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Bi 4 Ti 3 O 12 high-temperature piezoelectric ceramics composed of 0.03 mol (Nb, Ta) 5+ substituting B site and x mol CeO 2 (x = 0-0.05, abbreviated as BCTNT100x) substituting A site were synthesized by the conventional solid-state reaction method. The effects of Ce additive on the structures and electrical properties of resulting Bi 4 Ti 3 O 12 -based ceramics were systematically investigated. In-situ temperature-dependent X-ray diffraction (XRD) confirmed that the phase structure of BCTNT100x ceramics change from orthorhombic structure to tetragonal structure as temperature increased. The ceramics at Ce content x = 0.03 illustrated optimal performances with superior piezoelectric constant (d 33 = 36.5 pC/N), high Curie temperature (T C = 649 • C), and large remanent polarization (2P r = 21.6 μC/cm 2 ). BCTNT3 ceramics also possessed high d 33 of 32.5 pC/N at an annealing temperature of 600 • C, with electrical resistivity preserved at 10 6 Ω cm at 500 • C. These results demonstrate that BCTNT100x ceramics can be used as high-temperature piezoelectric devices.

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CaBi 2 Nb 2 O 9 (CBN), one of the bismuth-layered structural ferroelectrics, with high Curie temperature (T C ), has great potential in high-temperature applications. In this work, high Curie temperature and piezoelectric constant (d 33 ) are realized in modified CaBi 2 Nb 2 O 9 ceramics with Ce-substitution. Ce-substitution changes the crystal structures and domain structures of CBN-based ceramics, so as to improve the piezoelectric properties. The optimal performances are obtained with a high d 33 value (∼18.0 pC/N) and a T C value (∼930 • C), together with a low tan δ value (∼0.028 at 500 • C). Moreover, the thermal stability is also enhanced, where the d 33 value maintains 93.9% of its original value after annealing at 900 • C for 2 h. Thus, these findings play a meaningful role in devices manufacturing, where the apply temperature is often more than 500 • C.

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