Thermal Behaviour of PrCo1-xFexO3 Probed by X-ray Synchrotron Powder Diffraction and Impedance Spectroscopy Measurements

O. Pekinchak a, D.Yu. Sugak a, S.B. Ubizskii a, Yu. Suhak b, H. Fritze b and L. Vasylechkoa aLviv Polytechnic National University, Lviv, Ukraine bInstitute of Energy Research and Physical Technologies, Clausthal University of Technology, Goslar, Germany

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Crystal structure and transport properties of the mixed praseodymium cobaltites-ferrites PrCo1-xFexO3 have been studied in the temperature range of 298-1173 K by a combination of in situ X-ray synchrotron powder diffraction and temperature dependent impedance spectroscopy measurements. In situ high temperature powder diffraction examination of PrCo1-xFexO3 series revealed considerable anomalies in the lattice expansion which are especially pronounced for the cobalt-rich specimens. These anomalies, which are reflected in a sigmoidal dependence of the unit cell dimensions and in the considerable increase of the thermal expansion coefficients, are obviously associated with transitions of Co3+ ions from low spin to the higher spin states and the coupled metal-insulator transitions, occurring in in rare earth cobaltites at the elevated temperatures. Indeed, the temperature-dependent impedance measurements clearly prove the change of conductivity type from dielectric to the metallic behaviour in the mixed cobaltite-ferrites PrCo1-xFexO3 at the elevated temperatures.

DOI: 10.12693/APhysPolA.133.763 PACS numbers: 61.66.Fn, 61.05.cp, 65.40.De, 72.60.+g