MS19-P04 Structural, dielectric and photoelectrochemical properties of new lead-free ceramics of composition Ba0.925Bi0.05(Ti0.95-x Zrx)Sn0.05O3Classical ferroelectrics and relaxors are two distinct classes of materials . Among these, BaTiO3 is the best-known prototype of classical ferroelectric materials characterized by three phase transitions: rhombohedral-orthorhombic-tetragonal-cubic. The ferroelectric (tetragonal) -paraelectric (cubic) phase transition occurs at 120 °C and the orthorhombic-tetragonal transition occurs at low temperature (~ 5 °C). The improvement of the properties of BaTiO3 has been the subject of considerable efforts for several years. The abundant literature has shown that many substitutions have been tried in (Ti and/or Ba) sites. Some of these substitutions give rise to a particular dielectric behavior known as relaxor. In addition to the usual applications of ferroelectric materials, relaxors are used in the fabrication of dielectrics for capacitors and actuators . Unfortunately, these materials are based on lead which is harmful to the environment. As a result, research is directed towards environmentally friendly applications using lead-free materials as alternatives. It is in this context that the present study was conducted. We have initially elaborated new ceramics of formula Ba0.925Bi0.05 (Ti0.95-xZrx) Sn0.05O3 and symbolized by the term BBiTZxS (x = 0.05, 0.15, 0.20; 25, 0.30). After that, we studied the evolution of the structure and the dielectric properties as a function of Zr composition. The characterizations were performed by X-ray Diffraction, Raman Spectroscopy and dielectric measurements as a function of temperature. The results show a classical ferroelectric behavior at low concentrations of Zr which turns into a relaxor when the Zr content increases. On the other hand, preliminary photoelectrochemical investigations showed appropriate position of the energetic band of these materials which is very interest for photocatalysis applications while respecting the environment.
 Cross, L. E, (1994) Ferroelectrics 151, 305-320.
 Uchino, K, (1994) Ferroelectrics 151, 321-330
Keywords: Lead-free, Ferroelectric relaxor, Photoelectrochemical