The improved pyroelectric properties, high depolarization temperature and excellent thermal stability in lead-free (1−x)(Bi0.5Na0.5)TiO3-xBa(Ni0.5Nb0.5)O3 ceramics

Abstract

(1−x)(Bi0.5Na0.5)TiO3-xBa(Ni0.5Nb0.5)O3 (x = 0–0.04) lead-free ceramics (abbreviated as (1−x)BNT-xBNN) were synthesized by a conventional solid-state reaction method. The effect of BNN contents on phase structure, microstructure, ferroelectric, dielectric, pyroelectric properties and thermal stability of (1−x)BNT-xBNN ceramics were systematically investigated. The pyroelectric coefficient (p) at room temperature increased gradually from 3.01 × 10−8 C cm−2K−1 at x = 0 to 5.94 × 10−8 C cm−2K−1 at x = 0.04. The dielectric loss (tan δ) and dielectric constant (εr) decreased first with the small amount of BNN content, then increased slightly with further BNN addition, acquiring the minimum tan δ and εr at x = 0.02. When x = 0.02, the optimal over-all properties were observed with pyroelectric figure of merit (FOMs) of Fv = 3.82 × 10−2 m2 C−1 and figure of merit of Fd = 2.74 × 10−5 P a −1/2. More importantly, the depolarization temperature (Td) of 0.98BNT-0.02BNN ceramics is up to ∼195 °C which is higher than most other reported BNT-based ferroelectric ceramics. In addition, it can be exposed to temperature up to ∼145 °C with negligible deterioration of pyroelectric properties, showing excellent thermal stability. The overall properties reveal that 0.98BNT-0.02BNN ceramics is a promising pyroelectric material for infrared detectors.