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  • 02월 22일 16시 이후 : 초록수정 불가능, 일정확인 및 검색만 가능

Structural characterization of niobate oxyfluorides, A’ANb2O6F (A’ = Li, Na, K, Rb, Cs, A = Ca, Sr)

등록일
2008년 2월 14일 11시 17분 52초
접수번호
1300
발표코드
34P229포 이곳을 클릭하시면 발표코드에 대한 설명을 보실 수 있습니다.
발표시간
금 <발표Ⅳ>
발표형식
포스터
발표분야
재료화학
저자 및
공동저자
김성철, 김승주
아주대학교 에너지시스템학부,
A series of oxyfluorides, A’ANb2O6F (A’ = Li, Na, K, Rb, Cs, A = Ca, Sr) have been prepared employing solid-state reaction. Structural analysis of the compounds has been performed through Rietveld refinement from the X-ray powder diffraction data. LiCaNb2O6F, LiSrNb2O6F, NaCaNb2O6F, NaSrNb2O6F, and KCaNb2O6F exhibit the cubic pyrochlore structure, while KSrNb2O6F, RbCaNb2O6F, RbSrNb2O6F, CsCaNb2O6F, and CsSrNb2O6F crystallize in the Dion-Jacobson type layered perovskite. For the A’ANb2O6F compounds, the size of A’ and A ion plays a crucial role in the modification of crystal structure. The phase boundary of pyrochlore and layered perovskite is around 2.1 of RA’A/RNb ration for A’ANb2O6F, where RA’A is the average radius of A’ and A cations and RNb is the radius of Nb5+ ion. The F- ions located at the cavities in the channels of the [Nb2O6]2- network for pyrochlores. In contrast, the F- ions of the perovskites form corner-shared Nb(O,F)6 octahedra. The locations of F- ions were confirmed with bond valence sum calculations.

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