Gadolinium trisilicide − a paramagnetic representative of the YbSi3type series

Binary gadolinium trisilicide GdSi3was prepared by high-pressure high-temperature synthesis at typically 9.5(5) GPa and 870 K before quenching to ambient conditions. At ambient pressure, GdSi3exhibits an exothermic decomposition at 647(10) K into the thermodynamically stable phases GdSi2–xand Si, indicating its metastable character. Powder X-ray diffraction data is consistent with the YbSi3-type crystal structure comprising slabs of condensed Si2dumbbells, 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) µBis consistent with Gd4f7(Gd3+state) and antiferromagnetic ordering is observed below 64(1) K.