Poling effects and piezoelectric properties of PVDF-modified 0–3 connectivity cement-based/lead-free 0.94(Bi_0.5Na_0.5)TiO₃–0.06BaTiO₃ piezoelectric ceramic composites

PVDF-modified 0–3 connectivity cement-based/lead-free 0.94(Bi_0.5Na_0.5)TiO₃–0.06BaTiO₃ piezoelectric ceramic composites were fabricated using 0.94(Bi_0.5Na_0.5)TiO₃–0.06BaTiO₃ (BNBT), Portland cement, and polyvinylidene fluoride (PVDF). The microstructure, acoustic impedance (Z _c), dielectric properties, and influence of poling temperature and electrical poling field on the piezoelectric coefficient (d ₃₃) and the total period of the poling process of composites with 50 vol% BNBT and 1–10 vol% PVDF were investigated. The results indicated that Z _c, the dielectric constant, and the dielectric loss of the composites decrease as the PVDF content increases. The d ₃₃ of the composites was found to enhance more clearly when the content of PVDF is more than 2 vol%. The d ₃₃ results of the composites showed an optimum increase of 45% when 5 vol% PVDF was used (under an electrical poling field of 1.5 kV/mm and a poling temperature of 80°C). Moreover, these composites with PVDF were found to exhibit enhanced poling behavior in that the PVDF was able to reduce the total period of the poling process. Interestingly, the piezoelectric voltage coefficient (g ₃₃) of the composite with 5 vol% PVDF content had the highest value of 33.59 mV·m/N. Therefore, it can be safely concluded that this new kind of PVDF-modified 0–3 connectivity cement-based/lead-free 0.94(Bi_0.5Na_0.5)TiO₃–0.06BaTiO₃ piezoelectric ceramic composite has the potential to be used in concrete as a sensor for structural health monitoring applications.