Piezoelectric materials of (1 − x)Pb(Zr0.53Ti0.47)O3–xBi(Y0.7Fe0.3)O3 for energy-harvesting devices

Abstract

The piezoelectric ceramics (1−x)Pb(Zr0.53Ti0.47)O3–xBi(Y0.7Fe0.3)O3 [(1−x)PZT–xBYF] (where, x=0.00–0.05) has been synthesized by a modified conventional solid state method. Initially the Pb(Zr0.53Ti0.47)O3 [PZT] and Bi(Y0.7Fe0.3)O3 [BYF] was pre-synthesized and mixed to prepare (1−x)PZT–xBYF ceramic composites. The effects of simultaneous addition of BYF on PZT system were measured as a function of sintering temperature, phase formation, microstructure and piezoelectric/dielectric properties. It was found that between 1150°C and 1190°C, these ceramics were well sintered showing a maximum density of approximately ⩾97.8% of the theoretical value. X-ray diffraction analysis revealed some minor second phases of BiYO3 and BiFeO3 at x>0.01. A uniform, fine grained and relatively pore-free microstructure is obtained at x=0.01 whereas, the average grain size abruptly decreased on further addition of BYF. All the (1−x)PZT–xBYF ceramics doped with various BYF content provided a high TC in the range of 382–387°C. It was found that the piezoelectric and the dielectric properties of (1−x)PZT–xBYF ceramics vary significantly with increasing BYF content. In addition, the piezoelectric voltage constant (g33), and transduction coefficient (d33×g33) of (1−x)PZT–xBYF ceramics have been calculated. For energy-harvesting materials, a high piezoelectric voltage constant expressed by g33=d33/(ε0×K33T) (where K33T is the dielectric constant and ε0 is dielectric permittivity of free space) is desirable. At the sintering temperature of 1170°C, the (1–x)PZT–xBYF ceramic with 0.01mol BYF content showed a considerably higher d33 and kp with lower K33T values which results in significantly higher g33 of 53.07×10−3Vm/N and (d33×g33) of 20,167×10−15m2/N. The large (d33×g33) indicates that the 0.99Pb(Zr0.53Ti0.47)O3–0.01Bi(Y0.7Fe0.3)O3 ceramic is a good candidate material for energy harvesting devices. The detail investigations and observations revealed that, the composition with x=0.01mol BYF could be the optimum magnitude of doping level in the PZT system.