Dielectric behavior of Nb 2O 5-doped TiO 2/epoxy thick films

Abstract

TiO 2/epoxy composite thick films containing the TiO 2 powders doped with 4 and 10 vol% Nb 2O 5 heat treated under vacuum at 1050 and 1150 °C, were prepared by the screen printing and curing steps. The Nb 2O 5-doped TiO 2 ceramic bulks demonstrated a higher effective dielectric constant at different densification environments, as compared with pure TiO 2. The dielectric properties of the TiO 2/epoxy thick films were improved if the heat-treated 4 vol% Nb 2O 5-doped TiO 2 powder was incorporated instead of the un-doped and heat-treated 10 vol% Nb 2O 5-doped TiO 2 powders. The disadvantage of the doped TiO 2 having higher dielectric loss tangent could be minimized after its powder was properly treated and mixed with epoxy to form the TiO 2/epoxy composite. A best result with the dielectric constant of 23 and the loss tangent of 0.046 was obtained for the 40 vol% TiO 2/epoxy composite thick films, where the TiO 2 powder was doped with 4 vol% Nb 2O 5 followed by calcination at 1000 °C in air and heat treatment at 1150 °C under vacuum.