Abstract: Effect of annealing temperature on the structure and ferromagnetic properties was investigated for 3;Co doped CeO2 diluted magnetic oxide thin films prepared on Si(100) and quartz glass substrates by sol-gel method.The film samples were annealed at temperature of 500 ℃, 600 ℃ and 700 ℃.Then, X-ray diffraction (XRD), Raman spectroscopy, optical transmittance spectrum and superconducting quantum interference device (SQUID) were used to clarify the effect of annealing temperature on the structure and ferromagnetism of the film.The XRD and Raman spectroscopy results show a clear increasing of the crystallization degree of the film annealed under high temperature.The XRD also show that all Ce0.97Co0.03O2 thin films polycryatalline with the same structure of CeO2.The average crystallite size increases with increasing annealing temperature.Transmission spectrum studies show that all Ce0.97Co0.03O films anneal have no significant variance over absorption edge, and the optical band gap Eg decrease as increasing annealing temperature.The magnetic measurements of all films using SQUID clearly indicate the room temperature ferromagnetic behavior, and the remanent magnetization and the coercive field increase with increasing annealing temperature.The largest remanent magnetization and coercive field are obtained for the film annealed at 700 ℃.The structure of the Ce0.97Co0.03O2 film is revealed to affect their ferromagnetic properties.

Key words: Effect of annealing temperature on the structure and ferromagnetic properties was investigated for 3;Co doped CeO2 diluted magnetic oxide thin films prepared on Si(100) and quartz glass substrates by sol-gel method.The film samples were annealed at temperature of 500 ℃, 600 ℃ and 700 ℃.Then, X-ray diffraction (XRD), Raman spectroscopy, optical transmittance spectrum and superconducting quantum interference device (SQUID) were used to clarify the effect of annealing temperature on the structure and ferromagnetism of the film.The XRD and Raman spectroscopy results show a clear increasing of the crystallization degree of the film annealed under high temperature.The XRD also show that all Ce0.97Co0.03O2 thin films polycryatalline with the same structure of CeO2.The average crystallite size increases with increasing annealing temperature.Transmission spectrum studies show that all Ce0.97Co0.03O films anneal have no significant variance over absorption edge, and the optical band gap Eg decrease as increasing annealing temperature.The magnetic measurements of all films using SQUID clearly indicate the room temperature ferromagnetic behavior, and the remanent magnetization and the coercive field increase with increasing annealing temperature.The largest remanent magnetization and coercive field are obtained for the film annealed at 700 ℃.The structure of the Ce0.97Co0.03O2 film is revealed to affect their ferromagnetic properties.