Internal friction characterization in lead-rree ferroelectrics for ultrasonic generation

Oral presentaiton given at the 18th International Conference on Internal Friction and Mechanical Spectroscopy, held in Foz do Iguaçu (Brazil) on September 12-15, 2017.Ferroelectric solid solutions based on PbTiO3, mainly the one with lead zirconate (PbZrO3), also known as PZT, dominate the industrial applications of ferro-piezoelectric materials in polycrystalline form, also known as piezoelectric ceramics. The use of PbO in the fabrication of PZT and the end of the life-cycle of this omnipresent material involves hazards for the human health and the environment [1]. European Union regulations arising in 2003 [2,3] were the first to include the substitution of PZT with lead-free ferroelectrics. These regulations triggered the study of lead-free ferro-piezoelectrics [4] and are now worldwide extended. This scientific research field experienced a strong growth from that time [5] and has reached today a great level of maturity in some scientific themes, industrial transference and expansion of the topic from the scientific community to the society and to the business schools [6]. In-operando characterization techniques of the materials as ultrasonic generators, including elastic, dielectric and piezoelectric losses are presented [7,8]. Ecological, lead-free, ferroelectrics perovskites based on BaTiO3 and Ba substituted (Bi0.5Na0.5)TiO3 are here considered and matrix characterization of potentially applicable compositions is discussed