Phase analysis of sintered yttria–zirconia ceramics by x-ray diffraction

1986 ◽  
Vol 1 (2) ◽  
pp. 295-299 ◽  
Author(s):  
A. Paterson ◽  
R. Stevens
Keyword(s):  
Tetragonal Phase ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Zirconia Ceramics ◽  
X Ray ◽  
Different Temperatures ◽  
Shear Transformation ◽  
Original Amount ◽  
Good Agreement

Determination of the amount of cubic and tetragonal phase in yttria–zirconia using high-angle XRD (x-ray diffraction) has been complicated by problems of resolution and interpretation. The evidence, from electron diffraction studies, for a c→t shear transformation also needs to be taken into account. Two compositions, a 3 and a 5.7 mol % Y2O3−ZrO2, were sintered and thermally treated at different temperatures between 1450°and 1700°C. X-ray diffraction traces revealed the anticipated tetragonal (400) and (004) reflections. The region of the diffraction pattern that was thought to arise from the cubic phase could be best interpreted as a second tetragonal phase t'. The original amount of cubic phase computed from the t' reflections showed good agreement with the phase diagram of Scott. The lattice parameters of the t' phase were determined, and the volume of the tetragonal (t') unit cell was calculated.

Local atomic structure in tetragonal pure ZrO2nanopowders

2010 ◽  
Vol 43 (2) ◽  
pp. 227-236 ◽  
Author(s):  
Leandro M. Acuña ◽  
Diego G. Lamas ◽  
Rodolfo O. Fuentes ◽  
Ismael O. Fábregas ◽  
Márcia C. A. Fantini ◽  
...  
Keyword(s):  
Tetragonal Phase ◽  
Local Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Atomic Structures ◽  
Crystallite Sizes ◽  
Exafs Study ◽  
The Difference ◽  
X Ray Absorption ◽  
Good Agreement

The local atomic structures around the Zr atom of pure (undoped) ZrO2nanopowders with different average crystallite sizes, ranging from 7 to 40 nm, have been investigated. The nanopowders were synthesized by different wet-chemical routes, but all exhibit the high-temperature tetragonal phase stabilized at room temperature, as established by synchrotron radiation X-ray diffraction. The extended X-ray absorption fine structure (EXAFS) technique was applied to analyze the local structure around the Zr atoms. Several authors have studied this system using the EXAFS technique without obtaining a good agreement between crystallographic and EXAFS data. In this work, it is shown that the local structure of ZrO2nanopowders can be described by a model consisting of two oxygen subshells (4 + 4 atoms) with different Zr—O distances, in agreement with those independently determined by X-ray diffraction. However, the EXAFS study shows that the second oxygen subshell exhibits a Debye–Waller (DW) parameter much higher than that of the first oxygen subshell, a result that cannot be explained by the crystallographic model accepted for the tetragonal phase of zirconia-based materials. However, as proposed by other authors, the difference in the DW parameters between the two oxygen subshells around the Zr atoms can be explained by the existence of oxygen displacements perpendicular to thezdirection; these mainly affect the second oxygen subshell because of the directional character of the EXAFS DW parameter, in contradiction to the crystallographic value. It is also established that this model is similar to another model having three oxygen subshells, with a 4 + 2 + 2 distribution of atoms, with only one DW parameter for all oxygen subshells. Both models are in good agreement with the crystal structure determined by X-ray diffraction experiments.

scholarly journals Compositional Dependence of Structural Properties of Prepared Alloys and Films

2011 ◽  
Vol 2011 ◽  
pp. 1-6
Author(s):  
M. F. A. Alias ◽  
A. A. J. Al-Douri ◽  
E. M. N. Al-Fawadi ◽  
A. A. Alnajjar
Keyword(s):  
Room Temperature ◽  
Thermal Evaporation ◽  
High Accuracy ◽  
Compositional Dependence ◽  
X Ray Diffraction ◽  
Thermal Evaporation Method ◽  
X Ray ◽  
Glass Substrates ◽  
Different Temperatures ◽  
Good Agreement

