Rosen-Type Piezoelectric Transformers Based on 0.5Ba(Zr_0.2Ti_0.8)O₃-0.5(Ba_0.7Ca_0.3)TiO₃ Ceramic and Doped with Sb₂O₃

In this study, the characteristics in the lead-free piezoelectric ceramic 0.5Ba(Zr_0.2Ti_0.8)O₃-0.5(Ba_0.7Ca_0.3)TiO₃ (0.5BZT-0.5BCT) were investigated to assess its potential for Rosen-type piezoelectric transformers. This piezoelectric ceramic has a piezoelectric charge coefficient d₃₃ of 430 pC/N, an electromechanical coupling factor k_p of 49%, a dielectric constant ε_r of 2836, a remnant polarization P_r of 4.98 μC/cm², and a coercive electric field E_c of 2.41 kV/cm. Sb₂O₃ was soft doped with 0.05, 0.1, 0.15, and 0.2 mol%, respectively, and exhibited excellent physical properties at 0.1 mol%. Based on this, a piezoelectric transformer was fabricated and measured, and it showed better output characteristics than pure 0.5BZT-0.5BCT. The amplification ratio (V_out/V_in) was optimized based on the device geometry and properties of the piezoelectric material. Moreover, the output characteristics of the Rosen-type piezoelectric transformer were simulated with the PSpice program. Output values of the fabricated and simulated piezoelectric transformers for the r vibrational frequency were compared and analyzed. Accordingly, the step-up amplification ratios V_out/V_in of the fabricated and simulated devices at the vibrational frequency were compared as well. This piezoelectric transformer could replace silicon steel transformers and be used for the creation of black light and for laptop chargers.