EFFECT OF DOPANTS (A = Mg2+, Ca2+ AND Sr2+) ON FERROELECTRIC, DIELECTRIC AND PIEZOELECTRIC PROPERTIES OF (Ba1-xAx)(Ti0.98Zr0.02)O3 LEAD-FREE PIEZOCERAMICS

The effects of Mg2+, Ca2+ and Sr2+ dopants on the ferroelectric, dielectric and piezoelectric properties of BZT (Ba1-xAx)(Ti0.98Zr0.02)O3 (x = 0.00, 0.01, 0.015, 0.02 and 0.03) (A = Mg2+, Ca2+ and Sr2+) ceramics were studied. The precursor powders were prepared by a mixed oxide route and calcined at 1000 C for 4 h. The calcined powders were then de-agglomerated, pressed into pellets and sintered at 1150 C for 3 h. SEM studies of polished sintered pellets revealed that the grains were mostly sub-micron sized for the pure BZT samples and larger (2-5 micron) for the doped BZTs. EDS confirmed the presence of dopants very close to their stoichiometric compositions. The piezoelectric charge constant was a maximum for 0.015 mol Sr2+ doped BZT (d33 = 330 pC/N). Similarly, the dielectric constant was a maximum for 0.015 mol Ca2+doped BZT (K = 2521) and the remanent polarisation was a maximum for 0.015 mol Sr2+ doped BZT (Pr = 4.69 microC/cm2).