Structural and charge transport properties of electron-doped manganites (La1-xPrx)0.85Zr0.15MnO3

The structural and magneto-transport properties of electron-doped manganites (La1-xPrx)(0.85)Zr0.15MnO3 (Pr-doped LZMO) with x = 0, 0.05, 0.10, 0.15, and 0.20 have been investigated. X-ray diffraction (XRD) patterns show that the Pr-doped LZMO has rhombohedral lattice structure with R (3) over barC space group. The Mn-O-Mn bond angle of the system refined by Rietveld technique decreases with increasing Pr content ranging from 165.38 degrees for x = 0 to 163.64 degrees for x = 0.20. A significant distortion of the MnO6 octahedra caused by the distinctively small Mn-O-Mn bond angle weakens the strength of Mn2+-O-Mn3+ double exchange (DE) interaction. The Curie temperature T-C increases with increasing average A-site ionic radius, < r(A)>, and the magnetoresistance (MR) ratio decreases with increasing < r(A)>, strongly suggesting that the DE mechanism plays an important role in the charge transport property of the Pr-doped LZMO. (C) 2006 Elsevier B. V. All rights reserved.