The Effects of Ta Substitution and K/Na Ratio Variation on the Microstructure and Properties of (K,Na)NbO3-Based Lead Free Piezoelectric Ceramics

• Published in: Journal of electronic materials 2014-05, Vol.43 (5), p.1424-1431
• Main Authors: Shang, Xunzhong, Guo, Jinming, Xiao, Wanping, Lu, Yinmei, Chang, Gang, Zhou, Taosheng, He, Yunbin
• Format: Article
• Language: English
• Subjects: Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Cross-disciplinary physics: materials science; rheology; Dielectric properties; Electronics and Microelectronics; Exact sciences and technology; Instrumentation; Lead free solders; Materials Science; Methods of nanofabrication; Microstructure; Optical and Electronic Materials; Physics; Solid State Physics
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-014-3082-9

[(Na 0.5+ y K 0.5− y ) 0.94 Li 0.06 ][(Nb 0.94 Sb 0.06 ) 1− x Ta x ]O 3 + 0.08 mol% MnO 2 lead-free piezoelectric ceramics were fabricated successfully by a conventional solid-state reaction method. The effects of Ta 5+ substitution and K/Na ratio variation on the microstructure and properties of the ceramics have been systematically investigated. With the increasing of Ta 5+ substitution content, the orthorhombic–tetragonal transition temperature T o–t presents obvious “V” type variation while the Curie temperature T c decreases monotonically. The ceramics properties were further enhanced by adjusting the Na/K ratio of the A-site. Under systematical optimization of the A-site and B-site elements, good overall electrical properties of d 33 = 276 pC/N, k p = 44.5%, ε 33 T / ε 0 = 1,175, tan δ = 0.027, T c = 309 °C, P r = 21.0 μ C/cm 2 , and E c = 1.14 kV/mm were obtained for ceramics with Ta 5+ content x of 0.05 and Na/K ratio of 57/43 ( y = 0.07).