scholarly journals The Influence of Surface Preparation, Chewing Simulation, and Thermal Cycling on the Phase Composition of Dental Zirconia

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2133
Author(s):  
Markus Wertz ◽  
Florian Fuchs ◽  
Hieronymus Hoelzig ◽  
Julia Maria Wertz ◽  
Gert Kloess ◽  
...  
Keyword(s):  
Phase Composition ◽  
Rietveld Method ◽  
Tetragonal Zirconia ◽  
Surface Preparation ◽  
Dental Restoration ◽  
X Ray Diffraction ◽  
X Ray ◽  
Chewing Simulation ◽  
Yttria Content ◽  
Dental Restorative

The effect of dental technical tools on the phase composition and roughness of 3/4/5 yttria-stabilized tetragonal zirconia polycrystalline (3y-/4y-/5y-TZP) for application in prosthetic dentistry was investigated. Additionally, the X-ray diffraction methods of Garvie-Nicholson and Rietveld were compared in a dental restoration context. Seven plates from two manufacturers, each fabricated from commercially available zirconia (3/4/5 mol%) for application as dental restorative material, were stressed by different dental technical tools used for grinding and polishing, as well as by chewing simulation and thermocycling. All specimens were examined via laser microscopy (surface roughness) and X-ray diffraction (DIN EN ISO 13356 and the Rietveld method). As a result, the monoclinic phase fraction was halved by grinding for the 3y-TZP and transformed entirely into one of the tetragonal phases by polishing/chewing for all specimens. The tetragonal phase t is preferred for an yttria content of 3 mol% and phase t″ for 5 mol%. Mechanical stress, such as polishing or grinding, does not trigger low-temperature degradation (LTD), but it fosters a phase transformation from monoclinic to tetragonal under certain conditions. This may increase the translucency and deteriorate the mechanical properties to some extent.

scholarly journals Dense zircon (ZrSiO4) ceramics by a simple milling-sintering route

2018 ◽  
Vol 50 (1) ◽  
pp. 15-28 ◽  
Author(s):  
Matías Gauna ◽  
María Conconi ◽  
Gustavo Suarez ◽  
Esteban Aglietti ◽  
Nicolás Rendtorff
Keyword(s):  
Vickers Hardness ◽  
Milling Time ◽  
Sintering Temperature ◽  
Rietveld Method ◽  
Tetragonal Zirconia ◽  
Time Effect ◽  
X Ray Diffraction ◽  
Refractory Powder ◽  
X Ray ◽  
Sintering Additives

In this work, a simple milling sintering route (pressure less) to process dense zircon ceramics from fine (D50 0.8 ?m) zircon powders is explored. Particularly, the milling time effect (0-120 min) and the maximum sintering temperature (1400-1600?C) were studied. The sintering grade developed microstructure and Vickers hardness (Hv) were evaluated and correlated. The dissociation of silicate into (monoclinic and tetragonal) zirconia and silica was evaluated by X-ray diffraction followed by the Rietveld method; it was found to be below 10 wt% in all the studied ranges. The sintering was enhanced by the milling pretreatment. No sintering additives were incorporated. Dense zircon (porosity below 1%) ceramics were obtained by a simple milling-sintering route of this high refractory powder at 100-200?C below the sintering temperature used with conventional processing routes to obtain equivalent final properties. The Vickers hardness reached: 9.0 GPa.

Application of the Rietveld method to quantitative analysis of impurities in synthetic diamond powder

2004 ◽  
Vol 19 (2) ◽  
pp. 141-144 ◽  
Author(s):  
Rashmi ◽  
Nahar Singh ◽  
A. K. Sarkar
Keyword(s):  
Phase Composition ◽  
Quantitative Analysis ◽  
Synthetic Diamond ◽  
Rietveld Method ◽  
Diamond Powder ◽  
X Ray Diffraction ◽  
X Ray ◽  
Amorphous Content ◽  
A Minor ◽  
Synthetic Diamond Powder

Synthetic diamonds are an important class of industrial material. During synthesis impurities may get introduced into diamond. Identification and quantification of impurities is important as they affect the properties and suitability of the diamonds for their application. Impurities in an industrial synthetic diamond powder sample were analyzed by X-ray diffraction (XRD) and also by chemical methods. X-ray diffraction pattern showed diamond as the major phase and α-iron as a minor phase. Quantitative analysis of crystalline phases was done by performing Rietveld refinement of the XRD profile. Chemical analysis showed the presence of several other impurities as well, though in small amounts. It was considered that the impurities other than iron were in amorphous form and an estimate of the amorphous content was made on this basis. Relative phase composition of diamond and iron as estimated by XRD were corrected for the amorphous content to obtain absolute phase composition.

