Substitution of CaO by BaO to improve the microwave dielectric properties of CaO-Li2O-Sm2O3-TiO2 ceramics

Sintered CaO-Li2O3-Sm2O3-TiO2(16:9:12:63) composition (CLST) at 1325 degree sC shows microwave dielectric properties: epsilon (r)=104.1, Q*f value=4320 GHz, and tau (F)=13.2 ppm/C-2. When BaO is used to substitute CaO in the C LST composition to form CaO-BaO-Li2O-Sm2O3-TiO2=16-x:x:9:12:63 (x=2 and 4 f or CBLST2 and CBLST4), the sintered CBLST2 and CBLST4 ceramics show coexist ence of two phases. the perovskite CaO-Li2O3-Sm2O3-TiO2 (CLST) phase and Ba Sm2Ti4O12 (BST). As the BaO content increases from 0 to 4 mol%, the dielect ric constant of CBLST ceramics decreases from 104.1 to 94.5, the Q*f value increases from 4320 to 6740, and the tau (f) value changes from 13.2 to 3.2 4 ppm/degreesC. (C) 2001 Elsevier Science Ltd and Techna S.r.l. All rights reserved.