MICROWAVE DIELECTRIC-PROPERTIES OF DOPED BA-6-X(SM1-Y'NDY)(8+2X 3)TI18O54 OXIDES/

Dielectric ceramic compositions for microwave applications belonging t o the (BaO)-(Nd2O3)-(Sm2O3)-(TiO2) phase diagram were studied. Two com positions were selected for study, the doping effect of MnO2, WO3, CaO on dilatometry, microstructure and microwave properties. The effect o f the nature and the amount of dopants on microstructure and microwave properties were clearly demonstrated. The effect of the addition of 1 or 2 wt % WO3, MnO2 and CaO to Ba-4 (Sm-0.6, Nd-0.4)(9.33)Ti18O54 and Ba-3.75 (Sm0.5Nd0.5)(9.5)Ti18O54 was studied. It was found that these two compositions lead to dense ceramics exhibiting excellent microwav e properties, for instance epsilon = 74-81, Qx f up to 9000 Ghz at 3 G hz and tau(f) around + 9 p.p.m. degrees C-1.