A new form of superconducting Josephson tunnel junction has been developed in which superconducting electrons tunnel through thick (∼600 Å) barriers formed by evaporated Ge‐Sn mixtures. By varying barrier composition and thickness a wide range of junction I‐V characteristics can be obtained. For thick barriers, or barriers with low Sn content, high tunneling resistances and no supercurrent result. Barriers of intermediate thickness or with moderate Sn content yield junctions with electrical properties very similar to conventional hysteretic oxide‐barrier junctions. Thin, or high Sn content barriers, give junctions with nonhysteretic I‐V characteristics similar to those expected for an ideal superconducting microbridge. The nonhysteretic junctions could be used in nonlatching Josephson logic circuits. In addition, the nonhysteretic junctions show excellent microwave response, and may be useful for millimeter‐wave mixing and detection.