No abstract

Horizontally assembled trapezoidal piezoelectric cantilevers driven by magnetic coupling were fabricated for rotational energy harvester applications. A dodecagonal rigid frame with an attached array of six trapezoidal cantilevers served as a stator for electrical power generation. A rotor disk with six permanent magnets (PMs) interacted magnetically with the counterpart cantilever’s tip-mass PMs of the stator by rotational motion. Each trapezoidal piezoelectric cantilever beam was designed to operate in a transverse mode that utilizes a planar Ag/Pd electrode printed onto lead zirconate titanate (PZT) piezoelectric thick film. The optimized distance between a pair of PMs of the rotor and the stator was evaluated as approximately 10 mm along the same vertical direction to make the piezoelectric cantilever beam most deflectable without the occurrence of cracks. The theoretically calculated resistance torque was maximized at 46 mN·m for the optimized trapezoidal piezoelectric cantilever. The proposed energy harvester was also demonstrated for wind energy harvester applications. Its harvested output power reached a maximum of approximately 22 mW at a wind speed of 10 m/s under a resistive load of 30 kΩ. The output performance of the proposed energy harvester makes it possible to power numerous low-power applications such as smart sensor systems.

PbTiO3 (PT) microstructures were fabricated by topochemical microcrystal conversion (TMC) and their morphological evolution was investigated with variation of synthesis temperature and relative molar ratio of reactants. Using molten salt synthesis, Aurivillius phase of PbBi4Ti4O15 (PBiT) synthesized at 1050°C was prepared as precursor. Large plate‐like PT microstructures with lengths of hundreds of micrometer were optimally obtained when the relative ratio (x) of (PbCO3)2·Pb(OH)2 to PBiT in reactants was 6. In addition, relatively homogeneous PT platelets were achieved at the annealing temperature of 1050°C by TMC; these materials are probably suitable for use in templated grain growth. However, a Pb‐deficient secondary phase of PbTi3O7 formed in cases of low x values of less than 4 and low annealing temperatures of less than 1050°C. The porous PT pellets, orthogonally assembled by numerous PT platelets, were achieved by increasing temperature to 1100°C. Further increase in temperature to 1150°C could lead to partial formation of denser PT blocks.