Patent ID: 6939822

Claim:
A method for making a dielectric ceramic having a ceramic structure comprising crystal grains and grain boundaries between the crystal grains, the crystal grains comprising a main component represented by the formula ABO 3 in which the average rare earth element concentration in the interior of the crystal grains is about 50% or less of the average rare earth element concentration at the grain boundaries, and about 20% to 70% of the crystal grains, by number, have a rare earth element concentration in the center of the crystal grain of at least about 1/50 of the maximum rare earth element concentration in a region extending inward from the surface by a distance corresponding to about 5% of the diameter of the crystal grain, comprising: mixing AO, BO 2 , and at least one rare earth element, calcining the mixture in air, and pulverizing the mixture to prepare a modified ABO 3 powder in which the rare earth element is present in the interiors of the particles; mixing AO and BO 2 , calcining the mixture in air, and pulverizing the mixture to prepare an ABO 3 powder in which the rare earth element is not present in the interiors of the particles; and mixing the modified ABO 3 powder, the ABO 3 powder, and additional rare earth element and firing the mixture, wherein A is barium or barium and at least one of calcium and strontium, and B is titanium or titanium and at least one of zirconium and hafnium.