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Modified Lead Calcium Titanate Ceramics with a Relatively Large Dielectric Constant for Hydrophone Applications

1994; Wiley; Volume: 77; Issue: 3 Linguagem: Inglês

10.1111/j.1151-2916.1994.tb05380.x

1551-2916

Louis M. Troilo, Dragan Damjanović, Robert E. Newnham,

Multiferroics and related materials

Modified lead titanate of the base composition (Pb,Ca)Ti‐(Co,W)O 3 + 0.01 mol% MnO was doped with 2 to 6 mol% strontium and barium to increase the dielectric constant, K , while preserving a high piezoelectric anisotropy ( d 33 /d 31 ). K was increased above 500 and a d 33 /d 31 ratio of 34/1 was achieved when the composition Pb 0.65 Ca 0.31 Sr 0.04 Ti 0.09 ‐(CO 0.5 W 0.5 ) 0.06 O 3 + 0.01 mol% MnO was fabricated. The large d 33 /d 31 resulted in an impressive hydrostatic piezoelectric coefficient ( d h = 81 × 10 —12 m 2 /V). The relatively low transition temperature ( T c = 120°C) did not result in an increased aging rate when samples were tested at 40°C and 99% humidity for 120 h after poling. A small tetragonality ratio (1.008) enabled saturation of ceramic properties at poling fields as low as 30 kV/cm at 100°C.