Constructing three-dimensionally interwoven structures for ceramic/polymer composites to exhibit colossal dielectric constant and high mechanical strength: CaCu3Ti4O12/epoxy as an example

Until now, the reported dielectric constants of the ceramic/polymer composites are rather low, even though their corresponding bulk ceramics have colossal dielectric constants. This work demonstrates that ceramic/polymer composites can achieve colossal dielectric constants by constructing three-dimensionally interwoven structures. Furthermore, the ceramic/polymer dielectric composites exhibit high mechanical strength. As an example, CaCu3Ti4O12/epoxy dielectric composites with such interwoven structures are fabricated in this work. The CaCu3Ti4O12/epoxy composites exhibit both colossal dielectric constant and high flexural strength, both of which rapidly increase with the CaCu3Ti4O12 content. When the CaCu3Ti4O12 content is about 57.7 vol%, the dielectric constant and flexural strength of the CaCu3Ti4O12/epoxy composites are about 1501 at 1 MHz and 118.8 MPa, respectively. Their dielectric constants are much higher than the predicted values by the existing theoretical models for ceramic/polymer dielectric composites. A modified parallel model is proposed to explain the presence of colossal dielectric constants of the ceramic/polymer composites.