Structure and piezoelectric properties of (Ba1−xCax)(Ti0.95Hf0.05)O3 lead-free ceramics

Abstract

Lead-free (Ba1−xCax)(Ti0.95Hf0.05)O3 (x=0.04–0.14) (BCHT) ceramics with good piezoelectric properties were successfully prepared using solid state reaction method. The structural and electrical properties of the BCHT ceramics were systematically studied. The polymorphic phase transitions (PPT) from orthorhombic phase to tetragonal phase shifts towards low temperature with increasing Ca contents, and the PPT can be obtained at room temperature (RT) in the composition range of 0.08–0.10 for the BCHT ceramics. The tetragonality of the BCHT ceramics at PPT is increased after poling treatment as depicted in the XRD patterns and Raman spectroscopy. The BCHT ceramics at x=0.08 exhibit good piezoelectric properties (d33=380 pC/N, kp=50% and Smax=0.19% under the applied electric field of 50kV/cm) and ferroelectric property (Pr=13.4μC/cm2), due to the coexistence of tetragonal phase and orthorhombic phase. The aging rate of d33 values from 20°C to 90°C is lower than 20% in this work, indicating that the BCHT ceramics have good temperature stability. The high piezoelectric properties with good temperature stability indicate that the BCHT ceramics are promising candidates as lead-free piezoelectric ceramics.