LAUSR

Abstract Stoichiometric lithium disilicate glasses were doped with up to 2 mol% B 2 O 3 , Na 2 O or K 2 O and the crystallization kinetics were determined as a function of the temperature using in situ hot-stage microscopy. The additives lead to a decrease of the glass viscosities in the studied temperature range with the exception of the boron-containing samples which show slightly higher viscosities in the nucleation range. While in the boron-containing samples, lithium disilicate solid solutions precipitate during thermal treatment, in the other samples a mixture of lithium disilicate, lithium metasilicate and cristobalite was detected. The steady-state nucleation rates decrease by up to one order of magnitude and especially in the case of the additive B 2 O 3 , the induction times for nucleation are remarkably longer. While the additives B 2 O 3 and K 2 O lead to a decrease of the crystal growth velocities, in case of Na 2 O, the contrary effect can be noticed. Possible reasons for the observed effects are discussed.