Thermal and vibrational energy harvesting using PZT- and BT-based ceramics

Thermal energy harvesting using pyroelectric effects in PZT-based ceramics with different Tc, PVDF films, and PMN-PT crystals were investigated. The output power and power density of PZT ceramics with Tc of 145°C were 5.2 μW and 1.66 μW/cm² under 5 K/s temperature change, respectively. Those of PMN-PT were 3.4 μW and 1.16 μW/cm² under 7 K/s temperature change, respectively. PZT-based ceramics with Tc of 300°C exhibited large energy generation of 40 J/L/cycle with temperature variations from 30°C to 145°C and field variations from 0 to 30kV/cm. Vibration-electrical energy converters using piezoelectric unimorphs were also investigated. The unimorph consisting of a PZT with higher Curie temperature produced larger power and energy. Mn-doping was also found to be effective for producing energy and power in barium titanate ceramics. A unimorph consisting of 18×10×0.5 mm PZT-based ceramics with a g₃₁ of 11.8 mVm/N and Q_m of 461 and lead-free Mn-0.2mol% doped BaTiO₃ ceramics with g₃₁ of 2.2 mVm/N and Q_m of 95.3 produced 1763 μJ and 432 μJ by 45 second oscillation with 0.8 mm relative displacement and a frequency of 80 Hz.