Applied Microscopy

Korean Society of Microscopy (한국현미경학회)
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Structure Determination of Nano-crystalline, $BaTiO_3$, using Precession Electron Diffraction

세차전자회절을 이용한 $BaTiO_3$ 나노 결정의 구조분석

  • Song, Kyung (Division of Electron Microscopic Research, Korea Basic Science Institute) ;
  • Kim, Youn-Joong (Division of Electron Microscopic Research, Korea Basic Science Institute) ;
  • Kwon, Ki-Hyun (Division of Electron Microscopic Research, Korea Basic Science Institute) ;
  • Kim, Jin-Gyu (Division of Electron Microscopic Research, Korea Basic Science Institute) ;
  • Moon, Sun-Min (Department of Materials Science and Engineering, Inha University) ;
  • Cho, Nam-Hee (Department of Materials Science and Engineering, Inha University)
  • 송경 (한국기초과학지원연구원 전자현미경연구부) ;
  • 김윤중 (한국기초과학지원연구원 전자현미경연구부) ;
  • 권기현 (한국기초과학지원연구원 전자현미경연구부) ;
  • 김진규 (한국기초과학지원연구원 전자현미경연구부) ;
  • 문선민 (인하대학교 신소재공학부) ;
  • 조남희 (인하대학교 신소재공학부)
  • Received : 2009.09.24
  • Accepted : 2009.12.24
  • Published : 2009.12.31
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Abstract

The crystal structure of nano-crystalline, $BaTiO_3$, with the average particle size of 100 nm was investigated using electron diffraction techniques. We characterized the precession electron diffraction system and then carried out the structure determination using precession electron diffraction and conventional selected area electron diffraction. As a result, it was revealed that $BaTiO_3$ nano-crystalline exist as a mixture of tetragonal structure and cubic structure by precession electron diffraction technique. In addition, it could be turned out that $BaTiO_3$ nano-crystalline is a core-shell structure consisted of a tetragonal phased core and a cubic phased surface layer by theoretical calculation. The thickness of the cubic surface layer was approximately 8.5 nm and the lattice parameters of cubic and tetragonal phases were a=3.999${\AA}$ and a=3.999${\AA}$, c=4.022${\AA}$, respectively. Finally, it is expected that precession electron diffraction is more useful technique for structure determination of complicated nano-crystalline materials because of its higher spatial resolution and minimization of dynamical scattering effect.

본 연구에서는 평균 입자크기가 100 nm인 $BaTiO_3$ 나노 결정체의 결정 구조를 전자회절을 이용하여 분석하였다. 전자회절을 이용하여 구조분석을 수행하기 위해 PED 장치의 실험인자를 보정한 후, PED와 일반적인 SAED를 이용하여 전자회절도형을 획득하여 비교 분석을 수행하였다. $BaTiO_3$ 나노 결정체에 대해 PED를 이용한 구조분석을 수행한 결과, $BaTiO_3$ 나노입자는 상온에서 입방정계와 정방정계의 구조가 혼합되어 존재함을 알 수 있었다. 또한 이론적 계산을 통해 두 상이 혼재된 $BaTiO_3$ 나노입자는 입방정계의 구조가 약 8.5nm의 표면을 형성하고 있는 coreshell 구조를 이루고 있음을 예측할 수 있었다. 이러한 $BaTiO_3$ 나노입자에 대한 입방정계와 정방정계 구조의 각각의 격자상수는 a=3.999${\AA}$과 a=3.999${\AA}$, c=4.022${\AA}$이었다. 이와 같이 일반적인 SAED에 비해 뛰어난 공간분해능과 다중산란 효과를 억제할 수 있는 PED 기법은 복합 나노 구조체의 결정구조분석에 보다 유용한 분석 기술로 활용할 수 있을 것으로 기대된다.

Keywords

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