Synchrotron X-Ray Study of the Crystal Structure and Hydrothermal Degradation of Yttria-Stabilized Tetragonal Zirconia Polycrystal

2008 ◽  
Vol 91 (5) ◽  
pp. 1634-1639 ◽  
Author(s):  
Isao Yamashita ◽  
Koji Tsukuma ◽  
Takeo Tojo ◽  
Hitoshi Kawaji ◽  
Tooru Atake
Keyword(s):  
Crystal Structure ◽  
Tetragonal Zirconia ◽  
X Ray ◽  
Hydrothermal Degradation ◽  
Tetragonal Zirconia Polycrystal

scholarly journals Effect of Cooling Rate during Glazing on the Mechanical and Optical Properties of Monolithic Zirconia with 3 mol% Yttria Content

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7474
Author(s):  
Mi-Hyang Cho ◽  
Hyo-Joung Seol
Keyword(s):  
Crystal Structure ◽  
Grain Size ◽  
Optical Properties ◽  
Flexural Strength ◽  
Cooling Rate ◽  
Weibull Modulus ◽  
Tetragonal Zirconia ◽  
General Cooling ◽  
Monolithic Zirconia ◽  
Tetragonal Zirconia Polycrystal

Glazing is the final heat treatment process in the manufacturing of a monolithic zirconia prosthesis. Herein, the effect of cooling rate during zirconia glazing was investigated. A 3 mol% yttria-stabilized tetragonal zirconia polycrystal was glazed at the general cooling rate suggested by the manufacturer, as well as at higher and lower cooling rates, and the differences in flexural strength, hardness, optical properties, and crystal structure were evaluated. A higher cooling rate did not affect the flexural strength, hardness, grain size, optical properties, or crystal structure; however, the Weibull modulus decreased by 1.3. A lower cooling rate did not affect the flexural strength, optical properties, or crystal structure; however, the Weibull characteristic strength increased by 26.7 MPa and the Weibull modulus increased by 0.9. The decrease in hardness and the increase in grain size were statistically significant; however, the numerical differences were negligible. This study revealed that a lower cooling rate provides more reliable flexural strength. Therefore, glazing can proceed at a general cooling rate, which takes 3–4 min; however, glazing at a lower cooling rate will provide a more consistent flexural strength if desired, despite being time-consuming.

Nondestructive Reliability Monitoring of Zirconia Degraded under Hydrothermal Condition

2012 ◽  
Vol 249-250 ◽  
pp. 968-971
Author(s):  
Chan Yang Choi ◽  
Jai Won Byeon
Keyword(s):  
Exposure Time ◽  
Tetragonal Zirconia ◽  
Hydrothermal Condition ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrothermal Degradation ◽  
Reduction Potentials ◽  
Long Time ◽  
Water Vapor Atmosphere ◽  
Reliability Monitoring

3%yttria-stabilized tetragonal zirconia polycrystal (3mol% Y2O3-ZrO2, 3Y-TZP) ceramic suffers from low temperature degradation (LTD) during long time use under hydrothermal condition. In this research, an attempt was made for monitoring hydrothermal degradation of the ceramic by using semi-nondestructive X-ray diffraction (XRD) method. In order to simulate accelerated hydrothermal degradation, the specimen was placed under water vapor atmosphere at 134°C, 150°C, and 200°C in an autoclave for various exposure time up to 40 hours. From the X-ray diffraction peak, two feature parameters including intensity ratio and full width at half maximum were determined and observed to increase with hydrothermal exposure time and temperature. The consistent changes in XRD parameters were correlated with the tetragonal-to-monoclinic microstructural change. Based on the established linear correlations with hardness reduction, potentials of the two XRD parameters were suggested for health-monitoring of the hydrothermally exposed 3Y-TZP ceramic.

scholarly journals Comparison of zirconia degradation in dental implants and femoral balls: an X-ray diffraction and nanoindentation study

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Javier Gil ◽  
José Angel Delgado-García-Menocal ◽  
Eugenio Velasco-Ortega ◽  
Begoña Bosch ◽  
Luis Delgado ◽  
...  
Keyword(s):  
Dental Implants ◽  
Degradation Mechanism ◽  
Tetragonal Zirconia ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrothermal Degradation ◽  
Implant System ◽  
Dental Applications

Abstract Background New tetragonal zirconia polycrystal dental implants stabilized with yttria (Y-TZP) have appeared in the implantology market in the form of single piece or two-piece zircona implant system. These new type of implants improve the aesthetical properties compared to conventional commercially pure (c.p.) titanium used for implants, although the long term mechanical behavior of these new implants is not yet well known. In orthopaedics, the application of zirconia as femoral balls presented an important controversial use due to the premature fracture once implanted. Y-TZP dental implants can be affected by hydrothermal degradation and its behavior should be analysed to avoid a premature fracture. The scientific question behind the study is to analyse if the degradation mechanism observed in orthopaedics applications of Y-TZP is similar to that of Y-TZP for dental applications. Materials and methods For this purpose, 30 original Y-TZP dental implants and 42 Y-TZP femoral balls fractured in vivo have been studied. Dental implants were submitted to an accelerated hydrothermal degradation to compare with the femoral balls fractured in vivo. Phase transformation as well as the mechanical behaviour of the degraded samples was studied by X ray diffraction and nanoindentation tests, respectively. Results Results have shown that the fracture mechanism of dental implants does not resemble the mechanism observed in orthopaedic samples, presenting a good long-term behaviour. Conclusion The results ensure the good performance of zirconia dental implants, because the degradation of the ceramic is very limited and does not affect the mechanical properties.

