Phase diagram of the La-S system

The phase diagram of the La-S system is studied by the visual-polythermal method, high-temperature annealing, microhardness measurement, metallographic and X-ray analyses. Maxima on the melting diagrams and singular points on composition vs. property curves characterize phases LaS and La3S4 as stable compounds of the daltonide type. There are two eutectic points, one with coordinates 1710 deg and 54.6+-0.5 at% of S. Formation of a continuous series of solid solutions with closely situated liquidus and solidus lines is stated