Effect of rare-earth cations on properties of sialon glasses

The preparation of bulk glasses in Ln-Si-Al-O-N systems (Ln = Y, Ce, La, Eu, Gd, Dy, Er and Yb) with the composition in equivalent % of 35e/oLn:45e/oSi:20e/oAl:83e/oO:17e/oN are reported. The properties of these glasses are examined in detail. Changes observed in density, Young's modulus, thermal expansion and glass transition temperature are represented. It is found that the mechanical properties vary linearly with cationic field strength (CFS) or ionic radius of the rare-earth modifier (E-min = 92 GPa for Eu2+ and E-max = 160 GPa for Er3+). The thermal properties do not show a linear behaviour. The glass transition temperature increases linearly through Gd followed by a linear decrease. The thermal expansion coefficient shows a linear decrease with a discontinuity at Gd as substituting cation. (C) 2000 Elsevier Science B.V. All rights reserved.