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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 32, Number 1
JKCSEZ 32(1)
February 20, 1988 

A Study on Nonstoichiometry and Physical Properties of the Mixed Valency Sr1+xDy1-xFeO4-yFerrite System

혼합원자가 Sr1+xDy1-xFeO4-y훼라이트계의 비화학양론과 물성 연구
Chul Hyun Yo, Eun Seok Lee, Woong Bum Pyon, Moo Sil Pyon

여철현, 이은석, 편웅범, 편무실
K2NiF4 형 층상구조를 갖는 새로운 Sr1+xDy1-xFeO4-y 계에서 x = 0. 00, 0. 25, 0. 50, 0. 75 및 1. 00 인 비화학양론적 화합물 고용체를 1200℃ 대기압하에서 제조하였다. X-선 회절분석에 의하여 결정구조학적 상들은 모든 시료의 경우 정방정계임을 알 수 있었다. Mohr 염 분석으로 비화학양론적 화학식을 결정하였고 x가 증가함에 따라 Fe4+의 몰수(τ값)가 증가하였다. -100∼200℃의 온도범위에서 측정한 각 시료의 전기전도도는 l0-8∼10-2(ohm-1·cm-1)범위의 반도성을 보이며 활성화 에너지는 0.02∼0.08(eV)의 범위에서 변하였다. Sr1.00Dy1.00FeO4.04에 대한 Fe3+와 Fe4+의 혼합원자가 상태를 200K에서 측정한 Mossbauer spectrum으로 재확인하였다.

Nonstoichiometric solid solutions of the Sr1+xDy1-xFeO4-ysystem (x = 0. 00, 0. 25, 0. 50, 0. 75 and 1. 00) with layered K2NiF4 type structure were prepared at 1200℃ under atmospheric pressure. X-ray powder diffraction spectra show that the crystallographic phases of the samples are tetragonal within the x range. Nonstoichiometric chemical formulas have been determined by Mohr salt analysis and it shows that the amount of Fe4+ ion or τ value increases with increasing x. Electrical conductivities of the samples which were measured in the temperature range of -100∼200℃ under atmospheric air pressure are varied within the semiconductivity range of l0-8∼10-2(ohm-1·cm-1) and the activation energies are also varied from 0.02 to 0.08 eV. Mixed valency state of Fe3+and Fe4+in the sample of Sr1.00Dy1.00FeO4.04 was identified again by Mossbauer spectrum at 200K.

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