Ba0.92Ca0.08Ti0.95Zr0.05O3 Lead-free Ceramic for Piezoelectric Energy Harvesting
HERNÁNDEZ-MORENO A. 1,2, REYES-MONTERO A. 1, CARREÑO-JIMÉNEZ B. 3,4, ACUAUTLA M. 4, PARDO L. 5
1 Instituto de Investigaciones en Materiales-UNAM, CDMX, Mexico; 2 Facultad de Química-UNAM, CDMX, Mexico; 3 Instituto de Investigaciones en Materiales (Unidad Morelia)-UNAM, Morelia, Mexico; 4 Faculty of Science and Engineering, University of Groningen, Groningen, Netherlands; 5 Instituto de Ciencia de Materiales de Madrid-CSIC, Madrid, Spain
In the search for new materials with energy storage/production potential, extensive research into complex metal oxides systems has been carried out. Many of these studies have focused on the group of perovskite-like structure ferroelectric oxides. multifunctional materials. Ferroelectrics possess a bistable, spontaneous, electric dipoles that can be reversed by a suitable electric field and changes with mechanical stress (piezoelectricity), temperature (Pyroelectricity) and provide a high capacitance and a strong anisotropy in some other properties, e.g., electro-optical. Therefore, the functionalities and intriguing physical/chemical properties of ferroelectric perovskites are and ideal playground for fascinating wide areas of application .
Ba0.92Ca0.08Ti0.95Zr0.05O3 (BCZT8-5) ceramic materials have been scarcely studied as a lead-free piezo/ferroelectric despite of their enhanced Curie temperature (>100ºC) with respect to most studied BCZT compositions . In this work, homogeneous dense BCZT8-5 ceramics with grain size in the range of 20μm were prepared by mixed oxides route using moderate synthesis (1250ºC-2h) and sintering (1400ºC-2h) conditions. Thickness poled thin disks and monomodal shear plate resonators  were used for determination of piezoelectric coefficients, coupling factors, elastic and dielectric permittivity coefficients, including all losses. The thermal evolution of the piezoelectric coefficients was used to determine the working range of the ceramics. Ferroelectric hysteresis loops and strains vs. electric-field, butterfly loops were also measured. Moreover, dielectric properties as a function of the temperature and a polarization fatigue study were also accomplished. A comparison with the more currently studied Ba0.90Ca0.10Ti0.90Zr0.10O3 (BCZT10-10) and Ba0.85Ca0.15Ti0.90Zr0.10O3 (BCZT15-10) compositions  was drawn showing that these ceramics have high sensitivity and higher stability that makes them amenable for piezoelectric energy harvesters.
 A. Reyes-Montero, R. Castañeda-Guzmán, M. E. Villafuerte-Castrejón, J. A. Chávez-Carvayar and L. Pardo, “Perovskite-like structure ceramic materials and their design for electrical applications” Chapter 10 in Perovskite Ceramics: Recent Advances and Emerging Applications, J. Huaman and V. García-Rivera Eds. Amsterdam: Elsevier, 2023.
 W. Li, Z. Xu, R. Chu, P. Fu and G. Zang, "Piezoelectric and Dielectric Properties of (Ba1−xCax)(Ti0.95Zr0.05)O3 Lead-Free Ceramics," J. Am. Ceram. Soc., vol. 93, no. 10, pp. 2942-2944, 2010.
 A. Reyes-Montero, L. Pardo, A. García, A. M. González and M. E. Villafuerte-Castrejón, "Ba1-xCaxTi0.90Zr0.10O3 shear properties and their frequency dependence determined from ceramic plates by an effective method for resonance decoupling," J. Alloy Compd., vol. 806, pp. 428-438, 2019.
 A. Reyes-Montero, L. Pardo, R. López-Juárez, A. M. González, S. O. Rea-López, M. P. Cruz and M. E. Villafuerte-Castrejón, "Sub-10 μm grain size, Ba1−xCaxTi0.9Zr0.1O3 (x = 0.10 and x = 0.15) piezoceramics processed using a reduced thermal treatment," Smart Mater. Struct., vol. 24, no. 6, p. 065033, 2015.