Single crystals of pure and L-threonine added tartaric acid (LT/TA), organic nonlinear optical (NLO) materials were grown from their respective aqueous solution by slow evaporation method. The crystalline nature of the grown crystals was confirmed by powder X-ray diffraction analysis (XRD). UV-Vis-NIR absorption and transmission spectra revealed that the lower cut-off wavelength was around 281 nm and the crystals exhibited high transmission over visible and near IR region. The presence of the functional groups such as O–H, C–H, C–O, C=O in the grown crystals was confirmed by FT-IR analysis. CHN analysis was carried out to confirm the presence of L-threonine in the grown crystals. Microhardness study on the crystals revealed that the hardness number Hv increased with the applied load. The growth pattern of the crystals were analyzed through etching analysis from which the etch patterns in the shape of ‘step-triangle’ were observed. The second harmonic generation (SHG) properties of pure and L-threonine doped tartaric acid crystals were confirmed by Kurtz-Perry powder technique.
Artur Wiatrowski, Michał Mazur, Agata Obstarczyk, Danuta Kaczmarek, Roman Pastuszek, Damian Wojcieszak, Marcin Grobelny and Małgorzata Kalisz
In this paper, comparative studies on the structural, surface, optical, mechanical and corrosion properties of titanium dioxide (TiO2) thin films deposited by continuous and sequential magnetron sputtering processes were presented. In case of continuous process, magnetron was continuously supplied with voltage for 90 min. In turn, in sequential process, the voltage was supplied for 1 s alternately with 1 s break, therefore, the total time of the process was extended to 180 min. The TiO2 thin films were crack free, exhibited good adherence to the substrate and the surface morphology was homogeneous. Structural analysis showed that there were no major differences in the microstructure between coatings deposited in continuous and sequential processes. Both films exhibited nanocrystalline anatase structure with crystallite sizes of ca. 21 nm. Deposited coatings had high transparency in the visible wavelength range. Significant differences were observed in porosity (lower for sequential process), scratch resistance (better for sequential process), mechanical performance, i.e. hardness:elastic modulus ratio (higher for sequential process) and corrosion resistance (better for sequential process).
G.W. Strzelecki, K. Nowakowska-Langier, R. Chodun, S. Okrasa, B. Wicher and K. Zdunek
The research on the influence of modulation frequency on the properties of films synthesized using a unique pulsed power supply combined with a standard unbalanced circular magnetron was conducted in the process of pulsed magnetron sputtering (PMS). It was shown that by using different levels of modulation, the composition of plasma (measured by optical emission spectroscopy, OES) as well as film growth rate and morphology (observed with scanning electron microscope, SEM), can be changed. The impact of modulation is related to the used materials and gases and can vary significantly. It was concluded that modulation frequency can greatly influence the synthesis of materials and can be used as an additional parameter in PMS. Specific relations between modulation frequency and synthesized material require further investigation.
R. Sabarish, N. Suriyanarayanan, J.M. Kalita, M.P. Sarma, G. Wary, Vipul Kheraj and Sampat G. Deshmukh
In this report, ternary semiconducting NixBi2−xS3(x = 0.2 M and 0.5 M) thin films were synthesized in situ for the first time by a chemical bath deposition technique at different bath temperatures (60 °C, 70 °C and 80 °C). The effects of concentration and deposition temperature on the deposited films were studied by combining the results of structural, morphological, optical and electrical analyses. The growth of NixBi2−xS3 films with good crystalline nature and interconnected grain arrangement takes place due to increasing the concentration of Ni2+ ions in bismuth sulfide matrix. EDS result confirmed the stoichiometry of NixBi2−xS3 formation. Wettability test demonstrated that the surface of the film was hydrophilic in nature. The optical absorption spectra revealed that the bandgap Eg of the x = 0.5 M film deposited at 70 °C was about 1.36 eV. Current-voltage (I-V) characteristics of the x = 0.5 M film deposited at 70 °C were studied under X-ray radiation and dark condition. An X-ray detection sensitivity analysis showed that the detection sensitivity is optimum when the bias voltage applied across the film is low (~0.9 V). These findings reveal that the film with x = 0.5 M deposited at 70 °C can be used as an efficient low cost X-ray sensor.
