Phase transformation of nanocrystalline anatase-to-rutile via combined interface and surface nucleation

2000 ◽  
Vol 15 (2) ◽  
pp. 437-448 ◽  
Author(s):  
Hengzhong Zhang ◽  
Jillian F. Banfield
Keyword(s):  
Phase Transformation ◽  
Particle Packing ◽  
X Ray Diffraction ◽  
Dense Particle ◽  
Free Surfaces ◽  
Size Dependent ◽  
Surface Nucleation ◽  
Bulk Nucleation ◽  
Alumina Particles ◽  
Kinetics Of

The kinetics of phase transformation of nanocrystalline anatase samples was studied using x-ray diffraction at temperatures ranging from 600 to 1150 °C. Kinetic data were analyzed with an interface nucleation model and a newly proposed kinetic model for combined interface and surface nucleation. Results revealed that the activation energy of nucleation is size dependent. In anatase samples with denser particle packing, rutile nucleates primarily at interfaces between contacting anatase particles. In anatase samples with less dense particle packing, rutile nucleates at both interfaces and free surfaces of anatase particles. The predominant nucleation mode may change from interface nucleation at low temperatures to surface nucleation at intermediate temperatures and to bulk nucleation at very high temperatures. Alumina particles dispersed among the anatase particles can effectively reduce the probability of interface nucleation at all temperatures.

Kinetics of the γ → α-alumina phase transformation by quantitative X-ray diffraction

2007 ◽  
Vol 42 (8) ◽  
pp. 2830-2836 ◽  
Author(s):  
Maria Iaponeide Fernandes Macêdo ◽  
Celso Aparecido Bertran ◽  
Carla Cristiane Osawa
Keyword(s):  
Phase Transformation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Alumina Phase ◽  
Kinetics Of

Phase Transformation in Austenitic Steel Induced by Plastic Deformation

2010 ◽  
Vol 163 ◽  
pp. 295-298 ◽  
Author(s):  
Jan Drahokoupil ◽  
Petr Haušild ◽  
Vadim Davydov ◽  
P. Pilvin
Keyword(s):  
Plastic Deformation ◽  
Phase Transformation ◽  
Martensitic Transformation ◽  
Neutron Diffraction ◽  
Volume Fraction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Deformed State ◽  
Kinetics Of ◽  
Electron Back Scattered Diffraction

Kinetics of deformation induced martensitic transformation in metastable austenitic AISI 301 steel was characterized by several techniques including classical light metallography, X-ray diffraction, neutron diffraction and electron back scattered diffraction. In order to characterize the martensitic transformation, several specimens were tensile pre-deformed to 5%, 10% and 20% of plastic deformation and compared with non-deformed state. During straining, the volume fraction of α’-martensite rapidly prevails over the volume fraction of original austenite and reach the value circa 70%.

Enhancement of Aurivillius Phase Formation Kinetics in SBT Thin Films using Nanoparticle Seeding

2003 ◽  
Vol 784 ◽  
Author(s):  
Yun-Mo Sung ◽  
Woo-Chul Kwak ◽  
Se-Yon Jung ◽  
Seung-Joon Hwang
Keyword(s):  
Thin Films ◽  
Activation Energy ◽  
Phase Transformation ◽  
Phase Formation ◽  
X Ray Diffraction ◽  
Aurivillius Phase ◽  
X Ray ◽  
Si Substrates ◽  
Formation Kinetics ◽  
Kinetics Of

ABSTRACTPt/Ti/SiO2/Si substrates seeded by SBT nanoparticles (∼60–80 nm) were used to enhance the phase formation kinetics of Sr0.7Bi2.4Ta2O9 (SBT) thin films. The volume fractions of Aurivillius phase formation obtained through quantitative x-ray diffraction (Q-XRD) analyses showed highly enhanced kinetics in seeded SBT thin films. The Avrami exponents were determined as ∼1.4 and ∼0.9 for unseeded and seeded SBT films, respectively, which reveals different nucleation modes. By using Arrhenius–type plots the activation energy values for the phase transformation of unseeded and seeded SBT thin films were determined to be ∼264 and ∼168 kJ/mol, respectively. This gives a key reason to the enhanced kinetics in seeded films. Microstructural analyses on unseeded SBT thin films showed formation of randomly oriented needle-like crystals, while those on seeded ones showed formation of domains comprised of directionally grown worm-like crystals.

