Samarium(III) sulfide
Samarium(III) sulfide (Sm2S3) is a chemical compound of the rare earth element samarium, and sulfur. In this compound samarium is in the +3 oxidation state, and sulfur is an anion in the −2 state.
Production
One way to make samarium(III) sulfide is to heat samarium metal with sulfur. Another way to make a thin film is to alternatively soak in samarium(III) chloride tartaric acid complex, and sodium thiosulfate.[1]
Properties
The low temperature α form crystallises in the orthorhombic crystal system. The unit cell has dimensions a=7.376, b=3.9622 c=15.352 Å with volume 448.7 Å3. There are four of the formula in each unit cell (Sm8S12). The density comes out to 5.88 kg/liter. There are two kinds of samarium coordination in the solid, one is eight coordinated with sulfur surrounding in a bicapped trigonal pyramid. The other is a sevenfold capped distorted octahedral arrangement. This structure is similar to other light rare-earth element sulfides.[2]
Samarium(III) sulfide is a semiconductor with a band gap of 1.7 eV.[3] As a thin film on high area electrodes, it is under investigation as a super capacitor dielectric, with specific capacitances of up to 360 Farads per gram.[4]
Related
Related samarium sulfides include the monosulfide SmS and the mixed valent Sm3S4 which are also semiconductors.[5] KSm2CuS6 is a layered quaternary sulfide.[6]