Low-Temperature Co-Fired Unipoled Multilayer Piezoelectric Transformers.

Area of Science:

• Materials Science
• Ceramic Engineering
• Electrical Engineering

Background:

• Reliability of piezoelectric transformers (PTs) is crucial and depends heavily on fabrication quality.
• Heterogeneity, prestress, and misalignment can negatively impact PT performance.

Purpose of the Study:

• Investigate unipoled multilayer PTs for high-power applications.
• Optimize composition and co-firing profiles for low-temperature synthesis.
• Achieve high efficiency and power density in fabricated PTs.

Main Methods:

• Addition of 0.2 wt% CuO to Pb$_{0.98}$Sr$_{0.02}$ (Mg$_{1/3}$Nb$_{2/3}$)$_{0.06}$(Mn$_{1/3}$Nb$_{2/3}$)$_{0.06}$(Zr$_{0.48}$Ti$_{0.52}$)$_{0.88}$O$_{3}$ (PMMnN-PZT).
• Reduced co-firing temperature from 1240 °C to 930 °C.
• Utilized Ag/Pd inner electrodes instead of Pt.

Main Results:

• CuO addition significantly lowered the co-firing temperature of PMMnN-PZT.
• Low-temperature synthesized material exhibited excellent piezoelectric properties.
• PTs co-fired at 930 °C with Ag/Pd showed performance comparable to those fired at 1240 °C with Pt.
• Achieved 5-W output power, >90% efficiency, and 11.5 W/cm³ power density.

Conclusions:

• Low-temperature synthesis of high-quality PTs is feasible using CuO-modified PMMnN-PZT.
• Reduced sintering temperatures allow for cost-effective electrode materials (Ag/Pd).
• The developed PTs offer high performance suitable for demanding applications.