Powder X-ray diffraction and Rietveld analysis of La1−xCaxMnO3(0

2006 ◽  
Vol 21 (1) ◽  
pp. 40-44 ◽  
Author(s):  
P. R. Sagdeo ◽  
Shahid Anwar ◽  
N. P. Lalla
Keyword(s):  
Phase Transformation ◽  
Calcium Concentration ◽  
Single Phase ◽  
Structural Phase ◽  
Rietveld Analysis ◽  
Linear Variation ◽  
X Ray Diffraction ◽  
Structural Phase Transformation ◽  
Magnetic Phases ◽  
X Ray

Single-phase samples of La1−xCaxMnO3compounds have been synthesized by solid-state reaction. Detailed Rietveld analysis of powder X-ray diffraction data showed that La1−xCaxMnO3undergoes a structural phase transformation fromR-3ctoPnmaatX=0.05–0.075. There is a linear variation of lattice parameters as a function of calcium concentration. The slope of this linear variation changes atX=0.6. A correlation between observed Mn-O bond lengths, corresponding to different compositions, and possible magnetic phases is discussed.

Powder X-ray diffraction and Rietveld analysis of La1−xBaxCoO3 (0

2006 ◽  
Vol 21 (4) ◽  
pp. 304-306 ◽  
Author(s):  
Wanju Luo ◽  
Fangwei Wang
Keyword(s):  
Phase Transformation ◽  
Bond Length ◽  
Structural Properties ◽  
Powder Diffraction ◽  
Bond Angle ◽  
Structural Phase ◽  
Rietveld Analysis ◽  
X Ray Diffraction ◽  
Structural Phase Transformation ◽  
X Ray

Detailed structural properties of La1−xBaxCoO3 (LBCO) have been investigated by means of X-ray powder diffraction and Rietveld analysis. A structural phase transformation from R3c to Pm3m at x=0.30–0.35 has been detected based on a comparison between the refinements of R3c and Pm3m. The Co–O bond length of the CoO6 octahedron expanded rapidly with increasing Ba content when x<0.1, and then it leveled off and kept constant at 0.1⩽x⩾0.35, where the Co–O–Co bond angle reaches 180°. The Co–O bond length expansion resumed with increasing Ba content beyond x=0.35.

Powder X-ray diffraction and Rietveld analysis of Cd1−xCuxCr2O4(0.1≤x≤0.7)

2007 ◽  
Vol 22 (4) ◽  
pp. 340-343 ◽  
Author(s):  
L. Q. Yan ◽  
Z. W. Jiang ◽  
X. D. Peng ◽  
L. H. He ◽  
F. W. Wang
Keyword(s):  
Magnetic Properties ◽  
Phase Transformation ◽  
Structural Phase ◽  
Rietveld Analysis ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Structural Phase Transformation ◽  
X Ray ◽  
Cu Content ◽  
Tetragonal Cell

Structural properties of Cd1−xCuxCr2O4(CCCO) have been investigated by means of X-ray powder diffraction and Rietveld analysis. A structural phase transformation from Fd3m to I42d at x=0.64 has been detected. The lattice constant a of the cubic unit cell decreases rapidly with increasing Cu content up to x=0.62. At x=0.64, the cubic unit cell is compressed into a tetragonal cell and CrO6 octahedrons are distorted. With continuing Cu content increases above 0.64, the distortion of the unit cell is released slightly according to the changes in c/a. Magnetic properties of Cd1−xCuxCr2O4(x=0.1,0.3,0.5,0.7) have also been measured and are discussed.

scholarly journals Equimolar Yttria-Stabilized Zirconia and Samaria-Doped Ceria Solid Solutions

Ceramics ◽  
2018 ◽  
Vol 1 (2) ◽  
pp. 343-352 ◽  
Author(s):  
Reginaldo Muccillo ◽  
Daniel de Florio ◽  
Eliana Muccillo
Keyword(s):  
Tetragonal Phase ◽  
Room Temperature ◽  
Single Phase ◽  
Rietveld Analysis ◽  
X Ray Diffraction ◽  
Ceramic Powders ◽  
Stabilized Zirconia ◽  
X Ray ◽  
Ceria Solid Solutions ◽  
Attrition Milling

