Accessing magnetic chalcogenides with solvothermal synthesis: KFeS2 and KFe2S3

Semiconducting binary sulfides are often produced with controlled size and shape by solvothermal synthesis using amine solvents. The versatility of this method, however, has not been extended to dense ternary sulfides that include alkali and transition metal ions, which are renowned for their complex magnetic and electronic properties. We report the solvothermal synthesis of the alkali–transition metal sulfides KFeS2 and KFe2S3. The latter compound is not accessible by direct solid-state synthesis. Magnetic susceptibility measurements indicate antiferromagnetic ordering of KFeS2 and KFe2S3, which contain single and double chains of FeS4 tetrahedra, respectively. Given the ability to access KFe2S3 here, further development of this method may lead to isolation of new functional compounds.