Influence of rare-earth ions on fluorogallate glass formation and properties

Various rare earths have been incorporated in a lead fluorogallate glass with the following chemical composition: 30PbF(2)-20GaF(3)-15InF(3)-20CdF(2)-15ZnF(2) (PGICZ). Selected rare earths are La, Ce, Pr, Nd, Gd, Er, Yb and Lu, and the doping level varies between 1 and 10 mol%. The influence of rare earth fluorides on glass forming ability and on physical properties is investigated. At low concentration (<3 mol%) lanthanide incorporation increases glass stability. While large amounts of rare earths may enter glass composition, thick samples are difficult to obtain with this glass composition. Larger samples containing 9 mol% NdF3 in a modified PGCIZ glass have been cast. Experimental results suggest that rare earths act as modifiers rather than vitrifiers in this fluorogallate system. The effect of rare earths on the values of glass transition temperature, refractive index, density and thermal expansion is reported. (C) 1998 Elsevier Science S.A.