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Open access

Esra Öztürk and Erkul Karacaoglu

Abstract

In this study, silicate systems, M2SiO4 (M = Ca, Zn) were produced by solid state reaction and doped with 1 mol% Eu3+ rare-earth ion. Their heat treatments, which were conducted at 1200 °C and above for minimum 3 hours under an open atmosphere, were applied according to the DTA/TG results. Powder X-ray diffraction XRD analyses were performed to determine the phase properties of the phosphor systems after the sintering process. It was proved that the structures of two of the phosphor systems were well formed in except that the Zn2SiO4 had some ZnO secondary phases. The expected photoluminescence (PL) results were presented and the transitions of the Eu3+ ions were observed for both phosphors.

Open access

S. Anbu Chudar Azhagan, V.S. Kathiravan and N. Sathiya Priya

Abstract

The influence of magnesium sulfate as an additive in the nucleation of α and γ-polymorphs of glycine crystallized from aqueous solutions has been explored for the first time. Based on crystallization experiments, it was concluded that lower concentration of magnesium sulfate, say less than 2 g/mL, favors α-nucleation sites, whereas the optimized concentration of magnesium sulfate impurity to yield -nucleation sites is 2 g/mL and above. The nucleation time span (in days), solubility and pH were measured for α- and γ-nucleation sites in the aqueous solutions doped with magnesium sulfate. The glycine polymorphs α- and γ-single crystals were grown by slow solvent evaporation technique at ambient temperature. Crystal habit of glycine polymorphs was investigated and analyzed using goniometry. The unit cell dimensions and space group of the as-grown crystal were identified by single crystal XRD analysis. Both α- and γ-polymorphs of glycine were characterized structurally by powder XRD studies. The percentage of magnesium present in the grown glycine crystals was estimated by inductively coupled plasma optical emission spectrometry elemental analysis (ICP-OES). The nonlinear optical properties of the γ-glycine crystals were examined by Q-switched high energy Nd:YAG laser. The second harmonic generation output efficiency of the as-grown gamma glycine single crystals was computed to be 1.31 times superior than that of the reference material potassium dihydrogen phosphate (KDP).

Open access

B.O. Adetoye, A.B. Alabi, T. Akomolafe, P.B. Managutti, N. Coppede, M. Villani, D. Calestani, A. Zappetini and C. Maurizio

Abstract

One-dimensional (1D) zinc oxide (ZnO) nanostructures (nanorods) were synthesized on a glass slide and fluorine-doped tin oxide (SnO2/F or FTO) coated glass (FTO/glass) by a wet chemical method. The structural, morphological and optical analyses of the as-deposited ZnO nanostructures were performed by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and UV-Vis spectroscopy, respectively. The XRD results showed that the nanostructures as-deposited on the glass and the FTO/glass substrates were of ZnO wurtzite crystal structure, and the crystallite sizes estimated from the (0 0 2) planes were 60.832 nm and 64.876 nm, respectively. The SEM images showed the growth of densely oriented ZnO nanorods with a hexagonal-faceted morphology. The UV-Vis absorption spectrum revealed high absorbance properties in the ultraviolet range and low absorbance properties in the visible range. The optical energy band gap of the ZnO nanostructure was estimated to be 3.87 eV by the absorption spectrum fitting (ASF) method.

Open access

Arpit Swarup Mathur, Praveen Kumar and B.P. Singh

Abstract

Titanium dioxide (TiO2) is one of the most favored metal oxide semiconductors for the use as photoanode in photoelectrochemical cells (PEC) splitting the water into hydrogen and oxygen. However, the major impediment is its large bandgap that limits its utilization as photoanode. Doping has evolved as an effective strategy for tailoring optical and electronic properties of TiO2. This paper describes the synthesis of undoped as well as iron (Fe, cationic) and nitrogen (N, anionic) doped nanocrystalline titanium dioxide by sol-gel spin coating method for solar energy absorption in the visible region. All the prepared thin films were characterized by X-ray diffraction and UV-Vis spectroscopy. Doping of both Fe and N into TiO2 resulted in a shift of absorption band edge towards the visible region of solar spectrum.

Open access

Mohd Anis, G.G. Muley, Mohd Shkir, S. Alfaify and H.A. Ghramh

Abstract

Present investigation is aimed to explore the single crystal growth, microhardness and third order nonlinear optical (TONLO) properties of Nd3+ doped zinc tris-thiourea sulphate (ZTS) crystal. The commercial slow solvent evaporation technique has been chosen to grow a good quality ZTS (12 mm × 0.5 mm × 0.3 mm) and Nd3+ doped ZTS (11 mm × 0.6 mm × 0.4 mm) single crystals. Vickers microhardness test has been employed to analyze the influence of Nd3+ dopant on the hardness behavior of ZTS single crystal. The TONLO effects occurring in Nd3+ doped ZTS single crystal have been evaluated by means of Z-scan technique using a He–Ne laser operating at 632.8 nm. The close and open aperture Z-scan configuration have been used to determine the nature of TONLO refraction n2 and absorption β, respectively. The magnitudes of vital TONLO parameters, such as refraction n2, absorption coefficient β, figure of merit and susceptibility χ3 of the Nd3+ doped ZTS single crystal, have been determined using Z-scan transmittance data. The n2, β, and χ3 of Nd3+ doped ZTS single crystal were found to be of the order of 10−10 cm2/W, 10−6cm/W and 10−5 esu, respectively.

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.