Compositions of (ZrO2)0.92(Y2O3)0.08 (zirconia: 8 mol % yttria—8YSZ) and (CeO2)0.8(Sm2O3)0.2 (ceria: 20 mol % samaria—SDC20) ceramic powders were prepared by attrition milling to form an equimolar powder mixture, followed by uniaxial and isostatic pressing. The pellets were quenched to room temperature from 1200 °C, 1300 °C, 1400 °C and 1500 °C to freeze the defects configuration attained at those temperatures. X-ray diffraction analyses, performed in all quenched pellets, show the evolution of the two (8YSZ and SDC20) cubic fluorite structural phases to a single phase at 1500 °C, identified by Rietveld analysis as a tetragonal phase. Impedance spectroscopy analyses were carried out in pellets either quenched or slowly cooled from 1500 °C. Heating the quenched pellets to 1000 °C decreases the electrical resistivity while it increases in the slowly cooled pellets; the decrease is ascribed to annealing of defects created by lattice micro-tensions during quenching while the increase to partial destabilization of the tetragonal phase.

THE MICRO-REGION COMPOSITIONAL VARIATION OF Y1Ba2Cu3O9−x SINGLE PHASE SUPERCONDUCTOR

1987 ◽  
Vol 01 (02) ◽  
pp. 231-236 ◽  
Author(s):  
Zhenhong Mai ◽  
Liquan Chen ◽  
Xi Chu ◽  
Daoyang Dai ◽  
Yongming Ni ◽  
...  
Keyword(s):  
Single Phase ◽  
Structural Phase ◽  
Compositional Variation ◽  
Interfacial Region ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compositional Distribution ◽  
New Superconductor ◽  
Phase Superconductor ◽  
The Ideal

We have investigated the microstructure and compositional distribution of the Y 1 Ba 2 Cu 3 O 9−x single phase superconductor with scanning electron microscopy, energy dispersion x-ray spectrometry and x-ray diffraction. It has been found that the micro-region compositions are far front the ideal values, especially the yttrium content is quite higher than the suspected amount in the interfacial region. between crystalline grains. We propose that there might be another structural phase co-existed with the Y 1 Ba 2 Cu 3 O 9−x compound and it can not be distinguished from the main phase with diffraction methods. This phase would influence the properties, in particular the critical current density jc of the new superconductor.

Studies on Internal Friction and Curie Temperature of NiMgCuZn Spinel Ferrites for Micro-Inductor Applications

2015 ◽  
Vol 241 ◽  
pp. 202-225
Author(s):  
N. Varalaxmi ◽  
K.V. Sivakumar ◽  
Hardev Singh Virk
Keyword(s):  
Internal Friction ◽  
Curie Temperature ◽  
Single Phase ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
X Ray Diffraction ◽  
Piezoelectric Resonator ◽  
X Ray ◽  
Compositional Changes ◽  
Single Stress

Three series of NiMgCuZn ferrites were prepared by conventional double sintering ceramic process. The formation of single phase in these ferrites was confirmed by X-ray diffraction. A brief review of the important investigations carried out on the internal friction behaviour of NiMgCuZnFe2O4, in the temperature range 40oC to 360oC, has been reported. In the present investigation, the composite piezoelectric resonator method has been used. The effect of compositional changes of ferrites on Curie temperature and internal friction are reported. Results and discussions on the temperature variation of internal friction of the three series of NiMgCuZnFe2O4samples are discussed. In all the series studied, only single stress induced relaxation peaks are observed. These studies were carried out to develop a ferrite composition for their use as core materials for microinductor applications. The results are explained in the light of structural phase transitions.

Phase Transformations in physical mixtures of Pd-Cu nanoparticles

2013 ◽  
Vol 1528 ◽  
Author(s):  
Vineetha Mukundan ◽  
Jun Yin ◽  
Chuan-Jian Zhong ◽  
Oana Malis
Keyword(s):  
Structural Phase ◽  
Alloy Nanoparticles ◽  
Thermal Treatments ◽  
Cu Nanoparticles ◽  
X Ray Diffraction ◽  
Structural Phase Transformation ◽  
X Ray ◽  
Random Alloy ◽  
Physical Mixtures

ABSTRACTThe temperature induced structural transformations in physical mixtures of 1nm palladium and ultrafine (∼0.5nm) copper nanoparticles supported on carbon were studied using in-situ real time synchrotron based x-ray diffraction. These nanoparticles were subjected to two-step thermal annealing from 25°C to 700°C. The Pd and Cu nanoparticles were found to coalesce forming alloy nanoparticles that subsequently undergo a structural phase transformation from ordered B2 to disordered fcc. The random alloy formed at the end of the thermal treatments was found to be copper-rich.

