Affiliation: | 1. CEITEC—Central European Institute of Technology, Brno University of Technology, Brno, Czech Republic;2. CEITEC—Central European Institute of Technology, Brno University of Technology, Brno, Czech Republic Department of Physics, Faculty of Electrical Engineering and Computer Science, Brno University of Technology, Brno, Czech Republic;3. CEITEC—Central European Institute of Technology, Brno University of Technology, Brno, Czech Republic Department of Ceramics and Polymers, Faculty of Mechanical Engineering, Brno University of Technology, Brno, Czech Republic;4. Department of Physics, Technical University of Liberec, Liberec, Czech Republic |
Abstract: | We report a large piezoelectric constant (d33), 720 pC/N and converse piezoelectric constant (d33*), 2215 pm/V for 0.55(Ba0.9Ca0.1)TiO3-0.45Ba(Sn0.2Ti0.8)O3 ceramics; the biggest value achieved for lead-free piezoceramics so far. The ceramic powders were calcined between 1050°C-1350°C and sintered at 1480°C. The best properties were obtained at a calcination temperature (CT) of 1350°C. The fitting combination of processing and microstructural parameters for example, initial powder particle size >2 µm, ceramics density ~95%, and grain size ~40 µm led to a formation of orthorhombic-tetragonal-pseudo-cubic (O-T-PC) mixed phase boundary near room temperature, supported by Raman spectra, pointed to the extremely high piezoelectric activity. These conditions significantly increase piezoelectric constants, together with high relative permittivity (εr) >5000 and a low loss tangent (tan δ) of 0.029. In addition, the d33 value stabilizes in the range of 400-500 pC/N for all samples calcined between 1050°C and 1250°C. The results entail that the (Ba,Ca)(Sn,Ti)O3 ceramics are strong contenders to be a substitute for lead-based materials for room temperature applications. |