Low-frequency dielectric properties of CaNb2O6 ceramics over a wide temperature range

Abstract CaNb 2 O 6 ceramics were prepared by a conventional solid-state reaction method. By means of the complex dielectric permittivity, electric modulus spectroscopy, and impedance analysis, the dielectric properties of CaNb 2 O 6 ceramics were investigated in the temperature range (180–1050 K) and frequency range (50–1×10 7 Hz). The sample exhibits an intrinsic dielectric response with a dielectric constant of 18.06 below 400 K. In the temperature range from 400 to 1023 K, the sample successively shows a relaxor-like peak and an increasing ramp. Annealing treatments in N 2 and O 2 atmospheres revealed that the relaxor-like peak is consisted of two different relaxations (R1 and R2) and the ramp is evidenced to be another relaxation (R3). Our results demonstrated that the low-temperature relaxation (R1) belongs to Maxwell–Wagner-type dielectric relaxation caused by surface-layer effect due to the inhomogeneous distribution of oxygen vacancies. The high-temperature relaxations R2 and R3 are conduction relaxation due to hopping motions of singly and doubly charged oxygen vacancies, respectively. A phase transition is revealed to have affinity relationship with oxygen vacancies and most possibly related to the transition of oxygen-vacancy-distribution from a static disorder state to a dynamic disorder state.