High performance Bi0.5Na0.5TiO3-BiAlO3-K0.5Na0.5NbO3 lead-free pyroelectric ceramics for thermal detectors

Abstract

Both high pyroelectric properties and good temperature stability of ferroelectric materials are desirable when used for applications in infrared thermal detectors. In this work, we report lead-free ternary 0.97(0.99Bi0.5Na0.5TiO3-0.01BiAlO3)-0.03K0.5Na0.5NbO3 (BNT-BA-KNN) ceramics, which not only exhibits a large pyroelectric coefficient (p ∼ 3.7 × 10−8 C cm−2 K−1) and figures of merit (Fi, Fv, and Fd) but also shows excellent thermal stable properties. At room temperature, Fi, Fv, and Fd are determined as high as 1.32 × 10−10 m/V, 2.89 × 10−2 m2/C, and 1.15 × 10−5 Pa−1/2 at 1 kHz and 1.32 × 10−10 m/V, 2.70 × 10−2 m2/C, and 1.09 × 10−5 Pa−1/2 at 20 Hz, respectively. During the temperature range of RT to 85 °C, the achieved p, Fi, Fv, and Fd do not vary too much. The high depolarization temperature and the undispersed ferroelectric-ergodic relaxor phase transition with a sharp pyroelectric coefficient peak value of ∼400 × 10−8 C cm−2 K−1 are suggested to be responsible for this thermal stability, which ensures reliable actual operation. The results reveal the BNT-BA-KNN ceramics as promising lead-free candidates for infrared thermal detector applications.

Enhanced pyroelectric properties of lead‐free BNT‐BA‐KNN ceramics for thermal energy harvesting

“…Figure shows the XRD patterns of BNT‐BA‐ x KNN ceramics with various content of KNN. As indicated in Figure (A), doping a moderate amount of KNN has no influence on the second phase structure for BNT‐BA‐ x KNN ceramics and a pure perovskite structure with a good degree of crystallinity is obtained, whereas a faint Bi 2 Al 4 O 9 secondary phase starts to emerge as the KNN content increases to 3 mol% . This is ascribed to the insolubility of excessive content of KNN into BNT‐BA crystal lattice during the high‐temperature sintering process.…”

“…Even though ferroelectric and antiferroelectric phase can coexist in the BNT‐BA‐0.03KNN ceramics, they present an inferior pyroelectric coefficient due to secondary impurity phase as shown in XRD results. Table presents the room‐temperature pyroelectric properties compared with other reported lead‐free and lead‐based ceramics , . Generally, the room‐temperature pyroelectric coefficients of the currently available lead‐free materials are almost inferior to that of BNT‐BA‐0.02KNN ceramics.…”

“…As possible replacements for lead‐based ceramics, Bi 0.5 Na 0.5 TiO 3 (BNT)‐based lead‐free ceramics have been investigated due to their excellent ferroelectric properties and high Curie temperature of 320°C. However, their low resistivity and high coercive field hinders the practical application for pyroelectric energy harvesting . Researchers have engaged to improve the pyroelectric coefficient of BNT ceramics by combing the BNT‐based ceramics with another compositions, such as BaTiO 3 (BT), (Bi 0.5 K 0.5 )TiO 3 (BKT), etc., to construct new phase structures .…”

Synthesis, Crystal Structures, Spectroscopic Characterization, and Thermal Analyses of the New Bismuth Sulfates NaBi(SO4)2·H2O and ABi(SO4)2 (A = K, Rb, Cs)

“…[1][2][3] Materials featuring these fundamental properties are used in a large number of applications such as laser frequency conversion, thermal detectors, energy harvesting, and optical communications, etc. [4][5][6][7] A number of bismuth sulfates have already been reported: Bi 2 O 2 SO 4 •H 2 O, [8] [Bi 2 O(OH) 2 ](SO 4 ), [9] Bi 6 S 2 O 15 , [10] KBiCl 2 (SO 4 ), [3,11] A 2 Bi 2 (SO 4 ) 2 Cl 4 (A = NH 4 , K, Rb) [12] and (C 4 H 16 N 3 )[Bi(SO 4 ) 3 (H 2 O)] [13] are one-dimensional chains. For instance, the structure of KBiCl 2 (SO 4 ) [3] and [Bi 2 O(OH) 2 ](SO 4 ) [9] both exhibit one-dimensional double chains, consisting of [BiCl 2 O 3 ] 5octahedron or [Bi 2 O(OH) 2 ] 2+ polycations and SO 4 2-anions.…”

Enhanced pyroelectric properties in (Bi0.5Na0.5)TiO3–BiAlO3–NaNbO3 ternary system lead‐free ceramics

“…A lot of lead‐free ferroelectric systems based on potassium sodium niobate (KNN), barium titanate (BT), strontium barium niobate (SBN), sodium bismuth titanate (BNT) etc. have been widely investigated on the pyroelectric performance.…”