Studies on Pb(Zr-Ti)O3Ceramics with Addition of Cr2O3

The solubility limit of Cr 2 O 3 into Pb(Zr-Ti)O 3 was determined as about 2.2 mole % of ½Cr 2 O 3 . In a region out of the limit, three phases were found; the perovskite-type solid solution, the baddeleyite-type ZrO 2 and 2PbO·CrO 3 . By additions of Cr 2 O 3 within the limit, the tetragonality or the difference of rhombohedral angle from π/2 is decreased, and the Curie point is lowered. The temperature, bias and aging characteristics of the piezoelectric ceramics with Cr additives were measured. The temperature coefficient of frequency constant decreases with Cr concentration. The addition of Cr 2 O 3 decreases the dielectric and elastic anisotropies, and increases the coercive field. The remanent electrostriction if notably large compared with that in the plain Pb(Zr-Ti)O 3 ceramics. The back-rotation of 90°-rotated domains with time tends to play a significant role in the ceramics with Cr additives, and this is considered as one of the reasons for the improved time stability in this system.