Abstract
The authors' research work results, obtained from the Pb(Mg1/2W1/2)O3-Pb(Ni1/3Nb2/3)O3-PbTiO3 system, are summarized as follows.
(a) The specimens dielectric properties are improved by the columbite precursor method, using MgWO4 and NiNb2O6 as raw materials. The dielectric constant for the specimens sintered at 1000° to 1025°C is above 13000 at 20°C. Its temperature dependence meets the EIA standard specification, Y5U, and the Curie temperature is almost constant with regard to the sintering temperature. The dielectric properties for specimens prepared by the columbite method do not depend on the sintering temperature, unlike those prepared by the conventional method. This feature is advantageous to the dielectric property reproducibility.
(b) Since reactivities for MgO and NiO, supplied by the convenional method, are low, the Pb-W-O compound remains in the sintered specimens and results in decrease in the dielectric constant.
(c) The Curie temperature shift for specimens prepared by the conventional method, with an increase in the sintering temperature, is thought to be caused by the increased fraction of PMW component, which forms from the reaction in the remained Pb-W-O compound with MgO.
(d) DTA characterization data for the powders gave valuable information regarding how to achieve on an effective process control.
