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 (Dy2O3, Eu2O3, and La2O3) 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.% La2O3 contained more [BO4] and [AlO4], which optimized the polymerization degree of the glass network, and strengthened the structure. This glass had a lower dielectric constant (epsilon r = 2.27) and dielectric loss (tan delta = 0.0019) at 13 GHz. Additionally, the glass transition temperature (Tg), initial crystallization temperature (Tc), and thermal stability (oT) all increased with higher rare earth ionic radius (Dy3+, Eu3+, La3+), due to decreased non-bridging oxygen levels (NBO) of [SiO4] and increased [BO4] and [AlO4] in the glass grid. However, co-doped rare earth oxide glasses inhibited conversion from [BO3] to [BO4] when equal amounts of La2O3 and Dy2O3 or Eu2O3 were added, which resulted in a looser glass network and a higher dielectric constant. As La2O3 gradually replaced Dy2O3 or Eu2O3, the dielectric constant initially increased and then decreased, ascribed to the shift polarization of RE3+ in the glass structure.