The Comparative Study of Phase Composition of Steels Using X-Ray Diffraction and Mössbauer Spectroscopy Methods

2013 ◽  
Vol 203-204 ◽  
pp. 150-155
Author(s):  
Piotr Pawluk ◽  
Emilia Skołek ◽  
Michał Kopcewicz ◽  
Wiesław Świątnicki
Keyword(s):  
Mössbauer Spectroscopy ◽  
Phase Composition ◽  
Retained Austenite ◽  
Mossbauer Spectroscopy ◽  
Rietveld Method ◽  
Bainitic Ferrite ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mößbauer Spectroscopy ◽  
Diffraction Patterns

In this paper phase composition of several steels was investigated by X-ray diffraction and conversion electron Mössbauer spectroscopy (CEMS) methods. Different heat treatments were performed on steel samples in order to obtain various phase compositions (containing bainitic ferrite, martensite and retained austenite). The diffraction patterns were analysed using the Rietveld method. Mössbauer spectra were fitted and studied for existent phases. A comparison between results obtained by each method was performed. Both methods revealed some supersaturation of carbon in the retained austenite and in the bainitic ferrite phases, various after different treatments. The quantitative phase composition measured by X-ray diffraction results differ significantly from the Mössbauer spectroscopy results. The possible reasons of the observed differences were discussed.

Control of the phase composition of advanced calcium phosphates using an x-ray diffractometer with a curved position-sensitive detector

2020 ◽  
Vol 86 (6) ◽  
pp. 29-35
Author(s):  
V. P. Sirotinkin ◽  
O. V. Baranov ◽  
A. Yu. Fedotov ◽  
S. M. Barinov
Keyword(s):  
Phase Composition ◽  
Calcium Phosphates ◽  
Position Sensitive Detector ◽  
Sensitive Detector ◽  
X Ray Diffraction ◽  
X Ray ◽  
Impurity Phases ◽  
Position Sensitive ◽  
Diffraction Peaks ◽  
Diffraction Patterns

The results of studying the phase composition of advanced calcium phosphates Ca10(PO4)6(OH)2, β-Ca3(PO4)2, α-Ca3(PO4)2, CaHPO4 · 2H2O, Ca8(HPO4)2(PO4)4 · 5H2O using an x-ray diffractometer with a curved position-sensitive detector are presented. Optimal experimental conditions (angular positions of the x-ray tube and detector, size of the slits, exposure time) were determined with allowance for possible formation of the impurity phases during synthesis. The construction features of diffractometers with a position-sensitive detector affecting the profile characteristics of x-ray diffraction peaks are considered. The composition for calibration of the diffractometer (a mixture of sodium acetate and yttrium oxide) was determined. Theoretical x-ray diffraction patterns for corresponding calcium phosphates are constructed on the basis of the literature data. These x-ray diffraction patterns were used to determine the phase composition of the advanced calcium phosphates. The features of advanced calcium phosphates, which should be taken into account during the phase analysis, are indicated. The powder of high-temperature form of tricalcium phosphate strongly adsorbs water from the environment. A strong texture is observed on the x-ray diffraction spectra of dicalcium phosphate dihydrate. A rather specific x-ray diffraction pattern of octacalcium phosphate pentahydrate revealed the only one strong peak at small angles. In all cases, significant deviations are observed for the recorded angular positions and relative intensity of the diffraction peaks. The results of the study of experimentally obtained mixtures of calcium phosphate are presented. It is shown that the graphic comparison of experimental x-ray diffraction spectra and pre-recorded spectra of the reference calcium phosphates and possible impurity phases is the most effective method. In this case, there is no need for calibration. When using this method, the total time for analysis of one sample is no more than 10 min.

Formation of nanoscale sodium dodecahydro-closo- dodecaborate Na2[B12H12] on silicate matrix surface

2019 ◽  
Vol 484 (1) ◽  
pp. 41-43
Author(s):  
E. A. Malinina ◽  
V. K. Skachkova ◽  
I. V. Kozerozhets ◽  
V. V. Avdeeva ◽  
L. V. Goeva ◽  
...  
Keyword(s):  
Phase Composition ◽  
Ammonium Salt ◽  
Liquid Glass ◽  
Silicate Matrix ◽  
X Ray Diffraction ◽  
X Ray ◽  
Salt Sample ◽  
Matrix Surface

The method of nanoscaled sodium dodecahydro-closo-dodecaborate Na2[B12H12] synthesis is presented. The composite is heated to 200°C to yield the desired product, forming with the introduction of triethyl- ammonium salt [Et3NH]2[B12H12] into the silicate matrix of a sodium liquid glass. The morphology and phase composition of the synthesized sample are studied through SEM and X-ray diffraction methods, in comparison to those of a standard salt sample Na2[B12H12]. Based on the obtained data, the sample under study is an amorphous composite, on the surface of which nanoscale crystals of Na2[B12H12] form.

