Microstructure and properties of Cr/sub 2/O/sub 3/ doped lead titanate piezoceramics

The effect of Cr/sub 2/O/sub 3/ additives (0-0.6 wt.%) on the microstructure and electrical properties of Pb/sub 0.88/Ln/sub 0.08/ (Ti/sub 0.98/Mn/sub 0.02/)O/sub 3/ ceramics, where Ln=Nd, La, is studied. In Nd-modified PT (lead titanate) ceramics, the chromium ions enter into the lattice of the perovskite structure. They behave as a grain growth promoter and accelerate densification in microstructure, and they also act as a hardener which favors higher mechanical quality factor, lower dielectric loss, and lower electrical resistivity. In the La-modified PT ceramics, with increasing Cr/sub 2/O/sub 3/ additives the tetragonality and the Curie temperature remains nearly unchanged. Thus, the chromium ions perhaps tend to mostly segregate at the grain boundaries and to act as grain growth inhibitors and binders, being responsible for increases in porosity, dielectric constant, epsilon /sub 33//sup T/, and electrical resistivity.<
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