Ceramics-Silikáty 48 (4) 197-206 (2004)

Characterization of transition metal-containing oxide systems by Mössbauer Spectroscopy

Z. Homonnay, E. Kuzmann, Z. Németh, Z. Klencsár, S. I. Nagy, A. Vértes

High-temperature (high-T_c) superconductors and colossal magnetoresistant (CMR) materials belong to the most promising materials of the past 2-3 decades for technical applications. Most of them are oxides and the crucial element which determines their useful physical properties is often a transition metal (Cu, Co, Fe, Mn). ⁵⁷Fe Mössbauer Spectroscopy can be used to characterize the electronic and structural properties of transition metal-containing oxides by providing information on the local electronic structure of the lattice site where the Mössbauer probe is accommodated. By reviewing several Mössbauer studies, it is demonstrated how the layered (2D) electronic structure of high-T_c superconductors can be deduced from the analysis of the Mössbauer isomer shift and quadrupole splitting. We also show how the Mössbauer isomer shift indicates metallicity of the ferromagnetic phase in the CMR material La_xSr_1-xCoO₃.

Keywords: Mössbauer spectroscopy, High temperature superconductors, Colossal magnetoresistance, Isomer shift, Metallicity