abstract: Preparation of nanohybrid PMMA/TiO2 hybrid was reported by using mixture sol-gel spin coating method. This studied involve modification band gap of TiO2 at different molar concentration of TTiB precursor. AFM image show TiO2 particles encapsulated with PMMA matrix. From UV-Vis spectroscope, we have found as increase of TTiB precursor molar concentration, optical band gap is 3.34 eV, increase in UV-range from 3.25 eV. This study suggested for improvement of optical band gap TiO2 coated glass.

Abstract: The present paper reports on the structural properties of Lanthanum Phosphate (LaPO4) nanostructure film in term of its surface morphology. In this study, the LaPO4 samples were prepared by sol-gel spin coating method with different layers. Photoluminescent (PL) properties of the samples were investigated using FluoroMax-4 Spectrofluorometer - Horiba Scientific at room temperature with excitation spectra 254 nm. While its physical structural properties was investigated using atomic force microscopy (AFM-XE100).

Abstract: We report the synthesis of phosphorus-doped (P-doped) and undoped ZnO nanostructures using a thermal evaporation and vapor transport on Si(100) substrate without any catalyst and at atmospheric argon pressure. The structural and optical properties of P-doped ZnO nanostructures and undoped ZnO nanostructures have been extensively investigated using filed emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Photoluminescence (PL). FESEM observation reveals that the morphology of ZnO nanostructures was changed from a hexagonal-like shape to a spherical shape when doping with P. While, XRD results indicate that P-doped ZnO nanostructures lost the (002) orientation preference and became randomly oriented. In addition, shifting of (002) diffraction peak has been found due to the incorporation of P into ZnO. Room temperature (PL) spectrum of P-doped ZnO nanostructures shows a high efficiency of green emission which was attributed to the presence of phosphorus atoms in the ZnO nanostructures.

Abstract: In this work, the electrical properties of carbon nanotubes were deposited on silicon substrate at different temperatures studied. CNTs were deposited on silicon at temperature 700 to 850 0C by using double-furnace thermal chemical vapor deposition technique. Carbon nanotubes with diameters of 20 to 30 nm were successfully synthesized on a silicon substrate. In this system, carbon nanotubes were grown directly on the p-type silicon. The samples were characterized using field emission scanning electron microscopy and micro-Raman spectroscopy. Based on micro-Raman spectroscopy result, the peak carbon nanotube (around 1 300 to 1 600 nm) was detected. Good electrical contact produced when Au sputter on CNTs characterized by I-V probe. Samples CNTs produced at 850 OC possess good conducting compare to other.

Abstract: Low-temperature solution immersion growth of low-dimensional ZnO nanostructures on gold-seeded Si substrate has been demonstrated. pH environment of the precursor solution, Zn(NO3)2.6H2O (zinc nitrate hexahydrate) and C6H12N4 (HMTA) was found to have considerable effect to ZnO morphology and photoluminescence. Structural, morphological and photoluminescence (PL) properties of the samples were obtained from XRD, SEM and PL-Raman characterisation. A near neutral (pH = 6.8) and acidic (pH = 5) precursor solution aided a dense near-aligned ZnO nanorods growth with smallest rods diameter of 30 and 20 nm respectively. Whereas alkaline precursor solution (pH = 9) gave rise to flower-like structures of ZnO. Chemical equations for the reactions and the role of H+ and OH- ions role in affecting the XRD diffraction peaks and morphology, are suggested. Room temperature PL emission spectra of ZnO were collected after excitation at 325 nm. UV and visible emission distinctive of ZnO were formed and the rationale for significant shifts of the visible emission was also discussed.

Abstract: Films of hexanoyl chitosan-based polymer electrolyte were prepared by solution casting technique. LiCF3SO3, EC and Al2O3 were employed as the doping salt, plasticizer and filler, respectively. The ac conductivity of the electrolyte system under investigation has been studied in the frequency range from 100 Hz to 1 MHz over the temperature range from 273 K to 333 K. The exponent s in the Jonscher’s universal power law equation was analyzed as a function of temperature. The analysis suggests that the conduction mechanism for the nanocomposite electrolyte system can be interpreted based on the correlated barrier hopping (CBH) model. The ac parameters such as the barrier height, WM and cut-off hopping distance, Rmin were calculated. The values of WM and Rmin are found to decrease with increasing temperature in the same manner as the exponent s.

Abstract: We make clusters of atoms of the size of less than 1 nanometer by using the density functional theory and from that we obtain the bond lengths corresponding to the minimum energy configuration. We are able to optimize large clusters of atoms and find the vibrational frequencies for each cluster. This calculation provides us with a method to identify the clusters present in an unknown sample of a glass by comparing the experimental Raman frequency with the calculated value. We start with the experimental values of the Raman frequencies of PSe (Phosphorous-Selenium) glass. We calculate the structural parameters of PSe, P4Se, P2Se2, P4Se5, PSe4, P4Se3 clusters of atoms and tabulate the vibrational frequencies. We compare the calculated values with those measured. In this way we find the clusters of atoms present in the glass. Some times, the same number of atoms can be rearranged in a different symmetry. Hence we learn the symmetries of molecules. We find that certain symmetries are broken due to self-organization in the glassy state.

Abstract: Optimization of titanium dioxide (TiO2) nanostructures deposited on glass substrate by Radio Frequency (RF) magnetron sputtering has been studied. The aim of this paper is to determine which parameter of RF powers influence the optimization of TiO2 nanostructures. The surface morphology and topology, roughness properties and cross-sectional of TiO2 nanostructures were observed by Atomic Force Microscope (AFM). The particle size of TiO2 nanostructures were observed by Field Emission Scanning Electrons Microscope (FESEM) and the UV-vis transmission spectra were recorded using UV-vis spectroscopy. The lowest surface roughness has the smallest average TiO2 size particle with indirect optical band gap of 3.39 eV for optimum TiO2 nanostructures deposited at varies RF power.

Abstract: ZnO nanorods were prepared by immersion method deposited onto Silicon (Si) and gold-seeded Si (Au/Si) substrate. The annealing temperatures were varied from 400, 500 and 600 °C. The effect of annealing temperature on the surface morphology and photoluminescence characteristics was investigated. The samples were characterized by Field Emission Scanning Electron Microscope (FESEM) to study their morphology and structural properties while the optical properties were characterized at room temperature using Photoluminescence Spectroscope. The shape of ZnO showed growth of nanorods with hexagonal shape. As the annealing temperature increased, the morphology study indicates that particle size of ZnO decreased while the crystallinity increases. The structures has high surface area, is a potential metal oxide nanostructures to be develop for optoelectronic devices and chemical sensors.

Abstract: This paper discussed on the structural properties of the PMMA/TiO2 nanocomposite films prepared using sonication-solution casting method. The structural properties of the nanocomposite films were compared by mixing the self-prepared TiO2 (~12 nm) and the commercially available TiO2 (25 nm) in the PMMA. The well dispersion of self-prepared TiO2 nanopowder was observed in the FESEM micrograph. XRD results show that the self-prepared TiO2 nanopowder decrease the crystallinity of the nanocomposite. Further, FTIR reveals that the interaction between the PMMA and TiO2 nanoparticles were detected.