Piezoelectric properties of some lead-free ferroelectric ceramics

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Abstract
The use of lead-free materials in piezoelectric ceramics has recently become a very important issue in environmental protection of the earth. Some lead-free piezoelectric materials, namely bismuth sodium titanate, (Bi1/2Na1/2)TiO3 (BNT) – based solid solution ceramics, such as (1-a)BNT-a·BaTiO3 [BNBT], (1-b)BNT-b·NaNbO3 [BNTN] and a(Bi1/2Na1/2)TiO3-b KNbO3-c 1/2(Bi2O3·Sc2O3) [KTNS] (a+b+c=1) systems, were studied for their dielectric, ferroelectric and piezoelectric properties as candidates for a new family of lead-free piezoelectric ceramics. The electromechanical coupling factor, k 33 in the longitudinal mode was found to be 0.55, 0.43 and 0.47 for BNBT-6. BNTN-3 and KTNS, respectively. On particular, the amount of modified Bi3+ ions has an effect on k 33. Consequently these ceramics are potential candidates as lead-free piezoelectric ceramics.