Method of making sulfide alloys exhibiting thermal bistability

A new ternary sulfide alloy exhibits a metal-semiconductor phase transition with hysteresis as a function of temperature. One embodiment of the bistable material includes barium, cobalt, nickel and sulfur in amounts in accordance with the formula Ba(Co1-x Nix)S2-y, and x is between 0 and 1 and y varies from 0 to 2.