Structural, transport, and magnetic properties of RMnO3 perovskites (R = La, Pr, Nd, Sm, 153Eu, Dy)

Structural, magnetic, and high-temperature thermogravimetric and resistive properties of stoichiometric RMnO3 (R = La, Pr, Nd, Sm, and Dy) and isotopically pure (EuMnO3)-Eu-153 perovskites have been studied. The structural parameters of (EuMnO3)-Eu-153 from neutron powder diffraction have been found to perfectly correlate with those for the other RMnO3 compounds. Resistivity measurements within a wide temperature range 300-1400K have provided the characteristic temperatures of the nucleation of the orbitally disordered phase and the Jahn-Teller ordering transitions. We have confirmed a linear dependence of these characteristic temperatures on the average R-O bond angle (cos(2) theta). We argue that the tolerance factor that is linearly related to the average of Cos(2) theta is the most convenient parameter for reliable description of the structural and physical properties. (c) 2005 Elsevier Inc. All rights reserved.