scholarly journals Grain growth kinetics for B2O3-doped ZnO ceramics

2015 ◽  
Vol 33 (2) ◽  
pp. 220-229 ◽  
Author(s):  
Berat Yuksel ◽  
T. Osman Ozkan
Keyword(s):  
Activation Energy ◽  
Grain Growth ◽  
Growth Kinetics ◽  
Liquid Phase Sintering ◽  
Growth Exponent ◽  
Second Phase ◽  
Growth Activation ◽  
Doped Zno ◽  
Grain Growth Kinetics ◽  
Zno Ceramics

AbstractGrain growth kinetics in 0.1 to 2 mol % B2O3-added ZnO ceramics was studied by using a simplified phenomenological grain growth kinetics equation Gn = K0 · t · exp(-Q/RT) together with the physical properties of sintered samples. The samples, prepared by conventional ceramics processing techniques, were sintered at temperatures between 1050 to 1250 °C for 1, 2, 3, 5 and 10 hours in air. The kinetic grain growth exponent value (n) and the activation energy for the grain growth of the 0.1 mol % B2O3-doped ZnO ceramics were found to be 2.8 and 332 kJ/mol, respectively. By increasing B2O3 content to 1 mol %, the grain growth exponent value (n) and the activation energy decreased to 2 and 238 kJ/mol, respectively. The XRD study revealed the presence of a second phase, Zn3B2O6 formed when the B2O3 content was > 1 mol %. The formation of Zn3B2O6 phase gave rise to an increase of the grain growth kinetic exponent and the grain growth activation energy. The kinetic grain growth exponent value (n) and the activation energy for the grain growth of the 2 mol % B2O3-doped ZnO ceramics were found to be 3 and 307 kJ/mol, respectively. This can be attributed to the second particle drag (pinning) mechanism in the liquid phase sintering.

Microstructural Features of the ZnO-Bi2O3 Binary System

2013 ◽  
Vol 545 ◽  
pp. 8-13 ◽  
Author(s):  
Niti Yongvanich ◽  
Visuttipitukul Patama ◽  
Wassa Kijsiri ◽  
Nawarat Pancharoen
Keyword(s):  
Activation Energy ◽  
Grain Growth ◽  
Growth Kinetics ◽  
Transport Processes ◽  
Liquid Phase Sintering ◽  
Growth Exponent ◽  
Size Difference ◽  
Rapid Improvement ◽  
New Findings ◽  
Grain Growth Kinetics

Grain growth in ZnO with Bi2O3 addition of up to 1 mol% was examined in great detail for sintering in air. The results are analyzed and compared with previous reports in the context of the simplified phenomenological grain growth kinetics equation along with the physical properties of the sintered ceramics. In spite of the eutectic temperature at 735 °C, high density (> 90%) was not achieved at all Bi2O3 contents; this finding was contradictory to the well-known liquid-phase sintering. At 800 °C, rapid improvement in sintering occurred when increasing the content of Bi2O3 from 0.125mol% to 0.25mol%. Schematic study on weight loss also demonstrated an insignificant level of Bi2O3 volatilization under certain content. Analysis of the grain growth kinetics from isothermal sintering (900 °C - 1,000 °C) revealed strikingly different results in both grain growth exponent (n) and activation energy previously reported in literature. The n values ranged from 3.2 to 5.6 whereas the activation energy from 335 to 598 kJ/mol. Such large disparities were believed to be associated with various mass transport processes. The grain sizes in this study were much smaller than those published in literature (> 10 μm). This size difference, along with other microstructural features, was discussed and correlated in order to explain such anomalies and new findings obtained from the grain growth kinetics results.

