Aging behavior and electrical properties of low-temperature sintered (Ba, Ca)(Ti, Zr)O₃-Ba(Cu, W)O₃ ceramics and plate loudspeaker

Lead-free (1 - x)wt.% (Ba_0.85Ca_0.15)(Zr_0.10Ti_0.90)O₃ - x wt.% (Ba(Cu_0.5W_0.5)O₃ (BCZT - x wt.% BCW) piezoelectric ceramics were prepared by solid-state reaction. The phase structure of the ceramics showed that the orthorhombic-tetragonal phase boundary was identified in the range of 1.2 ≤ x ≤ 1.6 wt.%. The dense microstructure and optimal electrical properties of the ceramics were obtained at x = 1.2 wt.%. Fatigue behavior of the ceramics was also investigated as a function of temperature and keeping time, where the BCZT - 1.2 wt.% BCW materials were found to possess improved fatigue characteristic. In addition, the sound pressure level (SPL) of 16.0 mm length × 16.0 mm width × 0.1 mm piezoelectric loudspeakers using lead-free BCZT ceramics with 1.2 wt.% BCW content at drive voltage of 10-20 V was more than 80 dB at frequency of 2.2-20.0 kHz. These results indicated that the 98.8 wt.% BCZT - 1.2 wt.% BCW ceramics was potential for piezoelectric loudspeaker applications.