STUDY OF THE RELATIONSHIP BETWEEN ELECTRICAL AND MAGNETICPROPERTIES AND JAHN-TELLER DISTORTION IN R_(0.7)Ca_(0.3)Mn_(0.95)Fe_(0.05)O_3PEROVSKITES BY MOSSBAUER EFFECT

摘要

In this work structural, magnetic and electrical properties of R_(0.7)Ca_(0.3)Mn_(0.95)Fe_(0.05)O_3(R= Pr and Nd) perovskitemanganites are presented. Structural characterization of these compounds shows that both have orthorhombic (Pbmn)phase. The Mossbauer spectra show clear evidence of the local structural distortion of the Mn(Fe)O_6 octahedron on thebasis of non-zero nuclear quadrupole interactions for high-spin Fe~(3+)ions. It was found that the local structural distortiondecreases significantly with replacing Pr~(3+)by Nd~(3+). This replacing dependence of the Jahn-Teller coupling strengthestimated from the Mossbauer results was found to be consistent with the electrical and magnetic properties.