A study on α-RuCl3 crystal structure by scanning tunneling microscopy

1989 ◽  
Vol 47 ◽  
pp. 30-31
Author(s):  
H.-J. Cantow ◽  
H. Hillebrecht ◽  
S. Magonov ◽  
H. W. Rotter ◽  
G. Thiele
Keyword(s):  
Crystal Structure ◽  
Density Distribution ◽  
Scanning Tunneling Microscopy ◽  
Electron Density ◽  
Structure Determination ◽  
Electron Density Distribution ◽  
Scanning Tunneling ◽  
Monoclinic Space Group ◽  
Tunneling Microscopy ◽  
X Ray

From X-ray analysis, the conclusions are drawn from averaged molecular informations. Thus, limitations are caused when analyzing systems whose symmetry is reduced due to interatomic interactions. In contrast, scanning tunneling microscopy (STM) directly images atomic scale surface electron density distribution, with a resolution up to fractions of Angstrom units. The crucial point is the correlation between the electron density distribution and the localization of individual atoms, which is reasonable in many cases. Thus, the use of STM images for crystal structure determination may be permitted. We tried to apply RuCl3 - a layered material with semiconductive properties - for such STM studies. From the X-ray analysis it has been assumed that α-form of this compound crystallizes in the monoclinic space group C2/m (AICI3 type). The chlorine atoms form an almost undistorted cubic closed package while Ru occupies 2/3 of the octahedral holes in every second layer building up a plane hexagon net (graphite net). Idealizing the arrangement of the chlorines a hexagonal symmetry would be expected. X-ray structure determination of isotypic compounds e.g. IrBr3 leads only to averaged positions of the metal atoms as there exist extended stacking faults of the metal layers.

X-ray Crystal Structure of ?9-THC-tosylate

Planta Medica ◽  
2008 ◽  
Vol 74 (03) ◽  
Author(s):  
W Gul ◽  
P Carvalho ◽  
D Slade ◽  
M Avery ◽  
JR Duchek ◽  
...  
Keyword(s):  
Crystal Structure ◽  
X Ray

Crystal structure of an inclusion complex between chiral monoaza-15-crown-5 and S(–)-1-phenyl-ethyl ammonium percholorate

2003 ◽  
Vol 218 (5) ◽  
Author(s):  
Süheyla Özbey ◽  
F. B. Kaynak ◽  
M. Toğrul ◽  
N. Demirel ◽  
H. Hoşgören
Keyword(s):  
Crystal Structure ◽  
Inclusion Complex ◽  
Single Crystal ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
New Type

AbstractA new type of inclusion complex, S(–)-1 phenyl ethyl ammonium percholorate complex of R-(–)-2-ethyl - N - benzyl - 4, 7, 10, 13 - tetraoxa -1- azacyclopentadecane, has been prepared and studied by NMR, IR and single crystal X-ray diffraction techniques. The compound crystallizes in space group

Single Crystal Growth of High-Pressure Phases of Ice and Salt Hydrate Far Below the Original Melting Point by Mixing Alcohol: Crystal Structure Determination of Magnesium Chloride Heptahydrate

2020 ◽  
Author(s):  
Keishiro Yamashita ◽  
Kazuki Komatsu ◽  
Hiroyuki Kagi
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Crystal Growth ◽  
Single Crystal ◽  
Room Temperature ◽  
Growth Technique ◽  
Salt Hydrate ◽  
X Ray

An crystal-growth technique for single crystal x-ray structure analysis of high-pressure forms of hydrogen-bonded crystals is proposed. We used alcohol mixture (methanol: ethanol = 4:1 in volumetric ratio), which is a widely used pressure transmitting medium, inhibiting the nucleation and growth of unwanted crystals. In this paper, two kinds of single crystals which have not been obtained using a conventional experimental technique were obtained using this technique: ice VI at 1.99 GPa and MgCl<sub>2</sub>·7H<sub>2</sub>O at 2.50 GPa at room temperature. Here we first report the crystal structure of MgCl2·7H2O. This technique simultaneously meets the requirement of hydrostaticity for high-pressure experiments and has feasibility for further in-situ measurements.

Sign in / Sign up

Export Citation Format

Share Document