Effect of R³⁺ Ions on the Structure and Properties of Lanthanum Borate Glasses

Abstract

Glass formation in the systems (mole percent) 25La2O3· xR2O3· (75 - X)B2O3 (R = Al, Ga) and (25 - x)La2O3· xLn2O3· 75B2O3 (Ln = Gd, Er, Y) was investigated. Up to 25 mol% Al2O3 or Ga2O3 can be substituted for B2O3, but more than ~ 5 mol% Ln2O3 substituted for La2O3 caused macro phase separation. X-ray diffraction and infrared analysis of these glasses and their devitrified products indicate that the basic structural units are similar to (B3O6)∞ chains found in binary 25La2O3* 75B2O3 glass. However, the BO4 units in the (B3O6)∞ chains are replaced by AlO4 or GaO4, units when Al2O3 or GaZO3 is substituted for B2O3. In these systems, Al2O3, Ga2O3, and B2O3 act as glass formers, whereas Ln2O3 and La2O3 act as network modifiers. The substitution of either R2O3 or Ln2O3 in the lanthanum borate system changes the separation distance between adjacent (B3O6)∞ chains. The effect of this structural change on the molar volume, transformation temperature, thermal expansion coefficient, and transformation-range viscosity is discussed.

Department(s)

Materials Science and Engineering

Keywords and Phrases

Glass Manufacture - Control; Glass Formation; Molar Volume; Oxide Glasses; Transformation Temperature

International Standard Serial Number (ISSN)

0002-7820; 1551-2916

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 1985 Wiley-Blackwell, All rights reserved.

Publication Date

01 Dec 1985

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