نسرین قزکوب

In this research, hydrothermal method was used to made bismuth vanadate (BiVO4) thin layers.The X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectrometer (FTIR) and visible-ultraviolet absorption spectroscopy (UV-Vis) to study the structure Crystal, morphology, optical and photocatalytic properties of thin laters were used. The XRD pattern confirmed the formation of monoclinic pure phase for thin laters. EDS and FTIR analyzes showed that the thin laters do not contain any impurity elements. From FESEM image analysis, it was found that the average length of thin layers is 1.42 micrometers. Using UV-Vis analysis, an optical gap of 2.21 eV was obtained, which is in the visible light range. Investigating the photocatalytic activity of bismuth vanadate thin laters in the photodegradation of Congo red dye showed that this type of bismuth vanadate nanostructure with a monoclinic phase is a suitable choice for photocatalytic use and decomposition of organic matter with the help of sunlight.

In this research, bismuth vanadate (BiVO4) nanowires were made by hydrothermal method. To study the crystal structure, morphology, optical and photocatalytic properties of the samples, the X-ray diffraction analysis (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR) and ultraviolet– visible spectroscopy (UV-Vis) were used. The XRD patterns were indicated that the bismuth vanadate nanowires have a monoclinic structure. From EDS and FTIR analysis, it was found that nanowires do not contain impurities. From FESEM image, it was found that the average length and diameter of nanowires are 2.3 micrometers and 83 nanometers, respectively. The UV-Vis analysis was revealed the bismuth vanadate nanowires have an optical gap of 2.20 eV, which is in the visible light range. Investigating the photocatalytic activity of bismuth vanadate nanowires in the photodegradation of Congo red showed that bismuth vanadate nanowires are suitable choice for photocatalytic use and decomposition of organic matter with the help of sunlight.

In this study, structural characteristics and linear and nonlinear optical properties of TiO2/ZnO nanocomposite were investigated. In the first step, TiO2/ZnO composite nanostructure was prepared via a two-stage chemical coprecipitation approach by adding TiO2 nanoparticles into an aqueous solution containing zinc acetate precursor. In a second step, pure TiO2 and ZnO nanoparticles were synthesized by a co-precipitation method to investigate the presence portion of the basic structures on linear and nonlinear optical properties of TiO2/ZnO nanocomposite. Phase identification and chemical analysis of assynthesized nanostructures were performed by X-ray diffraction (XRD) crystallography and Fourier transform infrared (FT-IR) spectroscopy. Elemental properties of samples were studied by energy dispersive X-ray spectrometer (EDS) and surface mapping recorded by field emission scanning electron microscopy (FE-SEM). The morphological studies of the as-synthesized nanocomposite were analyzed by transmission electron microscopy (TEM). Linear optical studies were carried out to achieve the optical absorption edges and band-gap energies using UVVis spectra. Standard single-beam Z-scan technique with open-aperture (OA) and closed-aperture (CA) setups was utilized to determine nonlinear refraction index and nonlinear absorption coefficients, respectively. The optical nonlinear results showed a third-order optical susceptibility from the order of 10-4 esu under 532 nm laser radiations. 

In this paper, Structural, optical and photocatalytic properties of bismuth vanadate nanorods were studied. The bismuth vanadate (BiVO4) nanorods were made by thermal method in the presence of PEG (Polyethylene glycol) soft template. To study the nanorods, the X-ray diffraction analysis (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS) and ultraviolet– visible spectroscopy (UV-Vis) were used. The X-ray diffraction pattern were indicated that the nanorods have a monoclinic structure and the results of XRD and EDS analysis showed that there did not any impurity element in nanorods. From the FESEM image, it was found that the average diameter and length of the nanorods are 37 and 439 nm, respectively. The UV-Vis analysis showed that the optical band gap of bismuth vanadate nanorods is 2.22 eV, which is in the visible light range. The photocatalytic activity of nanorods were evaluated by photodegradation of Congo red under visible light irradiation. According to the results of this research, bismuth vanadate nanorods with monoclinic structure is a good choice for the degradation of organic matter with sunlight. 

In this paper, the bismuth vanadate (BiVO4) nanoparticles were synthesized at 600 °C calcination temperature by co-precipitation method. To study the crystal structure, morphology, optical and photocatalytic properties of the samples, the X-ray diffraction analysis, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy and ultraviolet– visible spectroscopy were used. The X-ray diffraction patterns were indicated that the BiVO4 samples have a monoclinic structure. The ultraviolet-visible analysis was revealed the BiVO4 samples have an optical band gap in the visible light range. The photocatalytic activities of the synthesized BiVO4 were evaluated by photodegradation of Congo red under visible light irradiation. According to the results of the analysis, the synthesized nanoparticles is a good choice for the degradation of organic matter into the sunlight.

In this paper, the effect of the cross-section on the critical current density (Jc) of a sample in ceramic superconductors YBa2Cu3O7-­δ (YBCO) and Bi1.6Pb0.4Sr2Ca2cu3Oy (BPSCCO) has been studied. Five orthorhombic bar samples of YBCO with cross-sections of 6.25, 7.67, 9.25, 11.76, 14.67 mm2­ and also five orthorhombic bar samples of BPSCCO with cross-section of 6.4, 9.01, 11.88, 13.86, 14.98 mm2­ with the same synthesis conditions by the solid state reaction method were prepared. After the preparation of the samples, the Meissner effect, the critical temperature (Tc), and the critical current density (Jc) measurements, XRD and SEM have been done on the samples. The results of XRD show that the dominant phase in YBCO and BPSCCO are 123 and 2223, respectively. The results of Jc measurements in 77 K show that in both superconductors, the Jc decreases with increasing of cross-section (A). The type of dissipation obeys a power law with the relation. For a given cross-section, Jc of the BPSCCO sample is smaller than the YBCO sample.