Prospect of application of polycarbosilane.

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... fibers of inorganic SiC are prepared from the organometallicpolymer of polycarbosilane [10- 12]. Polycarbosilane is prepared from dechlorinated dimethyldichlorosilane by polymerization in an autoclave at 450 • C for 15 h (Fig. 1). Obtained polycarbosilane is formed as a precursor fiber by melt-spinning. Then, precursor fiber is heated to produce the inorganic SiC fiber (Fig. 1, process (A)). Thus, the organic precursor is prepared in a subtle form of fiber which is extremely difficult to produce from an inorganic precursor [10]. On heating the organic precursor ...

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... are prepared from the organometallicpolymer of polycarbosilane [10- 12]. Polycarbosilane is prepared from dechlorinated dimethyldichlorosilane by polymerization in an autoclave at 450 • C for 15 h (Fig. 1). Obtained polycarbosilane is formed as a precursor fiber by melt-spinning. Then, precursor fiber is heated to produce the inorganic SiC fiber (Fig. 1, process (A)). Thus, the organic precursor is prepared in a subtle form of fiber which is extremely difficult to produce from an inorganic precursor [10]. On heating the organic precursor a ceramic skeleton remains. This inorganic residue is consisted of Si and C and it possesses many excellent characteristics not previously reported. The SiC fiber ...

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... acted as an excellent binder for ceramic powder that is difficult to sinter such as SiC. A method was developed to produce shaped SiC bodies using polycarbosilane as a binder (Fig. 1, process (B)) [14][15][16]. The polycarbosilane was added to the α-SiC powder (filler) and the mixture was sintered at several temperatures in N 2 stream. Hot pressing was not required. The SiC compacts obtained have a low density but a high bend strength as shown in Fig. 6 [14]. Polycarbosilane is also an excellent impregnation reagent [15]. ...

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... shown in Figs. 9 and 10, zinc oxide (ZnO) fiber was prepared from the precursor Zn(acac) 2 [22][23][24]. Fine polycrystalline Zn(acac)2 fiber was obtained by the sublimation of Zn(acac) 2 powder. When the Zn(acac) 2 fiber was pyrolyzed with superheated steam (Fig. 11), it was converted to ZnO fiber, while maintaining the original shape of the Zn(acac) 2 fiber. At this stage, polycrystalline ZnO, aggregated ZnO single crystal grains, which had diameters of a few nanometers, were present along with relatively large amounts of carbon (C) and hydrogen (H). The ZnO fiber sample produced after crystal ...

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... nanometers, were present along with relatively large amounts of carbon (C) and hydrogen (H). The ZnO fiber sample produced after crystal grain growth by heat treatment at 800 • C contained almost no C and H, and nearly complete mineralization was achieved [25- 28]. XRD patterns of compounds involved in the organicinorganic conversion are shown in Fig. 12. Final product of inorganic ZnO fiber consisted of ZnO microrods, and these microrods consisted of ZnO nanorods (Fig. 13). The surface of the ZnO nanorods was covered with scale-like nanosized-single-crystal grains (Fig. 14), which had high crystallinity, clean surfaces, and diameters of a few tens of nanometers [29,30]. This fiber ...

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... after crystal grain growth by heat treatment at 800 • C contained almost no C and H, and nearly complete mineralization was achieved [25- 28]. XRD patterns of compounds involved in the organicinorganic conversion are shown in Fig. 12. Final product of inorganic ZnO fiber consisted of ZnO microrods, and these microrods consisted of ZnO nanorods (Fig. 13). The surface of the ZnO nanorods was covered with scale-like nanosized-single-crystal grains (Fig. 14), which had high crystallinity, clean surfaces, and diameters of a few tens of nanometers [29,30]. This fiber efficiently decomposed a volatile organic compound (VOC), xylene as shown in Fig. 15. This decomposition of xylene was ...

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... mineralization was achieved [25- 28]. XRD patterns of compounds involved in the organicinorganic conversion are shown in Fig. 12. Final product of inorganic ZnO fiber consisted of ZnO microrods, and these microrods consisted of ZnO nanorods (Fig. 13). The surface of the ZnO nanorods was covered with scale-like nanosized-single-crystal grains (Fig. 14), which had high crystallinity, clean surfaces, and diameters of a few tens of nanometers [29,30]. This fiber efficiently decomposed a volatile organic compound (VOC), xylene as shown in Fig. 15. This decomposition of xylene was achieved by oxidation on the fiber surface under the illumination of white fluorescent light, which had a ...

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... and these microrods consisted of ZnO nanorods (Fig. 13). The surface of the ZnO nanorods was covered with scale-like nanosized-single-crystal grains (Fig. 14), which had high crystallinity, clean surfaces, and diameters of a few tens of nanometers [29,30]. This fiber efficiently decomposed a volatile organic compound (VOC), xylene as shown in Fig. 15. This decomposition of xylene was achieved by oxidation on the fiber surface under the illumination of white fluorescent light, which had a color temperature of 3500 K where visible light is dominant. This means that this fiber has a photocatalytic ability in response to visible light [22][23][24]. The visible-light photocatalytic ...

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... PL spectrum of the ZnO fibers were obtained using a fluorescence spectrophotometer (Shimazu RF-5300PC) with the violaceous LED (400 nm) as the excitation source. Figure 16 is a result of comparing the PL property of the commercially available ZnO powder and the ZnO fiber. PL spectrum is hardly seen from the ZnO powder though luminescence around 440 nm can be confirmed from the ZnO fiber. ...

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... originates in the intraband level. However, these results cannot prove the photocatalytic activity by the visible-light irradiation. The photocatalytic activity appears by the electron that exists in the conduction band. We paid attention to the bonding interface of nanosized-single-crystal grains, and proposed the band bending model like Fig. 17. In this model, the electron excited to the localized level under the conduction band moves to the conduction band via the bent position of the ...