@article{oai:niigata-u.repo.nii.ac.jp:00003599,
 author = {野田, 弘之 and 金, 煕濬},
 issue = {12},
 journal = {日本セラミックス協会学術論文誌, 日本セラミックス協会学術論文誌},
 month = {Dec},
 note = {Nano-structured γ-Al2O3 ceramics have been pelletized under a pressure of 2.5 GPa on uniaxial compaction of nano-size particles. Although the obtained γ-Al2O3 ceramics show low density, they have a good transparency. For estimating the influence of particle size on the transparency of nano-structured γ-Al2O3 ceramics, nano-sized particles with four different sizes have been used. Nano-structured γ-Al2O3 ceramics made of particles whose size is < 10 nm show a transmittance above 40%. Transmittance decreases with increasing particle diameter. In the case of particle size >20 nm the transmittance is less than 20%. This phenomenon is explained by Rayleigh scattering, which is applicable to a particle diameter much smaller than the wavelength of the incident light. The change in transmittance of nano-structured alumina ceramics on heat treatment is not observed below 1123 K. However the transmittance remarkably decreases at above 1223 K because of rapid grain growths with phase transition, although this temperature is 250 K lower than the γ->α-phase transition temperature (1473 K) of bulk alumina. When the sample produced from 11.2 nm particles was heat-treated at 1173 K, the transmittance was maintained for 2 h and then decreased with increasing the annealing time. At this time, the transmittance slowly decreased with gram growth without phase transition between 2 h and 6 h, and then it steeply decreased with grain growth after 6 h with phase transition.},
 pages = {1062--1066},
 title = {透光性ナノ構造γ-Al2O3の熱処理による光学特性変化},
 volume = {110},
 year = {2002}
}