scholarly journals Structural determination of Co/TiO2 nanocomposite: XRD technique and simulation analysis

2016 ◽  
Vol 34 (3) ◽  
pp. 534-539 ◽  
Author(s):  
F. Mostaghni ◽  
Y. Abed
Keyword(s):  
Band Gap ◽  
Simulation Analysis ◽  
Sol Gel ◽  
Experimental Studies ◽  
Pure Tio2 ◽  
X Ray Diffraction ◽  
Tio2 Anatase ◽  
Structural And Electronic Properties ◽  
Diffraction Patterns

AbstractSynthesis and complex theoretical and experimental studies of Co/TiO2 anatase have been reported. The preparation of Co/TiO2 was carried out by sol-gel method. Distribution of cations among the two tetrahedral and octahedral sites was estimated by analyzing the powder X-ray diffraction patterns by employing Rietveld refinement technique, and the results revealed the existence of tetragonal structure. Band structure and density of states calculations were performed using the first-principles methods. The structural and electronic properties of Co/TiO2 were calculated in the general gradient approximation (GGA). An additional comparison with pure TiO2 anatase allowed us to clarify cobalt doping effect on the electronic structure and the band gap. The band gap of Co/TiO2 was decreased by broadening the valence band as a result of the overlap among Co 3d, Ti 3d, and O 2p states, which made it respond better to visible and solar light.

scholarly journals Indexing the Diffraction Patterns and Investigating the Crystal Structure of Pb-doped Strontium Ferrites

2013 ◽  
Vol 5 (2) ◽  
pp. 235-244 ◽  
Author(s):  
Z. Ullah ◽  
S. Atiq ◽  
S. Naseem
Keyword(s):  
Crystal Structure ◽  
Diffraction Analysis ◽  
Hexagonal Phase ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Auto Ignition ◽  
Ray Density ◽  
Diffraction Patterns

Strontium hexaferrites were prepared in powder form by sol-gel auto-ignition technique and Pb was doped in different concentrations to attain the various compositions Sr1-xPbxFe12O19 (x = 0.00, 0.05, 0.10, 0.15, 0.20). Sintering treatment of the samples was made at 800 oC for the development of stable hexagonal phase. X-ray diffraction analysis of the samples was carried out for the confirmation and determination of crystal structure of the material. Data obtained from X-ray diffraction analysis helped in determining various parameters of the samples like lattice parameters, volume of the unit cell, crystallite size, bulk density of the samples, X-ray density and porosity of the samples.Keywords:Ferrites; Sol-gel method; X-Ray diffraction; Crystal structure.© 2013 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.doi: http://dx.doi.org/10.3329/jsr.v5i2.11578           J. Sci. Res. 5 (2), 235-244 (2013)

Crystallite Size Determination of MgO Nanopowder from X-Ray Diffraction Patterns Registered in GIXD Technique

2010 ◽  
Vol 163 ◽  
pp. 177-182 ◽  
Author(s):  
Tomasz Goryczka ◽  
Grzegorz Dercz ◽  
Krystian Prusik ◽  
Lucjan Pająk ◽  
Eugeniusz Łągiewka
Keyword(s):  
Crystallite Size ◽  
Sol Gel ◽  
Size Determination ◽  
X Ray Diffraction ◽  
Additional Line ◽  
X Ray ◽  
Diffraction Patterns ◽  
Α Angle ◽  
Sol Gel Synthesis

The problem of the crystallite size determination for nanomaterials from X-ray diffraction data obtained in asymmetrical GIXD geometry was analyzed. The studies were performed on nanocrystalline MgO powder prepared by sol-gel synthesis. The nanopowder was preliminary characterized from X-ray diffraction pattern registered in classical Bragg-Brentano geometry and electron microscope observation. The estimated crystallite size, calculated form Williamson-Hall method, equals to 5 nm whereas the lattice distortion is negligible (0.1%). The X-ray diffraction patterns were registered in 30-135º 2θ range using tunnel GIXD technique for the incident α angle: 0.25; 0.5; 1; 2.5 and 5 degrees, respectively. Additional broadening of diffraction lines originated from applied geometry was observed. The calculated crystallite size deviate significantly in comparison to results obtained from classical Bragg-Brentano data. Corrections for additional line broadening were determined, which should be applied for accurate crystallite size calculation in studies of thin nanocrystalline layers using GIXD technique.

