Effect of Thermal Neutron Irradiation on the Growth and Structure of K2SO4 Crystal

In this work we studied the effects of K2SO4 crystal which is exposure to thermal neutron radiation. This crystal was  grown by slow evaporation of the aqueous solution  technique to the size (28 x 6x 6  )mm3.X-ray powder diffraction was used to identify the structures for  before and after irradiation samples. Lattice  parameter calculations revealed orthorhombic crystal system for before irradiation and monoclinic for after irradiation sample. Then we followed it by DSC which  allowed us to highlight the high temperature phase transition around Tc581.9?Cfor before irradiation and at 670ºC for after irradiation .The difference in Tc at high temperature during heating run indicates for structural changed. Then IR study verifies the reduction in crystal symmetry, which indicates to the correlation between thermal neutron irradiation and structure of K2SO4. Keywords: Thermal neutron, Isomorphism, Single crystal, Phase transition, Symmetry reduction, after irradiation

Synthesis and Structural Characterization of Cr2O3 Nanoparticles Prepared by Using Cr(NO3)3.9H2O and Triethanolamine Under Microwave Irradiation

In this study, Chromium oxide nanoparticles (Cr2O3-NPs) was prepared by sol-gel method, using Cr(NO3)3.9H2O as a Precursor material, triethanolamine (TEA) as a template and water as green solvent under microwave irradiation . X- ray diffraction (XRD), Scanning electron microscopy (SEM), Rietveld refinement and Fourier Transform Infrared spectroscopy (FTIR) were employed to characterize the average  crystallite size, crystalline structure, morphology, unit cell parameters and chemical groups of the annealed powder. From  XRD data and Dicvol 91 software analysis, the crystal system was found to be rhombohedral structure for samples. The average  crystallite size is calculated by using Debye-Scherrer formula, crystallites size and strain are calculated by using Williamson-Hall formula. The effect of particle size on the crystal lattice distortion ratio, specific surface area, dislocation density and number of unit cell was discussed. A good agreement is between XRD data and FIR data. The qualitative phase analysis is performed by Rietveld analysis using “Fullprof” program of Cr2O3-NPs. Keywords: Cr2O3, Nanoparticles,  Sol – Gel , Structural Properties, Rietveld refinement

Effect of Fuel on the Structural and Optical Properties of MgO Nanoparticles Prepared by Auto–Combustion of Sol-Gel Method

Magnesium nitrate as precursor and citric acid as fuel are used as a starting material for the preparation  magnesium oxide (MgO) nanoparticles via sol- gel of auto–combustion  method.  X-ray diffraction patterns indicate that the obtain (MgO) nanoparticles are in good crystallinity and show that the all grain size was decreases with increasing of concentration citric acid as fuel. The crystallite size was calculated using Scherrer and Williamson-Hall formula at difference ratios of fuel which have maximum crystallite size (13.55 nm) and  (14.26 nm) respectively. The SEM images for MgO powder prepared with fuel (Citric acid) at three various molar ratios show the morphology of the oxides is mostly spherical with some agglomeration. The optical properties  show that  the transmittance decrease with increase the fuel amount and  additives ammonia and fuel played an important role in the combustion. Keywords: MgO , Nanoparticles , Sol-Gel, Auto–Combustion, Structural , Optica