Structural and electrical properties of lead-free Na0.685K0.315Nb1–yTayO3 (0 ≤ y ≤ 0.05) ceramics

Piezoceramic Na0.685K0.315Nb1–yTayO3 (NKNT) (where y ≤ 0.05) samples were prepared via a solid-state reaction using double sintering. The effects of Ta-doping on the phase structure and electrical properties of the NKNT ceramics were investigated. The temperature dependence of the dielectric constant, loss tangent, and dielectric conductivity of the prepared samples was measured from RT to 500 °C at 10 kHz and 1 MHz. High temperature X-ray diffraction (HT- XRD) measurements were carried out on the prepared samples between RT and ~200 °C, 200 and 380 °C, 380 and 460 °C, and above 460 °C, which showed monoclinic, tetragonal, tetragonal, and cubic phases, respectively. In Na0.685K0.315Nb1–yTayO3, all the transition peaks were observed to gradually shift towards lower temperatures upon increasing the Ta concentration at y ≤ 0.05 in the temperature range from RT to 500 °C. •In this article we report that the HT-XRD patterns observed between RT and ~200 °C, ~200 and 380 °C, 380 and 460 °C, and above 460 °C show monoclinic, tetragonal, tetragonal, and cubic phases, respectively.•In Na0.685K0.315Nb1-yTayO3 (y ≤ 0.05) all the transition peaks were observed to gradually shift towards lower temperatures upon increasing the Ta concentration at y ≤ 0.05 in the temperature range from RT to 500 °C.•Overall, the obtained results indicate that NKN-type ceramics can be good candidates for lead-free electronic applications.