Single crystal growth and the electronic structure of orthorhombic Tl3PbBr5: A novel material for non-linear optics

• Published in: Optical materials 2013-03, Vol.35 (5), p.1081-1089
• Main Authors: Khyzhun, O.Y., Bekenev, V.L., Parasyuk, O.V., Danylchuk, S.P., Denysyuk, N.M., Fedorchuk, A.O., AlZayed, N., Kityk, I.V.
• Format: Article
• Language: English
• Subjects: Ab initio calculations; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Crystal growth; Crystals; Electron states; Electronic band structure; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Methods of electronic structure calculations; Nonlinear optical crystals; Nonlinear optics; Nonlinearity; Optical materials; Optical susceptibility, hyperpolarizability; Optics; Physics; Plane waves; Semiconductors; Single crystals; Spectra; Valence band; X-ray photoelectron spectroscopy; X-rays
• ISSN: 0925-3467; 1873-1252
• DOI: 10.1016/j.optmat.2012.12.008

► XPS spectra of Tl3PbBr5 single crystals have been measured. ► High chemical stability of surface is characteristic of the Tl3PbBr5 single crystal. ► Electronic structure of Tl3PbBr5 has been calculated by the FP-LAPW method. ► The valence band is dominated by contributions of Br 4p states. ► Second order non-linear optical susceptibilities of Tl3PbBr5 have been investigated. The X-ray photoelectron core-level and valence-band spectra for pristine and Ar+-ion irradiated surfaces of a Tl3PbBr5 single crystal grown by the Bridgman–Stockbarger method have been measured. The present X-ray photoelectron spectroscopy (XPS) results reveal high chemical stability of Tl3PbBr5 single crystal surface. Total and partial densities of states of constituent atoms of low-temperature (LT) orthorhombic Tl3PbBr5 phase (space group P21212) have been calculated using the full potential linearized augmented plane wave (FP-LAPW) method. The FP-LAPW data reveal that contributions of the Br 4p-like states dominate in the valence band of LT-Tl3PbBr5; they contribute mainly into the top and the central portion of the valence band with also significant contributions throughout the whole valence-band region. The bottom of the valence band of LT-Tl3PbBr5 is composed mainly of the Tl 6s-like states, whilst the unoccupied Pb 6p- and Tl 6p-like states dominate at the bottom of the conduction band. We have explored the crystallochemistry and origin of the chemical bonds in Tl3PbBr5 with respect to the use as mid-IR non-linear optical crystals. Comparison of the spectral dependence to the second order susceptibilities for the titled crystals is performed with respect to the 3.39 μm illuminated crystals. Possibility of the use of Tl3PbBr5 crystals as IR operated non-linear optical crystals is discussed.