Influence of BaSnO3 addition on piezoelectric properties of K0.474Na0.474Li0.052Nb0.948Sb0.052O3 ceramic

In the (Ka,Na)NbO3 (KNN)-based ceramics, it is known that the piezoelectric properties of KNN-LiSbO3 system and K0.474Na0.474Li0.052Nb0.948Sb0.052O3 ceramic with MPB region exhibited a high d33 value of 221 pC/N. However, the... [ view full abstract ]

In the (Ka,Na)NbO₃ (KNN)-based ceramics, it is known that the piezoelectric properties of KNN-LiSbO₃ system and K_0.474Na_0.474Li_0.052Nb_0.948Sb_0.052O₃ ceramic with MPB region exhibited a high d₃₃ value of 221 pC/N. However, the details on the (1-x)KNLNS-xBaSnO₃ (BS) have not been reported to date. Therefore, in order to clarify the composition dependence of piezoelectric properties for the (1-x)KNLNS-xBS ceramics, these ceramics were synthesized and relationships among crystal structure, remnant polarization (P_r) and d₃₃ value were investigated in this study.

XRPD profiles of (1-x)KNLNS-xBS ceramics showed the single phase at the composition below x = 0.01. From the Raman spectra, the disappearance of F_2u mode was recognized for (1-x)KNLNS-xBS in comparison with that of KNN. The ⁹³Nb solid state NMR spectra showed the significant differences in the compositions, the shoulder peak around -1120 ppm was observed for KNLNS, though the spectra of KNN became single peak. The presence of shoulder peak implies the presence of different coordinated state for Nb cation; this result is probably due to the coexistence of orthorhombic and tetragonal phase. In addition, the shoulder peak is slightly shifted to lower filed by BS addition; it is considered that BS addition leads to the formation of tetragonal phase. The d₃₃ value was increased by BS addition up to x = 0.005; the enhancement of d₃₃ value was attributed to the increase in dielectric constant at room temperature by BS addition; the highest d₃₃ value was 302 pC/N for x = 0.005. The Rama spectra at room temperature showed the presence of E_g and A_1g modes in the range of 500 – 700 cm^-1. With increasing the temperatures from room temperature to 400℃, these peaks become single peak; the change in the peak shape is considered to relate with the shift of orthorhombic to tetragonal phase transition temperature by BS addition.