scholarly journals Born out of Fire and Ice: Polymorph Studies of the Antiviral Famciclovir

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 129
Author(s):  
Liana Vella-Zarb ◽  
Ulrich Baisch
Keyword(s):  
Variable Temperature ◽  
Chemical Properties ◽  
Crystal Form ◽  
X Ray Diffraction ◽  
Crystal Forms ◽  
X Ray ◽  
Physical Chemical ◽  
Diffraction Patterns ◽  
Crystalline Forms

There is much interest and focus on solid forms of famciclovir. However, in spite of the abundance of reported differences in oral bioavailability, compressibility, and other physical–chemical properties of the various crystal forms of this drug, very little precise structural analysis is available in the literature to date. The form used in the commercial formulation is the anhydrous form I. Patents and patent applications report three different anhydrous crystalline forms on the basis of unindexed powder diffraction patterns. Single-crystal and variable-temperature X-ray diffraction experiments using the commercially available anhydrous form of famciclovir were carried out and led not only to the crystal structure determination of the anhydrous form I, but also to discovery of a new crystal form of anhydrous famciclovir from powder data.

FeAl2O4 Nanopowders; Structural Analysis and Band Gap Energy

2017 ◽  
Vol 36 (8) ◽  
pp. 789-793 ◽  
Author(s):  
Morteza Enhessari
Keyword(s):  
Structural Analysis ◽  
Band Gap ◽  
Sol Gel ◽  
Band Gap Energy ◽  
Mixed Metal Oxide ◽  
Nanoscale Materials ◽  
X Ray Diffraction ◽  
Organic Precursor ◽  
Gap Energy ◽  
Acid Gel

AbstractNanoscale FeAl2O4 was successfully synthesized via sol–gel method. The sol constituents containing iron and aluminum cations were formed homogenously in stearic acid gel (formation of organic precursor). The pure structural analysis and the size of the spinels were confirmed by X-ray diffraction (XRD). It was observed that the size of the nanoscale materials obtained at around 30–40nm. The micrographs of FeAl2O4 evidenced the homogenous and nanosize formation of spinel. The semiconducting behavior of this mixed metal oxide was observed at 3.14eV based on the band gap energy (Eg). The final nanoscale materials exhibited a superparamagnetic behavior with a saturation magnetization of 9.8 emu/g at applied field of 10 kOe.

scholarly journals Effect of Re and Tm-site on morphology structure and optical band gap of ReTmO3 (Re: La, Ce, Nd, Gd, Dy, Y and Tm: Fe, Cr) prepared by sol-gel method

2018 ◽  
Vol 64 (4) ◽  
pp. 381
Author(s):  
Muhammad Tufiq Jamil ◽  
Javed Ahmad ◽  
Syed Hamad Bukhari ◽  
Murtaza Saleem
Keyword(s):  
Band Gap ◽  
Sol Gel ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
X Ray Diffraction ◽  
Orthorhombic Crystal ◽  
X Ray ◽  
Average Grain Size ◽  
Auto Combustion ◽  
Uv Visible

Rare earth nano sized pollycrystalline orthoferrites and orthocromites ReT mO3 (Re = La, Nd, Gd, Dy, Y and T m = Fe, Cr) have been synthesized by sol-gel auto combustion citrate method. The samples have been characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), and UV-visible spectroscopy. The samples are single phase as confirmed by XRD analysis and correspond to the orthorhombic crystal symmetry with space group pbnm. Debye Scherer formula and Williamson Hall analysis have been used to calculate the average grain size which is consistent with that of determined from SEM analysis and varied between 25-75 nm. The elemental compositions of all samples have been checked by EDX analysis. Different crystallographic parameters are calculated with strong structural correlation among Re and Tm sites. The optical energy band gap has been calculated by using Tauc relation estimated to be in the range of 1.77 - 1.87 eV and 2.77 - 3.14 eV, for ReFeO3 and ReCrO3, respectively.

scholarly journals Nanocrystalline composites in TiO2 and SnO2 system for ammonia resistance sensors

2018 ◽  
Vol 12 (3) ◽  
pp. 240-247
Author(s):  
Anna Szczygielska ◽  
Zbigniew Pędzich ◽  
Wojciech Maziarz
Keyword(s):  
Phase Composition ◽  
Sol Gel ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Medium Size ◽  
X Ray Diffraction ◽  
Nanocrystalline Tio2 ◽  
Tio2 Anatase ◽  
Transmission Electron ◽  
Sorption Method

