Synthesis of preferred-oriented BaTiO3 thin films via hydrothermal-galvanic method on TiN-coated substrates for photoelectrochemical, dielectric, and piezoelectric evaluations

Barium titanate (BaTiO 3 ; BTO) is a versatile material extensively used in dielectric , piezoelectric , and ferroelectric applications. The synthesis of (111) and (200) preferred-oriented BTO films was achieved through the hydrothermal-galvanic couple (HT-GC) method, employing conductive titanium nitride (TiN) film electrodes with corresponding preferred orientations. Notably, the TiN underlayers were deposited onto flexible Ti foils using a facile air-based sputtering method. The HT-GC process was conducted at 80 °C for 1 h in an alkaline solution comprising 0.5 M Ba(CH 3 COOH) 2 and 2 M NaOH. X-ray diffraction patterns confirmed that the resulting BTO films possessed a cubic structure, with (111) and (200) preferred orientations corresponding to those of the TiN underlayers. The (200)-preferred BTO films revealed a more robust photocurrent response of 10.6 ± 0.2 μA∙cm −2 , compared to 4.6 ± 0.1 μA∙cm −2 for (111)-preferred BTO. This enhanced response may be attributed to the more closely packed plane of (200) in BTO than (111). Regarding dielectric and piezoelectric properties , the (111)-oriented BTO films exhibited a higher dielectric constant of 7.7 ± 0.1 and a piezoelectric coefficient (d 33 ) value of 27 ± 4 p.m./V, compared to the (200)-oriented BTO films with a dielectric constant of 3.9 ± 0.2 and a d 33 values of 15 ± 2 p.m./V. This difference may be due to enhanced polarization mechanisms and reduced strain effects in (111)-oriented BTO. These differences highlight the influence of preferred orientation on physical properties, offering insights into tailoring BTO films for advanced technological applications.