Theoretical Modeling and Experimental Verification of Electrochemical Equilibria in the Ba−Ti−C−H2O System

Abstract

Listen

Translate article

The thermodynamic principles controlling the electrochemical synthesis of barium titanate (BaTiO3) films are discussed and explored. a variety of Eh−pH diagrams were generated for the Ba−Ti−C−H2O system as a function of temperature and whether CO2 was in the system. Barium titanate is predicted to form at 25 °C and higher temperatures under alkaline conditions. It is demosnstrated that the phase field for BaTiO3 enlarges as a function of pH with increasing temperature in the absence of CO2. The role of CO2, although still important in controlling the phase stability of BaTiO3 via the formation of BaCO3, becomes less important under solution pH conditions greater than pH ∼13 and temperatures greater than 100 °C. The theoretical Eh−pH predictions compare favorably with experimentally determined regimes, where BaTiO3 and films in the Ba−Ti−C−H2O system form through electrochemical reactions.