Abstract
Lithium niobate polycrystalline ceramics are fabricated by the sol-precipitate method. The addition of 9 m/o (MgF 2 + LiF) reduces the sintering temperature of LiNbO 3 . A MgO layer, resulting from the partial hydrolysis of MgF 2 , is observed on the top of the as-sintered surface in (MgF 2 + LiF) doped specimens. Doping of 9 m/o (MgF 2 + LiF) decreases the activation energy, but increases the pre-exponential term for the ion conduction. It is argued that the increase of the dielectric constant in proportion to the increase of test temperature is attributed to the space charge polarization between grains of LiNbO 3 ceramics. Addition of MgF 2 and LiF promote the space charge polarization. © 1990.