Enhanced Magnetoresistance of (La0.67Ca0.33MnO3) Composites Coated byZn0.95Co0.05O

La0.7Ca0.3MnO3:xZn0.95Co0.05O (x = 0.0, 0.05, 0.1, 0.15 mol) composites are prepared by a sol-gel process. X-ray diffraction and energy diffraction spectroscopy reveal that there is no evidence of a reaction between the La0.7Ca0.3MnO3(LCMO) and Zn0.95Co0.05O (ZCO). Magnetization M, Curie temperature TC and metal-insulator transition temperatures Tp are observed to decrease with increasing ZCO content. Compared with x = 0.0, a great enhancement in the magnetoresistance (MR) is observed at around TC for x = 0.05, 0.10, 0.15. Based on the tunneling MR and percolation models, this great change of MR is well explained.