Bi0.85La0.15FeO3 thin film was prepared on ATO glass substrates by sol-gel technique. The effect of La doping on phase structure, film surface quality, ion valence, and ferroelectric/magnetic properties of Bi0.85La0.15FeO3 film were investigated. La dop-ing suppressed the formation of impurity phases and the transition of Fe3+ to Fe2+ ions at room temperature. Compared with the un-doped BiFeO3, La-doping also increased the average grain size and the film density, which resulted in the decrease of film leakage current density. The remanent polarization and saturation magnetization were enhanced significantly by La doping. The remanent polarization of Bi0.85La0.15FeO3 films gradually decreased while saturation magnetization increased with the decrease of measuring temperature within a range from 50 to 300 K.
We used yttrium acetate, barium acetate, and copper acetate as the starting materials, benzalacetone (BzAcH) as chemical modifier, and methanol (MEOH) as solvent to synthesize a stable fluorine-free YBCO precursor sol. The coated YBCO gel film using this precursor sol exhibited photosensitivity to UV irradiation at a wavelength of 330 nm. After the subsequent exposing, the YBCO gel film showed a decreased solubility in several organic solvents. Based on the photosensitivity of the YBCO/BzAcH gel film, YBCO superconducting microarray with the pitch of 5 μm was fabricated by irradiating the gel film with UV light through a mask, followed by leaching the unirradiated area in a mixture solvent of methanol and n-butyl alcohol with the volume ratio of 1:1. After proper heat treatment the x-ray diffraction result showed that the as-prepared arrays were highly c-axis oriented and with a high T c by this new photosensitive sol-gel process.
