Ba 2 Ni 3 : A Missed Intermetallic Compound

The reinvestigation of the binary system Ba‐Ni revealed the existence of Ba 2 Ni 3 in the temperature range 450 °C–800 °C. Single crystals were grown at 700 °C in the presence of excess barium, followed by separation from the melt by use of the high‐temperature centrifugation aided filtration technique, HTCAF. At ambient temperature Ba 2 Ni 3 is in a metastable state which slowly transforms to the elements (side‐phases of the binary system). The extreme softness and the mechanical instability of the hygroscopic Ba 2 Ni 3 particles prevented a single crystal structure determination. The crystal structure was solved from X‐ray powder diffraction data ( P $\bar{3}$ m 1 (No. 164), a = 419.97(2) pm, c = 913.32(3) pm) and revealed Ba 2 Ni 3 to be an isotype of Sr 2 Ni 3 which was reported only recently.