退火温度对Co掺杂CeO2稀磁氧化物薄膜的结构和铁磁性能的影响

采用溶胶-凝胶法,在Si(100)和石英玻璃衬底上制备了3;Co掺杂CeO2稀磁氧化物薄膜,研究了不同退火温度(500 ℃, 600 ℃和700 ℃)对薄膜结构和铁磁性能的影响.XRD 和拉曼光谱结果表明,随着退火温度的升高,薄膜晶化度明显提高.不同退火温度下的3;Co掺杂CeO2薄膜为多晶薄膜,且未破坏CeO2原有的结构.随着退火温度的升高, 晶粒尺寸逐渐增大.另外,3;Co掺杂CeO2薄膜在可见光范围内都有很好的透射率,其室温下的光学带隙Eg随退火温度增加而减小.超导量子干涉磁强计(SQUID)测量表明所有样品都表现出室温铁磁性,随着退火温度的升高,饱和磁化强度和矫顽力增大,700 ℃退火的薄膜具有最大的饱和磁化强度和最大的矫顽力.不同退火温度导致样品的磁性有了明显的变化,这源于磁性产生的不同机理.可见薄膜的结构最终影响了其铁磁性能.

Effect of Annealing Temperature on the Structure and Ferromagnetic Properties of Co-doped CeO2 Diluted Magnetic Oxide Thin Films

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.