Results of a study of alloys and films with various Pb content have been reported and discussed. Films of of thickness 1.5 μm have been deposited on glass substrates by flash thermal evaporation method at room temperature, under vacuum at constant deposition rate. These films were annealed under vacuum around 10−6Torr at different temperatures up to 523 K. The composition of the elements in alloys was determined by standard surfaces techniques such as atomic absorption spectroscopy (AAS) and X-ray fluorescence (XRF), and the results were found of high accuracy and in very good agreement with the theoretical values. The structure for alloys and films is determined by using X-ray diffraction. This measurement reveals that the structure is polycrystalline with cubic structure and there are strong peaks at the direction (200) and (111). The effect of heat treatment on the crystalline orientation, relative intensity, and grain size of films is presented.

Synthesis and Characterization of CeO2 Doped ZrO2 Ceramics by a Simple Sol-Gel Route

2017 ◽  
Vol 907 ◽  
pp. 56-60
Author(s):  
Ummuhanı Hilal Özer ◽  
Kerim Emre Öksüz ◽  
Ali Özer
Keyword(s):  
Tetragonal Phase ◽  
Sol Gel ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Ceramic Powders ◽  
Zirconia Ceramics ◽  
Simple Method ◽  
X Ray ◽  
Gel Technique

It is well known that sol-gel technique is a simple method to produce nano sized ceramic powders. In this study, cerium oxide doped zirconia samples, with 10 mol%-12mol% and14mol% CeO2, were synthesized by sol-gel technique and characterized. The surface morphology, elemental composition, microstructure, and phase analysis, of the sintered CeO2 doped ZrO2 ceramics were characterized by field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDS) analysis, and X-ray diffraction (XRD) respectively. X-ray diffraction for samples sintered at 1550 °C for 4h revealed that the zirconia ceramics have a tetragonal phase structure. The addition of CeO2 can raise the content of the tetragonal phase, but the minor monoclinic phase exists even at the CeO2 content of 10 mol%. The effect of dopant concentration on the lattice parameter, average primary crystallite size and micro-strain was studied. Relative densities for CeO2 doped ZrO2 bulk ceramics varied between 95% and 99 %, depending on the CeO2 addition.

scholarly journals A first-prototype multi-determinant X-ray constrained wavefunction approach: the X-ray constrained extremely localized molecular orbital–valence bond method

2017 ◽  
Vol 73 (4) ◽  
pp. 312-316 ◽  
Author(s):  
Alessandro Genoni
Keyword(s):  
Valence Bond ◽  
Resonance Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Localized Molecular Orbitals ◽  
Structure Factors ◽  
Different Temperatures ◽  
Explicit Consideration ◽  
Bond Method

All the current variants of Jayatilaka's X-ray constrained wavefunction (XCW) approach work within the framework of the single-determinant wavefunctionansatz. In this paper, a first-prototype multi-determinant XCW technique is proposed. The strategy assumes that the desired XCW is written as a valence-bond-like expansion in terms of pre-determined single Slater determinants constructed with extremely localized molecular orbitals. The method, which can be particularly suitable to investigate systems with a multi-reference character, has been applied to determine the weights of the resonance structures of naphthalene at different temperatures by exploiting experimental high-resolution X-ray diffraction data. The results obtained have shown that the explicit consideration of experimental structure factors in the determination of the resonance structure weights may lead to results significantly different compared with those resulting only from the simple energy minimization.

scholarly journals Yttria stabilized tetragonal zirconia ceramics: preparation, characterization and applicationspplications

2018 ◽  
Vol 53 (2) ◽  
pp. 111-116 ◽  
Author(s):  
N Sultana ◽  
K Bilkis ◽  
R Azad ◽  
MR Qadir ◽  
MA Gafur ◽  
...  
Keyword(s):  
Sintering Temperature ◽  
Tetragonal Zirconia ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
Zirconia Ceramics ◽  
X Ray ◽  
Hardness Tester ◽  
Maximum Value ◽  
Different Temperatures ◽  
Temperature Water

