Single crystal growth and electronic structure of TlPbI3

High-quality inclusion-free TlPbI3 single crystals have been grown using Bridgman-Stockbarger method. The electronic structure of TlPbI3 is studied by using the possibilities of X-ray photoelectron spectroscopy (XPS). For the TlPbI3 crystal, XPS core-level and valence-band spectra for both pristine and Ar+ ion-bombarded surfaces are recorded. The present XPS data indicate that the TlPbI3 single crystal surface is somewhat sensitive with respect to Ar+ ion-bombardment. In particular, the XPS measurements reveal that thallium and lead atoms are in the formal valence +1 and +2, respectively, on the pristine TlPbI3 single crystal surface. Further, the 3.0 keV Ar+ ion-bombardment of the surface induces partial transformation of lead ions to lower valence state, namely Pb; however, no partial loss of iodine atoms belonging to TlI8 polyhedra occurs due to the Ar+ ion-bombardment of the TlPbI3 surface because after such a treatment thallium remains exclusively in the formal valence +1. The present XPS results indicate that low hygroscopicity is characteristic of the TlPbI3 single crystal surface. Photoinduced birefringence profiles in TlPbI3 are explored. (C) 2016 Elsevier B.V. All rights reserved.