Superconductivity by alloying the topological insulator <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:mi>SnBi</mml:mi></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mrow><mml:mi>Te</mml:mi></mml:mrow><mml:mn>4</mml:mn></mml:msub></mml:math>

Alloying indium into the topological insulator ${\mathrm{SnBi}}_{2}{\mathrm{Te}}_{4}$ induces bulk superconductivity with critical temperatures ${T}_{c}$ up to 1.85 K and upper fields about 14 kOe. This is confirmed by electrical resistivity, heat capacity, magnetic susceptibility measurements. The capacity shows a discontinuity at temperature dependence below consistent weak coupling BCS theory, suggests superconducting gap near 0.25 meV. type-II surface states have been verified photoemission. A simple picture analogies isostructural ${\mathrm{MnBi}}_{2}{\mathrm{Te}}_{4}$, in which natural heterostructure hosts complementary properties on different sublattices, motivates new interest this large family of compounds. existence both ${\mathrm{Sn}}_{1\ensuremath{-}\mathrm{x}}{\mathrm{In}}_{\mathrm{x}}{\mathrm{Bi}}_{2}{\mathrm{Te}}_{4}$ identifies these materials as promising candidates for study superconductivity.