Properties and crystallization kinetics of low temperature co-fired Li2O-Al2O3-SiO2 electroceramics

The glass-ceramic in the Li2O-Al2O3-SiO2 system has been prepared by melt quenching route. The crystallization kinetics was studied by differential scanning calorimetry. The effects of sintering temperature on the phase transformation, sintering behavior, bulk density, microstructure, thermal expansion, bending strength and dielectric properties were also investigated by X-ray diffractometry and scanning electron microscopy. (Li, Mg, Zn)1.7Al2O4Si6O12 is the first crystalline phase forming in the glass-ceramic and transforms to LiAlSi3O8 phase at 800 °C. The other two crystalline phases of ZrO2 and CaMgSi2O6 precipitate at 700 and 750 °C, respectively. The densification of this LAS glass-ceramic starts at around 730 °C and stops at about 805 °C. The coefficient of thermal expansion increases with the increasing sintering temperature. The sample sintered at 800 °C for 30 min exhibited excellent properties. The nonisothermal activation energy of crystallization is 149 kJ/mol and the values of Avrami constant (n) are in the range of 3.2 to 3.9. The LAS glass-ceramic sintered at 800 °C for 30 min showed excellent properties. This makes that this material suitable for a number of LTCC applications.