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Open access

Fatemeh Mostaghni and Yasaman Abed

Abstract

In this study, we present a systematic study of linear and nonlinear optical properties of Para Red with the aim of Z-scan technique and quantum mechanical calculations. The Z-scan experiments were performed using a 532 nm Nd: YAG (SHG) CW laser beam. Para Red exhibited a strong nonlinear refractive index, nonlinear absorption coefficient and third-order nonlinear susceptibility 3.487 × 10-6cm2/W, 2.341 × 10-1cm/W and 2.157 × 10-4esu, respectively. Also, quantum chemical analysis was used for the calculation of the dipole moment μ, dipole polarizability α, anisotropy of polarizability ∆α and molecular hyperpolarizabilities (β,γ). The results revealed that Para Red has large first and second hyperpolarizabilities. However, from the obtained results, it was found that Para Red can be a promising material for applications in the development of non-linear optical materials.

Open access

Maxwell Selase Akple and Holali Kwami Apevienyeku

Abstract

A novel and low-cost synthesis of tungsten disulfide (WS2) transition metal dichalcogenide was carried out via gas-solid reaction in a horizontal quartz reactor. In this process, the prepared hollow WO3 precursor was sulfided with CS2 at 550 °C at different durations under N2 gas atmosphere. The as-prepared WS2 samples were formed by substitution of O by S during the sulfidation process. The characterization of these samples was performed employing X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX), Brunauer-Emmett-Teller (BET) specific surface area, X-ray photoelectron spectroscopy (XPS) and UV-Vis absorption spectroscopy. The characterization results showed that the as-prepared WS2 samples were of high quality and purity. No significant differences were observed in various WS2 samples synthesized during different sulfidation periods. The calculated results obtained from the density functional theory (DFT) indicate that WS2 has an indirect band gap of ca. 1.56 eV, which is in agreement with experimental band gap of ca. 1.50 eV. Combining the experimental and DFT results suggests that the novel method used in the synthesis of WS2 has a potential application for large scale production. The obtained WS2 are of high quality and can be implemented in photocatalysis, catalysis, photovoltaics, optoelectronic devices and photosensor devices.

Open access

Durga Verma, R. P. Patel and Mohan L. Verma

Abstract

In the present paper, TL and PL study of Dy3+doped Sr2SiO4:Eu2+phosphor is reported. A polycrystalline sample of Sr2SiO4:Eu2+, Dy3+ was prepared by combustion method. The obtained phosphor was characterized by powder X-ray diffraction, scanning electron microscopy, UV-Vis spectroscopy, PL and thermoluminescence. The results of the XRD studies obtained for Sr2SiO4:Eu2+, Dy3+ phosphor revealed its monoclinic structure. The average crystallite size was calculated as 12.77 nm. Thermoluminescence study was carried out for the phosphor using UV irradiation and a single glow peak was found. The thermoluminescence glow curves of the samples were measured at various concentrations of co-dopant. The kinetic parameter has been calculated using Chen’s glow curve method. In this paper, the photoluminescence and afterglow behavior of these phosphors are reported.

Open access

Ali A. Aljubouri, Abdulqader D. Faisal and Wafaa K. Khalef

Abstract

Single phase, adherent films of copper oxide nanowires (CuO NWs) were successfully grown on a glass substrate. Titanium nanofilm was pre-coated on the glass substrate to assist the growth of a layer adherent to the substrate. The copper film of 1.5 μm thickness was deposited via physical vapor deposition technique followed by thermal oxidation in air at various temperatures for 4 h. The product was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible (UV-Vis) and Fourier transformation infrared (FT-IR) spectroscopy to find the crystal structure, morphology, phases, and optical properties of the deposited films. The CuO NWs film with 60%transmittance at wavelengths greater than 800 nm was obtained. It can be used as an infrared thermal imaging filter and in optoelectronic devices. The fabricated temperature sensor exhibited high sensitivity in the temperature range of 20 °C to 180 °C.

