Enhanced Quality Factor of Zinc Lanthanum Borates-Based Dielectrics via the Control of ZnO/B2O3 Ratio

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 · 16La 2 O 3 · (57-68)B 2 0 3 glass mixed with a fixed 50 wt% Al 2 O 3 filler. The ratio of ZnO/ B 2 0 3 was found to be critical in controlling the nature of glass and, consequently, performance of the dielectric mixture. For example, 27nO · 16La 2 O 3 · 57B 2 O 3 glass sample having the highest Zn content resulted in the lowest softening temperature of 647°C and the least porosity of ~6%. The enhanced densification and extensive crystallization of low loss phases, i.e., LaA) 2.03 (B 4 O 10 )O 0.54 and ZnAl 2 O 4 , are assumed to be responsible for better dielectric performance that resulted from the increase of Zn content in glass.