Abstract：
A typical piezoelectric energy harvester is a bimorph cantilever with two layers of piezoelectric material on both sides of a flexible substrate. Piezoelectric layers of lead-based materials, typically lead zirconate titanate, have been mainly used due to their outstanding piezoelectric properties. However, due to lead toxicity and environmental problems, there is a need to replace them with environmentally benign materials. Here, our main efforts were focused on the preparation of hafnium-doped barium titanate (BaHfxTi1-xO3; BHT) sol-gel materials. The original process developed makes it possible to obtain a highly concentrated sol without strong organic complexing agents. Sol aging and concentration can be controlled to obtain a time-stable sol for a few months at room temperature, with desired viscosity and colloidal sizes. Densified bulk materials obtained from this optimized sol are compared with a solid-state synthesis, and both show good electromechanical properties: their thickness coupling factor kt values are around 53% and 47%, respectively, and their converse piezoelectric coefficient d33∗ values are around 420 and 330 pm/V, respectively. According to the electromechanical properties, the theoretical behavior in a bimorph configuration can be simulated to predict the resonance and anti-resonance frequencies and the corresponding output power values to help to design the final device. In the present case, the bimorph configuration based on BHT sol-gel material is designed to harvest ambient vibrations at low frequency (<200 Hz). It gives a maximum normalized volumetric power density of 0.03 µW/mm3/Hz/g2 at 154 Hz under an acceleration of 0.05 m/s2.
摘要：
典型的压电能量收集器是双压电晶片悬臂,其在柔性基板的两侧上具有两层压电材料。铅基材料的压电层，通常是锆钛酸铅，已被主要用于由于其突出的压电性能。然而,由于铅的毒性和环境问题，有必要用环境友好的材料代替它们。这里,我们的主要工作集中在制备掺铪的钛酸钡（BaHfxTi1-xO3；BHT）溶胶-凝胶材料。开发的原始方法可以获得高度浓缩的溶胶，而无需使用强有机络合剂。可以控制溶胶的老化和浓度，以获得在室温下几个月时间稳定的溶胶，具有所需的粘度和胶体尺寸。将从该优化的溶胶获得的致密体材料与固态合成进行比较，两者都表现出良好的机电性能：它们的厚度耦合因子kt值约为53％和47％，分别,它们的相反压电系数d33*值大约为420和330pm/V，分别。根据机电特性，可以模拟双压电晶片配置中的理论行为，以预测谐振和反谐振频率以及相应的输出功率值，以帮助设计最终设备。在目前的情况下,基于BHT溶胶-凝胶材料的双压电晶片构造被设计成在低频(<200Hz)下获得环境振动。在0.05m/s2的加速度下，在154Hz时的最大归一化体积功率密度为0.03µW/mm3/Hz/g2。
