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Effects of Niobium Substitution for Titanium on Electrical Properties in Single Crystals of Lead Bismuth Titanate

1997; Institute of Physics; Volume: 36; Issue: 10A Linguagem: Inglês

10.1143/jjap.36.l1321

1347-4065

In-Sook Yi Miyayama,

Acoustic Wave Resonator Technologies

Single crystals of Nb-doped lead bismuth titanate, PbBi 4 (Ti 0.99 Nb 0.01 ) 4 O 15 , were synthesized by the vertical gradient freeze method, and electrical properties of the crystals were investigated by measuring DC conductivity, dielectric permittivity, and the D-E hysteresis loop. The p-type conductivity decreased upon Nb doping by as much as one to two orders of magnitude in the direction parallel to the bismuth layer. The dielectric permittivities decreased at Curie temperature ( T c ) but increased about threefold at room temperature upon Nb doping. From the D-E hysteresis curves, the absence of spontaneous polarization in the direction perpendicular to the bismuth layer was confirmed in undoped and Nb-doped single crystals. The coercive field decreased in the direction parallel to the bismuth layer upon Nb doping at room temperature. It was found that Nb doping has effects to give a lower conductivity, favorable to high-temperature poling for polycrystals, and to improve ferroelectricity and dielectric permittivity at room temperature.