Transport, magnetic, internal friction, and Young's modulus in the Y-doped manganites La0.9-xYxTe0.1MnO3

The resistivity, magnetization, internal friction, and Young's modulus for the polycrystalline samples La0.9-xYxTe0.1MnO3 (x = 0, 0.05, 0.10 and 0.15) have been investigated. All samples have rhombohedral crystallographic structure with the space group R C. The Curie temperature T-C, of the Studied samples decreases with increasing Y-doping level. For the samples with x = 0, 0.05 and 0.10, the temperature dependence of the resistivity rho(T) exhibits two metal-insulator transitions (MIT) at T-p1 (which is close to its Curie temperature T-C) and T-p2 (which is below T-p1). When the doping level to 0.15. these two MIT temperatures are Suppressed and an upturn at low temperatures below T* is observed from the rho(T) Curve. A change of Young's modulus E is observed in the vicinity of T-C accompanied by a broad peak of the internal friction Q(-1) for all Studied samples. The values of the relative Young's modulus Delta E increase with increasing Y-doping level at the low temperatures. These results are discussed in terms of the local Jahn-Teller (JT) distortion by the Substitution of smaller Y3+ ions for larger La3+ ions and the increased bending of the Mn-O-Mn bond with decreasing the average ionic radius of the A-site element <r(A)> and the tolerance factor t, resulting in the narrowing of the bandwidth, the decrease of the mobility of e(g) electrons and the weakening of double-exchange (DE) interaction. (C) 2006 Published by Elsevier Inc.