| Ferroelectric film is a kind of important functional thin film materials, due to its important characteristics, such as dielectric properties, ferroelectric properties, piezoelectric properties, pyroelectric properties and acousto-optic effect, electro-optic effect, photore-fractive effect, and nonlinear optical effect etc, which can be used to produce dynamic random access memory, surface acoustic wave device, pyroelectric detector, ferroelectric randomaccess memory, phase shifter acousto optic deflector and other device. As the development of machine and system towards the direction of compact and lightweight, these requirements of miniature, lightweight and integrated are requested by microelectronics, optoelectronics and MEMS, so the study on thin films have become the current hightech front and one of the hot spots.Perovskite Bi0.9Nd0.1FeO3(BNFO) thin films were deposited on Si(100) substrate by RF magnetron sputtering method. X-ray diffraction analysis indicated that the BNFO thin film grown on Si(100) substrate was of the perovskite phase. The SEM surface image showed that the BNFO thin film was compact and crack-free, and with the annealing temperature rising from450to750℃, the average grain size becoming larger and the crystallinity of the films increased. More important, the BNFO film annealed at750℃have the largest magnetic moment (3686emu/cm3), about2orders larger than those annealed at the other temperatures. The enhanced magnetic moment may be ascribed to the Fe2+ions and γ-Fe2O3impurity in BNFO films. BNFO thin films were deposited on Si(100), fused quartz and LSAT(100) substrates at the same deposited conditions by RF radio sputtering method. It is found that all the films deposited by RF magnetron sputtering are compact. On the other hand, there exists different optimum annealing temperature on different substrate. The film on the LSAT is more smoother than the one on Si and the grain size is smaller. All of the samples are shown strong magnetic and the film deposited on Si(100) is the largest, and the mainly reasons may be the product of Fe2+destroying the spiral spin structure or the anisotropy causes by extension stress.Bi3.4Nd0.6Ti3O12films were grown on Si(100) substrates by RF magnetron sputtering. SEM showed that the films were compact, uniform, smooth and crack-free. With the increase of annealing temperature, the average grain size of films gradually increases, and the forbidden gap of thin films decreases gradually. The refractive index(n) of all the films remains unchanged and transparent in visible spectral region. It is suggested that the optical constant such as forbidden gap, etc could be adjusted by the annealing temperature effectively and it is a potential materials in many aspects.Moreover, Ni0.5Co0.5Fe2O4nanoparticles have been successfully prepared by the chemical co-precipitation process. The structure and magnetic property of the samples have been measured. The effects of different annealing temperature on the properties of Ni0.5Co0.5Fe2O4samples were investigated. XRD patterns suggest that the as-prepared powders are spinel-typed and has a highly (311) orientation. And the average grain size of the NCFO nanoparticles ranging from15.6to49.5nm. The magnetic propertiy measurements show that the saturation magnetization of these samples first increased with annealing temperature and then decreased, which may be explained by super-exchange interactions of Fe ions occurring at A-and B-sites. The variation of coercivity with particle size is interpreted on the basis of domain structure and crystal anisotropy. |
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