Hydrothermal synthesis and dielectric properties of lead nickel niobate ceramics

Lead nickel niobate (Pb(Ni1/3Nb2/3)O-3) has been prepared by a newly develo ped hydrothermal process. During the hydrothermal reaction at 250 degrees C , a pyrochlore phase is formed. After calcining the 250 degrees C-hydrother mally derived precursors at 750 degrees C, a monophasic Pb(Ni1/3Nb2/3)O-3 c ompound is successfully produced. Increasing the hydrothermal temperature s ignificantly facilitates the formation of the perovskite phase. In comparis on with the solid-stale reaction, the hydrothermal process not only reduces the temperature for synthesizing Pb(Ni1/3Nb2/3)O-3, but also decreases its particle size to the submicron range. The dielectric properties of Pb(Ni1/ 3Nb2/3)O-3 strongly depend on the electric field frequency. Increasing the field frequency results in an increase in the apparent Curie temperature, w hich is associated with a decrease in the maximum dielectric permittivity. The critical exponent and diffuseness calculated by a modified permittivity -temperature equation verify the relaxer characteristics of Pb(Ni1/3Nb2/3)O -3.