Showing 6 results for Optical Properties
R. Lotfi Orimi, V. Asghari , M. Lashkarbolouki,
Volume 30, Issue 1 (6-2011)
Abstract
ZnS nanoparticles were synthesized by chemical precipitation method. As-prepared ZnS nanoparticles were found to be stabilized in the form of cubic phase. Cubic to hexagonal structural transformation was studied using X-ray diffraction (XRD). The effect of annealing temperature (100-700 ) on the band gap, particle size, and structural phase was investigated. Photoluminescence studies indicated two strong and narrow emission peaks in blue and orange regions. These two strong and narrow emission peaks were shifted to blue and red regions by increasing the annealing temperature..
S. Yousefi, B. Ghasemi, M. Tajalli, A. Asghari,
Volume 36, Issue 4 (3-2018)
Abstract
In this paper, high purity magnesium hydroxide nanoplates were successfully synthesized by using brine rich in magnesium ions as precursor and NaOH as precipitating agent without using dispersant agent in the room temoerature. The study and characterization of various properties of obtained nanopowder was carried out by X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray Fluorescence Spectrometer (EDX), Fourier Transform Infrared Spectrophotometer (FTIR) and Ultraviolet–visible spectroscopy (UV-Vis). The FESEM and XRD analysis results showed that magnesium hydroxide powder had nanoplates with the average crystallite size 17.1nm and no impurity; that was in agreement with the result of EDX and FTIR perfectly. Furthermore, optical characteristics of magnesium hydroxide nanoplates by UV-Vis spectroscopy showed an optical band gap of 5.5 eV. This wide band gap can be a useful innovation in optoelectronic sub-micron devices.
M. Hajfarajzadeh, A. Eshaghi, A. Aghaei,
Volume 37, Issue 4 (3-2019)
Abstract
A TEOS-GPTMS nano-hybrid thin film was deposited on the polymethyl methacrylate (PMMA) substrate by a sol-gel dip coating method. Morphology, roughness and surface chemical bonding of the thin films were evaluated by X-ray diffraction (XRD), field emission scanning electron microscopy(FE-SEM), atomic force microscopy, and Fourier transform infrared spectroscopy methods, respectively. UV-vis spectrophotometer was used to measure the transmittance spectra of the samples. Also, the adhesion and hardness of the coatings were investigated using pencil hardness the adhesion tape test and the test, respectively. XRD results proved that the thin film had an amorphous structure. Also, FE-SEM images indicated that addition of GPTMS to the TEOS yielded a crack-free thin film. Based on the UV-vis spectroscopy results, the transmittance of the polymer substrate in the visible region was increased by the deposition of the nano-hybrid coating. Moreover, the hardness of the PMMA substrate was increased from 3H to 6H by the deposition of the nano-hybrid thin film. Also, tape test confirmed the high adhesion of the nano-hybrid thin film on the PMMA substrate. Consequently, the transparent organic-inorganic GPTMS-TEOS hybrid coating can be used as a scratch resistant coating on the PMMA substrate.
M. Maniei, A. Eshaghi, A. Aghaei,
Volume 38, Issue 2 (9-2019)
Abstract
In this research, MgF2-2%SiO2/MgF2 thin films were applied on a glass substrate. At first, MgF2 thin films with the optical thickness were deposited on the glass slide substrates. Then, MgF2-2%SiO2 thin films were deposited on the glass coated with MgF2 thin films. Finally, the nanocomposite thin films were surface treated by the PFTS solution. Characterization of the thin film was done by X-Ray defractometry (XRD), attenuated total reflectance fourier transform infrared spectroscopy (ATR-FTIR), UV-Vis spectroscopy, and atomic force microscopy (AFM) techniques. Also, the hydrophobic properties of the samples were investigated by measuring the contact angle of the water. The results showed that the deposition of the six layer MgF2 thin films on the two sides of the glass substrate increased the transmission up to 96.4%. For the glass deposited by MgF2-2%SiO2 nanocomposite thin films, transmission was reduced to 94.4%, with its transmission being higher than the pure glass. Also, the water contact angle (WCA) analysis determined that the contact angle of the water droplet on the MgF2-2%SiO2 nanocomposite thin film coated glass was decreased. On the other hand, the contact angle of the water droplet on the MgF2-2%SiO2 nanocomposite thin film coated glass after modification with the PFTS solution was increased up to 119o. So, MgF2-2%SiO2 nanocomposite thin films could be used as an antireflective and self-cleaning coating on the surface of the optical devices.
N. Alirezaei Varnosfaderani, S. E. Mousavi Ghahfarokhi, M. Zargar Shoushtari,
Volume 38, Issue 3 (12-2019)
Abstract
In this paper, W-type SrCo2Fe16O27 hexaferrite nanostructures were synthesized by sol-gel auto-combustion method. Effect of annealing temperature on the structural, magnetic and optical properties of these SrCo2Fe16O27 nanostructures was investigated. In order to determine the annealing temperature of samples, the prepared gel was examined by thermo-gravimetric and differential-thermal analyses. Morphology and crystal structure of the prepared samples were characterized by field emission scanning electron microscopy and X-ray diffraction pattern. Based on X-ray diffraction results, at annealing temperature of 1000 °C, the maximum amount of main phase formed. A planar morphology was spectroscopy for the synthesized samples through scanning electron microscope images. Fourier transform infrared analysis was used to confirm the synthesis of the main properties obtained of samples were measured by the vibrating sample magnetometer and the results showed that by increasing temperature, magnetic saturation increases. Moreover, optical properties of samples were investigated by ultraviolet–visible absorption and photoluminescence spectroscopies. The result of measurements of the energy gap approximately is same in the ultraviolet- visible and photoluminescence spectroscopes and also the energy gap is constant with increasing temperature.
H. Salehi, N. Zhulayi Bakhoda, P. Amiri,
Volume 38, Issue 4 (1-2020)
Abstract
In this research, the optical properties of tungsten disulfide including dielectric function, the static refractive index, the imaginary part of the dielectric function, optical band gap, energy loss spectrum and its magnetic properties have been studied. Calculations have been done by using Quantum Espresso package which is based on density functional theory and pseudo-potential technique. The static refractive indices of this compound at diffrent x and z directions were calculated 3.66 and 2.55, respectively. The amount of optical band gap, obtained from the imaginary part of dielectric function, was estimated to be 1.45 eV. In addition, bulk plasmon energy, obtained from energy loss spectrum at x and z directions, were obtained to be 17.95 eV and 17.25 eV, respectively.
