Improvement of the dielectric properties of rutile TiO2 ceramics at megahertz

Boron nitride nanosheets (BNNS) were mixed with rutile TiO 2 and (Al, Nb)-codoped ceramics (ANTO) powders by heteroaggregation method. Homogeneous ceramics with the single phase of rutile TiO 2 were obtained by subsequent solid-state sintering. Scanning transmission electron microscope (STEM) and X-ray photoelectron spectrometer (XPS) results show that N was doped into the crystal lattice during sintering. It is shown that the strong electron localization of the covalent N i –O bond formed between interstitial N ( N i ) and adjacent O atom shifts the cutoff frequency of high permittivity from ∼100 kHz to 100 MHz in both rutile TiO 2 and the ANTO systems. Particularly, the ANTO-0.6BNNS sample exhibits optimum dielectric properties with a permittivity of 1.3 × 10 4 and tan δ of 0.04 measured at 1 MHz. Meanwhile, the colossal permittivity of ANTO-0.6BNNS with tan δ < 0.1 shows good temperature stability in the temperature range of 200–400 K.