Research on preparation and properties of BaTiO3 pyroelectric thin films

BackgroundTetragonal BaTiO3 exhibits temperature-dependent surface wettability as a pyroelectric material, hence is expected to be exploited to improve boiling and heat transfer efficiency on the surface of nuclear-reactor heat exchange components.PurposeThis study aims to prepare BaTiO3 pyroelectric thin films and explore their properties.MethodsFirstly, TiO2 nanotubes were prepared by anodic oxidation, and a controllable preparation of BaTiO3 nanotube array films was achieved using hydrothermal synthesis. Then, the X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) were employed to observe characteristics and analyze the growth mechanism of TiO2 nanotube and BaTiO3 nanotube array film. Finally, the surface morphology and phase structure changes of the nanotubes were investigated by adjusting the voltage, NH4F concentration, and oxidation time.ResultsThe results show that the size of the generated oxygen bubbles increase with the increase of electron current caused by high voltage, and the diameter of the nanotubes increases with the oxidation voltage. The tube diameter distribution ranges within 60~140 nm, and the tube wall thickness is 10 nm. Increasing the concentration of NH4F and oxidation time are beneficial for the formation of TiO2 nanotubes. Polishing the titanium sheet can considerably improve the flatness of the nanotube array generated by oxidation. By extending the hydrothermal time and increasing the high-temperature annealing treatment, the cubic phase of BaTiO3 is successfully converted into a tetragonal phase with pyroelectric effects. Compared with the sample prepared over longer hydrothermal time, the annealed sample exhibits better pyroelectric properties.ConclusionsThe results of this study provide a valuable reference for further analyzing the growth mechanism of anodized TiO2 nanotubes and exploiting the spontaneous polarization intensity change of pyroelectric materials to change the surface wettability and improve the boiling heat transfer.