Determination of the temperature coefficient distribution of dielectric ceramics using scanning photothermal dielectric microscopy

Two-dimensional images of the distribution showing the temperature coefficient of the dielectric constant for two types of two-phase composite ceramics composed of TiO₂-Bi₂Ti₄O₁₁ and BaTi₄O₉-BaPr₂Ti₄O₁₂ were obtained using scanning photothermal dielectric microscopy. The images of the TiO₂-Bi₂Ti₄O₁₁ ceramic showed that the TiO₂ and Bi₂Ti₄O₁₁ grains had negative and positive temperature coefficients, respectively, and that the macroscopic averaged temperature coefficient of the ceramic was relatively low because of the cancellation of the opposite signs of the coefficients. On the other hand, the images of the BaTi₄O₉-BaPr₂Ti₄O₁₂ ceramic showed that the temperature coefficient of both grains had the same sign (negative), although their absolute values were quite different.