Exploring the dielectric polarization and ionic conduction mechanisms in sodium-containing silicate and borosilicate glasses

•Conducted a comprehensive analysis on the dielectric and electrical properties of alkali- and alkali-earth-modified glasses.•Explored the impacts of electric field and temperature conditions.•Identification of Na+ migration as a crucial factor impacting the electrical properties of glass.•Thermally stimulated depolarization current (TSDC) measurements confirmed a distinct relaxation peak at approximately 150 °C for Na+ migration.•TSDC measurements uncover an additional relaxation peak at higher temperatures, revealing another transport mechanism where Na+ is coupled to secondary ionic charge in the glass.