Properties of Y₂Ti₂O₇ based microwave dielectric ceramics doped with lead titanate

A new kind of Y₂Ti₂O₇ microwave dielectric ceramics with middle dielectric constant was studied with an addition of lead titanate. The properties were characterized and measured by X-ray diffraction, scanning electron microscopy, network analyzer and impedance analyzer. The phase composition and dielectric properties of ceramics doped with PbTiO₃ were investigated. The results showed that the main phase of PbTiO₃ doped ceramics did not change and still exhibited a kind of pyrochlore structure. It could be speculated that PbTiO₃ came into the Y₂Ti₂O₇ crystal lattice. Pb²⁺ was incorporated into Y³⁺ site on the A site of pyrochlore structure, which also lead to the formation of a new kind of vacancy defects. The lattice diffusion rates increased due to the breaking of order in the structure, so the sintering temperature was effectively decreased. As a small amount of Pb elements was added, the lattice constant increased, the volume of unit cell became larger, the Ti⁴⁺ ions had more space to move, the total polarization of the materials increased, thereby the dielectric properties were enhanced, in particular, the value of dielectric constant slightly increased. When the amount of lead titanate was 2%, Y₂Ti₂O₇ ceramics sintered at 1345°C, exhibited better dielectrical properties: ε_r=56.4, tan δ=1.21×10^-3, Q×f=4776 GHz.