Enhanced pyroelectric properties in (Bi _0.5 Na _0.5 )TiO ₃ –BiAlO ₃ –NaNbO ₃ ternary system lead‐free ceramics

Abstract

Abstract High pyroelectric performance and good thermal stability of pyroelectric materials are desirable for the application of infrared thermal detectors. In this work, enhanced pyroelectric properties were achieved in a new ternary (1− x )(0.98(Bi 0.5 Na 0.5 )(Ti 0.995 Mn 0.005 )O 3 –0.02BiAlO 3 )– x NaNbO 3 (BNT–BA– x NN) lead‐free ceramics. The effect of NN addition on the microstructure, phase transition, ferroelectric, and pyroelectric properties of BNT–BA– x NN ceramics were investigated. It was found that the average grain size decreased as x increased to 0.03, whereas increased with further NN addition. The pyroelectric coefficient p at room temperature (RT) was significantly increased from 3.87 × 10 −8 Ccm −2 K −1 at x = 0 to 8.45 × 10 −8 Ccm −2 K −1 at x = 0.03. The figures of merit (FOMs), F i , F v and F d , were also enhanced with addition of NN. Because of high p (7.48 × 10 −8 Ccm −2 K −1 ) as well as relatively low dielectric permittivity (~370) and low dielectric loss (~0.011), the optimal FOMs at RT were obtained at x = 0.02 with F i = 2.66 × 10 −10 m/V, F v = 8.07 × 10 −2 m 2 /C, and F d = 4.22 × 10 −5 Pa −1/2 , which are superior to other reported lead‐free ceramics. Furthermore, the compositions with x ≤ 0.03 exhibited excellent temperature stability in a wide temperature range from 20 to 80°C because of high depolarization temperature (≥110°C). Those results unveil the potential of BNT–BA– x NN ceramics for infrared detector applications.