Study on novel rare-earth nitride chlorides GdNCl and Gd$_{2}$N$_{2}$Cl

We report a joint experimental and theoretical investigation of magnetic and structural properties for novel rare-earth nitride chlorides GdNCl and Gd$_{2}$N$_{2}$Cl. By using the method of gas-solid phase reaction at high temperature, a new layered rare-earth nitride chloride GdNCl was synthesized recently. The structure and morphology were characterized by X-ray diffraction and transmission electron microscope. The analysis results show that GdNCl compound has the same crystalline structure as the known phase CeNCl, which crystallized in a tetragonal structure with space group P4/nmm (No.129). The lattice constants are a $=$ b $=$ 4.42 nm, c $=$ 6.46 nm. The layered structure of GdNCl is comprised of the double Gd-N layers and Cl layers. In addition, another new stable phase Gd$_{2}$N$_{2}$Cl was also synthesized. The Gd$_{2}$N$_{2}$Cl structure belongs to a tetragonal system with P4mm space group (No.99) and lattice constants are a $=$ b $=$ 4.25 nm and c $=$ 5.92 nm. The temperature-dependent magnetic susceptibility measurements (ZFC and FC) were performed, which showed a ferromagnetic transition occurs at 70 K. The first-principle simulation based on the density functional theory was used to investigate the physical properties and structural stability of rare-earth nitride chlorides, which is consistent with the experiments.