中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 35 No. 2 February 2025 |
（1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
2. Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Hong Kong 999077, China）
Abstract:MnO2-doped Ca0.97Bi2.03Nb2O9 ceramics with greatly improved piezoelectric performance were prepared via conventional solid state sintering method. The effects of MnO2 doping on the microstructure and electrical properties of Ca0.97Bi2.03Nb2O9 ceramics were studied. X-ray diffraction (XRD) analysis and Rietveld refinement revealed a reduction in orthorhombicity with MnO2 doping, which contributed to the enhancement of the piezoelectric properties. Furthermore, the introduction of MnO2 lowered the sintering temperature, thereby reducing the formation of oxygen vacancies in the ceramic. The optimal performance was achieved in the Ca0.97Bi2.03Nb2O9-0.3wt.%MnO2 sample, exhibiting a piezoelectric coefficient (d33) of 13.6 pC/N, a DC resistivity of 3×106 Ω·cm at 500 °C, and a Curie temperature of 965 °C. Additionally, all doped samples demonstrated excellent thermal stability over a wide temperature range, from room temperature to 900 °C.
Key words: CaBi2Nb2O9 ceramics; MnO2 doping; crystal structure; oxygen vacancy
