Significantly enhanced pyroelectric performance in novel sodium niobate‐based lead‐free ceramics by compositional tuning

Abstract

In this study, (1 − x)NaNbO3–xBa0.6(Bi0.5K0.5)0.4TiO3 (abbreviated as NN‐xBBKT, x = 0.05, 0.10, 0.15, and 0.20) lead‐free pyroelectric ceramics were synthesized by conventional solid‐state reaction method. Moreover, their microstructure, phase structure, dielectric, ferroelectric, piezoelectric, and pyroelectric characteristics were studied systematically. The X‐ray diffraction result showed that the phase structure of NN‐xBBKT ceramics changed from orthorhombic to tetragonal and finally became pseudocubic symmetry. The ferroelectric‐paraelectric phase transition temperature and depolarization temperature shifted to lower temperature with the increase in BBKT content. Furthermore, with increasing BBKT content, piezoelectric coefficient, figures of merit, and pyroelectric coefficient first increased and then decreased. The optimum pyroelectric properties (eg Fd = 0.81 × 10−5 Pa−1/2, Fv = 1.02 × 10−2 m2 C−1, Fi = 1.04 × 10−10 m V−1, and p = 3.11 × 10−8 C cm−2 K−1) were observed in sample composition with x = 0.15. More importantly, the pyroelectric coefficient of ceramic with x = 0.15 also displayed relatively high thermal stability because of high depolarization temperature (~110°C). These parameters demonstrate that the novel Pb‐free NaNbO3‐based ceramics form an important class of pyroelectric material with broad range of application prospect.

Large pyroelectricity via engineered ferroelectric‐relaxor phase boundary

“…Up to now, various methods have been employed to improve pyroelectric properties of FE materials, such as compositional design, phase boundary construction, synthesis optimization 4–7 . Among them, phase boundary engineering is the most attractive and effective strategy owing to the coexistence and completion of energetically comparable polar phases near this boundary, which can exhibit not only excellent pyroelectricity but also outstanding ferroelectricity and piezoelectricity 8–14 .…”

“…Up to now, various methods have been employed to improve pyroelectric properties of FE materials, such as compositional design, phase boundary construction, synthesis optimization. [4][5][6][7] Among them, phase boundary engineering is the most attractive and effective strategy owing to the coexistence and completion of energetically comparable polar phases near this boundary, which can exhibit not only excellent pyroelectricity but also outstanding ferroelectricity and piezoelectricity. [8][9][10][11][12][13][14] In particular, a large room-temperature pyroelectric coefficient of 3.26 × 10 −4 C m −2 K −1 and FOMs values were obtained in 0.2(2/3K 0.5 Bi 0.5 TiO 3 -1/3BaTiO 3 )-0.8Na 0.5 Bi 0.5 TiO 3textured ceramic attributed to the FE to antiferroelectric phase transition causing coherent 180 • domain switching.…”

Positive and negative electrocaloric effect in the direct and indirect characterization of NaNbO3-based ceramics with tetragonal–cubic phase boundary

“…[11][12][13][14][15][16][17] Notably, it has been proved that antiferroelectric sodium niobate (NN) ceramics can be modified to the ferroelectric state using suitable additives. [18][19][20] Specifically, their phase structure and polarization can be modified with different additives and external parameters (e.g., electric field and thermal field), which is beneficial for optimizing the ECE. [18][19][20][21][22][23] Therefore, NN-based ceramics have potential to become a new type of ECE materials.…”

“…[18][19][20] Specifically, their phase structure and polarization can be modified with different additives and external parameters (e.g., electric field and thermal field), which is beneficial for optimizing the ECE. [18][19][20][21][22][23] Therefore, NN-based ceramics have potential to become a new type of ECE materials. [21][22][23] To date, phase boundary engineering has been demonstrated to be one of the most efficient tools to optimize the ECE.…”

Suppression of abnormal grain growth in K0.5Na0.5NbO3: phase transitions and compatibility

“…Composition homogeneity is highly desirable to explore the material’s potential therefore several approaches have been developed to suppress heterogeneities by solid solution precursor methods 36 or perovskite methods 37 . Still, abnormal grain growth or development of secondary phases persisted to occur 38–40 .…”