Phase tuning on BiCoO3 modified KNN ceramics with increased overall pyroelectric properties and high Curie temperature

Abstract

Lead-free pyroelectric materials have always been a significant research focus in the field of pyroelectric materials. Numerous studies have achieved a high level of pyroelectric coefficient at room temperature. However, this improvement often comes at the expense of thermal stability. In this study, bismuth-based perovskites with low symmetry and large tetragonal distortion as dopants in KNN ceramics were proposed to enhance their pyroelectric properties. This approach not only resulted in ceramics with high pyroelectric coefficients at room temperature but also exhibited low dielectric constants and high Curie temperatures, indicating excellent figures-of-merit (FOMs) and thermal stabilities for these ceramics. Therefore, the (1-x)(K_0.48Na_0.52)_0.97Li_0.03Nb-xBiCoO₃ ((1-x)KNLN-xBCO, x = 0, 0.005, 0.0075, 0.01, 0.0125) ceramics were investigated, achieving both high room-temperature pyroelectric properties (p = 6.298 × 10 ⁻⁴ C·m ⁻²·℃ ⁻¹, F_i = 3.159 × 10 ⁻¹⁰ m·V⁻¹, F_v = 4.538 × 10 ⁻² m²· C⁻¹, F_d = 2.115 × 10 ⁻⁵ Pa^−1/2, F_e = 56.34 J·m⁻³·K⁻²) and a high Curie temperature of 413 ℃ for x = 0.01, demonstrating exceptional overall performance among KNN ceramics.