Open AccessStudy on the structure and energy of the (0001) surface of α-Al2O3 substrate
Author(s) -
Yang Chun,
Yanrong Li,
Wenjing Xue,
Tao Bai-Wan,
Xingzhao Liu,
Ying Zhang,
Huang Wei
Publication year - 2003
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.52.2268
Subject(s) - pseudopotential , materials science , valence (chemistry) , ion , population , crystal (programming language) , density functional theory , relaxation (psychology) , crystallography , single crystal , atomic physics , molecular physics , condensed matter physics , chemistry , computational chemistry , physics , psychology , social psychology , demography , organic chemistry , sociology , computer science , programming language
There are three different structures of the α-Al2O3(0001) crystal surface b ecause different atoms are terminated on the outermost layer. Our calculations a re based on the density functional theory in local density approximation, and on ultra-soft pseudopotential methods, with the valence orbital expanded in plane- wave by using three-dimensional periodic boundary conditions in κ-space, first ly, the calculation result is that α-Al2O3(0001) crystal surface structure which the outermost layer is terminated by a single layer of Al atoms is much mo re stable than the other two structures. Secondly, a rhombohedral primitive cell is employed to perform cell optimizations, with ten atoms in the unit cell, and the calculated equilibrium parameters are:a00.48178nm,γ120.16, which are in excellent agreement with recent experimental values(a00.47591nm ),with a difference of less than 1.3%. Moreover, our calculations are performed with a su per-cell slab model in vacuum environment, in which the outermost layer is termi nated by single Al atoms. By investigating the four-layer relaxation and Al-O a toms population of the surface, we obtain results that the top single Al layer i s an inward relaxation of 0.0792 nm—0.098nm, that is, the second-layer O atoms are turned into the top layer,and the top O and Al atoms population analysis sho w that the valence electrons are concentrated on the surface oxygen ions with a greater probability,it is obvious that the α-Al2O3(0001) crystal surface ap pears in the O-surface state,which is discussed from the microstructure of α-Al 2O3(0001)crystals in details.