Determination of Residual Stresses in Transformation-Toughened Ceramics

1983 ◽  
Vol 27 ◽  
pp. 221-228
Author(s):  
M. R. James ◽  
D. J. Green ◽  
F. F. Lange
Keyword(s):  
Residual Stress ◽  
Phase Transformation ◽  
Ion Exchange ◽  
Structural Phase ◽  
Surface Chemical ◽  
Structural Phase Transformation ◽  
Surface Residual Stress ◽  
X Ray ◽  
Surface Chemical Reactions

The strength of ceramics or glasses can be increased by placing their surfaces into compression. Techniques include ion exchange, temperature glazing, surface chemical reactions and stress-induced phase transformations. Although most of these techniques are well recognized, little effort has been expended In experimentally determining the magnitude of the compressive stress, and in particular, to use experimental evidence to identify important material and process parameters that need to be controlled. The goal of this investigation was to determine some of the factors that effect the magnitude, profile and depth of the compressive layer introduced by a structural phase transformation. X-ray residual stress measurements were used to directly determine the state of the surface residual stress.

Effects of Manganese Addition on Phase Formation Behavior and Dielectric Properties of ((K0.5Na0.5)0.935Li0.065)NbO3 Ceramics

2014 ◽  
Vol 608 ◽  
pp. 206-211
Author(s):  
Supattra Wongsaenmai ◽  
Santi Maensiri ◽  
Rattikorn Yimnirun
Keyword(s):  
Dielectric Properties ◽  
Phase Formation ◽  
Single Phase ◽  
Structural Phase ◽  
Tetragonal Symmetry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Formation Behavior ◽  
Different Grain Size ◽  
Scanning Electron

In this study, ceramics in ((K0.5Na0.5)0.935Li0.065)NbO3+ xMnO2(mol%) ceramics (when x = 0.0025, 0.0050, 0.01 and 0.015) were successfully prepared by the conventional mixed-oxide technique. The structural phase formation and microstructure were characterized by x-ray diffraction technique (XRD) and scanning electron microscopy (SEM). The crystal structure was identified by XRD as a single-phase perovskite structure, with tetragonal symmetry. The microstructure shows different grain size with different composition x. This study clearly showed that the Mn has influence on the dielectric properties in ((K0.5Na0.5)0.935Li0.065)NbO3ceramics.

scholarly journals Phase Analysis of Bio-Based Derived Tricalcium Disilicate From 2CaO:1SiO2 By X-ray Diffraction

2021 ◽  
Vol 2129 (1) ◽  
pp. 012054
Author(s):  
Siti Nur Hazwani Yunus ◽  
Khor Shing Fhan ◽  
Banjuraizah Johar ◽  
Nur Maizatul Shima Adzali ◽  
Nur Hazlinda Jakfar ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Rice Husk ◽  
Single Phase ◽  
Sintering Temperature ◽  
Rietveld Analysis ◽  
Dicalcium Silicate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Complete Formation

Abstract In this paper, tricalcium disilicate was formed from dicalcium silicate compound powder, synthesised via a mechanochemical technique using a stoichiometric 2CaO:1SiO2. Compound CaO and SiO2 were derived from the bio-waste of eggshell and rice husk at the calcination temperature of 900°C and 800°C, respectively. The dicalcium disilicate powder was sintered for 2 hours at different temperatures ranging from 1150°C to 1350°C. Using X-ray diffraction with Rietveld analysis, it was found that the amount of tricalcium disilicate with monoclinic (beta) crystal structure increases on sintering temperature at the expense of dicalcium silicate. The complete formation of single-phase tricalcium disilicate began at a sintering temperature of 1300°C. The effect of sintering temperatures on the crystallisation and phase transition of dicalcium silicate is reported. The size of crystallites depends on the sintering temperature. The finding of this study rebound to the benefit of society by reducing the risk-off pollution cause by accessive redundant bio-waste eggshell and rice husk and also reduced the amount of CaO and SiO2 used in the fabrication of Ca3Si2O7.

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