Effect of dopants (A=Mg2+, Ca2+ and Sr2+) on ferroelectric, dielectric and piezoelectric properties of (Ba1-xAx) (Ti0.98Zr0.02) O3 lead-free piezo ceramics

The effect of Mg2+, Ca2+ and Sr2+ dopants on ferroelectric, dielectric and piezoelectric properties of BZT (Ba(1-x)A(x)) (Ti0.98Zr0.02) O-3 (x=0.00, 0.01, 0.015, 0.02 and 0.03) (A=Mg2+, Ca2+ and Sr2+) was studied. The precursor powders prepared by a "mixed oxide" route and calcined at 1000 degrees C for 4 h. The calcined powders were de-agglomerated, pressed into pellets and sintered at 1150 degrees C for 3 h. Scanning electron microscopy (SEM) studies of polished sintered pellets reveals the grains mostly of sub-micron sized for pure BZT samples, large (2-5 mu m) for doped BZTs. EDS analysis of the samples confirms the presence of dopants very close to their stoichiometric compositions. The piezoelectric charge constant was maximum for 0.015 mol Sr2+ doped BZT (d(33)=330 pC/N). Similarly, the dielectric constant was maximum for 0.015 mol Ca(2+)doped BZT (K=2521) and the remnant polarization was maximum for 0.015 mol Sr2+ doped BZT (P-r=4.69 mu C/cm(2)). (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.