ゾル-ゲル法で作製したCdS微結晶ドープガラスのCdS結晶生成

概要

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Glasses doped with small sized-CdS crystals with a significant quantum size effect were prepared by the sol-gel process. Gels synthesized through the hydrolysis of a complex solution of Si(OC_2H_5) 4 and Cd(CH_3COO)_2・2H_20 were heated at 500°to 700℃, then allowed to react with H_2S gas to form silica glasses doped with fine CdS microcrystals. The formation of CdS crystals was controlled by diffusion of H_2S gas into the porous glass and the diffusion coefficient was from 10-18 to 10^<-16>cm^2/s at 100°to 200℃ as determined from the measurement of weight gain of glass. The size of CdS microcrystals increased with heat-treatment time, reaching 2 to 6 nm in diameter, which was dependent on the heat-treatment temperature and CdO content in glass. The optical absorption edge exhibited a blue shift compared to that of a bulk CdS crystal and its energy shift was reciprocally proportional to the square of the crystal size. In the photoluminescence spectra, two peaks were observed at 2.0 and 2.5 eV, the intensity of which at 2.0 eV decreased as the heat-treatment time was increased. It was considered that the emission at 2.0 eV, pronounced at low temperature of 77 K, was due to the carrier recombination via the deep level due to oxygen impurity in CdS crystals.
社団法人日本セラミックス協会の論文
1991-07-01