Grain Growth in Nb-Alloyed Stainless Steel of AISI 347 during Heating

2013 ◽  
Vol 753 ◽  
pp. 345-348 ◽  
Author(s):  
Hai Wen Luo ◽  
Han Dong ◽  
Ling Feng Chen
Keyword(s):  
Activation Energy ◽  
Stainless Steel ◽  
Grain Growth ◽  
Growth Kinetics ◽  
Isothermal Holding ◽  
Growth Exponent ◽  
Microalloyed Steels ◽  
Nb Content ◽  
Grain Growth Kinetics ◽  
Kinetics Of

Grain growth kinetics in an AISI 347 stainless steel with Nb content up to 0.7%wt was studied during the isothermal holding in the temperature range of 1100-1270°C for various periods. Abnormal grain growth was observed even in the presence of a large amount of precipitates. The kinetics of normal grain growth was tracked by metallographic measurements and fitted by the classical modeling, which led to two important parameters of activation energy Q and growth exponent n derived. Both of them are larger than the usual values for grain growth in the Nb-microalloyed steels due to the much larger content of Nb in the present steel.

Densification and grain growth of Al-doped ZnO

2001 ◽  
Vol 16 (2) ◽  
pp. 459-468 ◽  
Author(s):  
Jiaping Han ◽  
P. Q. Mantas ◽  
A. M. R. Senos
Keyword(s):  
Electron Microscopy ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Spinel Phase ◽  
Growth Exponent ◽  
Second Phase ◽  
Surface Drag ◽  
Transmission Electron ◽  
Growth Activation ◽  
Doped Zno

The densification and grain growth of ZnO doped with Al from 0.08 to 1.2 mol% were investigated during isothermal sintering between 1100 and 1400 °C. The Al dopant significantly inhibited the grain growth of ZnO and increased the grain growth exponent from 3 for pure ZnO to 4–6 for Al-doped ZnO. The grain growth activation energy was also changed from approximately 200 kJ/mol for pure ZnO to approximately 480 kJ/mol for Al-doped ZnO. The results of x-ray diffraction, scanning electron microscopy, and transmission electron microscopy showed that a ZnAl2O4 spinel phase existed as a second phase at the ZnO grain boundaries in Al-doped ZnO specimens. The spinel particles exerted an effective drag (pinning) on the migration of ZnO grain boundaries. The analyses of the Al doping effect on the densification rate provided evidence that the driving force for densification was reduced by the second-phase particles. A mechanism of pore surface drag (pinning) on densification equivalent to the observed drag (pinning) of grain boundaries on grain growth was proposed.

Grain growth kinetics and microstructures of the high Tc GdBa2Cu3O7−δ superconductor

1992 ◽  
Vol 7 (12) ◽  
pp. 3194-3201 ◽  
Author(s):  
M.W. Shin ◽  
T.M. Hare ◽  
A.I. Kingon ◽  
C.C. Koch
Keyword(s):  
Aspect Ratio ◽  
Grain Growth ◽  
Growth Kinetics ◽  
Boundary Energy ◽  
Growth Exponent ◽  
Second Phase ◽  
High Tc ◽  
Microstructure Observation ◽  
Grain Aspect Ratio ◽  
Grain Growth Kinetics

Grain growth in the GdBa2Cu3O7−δ high Tc superconductor was investigated. The composition Gd1.09Ba1.91Cu3O7−δ, within the solid solubility region, was selected for the present grain growth study. Differential thermal analysis did not reveal any thermal event except the incongruent melting point, which is indicative of the absence of a liquid second phase during grain growth. The final densities of isothermally annealed samples ranged from 91.3% to 93.7% of theoretical density. The microstructure observation showed a greater grain aspect ratio in this material than in YBa2Cu3O7−δ. The average grain aspect ratio was about 4.7. A very low grain growth exponent of 0.07 was found in the isothermal annealing temperature range from 965 °C to 1020 °C. By comparison with the results on the YBa2Cu3O7−δ system previously reported, it was concluded that the grain growth kinetics in these materials are strongly controlled by the anisotropy of the grain boundary energy. The activation energy of grain growth was calculated to be about 77 kJ/mole.

