Relaxor based fine grain piezoelectric materials

The dielectric and piezoelectric properties of polycrystalline ceramics of relaxor ferroelectric lead magnesium niobate-lead titanate modified with La₂O₃ (1-x) (Pb_0.985 La_0.01) □_0.005(Mg_1/3Nb_2/3)O₃ -(x)PbTiO₃, were investigated. The compositional range of 0.2 ⩽x⩽0.4, being near the morphotropic phase boundary, was characterized. Lanthanum doping resulted in reduction of grain size, enhanced density, and a downward shift of the dielectric maximum temperature. The final microstructures of all compositions were fine with uniform grain size distributions. Room-temperature dielectric constants Ks of 5000 and piezoelectric constants d_33(s) of 500 pC/N were found for compositions near the morphotropic phase boundary (x≈0.33)