α(Al,1-xCr,x),2O,3氧化膜结构与性质的理论研究.pdf

文档介绍：河北工业大学
硕士学位论文
α(Al<,1-x>Cr<,x>)<,2>O<,3>氧化膜结构与性质的理论研究
姓名:褚勇
申请学位级别:硕士
专业:理论物理
指导教师:宋庆功
20091201
河北工业大学硕士学位论文

α-(Al1-xCrx)2O3 氧化膜结构与性质的理论研究

摘要

本文依据密度波理论对菱方晶系有序结构的预测结果,并考虑到α-Al2O3和α-Cr2O3都
是良好的抗高温氧化材料,选定设计有序α-(Al1-xCrx)2O3氧化膜的结构作为研究对象。使用
Materials Studio软件包建立有序α-(Al1-xCrx)2O3氧化膜的晶体结构,并对结构和性质进行计
算,分析其稳定性。研究结果表明:有序α-(Al1-xCrx)2O3的晶格参量a0随着x的增加而减小;
c0则随着x的增加而增大,最终趋于α-Cr2O3的结构。负的形成能说明有序α-(Al1-xCrx)2O3系
统的结构是稳定的。稳定性随着掺杂浓度变化的具体规律为:α-(Al1/2Cr1/2)2O3最稳定;
α-(Al3/4Cr1/4)2O3和α-(Al1/4Cr3/4)2O3次之。有序α-(Al1-xCrx)2O3中的O–Al键的布居数都有所增
加,共价性变强了;O–Cr键也显示出较强的共价性。这保证了有序α-(Al1-xCrx)2O3的结构稳
定性。从态密度的角度分析,由于轨道杂化作用,有序α-(Al1-xCrx)2O3的禁带宽度与α-Al2O3
相比较,都有变小的趋势;费米能级都与导带相交,因此会产生一定的导电性,导电性随
着Cr浓度的增加而增加,逐渐趋于α-Cr2O3的导电性,有可能成为功能导电材料。


关键词:刚玉型,氧化物,稳定性,第一性原理






i
α-(Al1-xCrx)2O3 氧化膜结构与性质的理论研究

THEORETICAL STUDY OF STRUCTURE AND PROPERTY
OF ORDERED α-(Al1-xCrx)2O3 OXIDE FILM



ABSTRACT


Based on the forecast on ordered structure of rhombohedral system by density-wave theory
and oxidation resistance of α-Al2O3 and α-Cr2O3 materials in high temperature, ordered
α-(Al1-xCrx)2O3 oxide film is chosen as our subject investigated. α-(Al1-xCrx)2O3 is studied by
Materials Studio software. Firstly the crystal structure of α-(Al1-xCrx)2O3 is established;
secondly the property is calculated; and finally the stability of the structure is analyzed. The
investigation shows that the lattice parameter a0 of ordered α-(Al1-xCrx)2O3 es smaller and
c0 es bigger when the value of x es bigger. The result is the structure of
α-(Al1-xCrx)2O3 approach that of α-Cr2O3 with increase of x. Negative formation energy illustrate
the structure of ordered α-(Al1-xCrx)2O3 is stable. The regularity of stability is: α-(Al1/2Cr1/2)2O3 is
the best; α-(Al3/4Cr1/4)2O3 and α-(Al1/4Cr3/4)2O3 is better. At the same time the populations of
O-Al bond and O-Cr bond of α-(Al1-xCrx)2O3 increase. This demonstrate α-(Al1-xCrx)2O3 is
stable further. B