No abstract

SiOC(H) ceramics were synthesized from polycarbosilane (PCS) by a combinatorial procedure of thermal oxidation curing and H 2 decarbonization. In the case of PCS precursor with particle form (diameters of 100500 nm), thermal oxidation curing at 340°C was most effective to achieve white appearance with photoluminescence even after H 2 decarbonization at 800 or 1100°C. In the case of fiber form (diameter of 10¯m), the curing temperature of 290°C was effective to obtain white PL fiber after the decarbonization at 800°C. Heat treatment at 1100°C, however, changed the color of the fiber to black. Spectroscopic analysis of the decarbonized products revealed that structure of the white materials with strong PL mainly consisted of SiO 4 SiO 3 C mixed units, whereas incorporation of SiC 4 units decreased PL intensity. In addition, the materials with apparent PL usually exhibited a sharp absorption band at 880 cm ¹1 in FT-IR spectra, which was possibly assigned to a kind of SiC bonds modified by hydrogen incorporated in the amorphous network.

Two kinds of SiOC(H) particles having intrinsic photoluminescence (PL) spectra were prepared from silicone resin microspheres by heat treatment in a hydrogen atmosphere at 800 or 1100°C. The obtained particles were painted on a Si substrate using a binder, and ion-beam-luminescence spectra were observed under proton beam irradiation with an acceleration energy in the range of 13 MeV. Observed spectra had peaks at wavelength of 520540 nm. These peak wavelengths were larger than those observed under UV light irradiation. The luminescence of H 2 1100 (sample decarbonized at 1100°C) was bright, and that of H 2 800 (sample decarbonized at 800°C) was faint. However, the intensity of luminescence decreased rapidly at an early stage of the beam irradiation. In air, a sharp luminescence band with a peak at 300 nm appeared together with the main emission with a peak in the range of 520540 nm. The existence of the sharp band at 300 nm was apparent in the H 2 800 spectra, whereas it appeared as a minor peak in the H 2 1100 spectra in air.