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Abstract:
Binary gadolinium trisilicide GdSi3 was prepared by high-pressure high-temperature synthesis at typically 9.5(5) GPa and 870 K before quenching to ambient conditions. At ambient pressure, GdSi3 exhibits an exothermic decomposition at 647(10) K into the thermodynamically stable phases GdSi2-x and Si, indicating its metastable character. Powder X-ray diffraction data is consistent with the YbSi3-type crystal structure comprising slabs of condensed Si-2 dumbbells, which enclose layered arrangements of gadolinium cations. Quantum chemical analysis of the chemical bonding shows, that the framework is formed by silicon dumbbells with homopolar bonds. The magnetic moment of 8.13(8) mu(B) is consistent with Gd4f(7) (Gd3+ state) and antiferromagnetic ordering is observed below 64(1) K.
