Structural study and luminescence of TlSrLa(AsO4)2

This work presents the crystal structure and luminescent properties of TlSrLa(AsO4)2. In this phase Tl+ ions are located in large tunnels delimited by chains of alternating (AsO4) and (Sr,La)O8 polyhedra. Thallium atoms are eightfold coordinated with C1 symmetry. Large TlO distances are observed revealing a low stereochemical activity of the 6s2 lone pair. Excitation and emission spectra of Tl+ in TlSrLa(AsO4)2 showed broad bands at lower energy than those observed in previous works. Excitation spectra are decomposed into multiple Gaussian bands and a theoretical analysis is made to explain the number of observed components. Two Gaussian components are revealed for emission spectra.