Analysis of the Dielectric Properties of Alkali-Free Aluminoborosilicate Glasses by Considering the Contributions of Electronic and Ionic Polarizabilities in the GHz Frequency Range.

Recently, the investigation of the dielectric properties of glasses in the GHz frequency range has attracted great interest for use in printed circuit boards (PCBs) as a reinforcing material in the application of high-speed 5G/6G communications. In particular, glasses with low dielectric properties are a prerequisite for high-frequency applications. In this study, the GHz dielectric properties of alkali-free aluminoborosilicate glasses without and with La 2 O 3 were analyzed using the Clausius-Mossotti equation where both the electronic and ionic polarizabilities contribute to the dielectric constant. The dielectric polarizability (α D ) and oxide ion polarizability (α O2- ) were calculated from the measured dielectric constant (ε GHz ) at 1 GHz and the glass density. The dielectric constants (ε opt ) at the optical frequencies and electronic polarizabilities (α e ) of the glasses were calculated from the refractive index measured at 633 nm and the glass density. The ε GHz values were found to be significantly higher than the ε opt values in both series of glasses, due to the ionic polarizability (α i ), which contributes additionally to the ε GHz . The lower dielectric constants of the La 2 O 3 -incoporated glasses than that of the reference glass without La 2 O 3 may be due to the lower ionic polarizability originated from the incorporation of the high cation field strength of the La 3+ ions.