Structural and electric properties of Ce‐doped Na_0.5Bi_4.5Ti₄O₁₅ piezoceramics with high Curie temperatures

Abstract

Na0.5Bi4.5‐xCexTi4O15 (x = 0, 0.02, 0.04, 0.06, 0.08, 0.10) lead‐free piezoelectric ceramics with high Curie temperatures are fabricated using the conventional solid‐phase method. The effects of the Ce content on the phase structures, morphologies, and electrical properties of the Na0.5Bi4.5‐xCexTi4O15 ceramics are systematically investigated. The appropriate content of Ce increases b/a and c/a and induces the distortion of the crystal structure. The increased b/a leads to a transverse asymmetry of the Na0.5Bi4.5‐xCexTi4O15 ceramics, which facilitates the dipole flipping, thus enhancing the piezoelectric properties (d33 = 20 pC/N). Although the improved c/a increases the degree of tetragonality of the Na0.5Bi4.5‐xCexTi4O15 ceramic, which decreases the Curie temperature (TC), the TC values of all samples are higher than 600°C, considerably higher than the practical application temperature. The Ce doping significantly reduces the dielectric loss of the sample and increases its dielectric performance. The improvements in electric properties by the cerium doping can expand its use in high‐temperature environments for oilfield logging, aerospace, and military applications.

Effectively improved piezoelectricity in high-temperature Arrhenius CBT ceramics by modifying potential energy profile and spontaneous polarization

“…], substituting ions with larger radii at A-site will increase the symmetry of CBT and reduce the tilting of oxygen octahedra. We conceived a CBT ceramic system with different substitution content of (Na1/2Bi1/2) 2+ (the radii of Ca 2+ , Na + and Bi 3+ is 1.34 Å, 1.39 Å and 1.45 Å, respectively) to modify oxygen octahedron tilting, as the positive effect of (Na1/2Bi1/2) 2+ on flattening potential energy profile is proven according to the previous studies of the Na0.5Bi4.5Ti4O15 (NBT, d33 ~20 pC/N and TC ~660 °C) system [20][21][22]. The large substitution of (Na1/2Bi1/2) 2+ at A-site can also be thought as the synthesis of CBT-NBT solid J u s t A c c e p t e d solution.…”

3D printing of CaBi4Ti3.925(Nb2/3Mn1/3)0.075O15 ceramics for high temperature ultrasound transducer

“…Bismuth layer-structured ferroelectric (BLSF) ceramics with high Curie temperatures (>500 • C) and good thermal stability have great potential in high-temperature piezoelectric sensor applications. Therefore, BLSF ceramics such as CaBi 2 Nb 2 O 9 (Tc ∼ 940 • C, d 33 ∼ 5 pC/N) [3], CaBi 4 Ti 4 O 15 (Tc ∼ 790 • C, d 33 ∼ 9 pC/N) [4], Na 0.5 Bi 4.5 Ti 4 O 15 (Tc ∼ 660 • C, d 33 ∼ 17 pC/N) [5], and Bi 4 Ti 3 O 12 (Tc ∼ 675 • C, d 33 ∼ 6 pC/N) [6,7] have drawn great attention in recent years. Among them, CaBi 4 Ti 4 O 15 (CBT) is often considered a good candidate for high-temperature piezoelectric materials because of its good comprehensive properties [4].…”

Distinguishable Separation of Artificial Electron–Oxygen Vacancy Pairs Using Heterovalent Doping Effect for Ferroelectric Photovoltaics

“…Generally, the ferroelectric polarization of Bi 4.5 Na 0.5 Ti 4 O 15 ferroelectrics is small along the c -axis and is preferred in the a – b plane. Many methods have been developed to modify the polarization intensity and orientation. , However, there is a long-standing and divisive debate about the close relationship between microstructures, such as grain boundaries, grain size, and ferroelectric polarization. The anisotropic electrical conductivity displayed the maximum value along the a – b axis, which originated from the highly anisotropic grain shape and grain size.…”