希土類含有高融点酸化物ガラスの作製とその二, 三の物性(<小特集>セラミック材料小特集)

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Thermal image furnace melting and twin-roller quenching were used to prepare glasses containing large amounts of rare earth oxides in Ln_2O_3-M_XO_Y systems (Ln_2O_3=La_2O_3, Nd_2O_3, Y_2O_3; M_X O_Y=SiO_2, Al_20_3, TiO_2, Nb_2O_5). The glass-forming regions were found at the following compositions close to the eutectic points of the phase diagrams: (20-30)Ln_2O_3-(70-80)SiO_2, 60Ln_2O_3-40SiO_2, 2OLn_2O_3-80Al_20_3, 2OLn_2O_3-80TiO_2, (20-30)Ln_2O_3-(70-80)Nb_2O_5 and 6OLn_2O_3-4ONb_2O_5. The glass transition temperature T_g was determined by DTA. All the glasses showed high glass transition temperatures over 700℃. Although T_g increased or decreased with Ln_2O_3 content depending upon the system, the change was linear with Ln_2O_3 content around the eutectic compositions. This seems to indicate that there is no peculiar behavior of viscosity itself at the eutectic compositions. The liquidus viscosity becomes the maximum at the eutectic compositions due to low liquidus temperatures, which makes glass-formation easier at the eutectic compositions. A glass model consisting of four-coordinated aluminum units was proposed for Ln_2O_3-Al_20_3 glasses based on the results of IR spectra and observed AlKα chemical shifts. On the other hand IR spectra of Ln_2O_3-TiO_2 glasses showed a mixture of six- and four-coordinated titanium units. Visible and ultraviolet absoption spectra of Nd^<3+> were studied on Nd_2O_3-M_XO_Y glasses. The peak positions of these absorption bands moved towards lower wave numbers linearly with increasing compositional basicity of the glasses. Their color changed from purple-like blue to green-like blue, as the absorption bands shifted towards lower wave numbers.
1986-01-15

希土類含有高融点酸化物ガラスの作製とその二, 三の物性(<小特集>セラミック材料小特集)

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