Lead free (Li,Na,K)(Nb,Ta,Sb)O3 piezoelectric ceramics: Influence of sintering atmosphere and ZrO2 doping on densification, microstructure and piezoelectric properties

(Li/Na/K)(Nb/Ta/Sb)O3 lead free piezoelectric materials (LTLS), “pure” or doped by 1 mass% ZrO2, were elaborated. The sintering was investigated both by classical way and buried in a powder-bed in order to prevent the alkali-elements losses. The effects of doping and of these processes on densification and piezoelectric properties (d33, kt and kp) were studied. The results demonstrated that the final densification is enhanced for ZrO2 doped samples. The sintering in powder-bed clearly enhanced the piezoelectric properties. The best results corresponds to d33 ≈ 180 pC/N and kt ≈ 45–50% for non-doped samples and, d33 ≈ 150 pC/N, with kt ≈ 45–50% for ZrO2 doped samples. Finally, the ultrasonic properties of piezoelectric transducers based upon these materials were also investigated experimentally and theoretically. The results clearly demonstrated that their bandwidth and sensitivity are suitable for use in piezoelectric transducers and comparable with similar PZT based transducers.