Effect of repeated composite sol infiltrations on the dielectric and piezoelectric properties of a Bi0.5(Na0.82K0.18)0.5TiO3 lead free thick film

Bi0.5(Na0.82K0.18)0.5TiO3 lead free thick films have been produced using a combination of screen printing and subsequent infiltration of corresponding composite sol. Their structure, dielectric, ferroelectric and piezoelectric properties were investigated with variation in the number of composite sol infiltrations and the nanopowder loading in composite sol. Dielectric constant, remanent polarization, and piezoelectric coefficient have been shown to increase with increasing numbers of composite sol infiltration. Dielectric and ferroelectric properties of the thick films are found to be strongly dependent on the powder concentration of composite sols. The resulting 40 μm thick films infiltrated with 1.5 g/ml composite sols have maximum relative permittivity of 569 (at 10 kHz), remanent polarization of 21.3 μC/cm2, coercive field of 80 kV/cm, and longitudinal effective piezoelectric coefficient d33eff of 109 pm/V. The performance of these lead free piezoelectric thick films is comparable to the corresponding bulk ceramics.