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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 35, Number 6
JKCSEZ 35(6)
December 20, 1991 

Nonstoichiometry and Characteristics of the Perovskite Y1-xAxFeO3-y (A = Ca, Sr) Systems

페롭스카이트 Y1-xAxFeO3-y (A = Ca, Sr)계의 비화학양론과 특성 연구
Chul Hyun Yo, Seung Hung Lee, Sung Joo Lee, Sung Ho Park

여철현, 이승현, 이성주, 박성호
페롭스카이트 구조를 갖는 Y1-xAxFeO3-y (A = Ca, Sr)계에서 x = 0.00, 0.25, 0.50, 0.75 및 1.00인 비화학양론적 화합물 고용체를 1200℃ 대기압에서 제조하였다. X-선 회절분석을 통하여 모든 조성의 고용체들에 대한 결정구조를 조사하였다. Y1-xCaxFeO3-y계의 경우는 x값이 증가함에 따라 환산 격자 부피가 감소하였고, Y1-xSrxFeO3-y계의 경우는 x의 증가에 따라 환산 부피가 증가하였다. 그 고용체들의 Fe3+에 대한 Fe4+의 몰비 τ값은 Mohr 분석법으로 구하였고 그 혼합 원자가 상태는 298K에서 Mossbauer 분광분석으로 확인하였다. x값과 τ값으로부터 y값을 계산하여 비화학양론적 화학식을 확정하였다. 전도성 메카니즘은 혼합원자가 상태간의 전도성 전자 건너뜀 모델로 설명하였다.

Nonstoichiometric solid solutions of Y1-xAxFeO3-y (A = Ca, Sr) systems with perovskite structure were prepared for x = 0.00, 0.25, 0.50, 0.75 and 1.00 at 1200℃ under atmospheric pressure, respectively. Crystallographic structures of the solid solutions of all compositions have been determined by the analysis of X-ray diffraction patterns. Reduced lattice volume of the Y1-xCaxFeO3-y system was decreased with increasing x value and that of the Y1-xSrxFeO3-y system was increased with increasing the x value. The mole ratios of Fe4+ to Fe3+,τ, values in the solid solutions have been determined by Mohr salt's method of analysis and then the mixed valency was identified by Mossbauer spectroscopic analysis at 298 K. The y values were calculated from the x and τ, and then nonstoichiometric chemical formulas were fixed. The conduction mechanism could be explained by hopping model of the conduction electrons between the mixed valence states.

617 - 624
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