Lead-Free Nanogenerator Made from Single ZnSnO₃ Microbelt

N on-centrosymmetric (NCS) oxides have attracted considerable attention due to their unique symmetrydependent and spontaneous polarization properties, which are technologically important and are the basis of numerous applications in ferroelectricity, piezoelectricity, and nonlinear optics. Among NCS oxides, ZnO is an environmentally friendly and piezoelectric material. Therefore, single ZnOnanowires/microwires have extensively been demonstrated as piezoelectric diodes, piezotronic transistors, nanogenerators, solar cells, and strain sensors. Besides ZnO, there are still many lead-free piezoelectricmaterials in theNCS group that remain to be undiscovered, especially in terms of perovskite structure. Despite the success in lead-based piezoelectricmaterials (i.e., lead zirconate titanate) due to their high polarization and piezoelectric performance as transducers, a consistent effort has been taken to replace Pb-based materials with some as yet undiscovered lead-free materials that would be more environmentally friendly and enable new piezoelectric applications for mechanical energy harvesting. Recently, Inaguma reported a lead-free LiNbO3 (LN)-type ZnSnO3 using a high-pressure (∼7 GPa) synthesized environment. Son et al. reported that the epitaxial (111) ZnSnO3 thin film exhibited a highly ferroelectric polarization of ∼47 μCcm 2 using a pulsed laser deposition process. In NCS oxides, ZnSnO3 is primarily characterized by a large displacement of Zn based on a strong covalent bond between three oxygen and zinc atoms, resulting in the ZnSnO3 having a strong piezoelectric response. Therefore, ZnSnO3 has also attracted a lot of attention recently. However, most works focused on the structural characterization and theoretical calculation of polarization, especially in thin film and bulk materials of ZnSnO3. 17 There is no complete report regarding crystallographic and energy harvesting using ZnSnO3 nanostructures. Therefore, the synthesis route, structural analysis, and energy harvesting application of ZnSnO3 nanostructures still remain unclear and are subject to a comprehensive investigation. In particular, the synthesis of the LN-type ZnSnO3 is a challenge due to the extreme conditions of high pressure. In this work, we report that ZnSnO3 nanobelts/microbelts can be successfully grown through a carbon-thermal reaction process at a temperature of 1173 K. On the basis of X-ray diffraction characterization, twomajor peaks of (110) and (104) appear in the spectrum of ZnSnO3 nanobelts, indicating that the ZnSnO3 nanostructures have a rhombohedral structure. Although there still exist several second phases in our products, this is the first case in which the * Address correspondence to [email protected].