Effect of bismuth and titanium ions on structural, optical and electrical properties of lead-free K0.5Na0.5NbO3 ceramics

([K0.5Na0.5](1-x)Bi-x [Nb1 - xTix])O-3- KNN-100xBT) ceramics with x = 0.00 to 0.08 were synthesized using the conventional sintering technique. X-ray diffraction studies confirmed the stable perovskite phase formation in all compositions without any sign of a secondary phase. No composition-driven structural phase transition was observed in the chosen composition range. Room-temperature Raman studies were performed on all the samples to identify the local lattice dynamics and crystal structure. Microstructure analysis showed dense features for higher concentration of dopants. X-ray photon spectroscopy confirmed the substitution of Bi3+ and Ti4+ ions in the host KNN lattice. The combined effects of bismuth and titanium substitution lead to a downward shift in the orthorhombic-tetragonal (TO-T) phase transition temperature and Curie temperature (T-c). An optimal dielectric constant (epsilon(r)) of 1700, spontaneous polarization (Ps) of 25 mu C/cm(2), piezoelectric strain of 0.24% and d(33) of 235 pC/N were obtained for the KNN-08BT. The improved properties of KNN-08BT make it a promising candidate for piezoelectric transducer applications.

Automated summary

([K0.5Na0.5](1-x)Bi-x [Nb1 - xTix])O-3- KNN-100xBT ceramics with varying x values from 0.00 to 0.08 were synthesized using conventional sintering technique. X-ray diffraction analysis confirmed the formation of stable perovskite phase in all compositions, with no secondary phase observed. Raman studies showed the local lattice dynamics and crystal structure. The optimal properties were observed in KNN-08BT, with a dielectric constant of 1700, spontaneous polarization of 25 μC/cm², piezoelectric strain of 0.24%, and d33 value of 235 pC/N.