An in situ (K0.5Na0.5)NbO3-doped barium titanate foam framework and its cyanate ester resin composites with temperature-stable dielectric properties and low dielectric loss

Abstract

Lower dielectric loss, higher dielectric constant and wider service temperature are prerequisites of high dielectric constant materials for renewable and new energy generation technology. Herein, an in situ doping strategy was set up to prepare a new foam ceramic (dBTF), in which the 3D skeleton is (K_0.5Na_0.5)NbO₃ (KNN)-doped barium titanate (BT). On this basis, a series of composites (dBTF/CE/cPES) using a blend of dBTF and cyanate ester/phenolphthalein poly(ether sulfone) (CE/cPES) as the matrix were prepared. Effects of both spatial and chemical structures on the dielectric properties of composites were studied. When the ceramic content is only 31.5 vol%, the resultant composite (6dBTF5/CE/cPES) not only has about a 6.3 times higher dielectric constant than the dBTF powder-filled CE/cPES composite (6dBTFp5/CE/cPES), but also exhibits outstanding temperature stability from −100 to 110 °C; moreover, the two composites have extremely low dielectric loss. The reason behind these attractive properties has been discussed.