X-ray powder diffraction data of LaNi0.5Ti0.45Co0.05O3, LaNi0.45Co0.05Ti0.5O3, and LaNi0.5Ti0.5O3 perovskites

2021 ◽  
pp. 1-6
Author(s):  
Mariana M. V. M. Souza ◽  
Alex Maza ◽  
Pablo V. Tuza
Keyword(s):  
Crystal Structure ◽  
Rietveld Method ◽  
Pechini Method ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Modified Pechini Method ◽  
Scanning Electron

In the present work, LaNi0.5Ti0.45Co0.05O3, LaNi0.45Co0.05Ti0.5O3, and LaNi0.5Ti0.5O3 perovskites were synthesized by the modified Pechini method. These materials were characterized using X-ray fluorescence, scanning electron microscopy, and powder X-ray diffraction coupled to the Rietveld method. The crystal structure of these materials is orthorhombic, with space group Pbnm (No 62). The unit-cell parameters are a = 5.535(5) Å, b = 5.527(3) Å, c = 7.819(7) Å, V = 239.2(3) Å3, for the LaNi0.5Ti0.45Co0.05O3, a = 5.538(6) Å, b = 5.528(4) Å, c = 7.825(10) Å, V = 239.5(4) Å3, for the LaNi0.45Co0.05Ti0.5O3, and a = 5.540(2) Å, b = 5.5334(15) Å, c = 7.834(3) Å, V = 240.2(1) Å3, for the LaNi0.5Ti0.5O3.

Phase composition depth profiles using spatially resolved energy dispersive X-ray diffraction

2004 ◽  
Vol 37 (6) ◽  
pp. 967-976 ◽  
Author(s):  
Andrew C. Jupe ◽  
Stuart R. Stock ◽  
Peter L. Lee ◽  
Nikhila N. Naik ◽  
Kimberly E. Kurtis ◽  
...  
Keyword(s):  
Phase Composition ◽  
Spatial Resolution ◽  
Zinc Coating ◽  
High Energy ◽  
Sulfate Attack ◽  
Energy Dispersive ◽  
X Ray Diffraction ◽  
X Ray ◽  
Spatially Resolved ◽  
Composition Profiles

Spatially resolved energy dispersive X-ray diffraction, using high-energy synchrotron radiation (∼35–80 keV), was used nondestructively to obtain phase composition profiles along the radii of cylindrical cement paste samples to characterize the progress of the chemical changes associated with sulfate attack on the cement. Phase distributions were acquired to depths of ∼4 mm below the specimen surface with sufficient spatial resolution to discern features less than 200 µm thick. The experimental and data analysis methods employed to obtain quantitative composition profiles are described. The spatial resolution that could be achieved is illustrated using data obtained from copper cylinders with a thin zinc coating. The measurements demonstrate that this approach is useful for nondestructively visualizing the sometimes complex transformations that take place during sulfate attack on cement-based materials. These transformations can be spatially related to microstructure as seen by computed microtomography.

Synthesis of CaWO4:(Eu3+,Tb3+) Thin Films by a Two-Step Method at Room Temperature

2013 ◽  
Vol 710 ◽  
pp. 170-173
Author(s):  
Lian Ping Chen ◽  
Yuan Hong Gao
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Phase Composition ◽  
Room Temperature ◽  
Electrochemical Techniques ◽  
Luminescent Properties ◽  
X Ray Diffraction ◽  
Step Method ◽  
X Ray ◽  
Rare Earth Doped

It is hardly possible to obtain rare earth doped CaWO4thin films directly through electrochemical techniques. A two-step method has been proposed to synthesize CaWO4:(Eu3+,Tb3+) thin films at room temperature. X-ray diffraction, energy dispersive X-ray analysis, spectrophotometer were used to characterize their phase, composition and luminescent properties. Results reveal that (Eu3+,Tb3+)-doped CaWO4films have a tetragonal phase. When the ratio of n (Eu)/n (Tb) in the solution is up to 3:1, CaWO4:(Eu3+,Tb3+) thin film will be enriched with Tb element; on the contrary, when the ratio in the solution is lower than 1:4, CaWO4:(Eu3+,Tb3+) thin film will be enriched with Eu element. Under the excitation of 242 nm, sharp emission peaks at 612, 543, 489 and 589 nm have been observed for CaWO4:(Eu3+,Tb3+) thin films.

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