Evidence of two-length-scale kinetics of R-phase transformation by high-energy X-ray diffraction

2010 ◽  
Vol 62 (8) ◽  
pp. 617-620 ◽  
Author(s):  
Y.D. Wang ◽  
Y. Ren ◽  
E.W. Huang ◽  
G. Wang ◽  
Z.H. Nie ◽  
...  
Keyword(s):  
Phase Transformation ◽  
High Energy ◽  
Length Scale ◽  
X Ray Diffraction ◽  
X Ray ◽  
Kinetics Of

scholarly journals Influence of Manufacturing Regimes on the Phase Transformation of Dental Zirconia

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4980
Author(s):  
Markus Wertz ◽  
Hieronymus Hoelzig ◽  
Gert Kloess ◽  
Sebastian Hahnel ◽  
Andreas Koenig
Keyword(s):  
Phase Transformation ◽  
Phase Composition ◽  
Low Temperature ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
X Ray ◽  
Dental Prostheses ◽  
Alumina Particles ◽  
History Of ◽  
Fixed Dental Prostheses

Background: The influence of typical manufacturing regimes for producing fixed dental prostheses (FDPs) from yttria partly-stabilized zirconia polycrystals (3Y/4Y/5Y-TZP) on the phase composition is quantified. Methods: Fixed dental prostheses (FDPs) were designed using a CAD process and machined from different Y-TZP blanks from two manufacturers differing in yttria contents. Subsequent to sintering, the FDPs were glaze fired and air-blasted using alumina particles. Phase composition was determined with X-ray diffraction and quantified with Rietveld refinement. Results: The blanks from VITA Zahnfabrik (VITA YZ HT, VITA YZ ST, VITA YZ XT) and Dental Direct (DD Bio ZX2, DD cube ONE, DD cube X2) featured a rhombohedral portion with rather small crystallites and a small monoclinic portion for 3Y/4Y-TZPs, which increased after machining and disappeared after sintering. Glaze firing and air-blasting with alumina particles had no significant influence on the phase composition. Conclusion: The phase history of dental zirconia is revealed, which may have implications on further processing and aging of the FDP (e.g. low temperature degradation) in mouth.

An Examination of the Kinetics of the Solution-Mediated Polymorphic Phase Transformation between α- and β-Forms ofl-Glutamic Acid as Determined Using Online Powder X-ray Diffraction†

2008 ◽  
Vol 8 (7) ◽  
pp. 2205-2216 ◽  
Author(s):  
Spoorthi Dharmayat ◽  
Robert B. Hammond ◽  
Xiaojun Lai ◽  
Caiyun Ma ◽  
Elida Purba ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Glutamic Acid ◽  
X Ray Diffraction ◽  
X Ray ◽  
Kinetics Of

Crystallization Kinetics and Phase Transformation of Li2O–Fe2O3–MnO2–CaO–P2O5–SiO2 Glass

1998 ◽  
Vol 13 (9) ◽  
pp. 2655-2661 ◽  
Author(s):  
Chi-Shiung His ◽  
Moo-Chin Wang
Keyword(s):  
Phase Transformation ◽  
Heating Rate ◽  
Crystallization Kinetics ◽  
Xrd Analysis ◽  
Nonisothermal Kinetics ◽  
Growth Morphology ◽  
Surface Nucleation ◽  
Activation Energy Of Crystallization ◽  
Dta Analysis ◽  
Kinetics Of

The crystallization kinetics and phase transformation of 10Li2O–14Fe2O3–11MnO2–25CaO–5P2O5–35SiO2 (LFMCPS) glass have been investigated using differential thermal analysis (DTA), Χ-ray diffraction (XRD), and scanning electron microscopy (SEM). The major crystalline phase determined by XRD analysis was triphylite [Li(Fe0.5Mn0.5)PO4], β–wollastonite (β CaO SiO2) and magnetite (Fe3O4) as the minor phases. The nonisothermal kinetics of crystallization of the LMFCPS glass was investigated using DTA analysis. The activation energy of crystallization for LFMCPS glass was 74.6 kcalymol. The growth morphology parameter n was 0.98 at a heating rate of 5 °C/min and decreased to 0.74 as the heating rate increased to 20 °C/min. The numerical factor of crystallization mechanism m was 0.57 at low crystallization temperature and gradually decreased as the temperature increased. For the experiment, the parameters n and m were approximately one. These results indicated that the surface nucleation was dominant in LFMCPS glass crystallization.

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