Electronic structure and laser induced piezoelectricity of a new quaternary compound TlInGe3S8

Abstract

New quaternary thallium indium germanium sulfide TlInGe3S8 was synthesized by co-melting high-purity elements at 1270 K. Its crystal structure was determined by X-ray single crystal method; it is a representative of its own structural type. TlInGe3S8 crystallizes in monoclinic space group Р21/a with lattice parameters a = 6.7245 (2) Å, b = 38.077 (1) Å, c = 6.7922 (2) Å, β = 90.616 (2)°, Z = 5. The as-synthesized TlInGe3S8 single crystal was probed with X-ray photoelectron spectroscopy (XPS). In particular, the XPS valence-band and core-level spectra were measured for pristine and Ar+ ion-irradiated surfaces of the TlInGe3S8 single crystal. The XPS measurements reveal partial sensitivity of the TlInGe3S8 single crystal surface with respect to Ar+ ion-irradiation. Comparison on a common energy scale of the X-ray emission S Kβ1,3 and the XPS valence-band spectrum allows for concluding that the main contributions of the S 3p states occur in the upper part of the valence band of TlInGe3S8, with also their substantial contributions in other valence band regions. Photoinduced piezoelectricity was explored versus the power of two coherent laser beams at 1540 nm Er:glass laser beams.