Abstract: Sol-gel derived Ba_0.80Sr_0.20TiO₃ and Pb_0.82La_0.12TiO₃ ferroelectric powders and a low-melting PbO-B₂O₃ glass powder were mixed to prepare paste. The composite
thick films were successfully prepared by screen printing onto the quartz glass substrates with the ITO bottom electrode and then calcined in the sealed silica tube at the low temperature between 550℃
and 750℃. XRD, SEM and LCR were used to measure the structure and dielectric constants of the composite thick films. The results show that the high infiltration of the PbO-B₂O₃ liquid
phase in the thick film gives rise to the ferroelectric powders uniform encapsulated by the PbO-B₂O₃ phase at the temperature of 750℃ and then the mass transport through the liquid phase, which
promote the densification of the thick film. The stable coexistence between the Ba_0.80Sr_0.20TiO₃ and Pb_0.82La_0.12TiO₃ crystal phases can be controlled directly by both the glass phase
encapsulated and the diffusion from the particles to the glass phase. The slight reduction of the lattice of the PLT-82 crystal phase in the thick film occurs due to Pb²⁺ ion vacancy generated by the diffusion.
The relative dielectric constant of the composite thick films exhibits the temperature-stable behavior. The variance of the dielectric constants is less than 18% in the temperature range 0--300℃

Key words: temperature-stable, composite thick film, BST, PLT