Open access

Aseel A. Kareem

Abstract

Polyimide/polyaniline nanofiber composites were prepared by in situ polymerization with various weight percentages of polyaniline (PANI) nanofibers. X-ray diffraction (XRD) and Fourier transform infrared spectra (FT-IR), proved the successful preparation of PANI nanofiber composite films. In addition, thermal stability of PI/PANI nanofiber composites was superior relative to PI, having 10 % gravimetric loss in the range of 623 °C to 671 °C and glass transition temperature of 289 °C to 297 °C. Furthermore, the values of the loss tangent tanδ and AC conductivity σAC of the nanocomposite films were notably higher than those of pure polyimide. The addition of 5 wt.% to 15 wt.% PANI nanofiber filler enhanced the activation energy of PI composites from 0.37 eV to 0.34 eV.

Open access

Esra Yildiz

Abstract

In the present study, ZrO2co-doped with Gd3+/Sm3+and Gd3+/Er3+ions have been synthesized using Pechini method. Phase composition, morphology and photoluminescence properties of the synthesized phosphors were investigated by using X-ray powder diffraction (XRD), differential thermal analysis/thermal gravimetry (DTA/TG), scanning electron microscopy (SEM) and photoluminescence spectrofluorometer (PL). After heating at 1200 °C, XRD revealed that the phosphors were crystallized as monoclinic and tetragonal multiphases. SEM images indicated that the phosphors consist of fine and spherical grains with a size around 200 nm to 250 nm. Luminescence studies of these phosphors have been carried out on the emission and excitation, along with lifetime measurements

Open access

Talat Zeeshan, Safia Anjum, Hina Iqbal and Rehana Zia

Abstract

A series of copper substituted cobalt chromium ferrites, CuxCo1 - xCr0.5Fe1.5O4 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) has been synthesized, by employing powder metallurgy method. Calcination of the samples has been carried out for 24 hours at 1100 °C. The resultant materials have been investigated by using a variety of techniques, including X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM)), scanning electron microscopy (SEM), and ultraviolet visible spectroscopy (UV-Vis). The XRD patterns confirmed that all compositions had a cubic spinel structure with a single phase and the lattice parameter was found to increase with increasing copper concentration. FT-IR spectroscopy has been used for studying the chemical bonds in the spinel ferrite. Shifting of the bands ν1 and ν2 has been observed. It has been revealed from VSM analysis that saturation magnetization and coercivity decrease with rising the Cu+2 doping. Magnetic properties have been explained on the basis of cation distribution. Scanning electron microscopy (SEM) has been used to study the surface morphology of prepared samples. UV-Vis analysis revealed the optical absorption of the samples. An increase in band gaps has been observed with increasing copper concentration in the sample.

Open access

Nouman Rafiq, Waqar A.A. Syed, Aulia Rifada, M. Asad Ghufran, Ijaz-Ur-Rehman Shah, Ahsan Ali and Wiqar Hussain Shah

Abstract

We report a simple approach for synthesizing monodispersed, crystalline and size-tunable tin sulfide nanoparticles for environment friendly next generation solar cell applications. Both SnS and SnS2 nanoparticles could be a potential nanomaterial for solar cells. The structural, morphological, thermal and optical properties were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), diffuse reflectance spectroscopy (DRS) and Fourier transform infrared spectroscopy (FT-IR). The XRD spectra revealed hexagonal and orthorhombic phases of SnS and SnS2 nanoparticles, respectively, where the grains size ranged from 11 nm to 30 nm. The weight percentage as a function of temperature was determined using TGA analysis. Functional groups were observed by FT-IR. The energy bandgap was determined as 1.41 eV showing usefulness of the nanoparticles in next generation environmental friendly solar energy applications.

Open access

A.M. Abd-Elnaiem, M. Mohamed, R.M. Hassan, M.A. Abdel-Rahim, A.A. Abu-Sehly and M.M. Hafiz

Abstract

Effect of annealing temperature on the structural and optical properties of As30Te60Ga10 thin film was studied using various techniques such as differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The DSC analysis revealed that the As30Te60Ga10 glass has a single glass transition and crystallization peak while XRD results confirmed that the as-prepared and annealed films have crystalline nature. The coexistence of the crystalline phases in the investigated films could be attributed to the formation of orthorhombic As, hexagonal Ga7Te10, and monoclinic As2Te3 phases. It was found that the average crystallite size and optical parameters of the studied films depend on the annealing temperature. For example, the optical band gap decreased from 1.54 eV to 1.11 eV as the annealing temperature increased from 300 K to 433 K.

Open access

Ziaul Raza Khan, Munirah, Anver Aziz and Mohd. Shahid Khan

Abstract

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.