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.
H. Mokhtari, M. Benhaliliba, A. Boukhachem, M.S. Aida and Y.S. Ocak
This work highlights some physical properties related to the influence of aluminum, tin and copper incorporation on nanostructured zinc oxide (ZnO:M; M:Al, Sn and Cu) thin films prepared by ultrasonic spray pyrolysis technique (USP) on glass substrate at 350±5 °C. For the as-grown layers, M- to Zn-ratio was fixed at 1.5 %. The effects of metal doping on structural, morphological, optical and electrical properties were investigated. X-ray diffraction pattern revealed that the as-prepared thin films crystallized in hexagonal structure with (0 0 2) preferred orientation. The surface topography of the films was performed by atomic force microscopy. AFM images revealed inhibition of grain growth due to the doping elements incorporation into ZnO matrix, which induced the formation of ZnO nanoparticles. Optical measurements showed a high transparency around 90 % in visible range. Some optical parameters, such as optical band gap, Urbach energy, refractive index, extinction coeffi-cient and dielectric constant were studied in terms of doping element. Particularly, dispersion of refractive index was discussed in terms of both Cauchy and single oscillator model proposed by Wemple and DiDomenico. Cauchy parameters and single oscillator energy E0 as well as dispersion energy Ed were calculated. Finally, electrical properties were investigated by means of electrical conductivity and Hall effect measurements. The measurements confirmed n type conductivity of the prepared thin films and a good agreement between the resistivity values and the oxidation number of doping element. The main aim of this work was the selection of the best candidate for doping ZnO for optoelectronics applications. The comparative study of M doped ZnO (M:Al, Sn and Cu) was performed. High rectifying efficiency of the Al/n-ZnO/p-Si/Al device was achieved and non-ideal behavior was revealed with n > 4.
The growth of AlN layers on glass substrates using magnetron sputtering method was performed and the grown layers were subjected to optical measurements. Transmission spectra of the layers grown at different content of N2 in the atmosphere were obtained. The transmission spectra as well as energy gap depended on N2 content. The annealing of the layers in air led to transmission changes and influenced energy gap and refractive index values.
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.
Joel Olayide Amosun, Gbenga Moses Olayanju, Oluseun Adetola Sanuade and Tokunbo Fagbemigun
Integrated geophysical methods have been used to investigate the competency of the subsoil. The geophysical surveys conducted involve very low-frequency electromagnetic (VLF-EM) and electrical resistivity (ER) methods (dipole-dipole). ABEM Wadi and Ohmega resistivity meter were used to acquire VLF-EM and ER data, respectively, along two traverses. Station interval of 5 m was used for the VLF-EM survey, while inter-electrode spacing for dipole–dipole was 10 m; the inter-dipole expansion factor (n) ranged from 1 to 5. KHFFILT software was used to generate VLF-EM profiles and pseudosection, while DIPRO software was used for ER. Results from the ER method revealed the pattern of resistivity variations within the study area. The low resistivity values (11–25 Ohm-m) observed at the southern part of the study area could be attributed to changes in clay contents and degree of weathering in the subsurface. The results from the VLF-EM investigation revealed the presence of near-surface linear geologic structures of varying lengths, depths and attitudes, which suggest probable conductive zones that are inimical to the foundation of the road subgrade.
Nanosized NaA zeolite was successfully synthesized by hydrothermal method using tetraethyl orthosilicate (TEOS) and aluminum isopropoxide (AIP) as the main raw materials. The surface modification of NaA zeolite was carried out by silane coupling agent 3-aminopropyltriethoxysilane (KH-550). The effects of silane coupling agent dosage, reaction temperature, reaction time, hydrolysis time and pH value on grafting rate of NaA zeolite were investigated in detail. The zeolites were characterized by XRD, SEM-EDS, FT-IR and TG-DTA. The results showed that the surface of NaA zeolite was modified successfully by KH-550. The optimal modification conditions obtained were as follows: the dosage of coupling agent in 95 % ethanol – 1.6 %, reaction temperature − 70 °C, reaction time – 2 h, hydrolysis time – 20 min, and pH value – 3.5. Under these conditions, the grafting rate of modified NaA zeolite was 3.95 %.