Environmental effect on the magnetic properties of Fe ions in glasses and ceramics

The effect of the environment on the magnetic properties of Fe-ions in a so dium germanate glass, a sodium silicate glass, and in the same devitrified glasses has been studied. In the four samples investigated. the inverse mag netic susceptibility (chi (-1)) follows a Curie-Weiss law behavior with a n egative Curie temperature Or indicating an antiferromagnetic interaction in the four samples. The measurements also revealed that \0(p)\ in both glass matrices is relatively low (< 10 K) while in the crystalline samples it in creased by 4-fold in the silicate and by about 20-fold in the germanate. Th e molecular field coefficients gamma (m) are negative for all four samples. The gamma (m) values for the Fe-germanate glass and the crystalline sample are 3 and 10 times larger than the corresponding values for Fe-silicate. T hese results reflect a stronger exchange interaction in the germanate (glas s and crystalline) than the silicate samples. (C) 2001 Elsevier Science B.V . All rights reserved.