A facile method to fabricate vertically aligned (K,Na)NbO3 lead-free piezoelectric nanorods

Abstract

This paper reports on a hydrothermal process to grow vertically aligned (K,Na)NbO₃ lead-free piezoelectric nanorods on a single crystal SrTiO₃ substrate. Under optimized conditions, micrometer-order-long (K,Na)NbO₃ nanorods with a sectional width of about 100 nm were vertically grown on a (100)-cut SrTiO₃ wafer with an oriented (K,Na)NbO₃ film as a seeding layer, whereas KNN rods were not preferentially grown on bare wafers and no vertical KNN rods were formed on (110)- or (111)-cut substrates even with the (K,Na)NbO₃ films. The growth direction of the nanorods was revealed to be along the 〈100〉 direction, which is deduced to contribute to the vertical growth of nanorods on (100)-cut SrTiO₃ substrates. The vertical arrays of KNN nanorods may find potential applications in energy harvesting nanodevices and nanoscale 1–3 type multifunctional composites.