DIELECTRIC-SPECTROSCOPY OF MGTIO3-BASED CERAMICS IN THE 10(9)-10(14) HZ REGION

Magnesium titanate (MgTiO3) powder was prepared by a chemical route (P echini method) and different dopants were added to prepare several com positions. These pure and doped compositions were sintered in air and dense ceramics were obtained. The pure MgTiO3 samples were also subjec ted to different heat treatments during sintering. Complex permittivit y spectra of ceramic samples were determined by various techniques in the 10(9)-10(14) Hz range. These techniques included infrared spectros copy in transmission and reflectivity modes and microwave dielectric m easurements. Extrapolation to microwave frequencies from infrared data , according to the proportionality epsilon''(nu) is-perpendicular-to n u, agrees quite well with the microwave data measured at 8 GHz and it is a useful procedure to estimate intrinsic microwave losses. Fast coo ling from high temperatures of MgTiO3 samples increased dielectric los s, probably due to a structural disorder. Dopants have two types of ef fect depending on whether they form a distinct second phase or a solid solution with MgTiO3. In this last case intrinsic losses are strongly affected.