The ternary systems Al–Ga–Pd and Ga–Sb–Pd. Search for new catalytic materials

Chem. Met. Alloys 11 (2018) 6-13

https://doi.org/10.30970/cma11.0377

Oksana MatselkO, Ulrich Burkhardt, Yuri Grin, Roman GLADYSHEVSKII

The phase relations in the Pd-rich region (≥ 50 at.% Pd) of the ternary systems Al–Ga–Pd at 600°C and Ga–Sb–Pd at 500°C have been investigated by means of X-ray powder diffraction and EDX analysis. Four continuous substitutional solid solutions were found in the Al–Ga–Pd system: Al_1-xGa_xPd (FeSi-type structure, space group P2₁3, Pearson symbol cP8), (Al_1-xGa_x)₃Pd₅ (Rh₅Ge₃-type structure, space group Pbam, Pearson symbol oP16), Al_1-xGa_xPd₂ (Co₂Si-type structure, space group Pnma, Pearson symbol oP12), (Al_1-xGa_x)₂Pd₅ (Pd₅Ga₂-type structure, space group Pnma, Pearson symbol oP28). In the Pd-rich part of the Ga–Sb–Pd system, three new ternary phases were revealed: Ga_1-xSb_xPd₂ (Fe₂P-type structure, space group P‑62m, Pearson symbol hP9) and two tetragonal phases with approximate compositions close to Ga_0.5Sb_0.5Pd₃, one of which crystallizes with Pt₃Ga-type structure (space group P4/mbm, Pearson symbol tP16). The existence of the previously reported phase Ga_4.5Sb_4.5Pd₂₅ was confirmed. The isothermal sections were constructed for the Pd-rich regions of both systems. The catalytic properties of the sample Ga_28.3Sb₅Pd_66.7 were investigated for semi-hydrogenation of acetylene.

Isothermal sections of the phase diagrams of the systems Al–Ga–Pd at 600°C and ≥ 50 at.% Pd and Ga–Sb–Pd at 500°C and ≥ 50 at.% Pd.

Keywords

Aluminum / Gallium / Antimony / Palladium / Isothermal section / Phase diagram / Semi-hydrogenation of acetylene