Engineering of heterogeneous oxide for grain boundaries and transport properties of La0.67Ca0.33MnO3

A special experimental procedure is designed to engineer the grain boundaries of La0.67Ca0.33MnO3 with a high resistivity and high chemical stability oxide of YSZ, where the YSZ represents yttria-stabilized zirconia (8 mol%Y2O3 + 92 mol%ZrO2). The effects of the YSZ doping level and distribution on the electrical transport and magnetic properties of La0.67Ca0.33MnO3 are investigated in a temperature range of 10-300 K. Experimental results show that the engineering of the YSZ heterogeneous oxide for grain boundaries has two different effects on the magnetization properties of La0.67Ca0.33MnO3: (1) In a lower field range, the engineering is of benefit to magnetization, which leads to an enhanced magnetization. (2) In a higher field range, the engineering shows a relaxation and pinning effect on the magnetization behavior, which leads to a reduced magnetization. On the basis of the analysis of scanning electron microscopy and X-ray diffraction, the results have been discussed. (C) 2004 Elsevier B.V. All rights reserved.