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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 38, Number 4
JKCSEZ 38(4)
August 20, 1994 

 
Title
Stable Defect Structure of La2O3-Modified BaTiO3

La2O3-변형 BaTiO3의 안정한 결함구조
Author
Jeong-Soo Kim, Hyu-Bum Park, Tae-Ho Ahn, Si-Joong Kim

김정수, 박휴범, 안태호, 김시중
Keywords
Abstract
La2O3-변형 BaTiO3의 안정한 결함구조와 단일상 영역을 X-선 회절분석기와 주사전자현미경을 사용하여 연구하였다. La2O3-변형 BaTiO3의 안정한 결함구조는 La3+ 이온이 격자구조내의 Ba3+ 이온을 치환하고 Ti빈자리가 전하 불균형을 보상하기 위한 결함으로 생성된 [(BaxBa)1-2x(La·Ba)x][TixTi)1-x/2(V""Ti)x/2]O3이다. 안정한 결함구조가 형성되도록 BaTiO3에 La2O3·3/2TiO3를 혼입할 때 단위격자는 약 3 mol%가 혼입될 때부터 정방정에서 입방정으로 변하였고, 고용한계는 약 14 mol%이었다. La2O3·3/2TiO2를 고용한계 이상으로 혼입할 때는 이차상으로 La4Ba2Ti5O18가 생성되었다. La2O3-변형 BaTiO3 조성에서 BaO가 과량 존재하면 소결성이 나쁘지만, TiO2가 과량으로 존재하면 액상소결에 의하여 소결성이 좋아짐을 확인할 수 있다.

The stable defect structure and the single phase region of La2O3-modified BaTiO3 have been studied by X-ray diffractometer and scanning electron microscope. The stable defect structure of La2O3-modified BaTiO3 has been identified as [(BaxBa)1-2x(La·Ba)x][TixTi)1-x/2(V""Ti)x/2]O3 which consists of La3+ ion substitution for Ba3+ ion in the lattice structure and the formation of Ti vacancies for the charge compensation. When 3 mol% of La2O3·3/2TiO3 was added to BaTiO3, the unit cell structure was transformed from tetragonal to cubic and the solubility limit was about 14 mol%. When La2O3·3/2TiO2 was added above this solubility limit, the second phase, La4Ba2Ti5O18, was formed. In the La2O3-modified BaTiO3, it was found by the liquid phase sintering process that the sinterability was decreased by excess BaO but increased by excess TiO2.

Page
309 - 318
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