In this study, the low thermal expansion ceramic, petalite (Li2O • Al2O3 • 8SiO2), was synthesized by using pyrophyllite, and their characteristics were examined. Pyrophyllite is consisted of SiO2 and Al2O3, which are the main component of petalite. For the synthesis of petalite, Li2CO3 or LiOH • H2O were used as a source of Li2O. In the mixing ratio of 6.7 : 1 wt% (pyrophyllite : Li2CO3), fully crystallized petalite was synthesized, and the powder compacts were densified at 1150 oC. Some Li compounds, which have low melting point, caused a formation of liquid phase in the densified samples. The petalite phase was transformed to β-spodumene during heating process, and the sintered petalite showed a negative thermal expansion coefficient of −0.43 × 10- 6/oC. Finally, the experimental results showed that the pyrophyllite is an expected material for the synthesis of low thermal expansion ceramics.

Keywords: Pyrophyllite, Petalite, Thermal expansion coefficient, Lithium carbonate, β-spodumene.