Evaluation of the effect of the addition of TiO₂ on the dielectric behaviour of YNbO₄ ceramic using impedance spectroscopy

The present article evaluates the effect of the addition of TiO₂ on the dielectric properties in the radiofrequency region of the YNbO₄ ceramic matrix. X-ray diffraction (XRD) showed that the YNT (Y(Nb_0.5Ti_0.5)₂O₆) phase formed from the reaction between YNbO₄ (YNO) and TiO₂ in the investigated composites. Complex impedance spectroscopy (CIS) analysis was utilized and it was observed that the activation energy (E_a) values of the materials varied between 1.13 and 2.31 eV. Nyquist diagrams were fitted for the materials using three associations of resistor-constant phase element (R-CPE), with an exception for the YNO40 composite that used only two associations. All compositions presented values of n in the range of 0.6 ≤ n ≤ 1 for grain resistance (R_g) and grain boundary resistance (R_gb), indicating a capacitive character. Temperature capacitance coefficient (TCC) values were also calculated. At many frequencies, it was observed that the composites presented values in the range of ± 1500 ppm °C⁻¹, indicating that the evaluated systems could be employed as Class 1 capacitors according to EIA RS-198.