A feedthrough assembly includes: a ferrule； an insulating structure； and a seal fixedly securing the insulating structure within the ferrule, the seal comprising a glass and single-phase particulate dispersed therein； wherein the glass includes: 25% to 40% B2O3； 0 to 25% CaO； 0 to 25% MgO； 0 to 25% SrO； 0 to 10% La2O3； 5% to 15% SiO2； and 10% to 20% Al2O3； wherein all percentages are mole percentages of the glass.
