Electrochemical synthesis of barium titanate thin films

Abstract

Polycrystalline films of barium titanate (BaTiO 3 ) have been synthesized on titanium (Ti) substrates by the galvanostatic anodization of Ti in a solution of 0.4 M Ba(OH) 2 . Crystalline films are formed at temperatures under 100 ± C within 10 min at a current density of 25 mA͞cm 2 at atmospheric pressure. Crystallinity of the films is found to increase with both current density and time of reaction. At 90 ± C, a film of 1 mm thickness is formed after 10 min; grain sizes up to 0.5 mm are obtained. Microstructure of the films is found to be critically dependent on the pretreatment of the titanium anode. Capacitance measurements on the film yield a dielectric constant of 200 with a minimum tan delta of 0.09 at 10 kHz. On the basis of the voltage-time curves, it is interpreted that an amorphous intermediate is formed which crystallizes to form perovskite BaTiO 3 .194

Hydrothermal Formation and Growth of Single- and Double-Layer BaTiO3 and SrTiO3 Films on the Flexible Polymer Film Substrates from Sol−Gel Amorphous Titanium Oxide Films

“…31-174. The formation of the cubic BaTiO 3 phase, observed in this work, is quite common in the hydrothermal treatment of titanium-loaded precursors in Ba(OH) 2 solution. − Figure a shows an XRD pattern of a PPS film, and Figure b shows the typical XRD pattern of a titanium oxide film. It is confirmed that the sol−gel titanium oxide film is XRD-amorphous.…”

“…The CO 2 might be introduced with starting solution, the thermal decomposition of organic components available in the sol−gel-derived film, and the PPS polymer substrate under hydrothermal conditions. It was reported that such BaCO 3 contamination could be avoided by washing with CO 2 -free, ammoniated water at pH 9, − but we found that the kind of washing could not completely remove the BaCO 3 contamination on the top of the BaTiO 3 grains. Incubated in pH 9, CO 2 -free water under N 2 atmosphere for 10 min, then washed thoroughly with CO 2 -free water, rinsed in ethanol, and dried under N 2 atmosphere, the BaCO 3 contamination could be extensively removed.…”

“…However, most of these methods need high temperature to form ferroelectric films. Previous investigations have shown that MTiO 3 (M = Ba, Sr) films can be synthesized on titanium substrates in M(OH) 2 (M = Ba, Sr) aqueous solutions at temperatures less than 200 °C by hydrothermal and hydrothermal−electrochemical methods. − In contrast to the conventional solid state route, the hydrothermal and hydrothermal−electrochemical methods offer an inexpensive and environmentally friendly route to synthesize thin (or thick), shaped, sized, and oriented ceramic films and coatings in aqueous solutions in one step for a variety of applications. − It is generally accepted that a layer of titanium oxide formed on Ti substrate under the hydrothermal or hydrothermal−electrochemical condition acts as a precursor for the formation of MTiO 3 . The hydrothermal−electrochemical method benefits from the electrochemical anodic oxidization of the metal substrate (e.g., Ti substrate) to form metal oxide film.…”

Investigations of micro‐stress and phase transition in sol–gel‐derived multideposited coatings of barium titanate using Raman spectroscopy

“…BT thin films have been prepared by a variety of deposition techniques, such as evaporation (thermal, flash and two-boat), sputtering (r.f. and magnetron), ion beam deposition, pulsed laser ablation deposition (PLD), electrochemical synthesis, 18 metal-organic chemical vapor deposition (MOCVD) 19 and others. 20 -22 Recently, significant attention has been given to the synthesis of BT thin films by the sol-gel or modified sol-gel technique.…”

Single-step fabrication of potassium tantalate films by hydrothermal-electrochemical method at lower temperatures

“…[35][36][37][38] The currently obtained results obviously benefit from the soluble property of the potassium carbonate. It is worth mentioning that for some dielectric films prepared by the hydrothermal or hydrothermalelectrochemical method, such as BaTiO 3 films, BaCO 3 always contaminates the formation of the BaTiO 3 films, although such surface contamination could be avoided by careful washing with CO 2 -free ammoniated water at pH 9.…”