Improved thermal stability of the piezoelectric properties of (Li, Ag)‐co‐modified (K, Na) NbO3‐based ceramics prepared by spark plasma sintering
High‐performance lead‐free piezoelectric ceramics 0.94(K0.45Na0.55)1−x Li x (Nb0.85Ta0.15)O3–0.06AgNbO3 (KNNLTAg‐x) were successfully prepared by spark plasma sintering technique. The doping effect of Li on the structural and electrical properties of KNNLTAg‐x (x=0, 0.02, 0.04, 0.06, 0.08 and 0.10) ceramics was studied. The lattice structure, ferroelectric and piezoelectric properties of the KNLNTAg‐x ceramics are highly dependent on the Li doping level. In particular, the Li dopant has a great impact on both Curie temperature T c and orthorhombic‐tetragonal transition temperature T O‐T. The 4% Li‐doped sample exhibited relatively high T O‐T of 95°C, leading to a stable dynamic piezoelectric coefficient (d33*) of 220‐240 pm/V in a broad temperature range from 25°C to 105°C. Additionally, the 2% Li‐doped sample shows a high d33* of 320 pm/V at 135°C, suggesting its great potential for high‐temperature applications.
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