Abstract: 0-3 type barium strontium titanate (BST)/polytetrafluoroethylene (PTFE) composites are new types of ceramic/polymer functional composites. They combine advantages of BST ceramic and PTFE polymer, and show high dielectric constant and dielectric adjustability. However, due to the low dielectric constant of polymer phase, the dielectric constant of composites with polymer as matrix and ceramic as filling phase prepared by conventional methods such as flow casting method is basically below 100. In order to further improve the dielectric properties of BST/PTFE composites, a new sintering process (cold sintering process) was used to realize the co-sintering of BST ceramic and PTFE polymer. In the experiment, 0-3 type BST/PTFE composites were prepared by introducing PTFE with a volume ratio of 5% into BST matrix, and solid barium hydroxide octahydrate (Ba(OH)2·8H2O) as transient liquid phase to assist the sintering process. The dielectric properties of the composites under different cold sintering conditions were investigated. The results show that the dielectric constant of the composite samples reach more than 500 (25 ℃, 1 kHz) under the conditions of cold sintering temperature of 275 ℃, pressure of 200 MPa and time of 2.5 h. Compared with the conventional preparation process, the dielectric constant of the composites prepared by cold sintering process has been greatly improved, which has a certain reference significance for the low-temperature preparation and research of ceramic/polymer functional composites.
Key words: barium strontium titanate, polytetrafluoroethylene, Ba(OH)2·8H2O, cold sintering, micro morphology, dielectric property
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