High‐Pressure Synthesis, Crystal Structure, and Properties of GdS 2 with Thermodynamic Investigations in the Phase Diagram Gd–S

Gadolinium disulfide was prepared by high‐pressure synthesis at 8 GPa and 1173 K. It crystallizes in the monoclinic space group P 12 1 / a 1 (No. 14) with lattice parameters a = 7.879(1) Å; b = 3.936(1) Å, c = 7.926(1) Å and β = 90.08(1)°. The crystal structure is a twofold superstructure of the aristotype ZrSSi and consists of puckered cationic [GdS] + double slabs that are sandwiched by planar sulfur sheets containing S 2 2– dumbbells. The thermal decomposition of GdS 2 proceeds via the sulfur‐deficient polysulfides GdS 1.9 , GdS 1.85 and GdS 1.77 and eventually results in the sesquisulfide Gd 2 S 3 . GdS 2 is a paramagnetic semiconductor which orders antiferromagnetically at T N = 7.7(1) K. A metamagnetic transition is observed in the magnetically ordered state.