Phase development and sintering behavior and dielectriccharacteristics of the composites of tungsten bronze structured Ba2NaNb5O15(BNN) and perovskite structured BaTiO3 (BT) were examined as afunction of molar ratio x in (1-x)Ba2NaNb5O15-xBaTiO3.A wide range of solid solution of BT in BNN was observed up to x=0.4~0.6, andthe lattice constants increased with BT contents. Since the solid solution of BTexpelled Na ions from BNN, liquid phase with excess Na might be produced duringsintering and resulted in accelerated densification and abnormal grain growth.More BT addition in BNN over the solubility limit produced a second phase of Ba6Ti7Nb9O40together with BT, and those phases played a role as grain growth inhibitors. TheCurie temperature (TC) and the maximum dielectric constant of BNN decreased asthe content of BT increased. Besides, when BNN is added to BT, the solubilitylimit of BNN in BT was very narrow compared to the case of BT addition to BNN,which resulted in the generation of Ba6Ti7Nb9O40second phase. The addition of BT to BNN also shifted the TC to lowertemperature. In the case of x=0.6, two dielectric relaxation peaks were observedwhich is believed due to the coexistence of BNN and BT in the sample.
