A dielectric system having an exceptionally high-quality factor of 1350 at 16.8 GHz is reported as a strong candidate for glass-based low-temperature cofireable materials. The dielectrics are based on unusual (16-27)ZnO center dot 16La(2)O(3)center dot(57-68)B2O3 glass mixed with a fixed 50 wt% Al2O3 filler. The ratio of ZnO/B2O3 was found to be critical in controlling the nature of glass and, consequently, performance of the dielectric mixture. For example, 27ZnO center dot 16La(2)O(3)center dot 57B(2)O(3) glass sample having the highest Zn content resulted in the lowest softening temperature of 647 degrees C and the least porosity of similar to 6%. The enhanced densification and extensive crystallization of low loss phases, i.e., LaAl2.03(B4O10)O-0.54 and ZnAl2O4, are assumed to be responsible for better dielectric performance that resulted from the increase of Zn content in glass.