Some lead-free ceramics of ferroelectric andphotoelectrochemical applications

The main ferroelectric materials are lead-based which cause serious environmental problem. Then, to develop environment friendly materials, lead-free ceramics derived from BaTiO3 were found to be interesting owing to their attractive ferroelectric performances. Moreover, the ferroelectric materials present interesting characteristics suitable for photoelectrochemical applications. In this perspective, ferroelectric and photoelectrochemical properties of Ba0.785Bi0.127Y0.017TiO3 (BBiYT), Ba0.975Eu0.017(Ti0.75Zr0.25)O3 (BETZ) and Ba(Ti0.96Mg0.013Nb0.026)O3 (BTMN) compositions are presented and discussed. The relative permittivity and losses are determined under dry helium as a function of both temperature(77-450 K) and frequency (102-2.105 Hz). BTMN compositions are characterized by a normal ferroelectric behaviour, while BBiYT and BETZ present relaxor ferroelectric properties. All these compounds present photoelectrochemical properties with different applications: eosin oxidation under solar light (BTMN), chromate reduction (BETZ) after 6 h of exposition to sunlight and H2 production upon visible light (BBiYT).