In this study, yttria stabilized tetragonal zirconia (YSTZ) ceramics were prepared and were sintered at different temperatures to find out the optimum sintering temperature for their better tetragonality and mechanical properties for their application as optical ferrule. Vicker’s hardness was performed by micro hardness tester and it was found to increase with the increase of sintering temperature to a maximum value, then it was decreased with higher sintering temperature. Water absorptivity and porosity were also seen to decrease as the densities of the specimens were increased. X-ray diffraction was employed to determine crystal structure of sintered samples. Surface morphology of the sintered samples was examined through field emission scanning electron microscope.Bangladesh J. Sci. Ind. Res.53(2), 111-116, 2018

Bismuth on GaSb(110): Structural Determination of the 1×1 and 1×2 Phases by Surface X-Ray Diffraction

1998 ◽  
Vol 05 (05) ◽  
pp. 1043-1052 ◽  
Author(s):  
L. Lottermoser ◽  
T. Van Gemmeren ◽  
O. Bunk ◽  
R. L. Johnson ◽  
E. Landemark ◽  
...  
Keyword(s):  
Structural Model ◽  
Layer Structure ◽  
Zigzag Chain ◽  
X Ray Diffraction ◽  
Surface Geometry ◽  
X Ray ◽  
Reconstructed Surface ◽  
Thermal Stability Of ◽  
Good Agreement

The surface geometry of the 1×1 and 1×2 phases of bismuth on GaSb(110) has been determined using surface X-ray diffraction with synchrotron radiation. The bismuth atoms form zigzag chains along the [Formula: see text] direction of the substrate. For the 1×1 phase four different registries of the bismuth chains with respect to the GaSb(110) substrate are possible. It was found that only the epitaxial continued layer structure was in good agreement with the experimental data. In the 1×2 reconstruction every second zigzag chain in the uppermost substrate layer is missing. The reconstructed surface is terminated with a full monolayer of Bi atoms which also form zigzag chains. The Bi atoms in the chains bond alternately to the first and second layer substrate atoms and the Bi chains are inclined at 34° to the surface. This new structural model explains the higher thermal stability of the 1×2 phase compared to that of the 1×1 phase.

Powder X-ray diffraction data of new bismuth yttrium gadolinium oxides

2008 ◽  
Vol 23 (3) ◽  
pp. 255-258
Author(s):  
M. Alizadeh ◽  
K. Ahmadi ◽  
A. Maghsudipour ◽  
F. Moztarzadeh
Keyword(s):  
Diffraction Data ◽  
Solid State Reaction Method ◽  
Cubic Phase ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Good Agreement

X-ray powder diffraction data for five new bismuth yttrium gadolinium oxide compounds synthesized by solid state reaction method are reported. The unit cell dimensions were determined from X-ray diffraction methods, using CuKα radiation, and evaluated by indexing programs. The cubic phase was the sole crystalline phase detected by X-ray diffraction analysis in Bi0.88Y0.06Gd0.06O1.5, Bi0.88Y0.08Gd0.04O1.5, Bi0.82Y0.09Gd0.09O1.5, Bi0.82Y0.12Gd0.06O1.5, and Bi0.82Y0.06Gd0.12O1.5 samples with lattice constants of a=5.5371(1) Å, a=5.5368(1) Å, a=5.5303(2) Å, a=5.53487(8) Å, and a=5.5279(1) Å, respectively. The results are in good agreement with those reported for bismuth yttrium oxide (Bi0.75Y0.25)O1.5 (PDF 01-084-1450).

