Transport properties and phase separation in La0.6Y0.1Ca0.3MnO3 ceramics

The electrical resistivity ρ(T), magnetization M(T), magnetoresistivity ρ(T,H), and the impedance spectroscopy Z(ω, T) of the polycrystalline La0.6Y0.1Ca0.3MnO3 compound were investigated. X-ray diffraction and scanning electron microscopy were used for microstructural characterization. The results show that the sample is single phase and has average grain size of ∝0.5 μm. ρ(T,H) and Z(ω,T) transport data revealed that the material undergoes a metal-insulator transition at TCR ∝175 K. In addition, the deconvolution of Z(ω,T) data indicates two well defined contributions to the electrical resistivity occurring at low and high frequencies. The temperature dependence of the dielectric constant associated with the low frequency component exhibits a percolation-like phase transition at TCR ∝175 K. The normalized ρ(T,H) data exhibit features of colossal magnetoresistivity CMR phenomenon. The combined results suggest that the transport properties of these manganites, assessed through macroscopic techniques, can provide some insights regarding the metal-insulator transition, which have been confirmed by spectroscopic measurements. (copyright 2003 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)