Electrical properties of Sb and Cr-doped PbZrO3–PbTiO3–PbMg1/3Nb2/3O3 ceramics

Abstract The pyroelectric, dielectric and DC resistive properties of Sb and Cr-doped ceramics with a base composition of Pb(Mg 1/3 Nb 2/3 ) 0.025 (Zr 0.825 Ti 0.175 ) 0.975 O 3 have been studied. Sb doping has been shown to produce a linear reduction in Curie temperature ( T C =−22 z +294 °C) with concentration ( z ) and to give an increase in pyroelectric coefficient from 250 to 310 μCm −2 K −1 for z increasing from 0 to 3 at.%. It also produces first a reduction and then an increase in both dielectric constant and loss, so that the 33 Hz pyroelectric figures of merit (FOM's) are as follows: F V peaks at 3.8×10 −2 m 2 C −1 and F D peaks at 1.2×10 −5 Pa −1/2 . The resistivity is increased substantially from 1.1×10 11 to ca 6×10 11 Ωm with 1 at.% Sb, thereafter changing little. The behaviour has been explained in terms of Sb acting as a donor ion, reducing oxygen vacancy concentrations up to 1 at.%, with conductivity dominated by hole hopping between traps ( E a =0.59±0.05 eV) that are not changed by the Sb doping. It is concluded that additions of higher levels of Sb do not produce electron-mediated hopping conduction. The Cr additions have no effect upon T C , but reduce dielectric constant and loss, pyroelectric coefficient and resistivity at doping levels up to 3 at.%. The FOM F V peaks at 3.6×10 −2 m 2 C −1 and F D at 1.9×10 −5 Pa −1/2 . The behaviour of the electrical resistivity as a function of dopant level is shown to produce a linear ln( σ o ) vs z −1/3 dependence ( σ o =DC conductivity), as would be expected for hole hopping conduction between Cr 3+ sites, with an E a =0.38±0.03 eV.