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Abstract
Dielectric and pyroelectric properties of relaxor ferroelectric in the (1 - x)(Pbl-3y/2Lay)(Mg1/3Ta2/3)-xPbTiO3 (PMT-PT) solid solution series have been investigated. The dielectric constant and loss of ceramic samples were determined. The pyroelectric coefficient and spontaneous polarization were measured by the static Byer-Roundy method as a function of temperature for various compositions in the La-doped PMT-PT system. The position of the morphotropic phase boundary in PMT-PT appeared not to be affected by La2O3 addition. Lanthanum-doping resulted in a reduction of grain size and shifting of the Tc by about 25°C/mole% downward in the PMT-PT system. Dielectric constants and pyroelectric coefficients for La-doped PMT-PT are much larger compared to the undoped PMT-PT system. Further additions of La2O3 could be used to shift the Tc downward without significantly changing the dielectric behavior. In the present study no clear morphotropic phase boundary (MPB) has been identified. A two-phase region is indicated between x ⋍ 0.27–0.4.
