Provided are novel azeotrope-like compositions of SF6 and N2O, as well as methods of using the same. Also provided are methods of using SF6 compositions, including azeotrope-like compositions, including a method for suppressing an electric arc or corona discharge and a method for flame suppression. Further provided are electrical devices using such SF6 compositions as a dielectric insulating gas and rigid closed-cell foams having such SF6 compositions within the cells, wherein the foam is both thermally and electrically insulative.