Improving the dielectric properties of aluminoborosilicate glasses for packaging ceramics by optimizing structure

Aluminoborosilicate glasses doped with different types and amounts of rare earth oxides (Dy 2 O 3 , Eu 2 O 3 , and La 2 O 3 ) were synthesized via the sol-gel method. The impacts of doping these rare earth oxides on the glass structure, thermal, and dielectric properties were discussed. IR analyses showed that glasses doped with 2 wt.% La 2 O 3 contained more [BO 4 ] and [AlO 4 ], which optimized the polymerization degree of the glass network, and strengthened the structure. This glass had a lower dielectric constant (ε r  = 2.27) and dielectric loss (tanδ = 0.0019) at 13 GHz. Additionally, the glass transition temperature (T g ), initial crystallization temperature (T c ), and thermal stability (△T) all increased with higher rare earth ionic radius (Dy 3+ , Eu 3+ , La 3+ ), due to decreased non-bridging oxygen levels (NBO) of [SiO 4 ] and increased [BO 4 ] and [AlO 4 ] in the glass grid. However, co-doped rare earth oxide glasses inhibited conversion from [BO 3 ] to [BO 4 ] when equal amounts of La 2 O 3 and Dy 2 O 3 or Eu 2 O 3 were added, which resulted in a looser glass network and a higher dielectric constant. As La 2 O 3 gradually replaced Dy 2 O 3 or Eu 2 O 3 , the dielectric constant initially increased and then decreased, ascribed to the shift polarization of RE 3+ in the glass structure.