Multiferroic Ceramic Composite with In Situ Glassy Barrier Interface and Novel Electromagnetic Properties

Abstract

The exploration of high-performance multiferroic composites is of great importance for the design of next-generation electromagnetic devices. In this article, BTO/NZFO, a universal percolative ceramic composite derived by sol–gel in situ method, was investigated both theoretically and experimentally. The composite exhibits super high percolation threshold (fc = 0.95) and thus giant permittivity as well as high permeability simultaneously. Glassy barrier layers at grain boundaries were designed to form in situ in the composite, leading to significant decrement in dielectric loss. Relaxation dispersion occurs in the composite with the relaxation time distributing from (6.0 to 2.0) × 10–7 s due to compositional discrepancy across the amorphous barrier layers at grain boundaries. The dielectric response of the composite can be described by hybrid dielectric model that combines both dipole polarization and space-charge polarization, theoretically supporting the view that amorphous barrier layers restraining the motion of space charges could result in low dielectric loss. The dielectric loss, which is generally high in percolative ceramic composites, could achieve a relatively low value of only ∼0.19 within the frequency of 10∼100 kHz, which is a practical applied frequency range in electromagnetic devices.