Isothermal Mechanical Spectroscopy in Equiatomic CuZr Alloy

2012 ◽  
Vol 184 ◽  
pp. 251-256
Author(s):  
D. Belamri ◽  
Veronique Pelosin ◽  
S. Belhas ◽  
Andre Rivière
Keyword(s):  
Room Temperature ◽  
Cubic Phase ◽  
Diffraction Spectrum ◽  
X Ray Diffraction ◽  
Mechanical Spectroscopy ◽  
X Ray ◽  
Different Temperatures ◽  
Measurement Experiment ◽  
Higher Temperature ◽  
Two Peaks

An equiatomic CuZr alloy quenched from 1073 K was studied by isothermal mechanical spectroscopy and X-Ray diffraction. Experiments were performed using a very large frequency range (10-4Hz – 50 Hz) at different temperatures. For each temperature of measurement, experiment started after complete microstructure stabilization of the sample. At room temperature, the X–Ray diffraction spectrum shows that there are two CuZr monoclinic phases as a consequence of a martensitic transformation. These structures are characterized by the existence of twinning defects for the first one and a high dislocation density for the other. Both monoclinic phases disappear at higher temperatures and first transform into the cubic CuZr phase, then this cubic phase transforms into Cu10Zr7and CuZr2phases above 763 K. Internal friction spectra exhibit two relaxation peaks (P1, P2), at low and high temperatures, respectively. After rapid cooling of the sample from 1273 K, the first peak P1appears from room temperature and disappears after annealing above 673 K. The P2peak appears at about 800 K and increases for measurements at higher temperature up to 880 K. This temperature range corresponds with the existence of both Cu10Zr7and CuZr2phases. These two peaks are associated with a relaxation linked to the dislocation microstructure in the two CuZr monoclinic phases for P1 and in the Cu10Zr7and CuZr2phases for P2.

scholarly journals Theoretical and experimental determination of mass attenuation coefficients of lead-based ceramics and their comparison with simulation

2016 ◽  
Vol 31 (2) ◽  
pp. 142-149 ◽  
Author(s):  
Alireza Vejdani-Noghreiyan ◽  
Elham Aliakbari ◽  
Atiyeh Ebrahimi-Khankook ◽  
Mahdi Ghasemifard
Keyword(s):  
Gamma Ray ◽  
Mass Attenuation Coefficient ◽  
X Ray Diffraction ◽  
Attenuation Coefficients ◽  
X Ray ◽  
Simulation Results ◽  
Theoretical Results ◽  
Good Agreement ◽  
Mass Attenuation

Mass attenuation coefficient of lead-based ceramics have been measured by experimental methods and compared with theoretical and Monte Carlo simulation results. Lead-based ceramics were prepared using mixed oxide method and the X-ray diffraction analysis was done to evaluate the crystal structure of the produced handmade ceramics. The experimental results show good agreement with theoretical and simulation results. However at two gamma ray energies, small differences between experimental and theoretical results have been observed. By adding other additives to ceramics and observing the changes in the shielding properties such as flexibility, one can synthesize and optimize ceramics as a neutron shield.

scholarly journals Microstrain Measurement in Plastically Deformed Austenitic Steel

1999 ◽  
Vol 33 (1-4) ◽  
pp. 219-230 ◽  
Author(s):  
K. Hirschi ◽  
M. Ceretti ◽  
P. Lukás ◽  
N. Ji ◽  
C. Braham ◽  
...  
Keyword(s):  
Austenitic Steel ◽  
Metallic Materials ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compressive Stresses ◽  
Cold Rolled ◽  
The Mean ◽  
Good Agreement

Some results of high-resolution neutron diffraction experiments resulting in determination of the microstrain in metallic materials are reported. The method of the diffraction line broadening analysis was verified in two materials, investigated earlier by X-ray diffraction: an austenitic steel prestrained up to 30% and a cold rolled aluminium magnesium alloy. For these materials, the mean-square microstrain and the dislocation density were determined, a good agreement was reached with the results of X-ray experiments. As an application of such analysis we investigated the influence of the shot-peening treatment on an austenitic steel. This treatment is commonly used to introduce compressive stresses in the surface of material, giving improved resistance to fatigue fracture. The microstrain distribution and the size of coherently diffracting blocks for a shot-peened sample of austenitic steel as a function of depth from the surface are determined by the above analysis and the results are presented.

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