Photocurrent of lead-free (K0.5Na0.5)(Mn0.005Nb0.995)O3 ferroelectric nanotubes

We fabricated (K0.5Na0.5)(Mn0.005Nb0.995)O3 (KNMN) nanotubes using (K0.5Na0.5)(Mn0.005 Nb0.995)O3 sol on an anodic aluminum oxide (AAO) template. The highly ordered AAO template was fabricated by a two-step anodization process. Lead-free (K0.5Na0.5)(Mn0.005Nb0.995)O3 ferroelectric nanotubes were fabricated by infiltration with KNMN sol inside the AAO template by a sol-gel process. The outer diameter and thickness of the wall in the KNMN nanotube were about 70 nm and 5 nm, respectively. The crystalline structure, surface morphology, and ferroelectric and photocurrent properties were investigated. The maximum power conversion efficiencies (η) of KNMN nanotubes were higher than that of KNMN film due to the greater effective area (KNMN nanotubes: η = 0.02%, KNMN film: η = 0.008%).