This work describes the production of nanocrystalline TiO2 and SnO2 oxides, as well as their nanocomposites (containing 26.9, 58.7 and 79.0wt.% of SnO2) with two-stage sol-gel method combined with high temperature treatment. The phase composition and medium size crystallites were determined using X-ray diffraction analysis (XRD) and revealed that the nanocomposites crystallize in tetragonal structures of TiO2 - anatase and SnO2 - cassiterite. Specific surface area of the nanopowders, measured using sorption method (BET), changed from 42.1 to 160.8m2/g. The morphology of the nanopowders was observed using transmission electron microscope (TEM). As indicated by TEM images, the manufactured nanopowders were well crystallized and consisted of small, spherical grains. The obtained nanopowders were also tested for NH3 gas detection application. The presented method of nanopowders synthesis enables to obtain nanocrystalline TiO2 and SnO2 oxides, as well as composites from TiO2-SnO2 of known and controlled chemical and phase composition. It also enables to obtain composites used for gas sensors. The sensor made of composite containing 58.7wt.% of SnO2 exhibited the best NH3 sensing features.

scholarly journals Synthesis of the Modifications of Ca2SiO4 and the Determination of their Powder X-ray Diffraction Patterns

1963 ◽  
Vol 71 (806) ◽  
pp. 63-68 ◽  
Author(s):  
Goro YAMAGUCHI ◽  
Yoshio ONO ◽  
Shigeo KAWAMURA ◽  
Yoshiaki SODA
Keyword(s):  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns

Sintering AlN Ceramics Below 1500°C with MgO-CaO-Al2O3-SiO2 Glass Addition

2007 ◽  
Vol 336-338 ◽  
pp. 1868-1871 ◽  
Author(s):  
Cheng Fu Yang ◽  
Chien Min Cheng ◽  
Ho Hua Chung ◽  
Chao Chin Chan
Keyword(s):  
Sintering Temperature ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Dielectric Characteristics ◽  
Sintering Aid ◽  
Glass Addition ◽  
X Ray ◽  
Crystal Phases ◽  
Diffraction Patterns ◽  
Scanning Electron

5~15 wt% MgO-CaO-Al2O3-SiO2 (MCAS, fabricated by sol-gel method) glass is used as the sintering aid of AlN ceramics. The sintering is proceeded from 1350oC~1550oC, scanning electron microscope is used to observe the sintered morphologies and X-ray diffraction pattern are used to confirm the crystal structures. From the SEM observations, as 10wt% and 15wt% MCAS is added, AlN ceramics can be densified at 1500oC and 1450oC, which are much lower than the before studies were. From the X-ray diffraction patterns, the crystal phases of MCAS-AlN ceramics are AlN, Al2O3, and cordierite phases. In this study, the dielectric characteristics of MCAS-AlN ceramics are also developed as a function of MCAS content and sintering temperature.

Influence of Li2+ Doping on the Structural and Optical Properties of CaO Synthesized by Sol–Gel Process

2019 ◽  
Vol 07 (01n02) ◽  
pp. 1950002
Author(s):  
Nadir Lalou ◽  
Ahmed Kadari
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Sol Gel ◽  
Calcium Nitrate ◽  
Lithium Nitrate ◽  
X Ray Diffraction ◽  
Structural And Optical Properties ◽  
Sol Gel Process ◽  
Ft Ir ◽  
First Time

This work proposes the synthesis of nanocrystalline calcium oxide (CaO) pure and doped with different concentrations of lithium (Li[Formula: see text]) ions by sol–gel process. Calcium nitrate (Ca(NO[Formula: see text]4H2O; 99.99%) and lithium nitrate (LiNO3; 99.99%) were used as precursors. The synthesized powders were characterized by several techniques such as: UV-Vis transmission spectroscopy, Fourier Transform Infra-red spectroscopy (FT-IR) and X-ray diffraction (XRD). The main objective of this paper is to study the influence of lithium (Li[Formula: see text] ratio) on the structural and optical properties of synthesized powders. The band gap values decreased with the increasing of Li[Formula: see text] ions in CaO lattice; the slight change in the band gap was directly related to the energy transfer between the CaO excited states and the 2s levels of Li[Formula: see text] ions. The influence of Li[Formula: see text] doping on the physical properties of CaO nanocrystalline will be studied for the first time in this work; no literature has previously published this kind of impurities.

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