The ternary Ho–V–Ga system at 750 °C, and new rare earth vanadium and chromium gallides

The ternary Ho–V–Ga phase diagram has been investigated at 750 °C by means of powder X–ray diffraction analysis and energy–dispersive X–ray spectroscopy. The studied system is characterized by the absence of detectable solubility for the binary compounds and by the existence of two new ternary phases, HoV₂Ga₄ (YbMo₂Al₄ structure type) and Ho₄V_1–xGa₁₂ (0 ≤ x < 1, related to the AuCu₃ structure type). Isostructural representatives REV₂Ga₄ have been found for RE = Tb, Dy and Tm and confirmed for RE = Er. Additionally, the formation of the new RECr₄Ga₈ phases (related to the ScFe₆Ga₆ structure type) with RE = Gd–Tm has been revealed. Structural peculiarities and interactions of the atoms in the HoV₂Ga₄ and HoCr₄Ga₈ compounds have been briefly discussed. - Highlights: • Isothermal section of the Ho–V–Ga at 750 °C was investigated. • Five new REV₂Ga₄ compounds with YbMo₂Al₄ type were studied. • Six new RECr₄Ga₈ phases with ScFe₆Ga₆ type were discovered.