Effects of Y2O3 and La2O3 addition on the crystallization of Li2O·Al2O3·4SiO2 glass-ceramic
- 122 Downloads
Effects of adding Y2O3 and La2O3 on the crystallization of β-quartz solid solution (ss) and the subsequent β-quartz ss to β-spodumene transformation of Li2O·Al2O3·4SiO2 glass-ceramic were investigated. Adding ≥ 4 mol% YO3/2 or 8 mol % LaO3/2 effectively improved the control of the crystallization process of the glass. Y2O3 did not effectively induce bulk crystallization of β-quartz ss, but can reduce the rate of surface crystallization. La2O3 completely suppressed the surface crystallization and promoted a uniform, bulk crystallization of β-quartz ss. For both the Y2O3- and La2O3-doped glasses, the kinetics for glass crystallization to β-quartz ss was delayed as the doping level increased. Except for the 8 mol % LaO3/2-doped glass in which no β-spodumene was formed, the kinetics for the β-quartz ss to β-spodumene transformation for the doped glasses was enhanced compared with that for the undoped glass. For the 4 and 8 mol % YO3/2-doped compositions, the relative amount of β-spodumene to β-quartz revealed an anomalous decrease trend with heating temperature in a particular temperature range. This can be explained by the surface crystallization characteristic, which induced an overlap of crystallization and β-quartz ss to β-spodumene transformation. Glass doped with 8 mol % LaO3/2 exhibited an Avrami exponent of about 2.4 and an activation energy for crystal growth of β-quartz ss of about 418 kJ mol−1.
KeywordsCrystallization Activation Energy Al2O3 Y2O3 Crystallization Process
Unable to display preview. Download preview PDF.
- 1.H. SCHEIDLER and E. RODEK,Amer. Ceram. Soc. Bull. 68 (1989) 1926.Google Scholar
- 2.Z. STRNAD, “Glass-Ceramic Materials, Glass Science and Technology”, Vol. 8 (Elsevier, Amsterdam, 1986) p. 85.Google Scholar
- 4.J.U. KNICKERBOCKER,Amer. Ceram. Soc. Bull. 71 (1992) 1393.Google Scholar
- 5.A. KUMAR, P.W. MCMILLAN and R.R. TUMMALA, US Patent 4301324, November (1981).Google Scholar
- 6.P.W. MCMILLAN “Glass-Ceramics”, 2nd Edn (Academic Press, London, 1979) p. 225.Google Scholar