THERMAL STABILITY OF NANOCRYSTALLINE COPPER FILMS

2006 ◽  
Vol 20 (25n27) ◽  
pp. 3830-3835 ◽  
Author(s):  
PENG CAO ◽  
DELIANG ZHANG
Keyword(s):  
Activation Energy ◽  
Grain Size ◽  
Grain Growth ◽  
Growth Kinetics ◽  
Phase Particle ◽  
Second Phase ◽  
Pinning Force ◽  
Nanocrystalline Copper ◽  
Grain Growth Kinetics ◽  
Kinetics Of

The grain growth kinetics of nanocrystalline copper thin film samples was investigated. The grain size of nanocrystalline copper samples was determined from the broadening of X-ray spectra. It was found that the grain size increased linearly with isothermal annealing time within the first 10 minutes, beyond which power-law growth kinetics is applied. The activation energy for grain growth was determined by constructing an Arrhenius plot, which shows an activation energy of about 21 – 30 kJ/mol. The low activation energy is attributed to the second phase particle drag and the porosity drag, which act as the pinning force for grain growth in nanocrystalline copper.

β Grain Growth Kinetics of a New Metastable β Titanium Alloy

2013 ◽  
Vol 747-748 ◽  
pp. 844-849 ◽  
Author(s):  
Yue Fei ◽  
Xin Nan Wang ◽  
Zhi Shou Zhu ◽  
Jun Li ◽  
Guo Qiang Shang ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Grain Growth ◽  
Kinetic Equations ◽  
Type Equation ◽  
Growth Exponent ◽  
Solution Treated ◽  
Growth Activation ◽  
Grain Growth Kinetics ◽  
Kinetics Of ◽  
Strength And Ductility

Ti-Mo-Nb-Cr-Al-Fe-Si alloy is a new metastable β titanium alloy with excellent combination of strength and ductility. The β grain-growth exponent and the activation energies for β grain growth for the investigated alloy at specified temperature were computed by the kinetic equations and the Arrhenius-type equation. The rate of β grain growth decreases with elongating solution treated time and increases with the increasing solution-treated temperature. The β grain-growth exponents, n, are 0.461, 0.464 and 0.469 at 1113, 1133 and 1153K, respectively. The β grain growth activation energy is determined to be 274 KJ/mol.

scholarly journals Grain growth kinetics and magnetic properties of a V-doped ZnO dilute magnetic oxide

2020 ◽  
Vol 46 (2) ◽  
pp. 2116-2121 ◽  
Author(s):  
Sion F. Olive-Méndez ◽  
Ricardo López Antón ◽  
José T. Holguín-Momaca
Keyword(s):  
Magnetic Properties ◽  
Grain Growth ◽  
Growth Kinetics ◽  
Magnetic Oxide ◽  
Doped Zno ◽  
Grain Growth Kinetics ◽  
Dilute Magnetic Oxide

3D MС Simulation of Grain Growth Kinetics and the Zener Limit in Polycrystals

2014 ◽  
Vol 598 ◽  
pp. 8-12
Author(s):  
K.R. Phaneesh ◽  
Anirudh Bhat ◽  
Gautam Mukherjee ◽  
Kishore T. Kashyap
Keyword(s):  
Monte Carlo ◽  
Grain Growth ◽  
Growth Kinetics ◽  
Large Scale ◽  
Volume Fraction ◽  
Growth Exponent ◽  
Cube Root ◽  
Second Phase ◽  
Two Phase ◽  
Second Phase Particles

Large scale Potts model Monte Carlo simulation was carried on 3-dimensional square lattices of 1003 and 2003 sizes using the Metropolis algorithm to study grain growth behavior. Simulations were carried out to investigate both growth kinetics as well as the Zener limit in two-phase polycrystals inhibited in growth by second phase particles of single-voxel size. Initially the matrices were run to 10,000 Monte Carlo steps (MCS) to check the growth kinetics in both single phase and two-phase poly-crystals. Grain growth exponent values obtained as a result have shown to be highest (~ 0.4) for mono-phase materials while the value decreases with addition of second phase particles. Subsequently the matrices were run to stagnation in the presence of second phase particles of volume fractions ranging from 0.001to 0.1. Results obtained have shown a cube root dependence of the limiting grain size over the particle volume fraction thus reinforcing earlier 3D simulation efforts. It was observed that there was not much difference in the values of either growth kinetics or the Zener limit between 1003 and 2003 sized matrices, although the results improved mildly with size.

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