Copper concentration effect in the dielectric properties of BiNbO4 for RF applications

Abstract In this paper, the structural and dielectric properties BiNbO 4 as a function of cooper addition level and the radio frequency was investigated. The BiNbO 4 ceramics, were prepared by using the solid-state reaction method with the addition of 3, 5, and 10 wt.% of CuO. The analysis by X-ray diffraction (XRD) using the Rietveld refinement confirmed the formation of single-phase compound with a orthorhombic crystal structure ( a  = 5.6792 A, b  = 11.7081 A and c  = 4.9823 A; α  =  β  =  γ  = 90°) for the calcined powders. Micrographs obtained by scanning electron microscope shows the distribution of grains and the behavior of addition of CuO on the sample surface. In the measurements of the dielectric properties of BiNbO 4 at room temperature, by complex impedance spectroscopy technique, showed that the largest values of dielectric permittivity ( e r ′ ) at frequency 10 kHz, were found for the samples: BNO3Cu (3 wt.%CuO), BNO5Cu (5 wt.% CuO) and BNO10Cu (10 wt.% CuO) with values e r ′  = 87.15, 88.63 and 140.73, respectively. The values of the dielectric loss (Tan  δ ) for the samples: BNO3Cu, BNO5Cu and BNO10Cu were around 10 −2 , with values of 1.27 × 10 −2 , 1.81 × 10 −2 , and 3.61 × 10 −2 , respectively at 10 MHz. The samples were investigated for possible applications in radio frequency devices like ceramic capacitors.