We contributed to this International Meeting, hold at “Colegio Oficial de Médicos de Navarra”, Pamplona, Navarra (Spain), with two oral presentations at SESSION 3, FUNCTIONAL CERAMICS AND FILMS:
O-28
Characterization of the performance of piezoceramics beyong a d33 coefficient: 30 years of the automatic iterative method for the analysis of the impedance at the electromechanical resonances,
by L. Pardo (lpardo@icmm.csic.es).
Instituto de Ciencia de Materiales de Madrid, CSIC. c/ Sor Juana Inés de la Cruz, 3. Cantoblanco. 28049-Madrid (Spain)
A good piezoelectric coefficient, as the commonly reported d33 charge coefficient for sensors, is a good starting point to establish potential applicability of poled ferro-piezoelectric ceramic materials, also known as piezoceramics. However, due to the anysotropic character of these materials, the full piezoelectric-elastic-dielectric (PED) matrix of material coefficients in complex form, i.e., including all losses, is required for the reliable material modelling in the design of new devices by numerical methods. This is carried out by impedance measurements at the electromechanical resonances of piezoceramics, which are known as resonance curves. To this aim, precise and accurate shear coefficients (d15, sE55 and εS11) must be determined. Due to the difficulties arising from coupling of modes when using shear resonators, these shear parameters are scarcely reported in publications concerning piezoceramics or by the manufacturers. The advantages over the standard analysis of the determination of the PED matrix by the iterative analysis of resonance curves developed at CSIC, includding non-standard shear items, will be discussed here.
O-29
Effect of the Milling Process on the synthesis, sintering and electric properties of BCTZ Ceramics
by Ana Laura Conejo-Martínez (1,2), Marzia Mureddu (3), Lorena Pardo (4), Armando Reyes-Montero (2) (arremo@materiales.unam.mx).
1) Facultad de Química, Universidad Nacional Autónoma de México (México)
2) Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México (México)
3) Department of Chemical, Physical, Mathematical, and Natural Sciences, University of Sassari (Italy)
4) Instituto de Ciencia de Materiales de Madrid, ICMM-CSIC (Spain)
Barium titanate (BaTiO3) derivatives have been widely studied in the search for lead-free piezoelectric ceramic materials for sensors, actuators and transducers, which can be an eco-friendly replacements for the market-leading lead-based ceramics. These smart ceramic materials play a crucial role in automotive and aircraft electronics, as well as in mobile phone components, e.g. surface acoustic wave filters, among many other classical applications. Besides, nowadays there are emerging biomedical applications in which lead-free piezoelectrics have obvious advantages. Particularly the (Ba1-xCax)(Ti1-yZry)O3 compositions (BCxTZy) has stood out as one of the most promising lead-free piezoceramics, as they do not contain critical raw materials and have high piezoelectric sensitivity. However, there are still a few challenges to overcome in the production of BCTZ, especially since environmental regulations in the chemical industry require the development of sustainable production methods with reduced energetic budgets. Mechano-activated solid-state reactions are being studied as a way to minimize synthesis and sintering temperatures. The driving force of mechano-activation is the increase of the surface area, by reduction of the reagents particle size, and promotion of its reactivity, by the formation of vacancies and defects on the particles’ surface. These morphological and structural changes enhance the ionic diffusion during the solid state synthesis. In this work, Ba₀.₈₅Ca₀.₁₅Ti₀.₉₀Zr₀.₁₀O₃ ceramics were obtained using the mixed oxides method with mechanical activation of the solid-state synthesis via high energy wet planetary ball milling of the mixture of reagents using a variable size of the zirconia balls. Under the optimum conditions, the BC15TZ10 phase was successfully obtained at only 750°C for 2h. The ceramic samples were prepared both by the conventional route, including a second ball milling after the BCZT synthesis, as well as by reactive sintering after moulding of the mixed powder. The ceramics exhibited soft ferroelectric behavior, comparable to values reported in the literature for ceramics obtained using more stringent solid-state synthesis conditions or by sol-gel synthesis.
«Épsilón de Oro» Award was given in this 2025 edition to Dr. Rosa Isabel Merino, Research Scientist and Group Coordinator of The Processing and Characterization of Structural and Functional Ceramics Group at the Instituto de Nanociencia y Materiales de Aragón (INMA, CSIC-UNIZAR). Congratulations!