Correlation between infrared, THz and microwave dielectric properties of vanadium doped antiferroelectric BiNbO4

Abstract: Terahertz (THz) transmissivity and infrared (IR) reflectivity spectra of orthorhombic microwave (MW) ceramics Bi(Nb1−x V x )O4 (0.002< x <0.032) were measured between 4 and 3000cm−1 (0.09–90THz) at room temperature. A well underdamped mode, presumably the ferroelectric soft mode, was observed at 25cm−1. Complex permittivity spectra obtained from the fits to our data were extrapolated down to the MW range and compared with the dielectric data near 5GHz. The linear extrapolation of dielectric losses from THz down to the MW range is in agreement with the experimental MW losses. Addition of 3.2% of vanadium reduces the sintering temperature to 850°C and the dielectric properties (ɛ′=42.2, Q·f =14,000GHz, τ f =+10ppm/°C) remain at a level satisfactory for MW applications. Somewhat lower MW losses were observed in a sample sintered in the N2 atmosphere. [Copyright &y& Elsevier]