Structural, magnetic, and transport properties in the Pr-doped manganites La0.9-xPrxTe0.1MnO3(0≤x≤0.9) -: art. no. 144421

The effect of Pr-doping on structural, magnetic and transport properties in electron-doped manganites La0.9-xPrxTe0.1MnO3 (0less than or equal toxless than or equal to0.9) with fixed carrier concentration is investigated. The room temperature structural transition from rhombohedral (R (3) over barC) to orthorhombic (Pbnm) symmetry is found in the samples with xgreater than or equal to0.36 by the Rietveld refinement of x-ray powder diffraction patterns. The Curie temperature T-C of samples decreases and the transition becomes broader with an increasing Pr-doping level. For the samples with xless than or equal to0.36, there exist insulator-metal (I-M) transition. And the low-temperature I-M transition is observed at about 66 K for the sample with x=0.36, which may be related to the opening of a new percolation channel. For the samples with xgreater than or equal to0.54, rho(T) curves display the semiconducting behavior (drho/dT<0) in both the high-temperature PM phase and low-temperature FM phase. The results are discussed in terms of 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 DE interaction caused by the substitution of smaller Pr3+ ions for a larger La3+ ion.