Mechanical and electrical properties of PZT ceramics (Zr:Ti=0.40:0.60) related to Nd3+ addition

Single phase lead zirconate titanate (PZT) of tetragonal structure (Zr:Ti = 0.40:0.60) was modified using a trivalent rare earth additive Nd2O3. The samples having composition Pb1-(3x/2)Ndx(Zr0.40Ti0.60)O-3 was prepared by solid state route. The Nd content in the samples was varied from 0-4 mol %. The effect of Nd3+ additive on mechanical and electrical properties of PZT ceramics has been studied. It was observed that Nd addition results in enhancement of fracture toughness (K-IC) and Vicker's hardness (H-v) in the samples, Nd addition also results in substantial increase in dielectric constant and d(33) piezo coefficient of PZT ceramics. The maximum value of K-IC obtained is 2.05 Mpam(1/2). Also the peak value of 680 for dielectric constant and a d(33) of 240 pCN (- 1) is obtained for the same composition. Both the mechanical and electrical properties seem to peak at 2% Nd3+ addition, which makes this composition attractive for actuator and other high pou er ultrasonic transducer applications. The increase in mechanical properties has been attributed the increased tetragonality (c/a ratio) and increase in sintered density with Nd addition. It seems that the ferroelastic domain switching is the main contributor to toughening in these ceramics. The increased tetragonality with Nd addition results in more work done in domain switching and, hence, enhanced toughness. The increase in electrical properties with Nd addition has been attributed to reduction in oxygen vacancies in the samples. The X-ray and the sintered density results also suggest that at 2 mol % Nd addition, Nd is reaching its solubility limit in PZT system. (C) 1999 Elsevier Science S.A. All rights reserved.