Tetragonal 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.

This study aims to prepare BaTiO₃ pyroelectric thin films and explore their properties.

Firstly, 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.

The 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.

The 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.