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The crystallization of the amorphous precursor of a Ba-ferrite thin film was studied in real-time synchrotron x-ray scattering experiments. We found that a very thin (~50 [Angstrom]) epitaxial [Fe.sub.3][O.sub.4] sublayer was formed in the as-deposited amorphous precursor grown on sapphire (001). The nucleation of crystalline [Alpha]-[Fe.sub.2][O.sub.3] phase from the amorphous precursor started at 300 [degrees] C and continued at higher annealing temperatures. The mosaic distribution of the [Alpha]-[Fe.sub.2][O.sub.3] grains was about 0.67 [degrees] full-width at half-maximum (FWHM), relatively large compared to that of the [Fe.sub.3][O.sub.4] sublayer. The crystallization of the Ba-ferrite phase occurred at 600 [degrees] C. The [Fe.sub.3][O.sub.4] sublayer was transformed from 600 [degrees] C to extremely well-aligned (0.05 [degrees] FWHM) [Alpha]-[Fe.sub.2][O.sub.3] phase. It is noteworthy that the crystallization of the Ba-ferrite phase occurred during the transformation of the [Fe.sub.3][O.sub.4] sublayer to the well-aligned [Alpha]-[Fe.sub.2][O.sub.3] grains. The [Fe.sub.3][O.sub.4] sublayer might play an important role in the crystallization of amorphous Ba-ferrite film. Index Terms--Ba-ferrite film, crystallization, iron oxide phase, [Fe.sub.3][O.sub.4], sublayer, synchrotron x-ray scattering.

We have studied the inhibition of abnormal acicular grain growth of the Ba-ferrite phase in the crystallization of Ba-ferrite films using real time synchrotron x-ray scattering, field emission scanning electron microscope, and vibrating sample magnetometer. Amorphous Ba-ferrite film on a SiO[sub 2] substrate is naturally crystallized into the abnormal acicular Ba-ferrite grains (major axis of ∼1000 nm in the in-plane direction). However, on [sup -]A1[sub 2]O[sub 3] substrate, fine grain sizes of the primary Ba-ferrite phase (∼70 nm) are obtained during crystallization. Nucleation of the α-Fe[sub 2]O[sub 3] phase on the α-A1[sub 2]O[sub 3] surface at an early stage induces the inhibition of the abnormal acicular grain growth of the Ba-ferrite phase. Because of the grain size refinement of the magnetic Ba-ferrite phase, the intrinsic coercivity of Ba-ferrite/α-A1[sub 2]O[sub 3] film enhances 4.4 kOe, much larger than that of Baferrite/SiO[sub 2] film (1.9 kOe). We suggest that the secondary α-Fe[sub 2]O[sub 3] phase act as a useful inhibitor to abnormal grain growth in Ba-ferrite films for high-density recording media. [ABSTRACT FROM AUTHOR]

Abstract: We have developed photocatalytic TiO2 nanofibers for the treatment of organic pollutants by using electrospinning method. We found that the optimized electrospinning conditions (electric field and flow rate) were 0.9kVcm−1 and 50μLmin−1. After annealing at 550°C for 30min, we fabricated TiO2 nanofibers (average 236nm thick) with anatase crystalline phase. To increase photocatalytic activity and effective surface area, we coated photocatalytic TiO2 particles on the TiO2 nanofibers by using sol–gel method. The degradation rate (k′=85.4×10−4 min−1) of composite TiO2 was significantly higher than that (15.7×10−4 min−1) of TiO2 nanofibers and that (14.3×10−4 min−1) of TiO2 nanoparticles by the sol–gel method. Therefore, we suggested that the composite TiO2 of nanofibers and nanoparticles be suitable for the degradation of organic pollutants. [Copyright &y& Elsevier]

Abstract: This work reports the development of a visible-light sensible photocatalyst and the photocatalytic degradation of organic pollutants under visible-light irradiation. A composite semiconductor of ZnS and ZnO was prepared through co-precipitation process of Zn(NO3)2 in the mixed solution of aqueous Na2S and NaOH followed by calcination at 400°C in N2 atmosphere. It was revealed that the composite semiconductor was a solid solution of ZnS and ZnO, a zincoxysulfide (ZnO x S1−x ) having advanced visible-light absorptivity. It was assured that the visible-light absorptivity was caused by modification of band structure while the solid solution had been prepared, thus we suggested a reasonable band structure model involved in a zincoxysulfide. To observe its photocatalytic activity under visible-light illumination, photodegradation test was done and we confirmed that zincoxysulfide showed predominant photocatalytic activity due to its superior visible-light absorptivity to pure ZnS and ZnO. [Copyright &y& Elsevier]

The thermal stability of the HfO[sub 2]–Al[sub 2]O[sub 3] laminate gate stack grown by atomic layer chemical vapor deposition was investigated using medium-energy ion scattering spectroscopy and high-resolution x-ray photoelectron spectroscopy. The laminate structure was maintained up to 800 °C under ultrahigh vacuum conditions, while it was drastically degraded at 850 °C, resulting in silicide formation on the film surface. Dissociated oxygen in the Hf–Al-oxide preferentially diffuses out through the film and desorbing at the surface. Volatile SiO species and Al–O components desorb through the sample surface, while HfO[sub 2] contributes to Hf silicide formation on the film surface. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]