Enhanced pyroelectric properties of BNT-xBNN lead-free ferroelectric ceramics for energy harvesting

Abstract

Pyroelectric energy harvesting has been explored to obtain high room temperature pyroelectric coefficient (p) along with high depolarization temperature (Td) for the practical applications. However, the problem that Td and p of Bi0.5Na0.5TiO3-based ceramics cannot be increased simultaneously has not been solved. In this work, (1-x)Bi0.5Na0.5TiO3-xBaNi0.5Nb0.5O3 (BNT-xBNN, x = 0, 0.02, 0.03, 0.04 mol) lead-free ceramics were prepared by conventional solid-state reaction method. Introduction of BaNi0.5Nb0.5O3 can facilitate lattice cell expansion and decrease of the O-B-O bond angles, providing more possibilities for the B-site ion to deviate from the equilibrium position, producing micrometer level grain size (3.25–6.15 µm) with good ferroelectric performance (Pr = 42 μC/cm2, Ps = 47 μC/cm2). The permittivity (εr) of pristine samples raises from 439 to 723 when the content of BNN ascends to 0.03 mol. Hence, an enhanced room temperature p of 7.91 × 10−4 C m−2 K−1 with a high Td of about 150 °C has been attained in BNT-xBNN with x = 0.03 mol, which concomitantly generates the energy density of 22.3 μJ/cm3 with 90 MΩ load. Our work contributes to the development of pyroelectric properties for practical applications in energy harvesting.