The effect of glass additives on the densification , phase evolution, microstructure and microwave dielectric properties of Ba(Mg1;3
Ta2i3)03 (BMT) was investigated . Different weight percentages of quenched glass such as B203 , Si02, B203-SiO2, ZnO-B203,
5ZnO-2B2O3, Al203-SiO2, Na20-2B203.10H20, BaO-B203-SiO2, MgO-B203-SiO2, PbO-B203-SiO2 , ZnO-B203-SiO2 and
2MgO-Al203-5SiO2 were added to calcined BMT precursor . The sintering temperature of the glass -added BMT samples were
lowered down to 1300 °C compared to solid-state sintering where the temperature was 1650 °C. The formation of high temperature
satellite phases such as Ba5Ta4O15 and Ba7Ta6O22 were found to be suppressed by the glass addition . Addition of glass systems such
as B203, ZnO-B203, 5ZnO-2B203 and ZnO-B203-SiO2 improved the densification and microwave dielectric properties. Other
glasses were found to react with BMT to form low-Q phases which prevented densification . The microwave dielectric properties of
undoped BMT with a densification of 93 . 1 % of the theoretical density were Cr = 24 . 8, Tr = 8 ppm/°C and Q„ x f= 80,000 GHz. The
BMT doped with 1.0 wt% of B203 has Q„ x f = 124,700GHz, Cr = 24.2, and T f = -1.3 ppm /°C. The unloaded Q factor of 0.2 wt%
ZnO-B203-doped BMT was 136,500 GHz while that of 1.0 wt% of 5ZnO-2B203 added ceramic was Q„ x f= 141,800 GHz . The best
microwave quality factor was observed for ZnO -B203-SiO2 (ZBS) glass-added ceramics which can act as a perfect liquid-phase
medium for the sintering of BMT. The microwave dielectric properties of 0.2wt% ZBS-added BMT dielectric was
Q„ x f= 152,800 GHz, F,= 25.5, and Tr = - 1.5 ppm/°C
Dielectric ceramics based on solid solution phases of [RE1_x= REr]TiNb06, where REI_s = Nd, Pr, Sm and RE' = Dy, Gd and Y, were prepared by the conventional solid-state ceramic route for values of x. The ceramic samples are characterized by X-ray diffraction and microwave methods. Ceramics based on RE (Pr, Nd and Sm) belonging to aeschynite group shows positive value of Tf and those based on RE (Gd, Dy and Y) belonging to euxenite group show negative value of r f. The solid solution phases between the aeschynite and the euxenite group shows intermediate dielectric constant and r f values. The results indicate the possibility of tailoring the dielectric properties by varying the composition of the solid solution phases. The range of solid solubility of euxenite in aeschenite and aeschenite
in euxenite are different for different rare earth ions