Disclosed may be a phase change material alloy, a phase change memory device including the same, and methods of manufacturing and operating the phase change memory device. The phase change material alloy may include Si and Sb. The alloy may be a Si—O—Sb alloy further including O. The Si—O—Sb alloy may be SixOySbz, wherein, when x/(x+z) may be x1, 0.05≦x1≦0.30, 0.00≦y≦0.50, and x+y+z may be 1. The Si—O—Sb alloy may further comprise an element other than Si, O, and Sb.