Controlled synthesis of ultra-long vertically aligned BaTiO_3 nanowire arrays for sensing and energy harvesting applications

摘要

A novel approach for the synthesis of ultra-long (up to ~45 μm) vertically aligned barium titanate (BaTiO_3) nanowire (NW) arrays on an oxidized Ti substrate is developed. The fabrication method uses a two-step hydrothermal reaction that firstly, involves the growth of ultra-long aligned sodium titanate NW arrays and secondly, involves the transfer of these precursor sodium titanate NW arrays to BaTiO_3 NW arrays while retaining the shape of the template nanowires. The ion-exchange during the second hydrothermal reaction in barium hydroxide solution results in the structural transformation from single-crystal sodium titanate NW arrays to BaTiO_3 NW arrays. This synthesis approach is low-cost, scalable, and enables control over the morphology and aspect ratio of the resulting BaTiO_3 NW arrays by tuning the hydrothermal reaction parameters. In addition to the synthesis methods reported here, the energy harvesting behavior of the BaTiO_3 NW arrays is evaluated as a function of their aspect ratio and demonstrated to produce significant impact on the energy produced. The newly developed hydrothermal synthesis process for controlled growth of ultra-long, vertically aligned BaTiO_3 NW arrays provides a promising method for their efficient utilization in nano-electromechanical system-based sensors, energy harvesters, and nano-scale electronic devices.