Crystal growth and the electronic structure of Tl3PbCl5

Total and partial densities of states of constituent atoms of two tetragonal phases of Tl3PbCl5 (space groups P4(1)2(1)2 and P4(1)) have been calculated using the full potential linearized augmented plane wave (FP-LAPW) method and Korringa-Kohn-Rostoker method within coherent potential approximation (KKR-CPA). The results obtained reveal the similarity of occupations of the valence band and the conduction band in the both tetragonal phases of Tl3PbCl5. The FP-LAPW and KKR-CPA data indicate that the valence band of Tl3PbCl5 is dominated by contributions of the Cl 3p-like states, which contribute mainly to the top and the central portion of the valence band with also significant contributions throughout the whole valence-band region. Further, the bottom of the valence band of Tl3PbCl5 is composed mainly of the Tl 6s-like states, while the bottom of the conduction band is dominated by contributions of the empty Pb 6p-like states. The KKR-CPA results allow to assume that the width of the valence band increases somewhat while band gap, E-g, decreases when changing the crystal structure from P4(1)2(1)2 to P4(1). The X-ray photoelectron core-level and valence-band spectra for pristine and Ar+-ion-irradiated surfaces of a Tl3PbCl5 monocrystal grown by the Bridgman-Stockbarger method have been measured. (C) 2011 Elsevier Ltd. All rights reserved.