Enhanced electrical properties in W/Cu co‐doped CaBi₂Nb₂O₉ high‐temperature piezoelectric ceramics

Abstract

CaBi2Nb2O9 (CBN)‐based high‐temperature piezoelectric ceramics with the formula of CaBi2Nb2−x(W3/4Cu1/4)xO9 were prepared via the traditional solid‐state reaction method. Both the bulk microstructure and the electrical performance of the W/Cu co‐doped CBN‐based ceramics were systematically investigated. The results indicated that the W/Cu incorporation into the Nb‐site altered the crystal structure, which enhanced the piezoelectricity and resistivity. The ceramic with the composition CaBi2Nb1.96(W3/4Cu1/4)0.04O9 exhibited good performance with a high d33 (~14 pC/N) and TC (~939℃). Moreover, the ceramic exhibited a good electrical resistivity (ρ) of 4.91 × 105 Ω·cm and a low dielectric loss (tanδ) of 0.1 at 600℃. Furthermore, the ceramic that was annealed at 900℃ for 2 h presented a d33 value of 13 pC/N, thus indicating good thermal stability of the piezoelectric properties. All these results confirm that the CaBi2Nb1.96(W3/4Cu1/4)0.04O9 ceramic may act as a potential promising candidate for piezoelectric device applications in high‐temperature environments.

Insight into the Ultrahigh Electric Performance of Aurivillius CBTa-CBN Solid Solution

“…Grain growth may be caused by the following two aspects: the lower melting point of Nb 2 O 5 (1520 °C) than that of Ta 2 O 5 (1800 °C) and increased concentration of the oxygen vacancy. 12,29 Moreover, the increasing grain size is conducive to polarization switch, thus leading to enhanced piezoelectric properties. 31 The change of element composition, valence state and relative amount have a close relationship with piezoelectric and for LCCBTa-0.0CBN, LC-CBTa-0.4CBN, and LC-CBTa-1.0CBN ceramics are given in Figure 5b.…”

“…Besides, the ceramic with x = 0.0 has a relatively uniform grain distribution and the average grain size gradually increases from 4.82 to 10.49 μm with increasing x . Grain growth may be caused by the following two aspects: the lower melting point of Nb 2 O 5 (1520 °C) than that of Ta 2 O 5 (1800 °C) and increased concentration of the oxygen vacancy. , Moreover, the increasing grain size is conducive to polarization switch, thus leading to enhanced piezoelectric properties …”

“…With W 6+ doping, the d 33 of CaBi 4 Ti 4 O 15 (CBT) was enhanced to 17.8 pC/N, which is two times larger than that of pure CBT ceramics . Comprehensive properties were realized in CaBi 2 Nb 2– x (W 3/4 Cu 1/4 ) x O 9 ceramics, with a d 33 of up to 14 pC/N, the T C maintained at 99 °C, and a good electrical resistivity ρ of ∼4.91 × 10 5 Ω·cm at 600 °C …”

“…11 Comprehensive properties were realized in CaBi 2 Nb 2−x (W 3/4 Cu 1/4 ) x O 9 ceramics, with a d 33 of up to 14 pC/N, the T C maintained at 99 °C, and a good electrical resistivity ρ of ∼4.91 × 10 5 Ω•cm at 600 °C. 12 Besides, introducing a second component into the main part to construct a complex Aurivillius solid solution is an effective way to improve the performances via combining the advantages of both components. For example, the Na 0.5 Bi 4.5 Ti 4 O 15 -CaBi 4 Ti 4 O 15 solid-solution ceramic provided excellent electrical properties (d 33 = 22 pC/N, T C = 655 °C, ρ ∼ 10 7 Ω•cm at 500 °C), in contrast with the pure Na 0.5 Bi 4.5 Ti 4 O 15 ceramic (d 33 = 14 pC/N, T C = 648 °C, ρ ∼ 10 6 Ω•cm at 500 °C).…”

“…In addition, the volatilized Bi 2 O 3 under a high sintering temperature environment will generate a large number of oxygen vacancies, producing increased carrier concentration and hampering polarization switching. To obtain excellent electric performances of BLSFs, great efforts have been paid to improve their comprehensive electrical properties, mainly including composition modification and grain orientation technologies [hot pressing (HP), spark plasma sintering (SPS), and template grain growth (TGG)]. − Between these tailoring methods, chemical modification is considered a comprehensive cost-effective method due to its simple fabrication process and enhanced result possibilities. − For Na 0.5 Bi 4.5 Ti 4 O 15 (NBT) ceramics, good electrical performance was obtained via Nd 3+ doping with a T C of 670 °C, d 33 of 24.5 pC/N, and P r of 10.8 μC·cm –1 . With W 6+ doping, the d 33 of CaBi 4 Ti 4 O 15 (CBT) was enhanced to 17.8 pC/N, which is two times larger than that of pure CBT ceramics .…”