Abstract :
The (1−x)La0.67Ca0.33MnO3+xCuO composites have been synthesized by a new liquid phase method. The XRD and SEM measurements reveal that little CuO is soluble in the structure of La0.67Ca0.33MnO3 and is mainly distributed at the grain boundary of La0.67Ca0.33MnO3. As CuO content x increases, the magnetization M values increase until x = 0.05 and M values decrease when x further increases at low temperature. For x = 0.10 , 0.20 and 0.30 composites, double metal–insulator transitions accompanying a single ferromagnetic transition are observed. Large low-field magnetoresistance is achieved for the composites and the largest magnetoresistance appeared when x = 0.20 .
