The effect of lanthanum substitution on the sintering behavior and the dielectric and piezoelectric properties of niobium doped Pb(Zr0.95Ti0.05)O3 ceramics

Lead zirconate titanate (PZT) based piezoelectric ceramics with a composition of (Pb0.99-3x/2Lax)(Zr0.95Ti0.05)(0.98)Nb0.02O3 where x = 0.0, 0.004, 0.005 and 0.006 were synthesized using conventional solid state sintering at 1250, 1275 and 1300 A degrees C. The effect of lanthanum substitution on the microstructure, dielectric and piezoelectric properties of the samples were studied. The results showed that lanthanum substitution was beneficial for densification of the samples during sintering and the samples with 0.6 mol% lanthanum exhibited the maximum density of 7.59 g/cm(3) when sintered at 1275 A degrees C. Moreover, the piezoelectric coefficients (d(33)) and (d(31)), voltage coefficients (g(33)) and (g(31)), relative dielectric constant (epsilon(r)), dielectric loss (tan delta) and electromechanical coupling coefficient (k(p)) of the samples reached the optimal values of 70 and -15 PC/N, 25.50 x 10(-3) and -5.36 x 10(-3) Vm/m, 310, 0.025 and 0.163, respectively at 0.4 mol lanthanum substitution. Furthermore, the elastic compliances (S (11) (E) ) and (S (12) (E) ), the Poisson's ratio (sigma), The Young's modulus (Y (11) (E) ), the sound velocity (v) and the mechanical quality factor (Q(m)) of the samples reached the optimal values of 7.93 and -2.01 x 10(-12) m(2)/N, 0.2535 and 126 x 10(9) N/m(2), 4079 m/s and 304, respectively for the same samples. The results indicate that the lanthanum doped PZTN ceramics can be hopefully used for pulsed power devices.