Elastic Properties and Molar Volume of Rare‐Earth Aluminosilicate Glasses

The elastic properties, molar volume, and glass transition temperature ( T g ) of rare‐earth‐containing aluminosilicate glasses were investigated in the compositions of SiO 2 –LnAlO 3 and SiO 2 –Ln 3/4 Al 5/4 O 3 , where Ln is Y, La, Nd, Eu, or Yb. The molar volume decreased with decreased ionic size of the Ln 3+ ion, and T g and elastic moduli increased in the same order. The Yb‐containing glasses showed the highest Young's modulus among all the oxide glasses, even higher than the highest value ever known for glass containing Y 2 O 3 , as expected from the smaller ionic radius of Yb 3+ than that of Y 3+ . The bulk modulus was found to be almost proportional to the inverse four‐thirds power of the molar volume of glasses in each composition, indicating that Ln 3+ ions can substitute for each other without changing the glass structure except for the size of the local structure around themselves. From the comparison of these properties, the structural role of rare‐earth ions in these glasses is discussed.