Abstract
Five new compounds belonging to the ABaMQ(4) family were synthesized by solid-state chemistry at 1123 K. The compounds RbBaPS4, CsBaPS4, CsBaVS4, RbBaVSe4, and CsBaVSe4 are isostructural and have the TlEuPS4 structure type. They crystallize in space group D-2h(16)-Pnma of the orthorhombic system. Their structure consists isolated MQ(4) tetrahedra separated by A and Ba atoms to form a salt-like structure. Density Functional Theory (DFT) calculations of the electronic structures with the use of the HSE functional suggest that the compounds are semiconductors with calculated band gaps of 33 eV (RbBaPS4), 3.4 eV (CsBaPS4), 23 eV (CsBaVS4), and 1.6 eV (RbBaVSe4).