Oxygen-vacancy-related dielectric relaxations in Na0.5K0.5NbO3

• Na0.5K0.5NbO3 ceramic samples were prepared via the solid-state reaction route.
• Dielectric behavior of the sample was studied by electric modulus spectroscopy.
• Two oxygen-vacancy-related relaxations were observed in Na0.5K0.5NbO3.

Na0.5K0.5NbO3 ceramic samples were prepared via the solid-state reaction route. The low-frequency (20–107 Hz) dielectric properties were investigated in the temperature range from room temperature to 1073 K. Two relaxations were observed in the spectra of electric modulus. Relaxation 1 occurs in the orthorhombic phase, which was ascribed to be related to the oxygen-vacancy clusters. Relaxation 2 appears in the tetragonal and cubic phases. It behaves as a Maxwell–Wagner-type and polaron-type relaxation in the tetragonal and cubic phase, respectively.