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Molecular dynamic simulations of La2...

Jiang, Yun.

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Molecular dynamic simulations of La2O3 and Lu2O3 doped silicate intergranular films in beta-Si 3N4.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Molecular dynamic simulations of La2O3 and Lu2O3 doped silicate intergranular films in beta-Si 3N4./
Author:	Jiang, Yun.
Description:	145 p.
Notes:	Source: Dissertation Abstracts International, Volume: 75-07(E), Section: B.
Contained By:	Dissertation Abstracts International75-07B(E).
Subject:	Materials science. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3617229
ISBN:	9781303843747

Molecular dynamic simulations of La2O3 and Lu2O3 doped silicate intergranular films in beta-Si 3N4.
Jiang, Yun.

Molecular dynamic simulations of La2O3 and Lu2O3 doped silicate intergranular films in beta-Si 3N4. - 145 p.

Source: Dissertation Abstracts International, Volume: 75-07(E), Section: B.

Thesis (Ph.D.)--Rutgers The State University of New Jersey - New Brunswick, 2014.

This item is not available from ProQuest Dissertations & Theses.

Thin, amorphous intergranular films (IGFs) ubiquitously exist at grain boundaries of polycrystalline ceramics. They play an important role in determining the macroscopic properties of high temperature structural ceramics. Silicon nitride ceramics (Si3N4) are high temperature structural ceramics due to their outstanding physical and mechanical properties at elevated temperature. The formation of the anisotropic grains of silicon nitride is very sensitive to the dopant cations used as sintering additives. HAADF-STEM images have shown that rare earth (RE) ions take very ordered locations, dependant upon the RE species, along the IGF/Prism interface in Si3N 4 ceramics. However, such segregation does not explain the differences in morphology resulting from incorporation of the different RE additives. Atomistic details not readily available in experiments need to be collected.

ISBN: 9781303843747Subjects--Topical Terms:

543314
Materials science.

Molecular dynamic simulations of La2O3 and Lu2O3 doped silicate intergranular films in beta-Si 3N4.
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020 $a 9781303843747
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100 1 $a Jiang, Yun. $3 1940832
245 1 0 $a Molecular dynamic simulations of La2O3 and Lu2O3 doped silicate intergranular films in beta-Si 3N4.
300 $a 145 p.
500 $a Source: Dissertation Abstracts International, Volume: 75-07(E), Section: B.
500 $a Adviser: Stephen H. Garofalini.
502 $a Thesis (Ph.D.)--Rutgers The State University of New Jersey - New Brunswick, 2014.
506 $a This item is not available from ProQuest Dissertations & Theses.
520 $a Thin, amorphous intergranular films (IGFs) ubiquitously exist at grain boundaries of polycrystalline ceramics. They play an important role in determining the macroscopic properties of high temperature structural ceramics. Silicon nitride ceramics (Si3N4) are high temperature structural ceramics due to their outstanding physical and mechanical properties at elevated temperature. The formation of the anisotropic grains of silicon nitride is very sensitive to the dopant cations used as sintering additives. HAADF-STEM images have shown that rare earth (RE) ions take very ordered locations, dependant upon the RE species, along the IGF/Prism interface in Si3N 4 ceramics. However, such segregation does not explain the differences in morphology resulting from incorporation of the different RE additives. Atomistic details not readily available in experiments need to be collected.
520 $a Molecular dynamics computer simulations are used to evaluate the structure, energy and fracture behavior of silicon oxynitride intergranular films (IGFs) containing rare-earth ions (La or Lu) between silicon nitride crystals as a function of IGF thickness, composition, and crystal orientations (prism, basal, and high index). La adsorption on the prism surface is observed at locations consistent with HAADF-STEM results. La segregation corresponding to N content is discussed. A variation in the local composition would cause some IGFs to show segregation of all La to the interface, leaving little La within the glassy IGF, while other IGFs may show more La remaining in the glassy IGF. Such differences affect strength. Lu does not adsorb onto a fully nitride prism surface. The presence of O at certain surface lattice sites plays a major role in the adsorption of Lu ions onto those sites consistent with HAADF-STEM results but has little effect on La siteing. Energies of the La or Lu ions as a function of location are calculated to provide an explanation for the segregation behavior as well as consideration of their role in the glassy state of the IGF. Growth along the crystal surface is studied, providing an atomistic mechanism for the experimentally observed anisotropic grain growth of silicon nitride influenced by the different additives. Fracture strengths via stress-strain curves are calculated.
590 $a School code: 0190.
650 4 $a Materials science. $3 543314
650 4 $a Molecular physics. $3 3174737
650 4 $a Condensed matter physics. $3 3173567
690 $a 0794
690 $a 0609
690 $a 0611
710 2 $a Rutgers The State University of New Jersey - New Brunswick. $b Materials Science and Engineering. $3 2094730
773 0 $t Dissertation Abstracts International $g 75-07B(E).
790 $a 0190
791 $a Ph.D.
792 $a 2014
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3617229