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: http://semiconductors.phys.msu.ru/publ/pbsns2e.html
Дата изменения: Sat May 26 15:29:42 2007 Дата индексирования: Mon Oct 1 20:28:04 2012 Кодировка: |
A.I. Lebedev, I.A. Sluchinskaya, I.H. Munro
Moscow State University, Vorob'evy gory, Moscow, 119899 Russia
Daresbury Laboratory, Warrington, WA4 4AD UK
The local environment of Pb atoms in the PbxSn1-xS solid solutions with cubic and orthorhombic structure was studied by EXAFS spectroscopy. The shortest Pb-S distance in samples with orthorhombic structure was found to be smaller by 0.2 A than that in cubic-lattice samples, which is a sign of stereochemical activity of the 6s2 lone electron pair of a Pb atom. The metal atom arrangement reveals strong short-range order, which results in the formation of -Pb-Sn-Pb-Sn-... zigzag chains aligned with the c axis (in the Pbnm system) in orthorhombic samples. It was shown that the onset of such short-range order in Pb0.5Sn0.5S can initiate the formation of superstructures belonging to the C2v7 or C2v2 space groups.Keywords: x-ray absorption spectroscopy, lead tin sulfide sulphide, semiconductor solid solutions, synchrotron radiation