Effect of Excess PbO on the Kinetics of the Growth of PMNT Polycrystals by Templated Grain Growth Method

2005 ◽  
Vol 475-479 ◽  
pp. 1137-1140
Author(s):  
Lili Zhao ◽  
Feng Gao ◽  
Wei Min Wang ◽  
Chang Sheng Tian
Keyword(s):  
Grain Growth ◽  
Templated Grain Growth ◽  
Experimental Conditions ◽  
Precipitation Mechanism ◽  
Oriented Structure ◽  
Diffusion Controlled ◽  
The Matrix ◽  
Growth Method ◽  
Final Composition ◽  
Kinetics Of

The oriented 0.67Pb (Mg1/3Nb2/3)O3-0.33PbTiO3 (PMNT) polycrystals were prepared by the conventional ceramic technique and the templated grain growth method adding excess PbO in the matrix. Kinetics of the development of oriented structure was investigated systemically. In the presence of PbO liquid phase, the oriented PMNT polycrystals mainly grow by the dissolution-precipitation mechanism. The diffusion is determined by the sintering temperature and the PbO-excess content in the matrix. The thickness of oriented PMNT polycrystals displays a t1/3 dependence, which is characteristic of diffusion-controlled growth. For the thicker oriented structure, 20% excess PbO in the PMNT matrix and 1150oC for 10h are the proper experimental conditions. Moreover, the addition of PbO in the matrix hardly affects the final composition of ceramic matrix.

Primary products and processes in the γ-radiolysis of 2-methyltetrahydrofuran

1965 ◽  
Vol 285 (1402) ◽  
pp. 319-338 ◽  
Keyword(s):  
Glassy Phase ◽  
Kcal Mole ◽  
Radical Species ◽  
Molecule Reaction ◽  
Positive Ions ◽  
Primary Products ◽  
Diffusion Controlled ◽  
Thermal Bleaching ◽  
The Matrix ◽  
Kinetics Of

From a study of the u. v., visible, near i. r. and e. s. r. spectra induced by γ -irradiation at 77°K in glassy MTHF and in glassy MTHF containing various additives and from a study of controlled temperature increases on these spectra, the following conclusions are drawn. (1) The primary products of the radiolysis are electrons ( e - ) and positive ions ( MTHF + ) which undergo a rapid ion-molecule reaction to give O CH 3 radicals ( R ⋅). (2) e - can either be trapped in the glassy MTHF matrix or can be captured by either napththalene, ferric chloride, carbon tetrachloride, nitrous oxide or trans -stilbene if these substances are present. (3) The e - T are bleachable by light or heat and disappear independently of the radicals R⋅ without either augmentation of R⋅ or the production of any new radical species. (4) e - T and R⋅ disappear thermally and independently by second-order reactions, the rate constants being K e - + e - (M -1 S -1 ) = 10 12⋅4±1⋅1 exp ─ [0⋅85 ± 0⋅10 kcal/mole/ R ( T ─ 75)] and K R˙ + R˙ (M -1 S -1 ) = 10 13⋅3±1⋅4 exp ─ [1⋅20 ± 0⋅15 kcal/mole/ R ( T ─ 75)]. These rate expressions suggest that both reactions are diffusion controlled at low temperatures in the glassy phase. (5) The kinetics of the thermal bleaching of e - T indicate that the electrons migrate distances of about 150 Å from their parent positive ions before being trapped in the matrix. (6) The effect of FeCl 3 in reducing the formation of e - T at 77°K and its lack of effect on the thermal bleaching of e - T suggests that the reaction e - + FeCl 3 → FeCl 2 + Cl - only occurs before the electron is thermalized.

Preparation of [110] Grain Oriented Barium Titanate Ceramics by Templated Grain Growth Method and Their Piezoelectric Properties

2007 ◽  
Vol 46 (10B) ◽  
pp. 7039-7043 ◽  
Author(s):  
Satoshi Wada ◽  
Kotaro Takeda ◽  
Tomomitsu Muraishi ◽  
Hirofumi Kakemoto ◽  
Takaaki Tsurumi ◽  
...  
Keyword(s):  
Barium Titanate ◽  
Grain Growth ◽  
Piezoelectric Properties ◽  
Templated Grain Growth ◽  
Growth Method ◽  
Titanate Ceramics

Kinetics of template growth in alumina during the process of templated grain growth (TGG)

2001 ◽  
Vol 49 (11) ◽  
pp. 2075-2081 ◽  
Author(s):  
E Suvaci ◽  
K.-S Oh ◽  
G.L Messing
Keyword(s):  
Grain Growth ◽  
Templated Grain Growth ◽  
Kinetics Of

Kinetics of Templated Grain Growth of 0.65Pb(Mg1/3Nb2/3)O3·0.35PbTiO3

2001 ◽  
Vol 84 (11) ◽  
pp. 2507-2513 ◽  
Author(s):  
Edward M. Sabolsky ◽  
Gary L. Messing ◽  
Susan Trolier-McKinstry
Keyword(s):  
Grain Growth ◽  
Templated Grain Growth ◽  
Kinetics Of

Diffusion Controlled Abnormal Grain Growth in Ceramics

2007 ◽  
Vol 558-559 ◽  
pp. 1227-1236 ◽  
Author(s):  
Shen J. Dillon ◽  
Martin P. Harmer
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Growth Kinetics ◽  
Abnormal Grain Growth ◽  
Growth Theory ◽  
Diffusion Controlled ◽  
Grain Growth Kinetics ◽  
Kinetics Of

The grain growth kinetics of silica and calcia doped alumina at 1400oC and their grain boundary complexion is characterized. These data are compared to predictions of both diffusion controlled and nucleation limited interface controlled grain growth theory. It is deduced from the indicators that the mechanism for normal and abnormal grain growth in these aluminas is diffusion controlled.

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