XAFS studies of the local structure and charge state of the Pr impurity in SrTiO3
Solid solutions of (Sr1 − xPrx)TiO3 have been studied using X-ray methods. It has been shown that, with an increase in the praseodymium concentration, the temperature of the structural phase transition to the phase with space group I4/mcm increases and, at x ≥ 0.15, the structure at 300 K is tetragonal. X-ray absorption fine structure (XAFS) spectroscopy studies have revealed that Pr ions are predominantly in the charge state 3+ and occupy the Sr sites. No indications of the off-centering of Pr atoms at the Sr sites have been revealed. The local environment of Pr atoms is characterized by a strong relaxation of the oxygen atoms, the value of which corresponds to the difference between the ionic radii of Pr3+ and Sr2+. It has been found that, in the second shell, there occurs a significant repulsion of the Pr3+ and Ti4+ ions, which is responsible for the weak dependence of the lattice parameter in the solid solution on the praseodymium concentration.
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- 7.A. I. Lebedev, I. A. Sluchinskaya, V. N. Demin, and I. Manro, Izv. Akad. Nauk, Ser. Fiz. 60(10), 46 (1996).Google Scholar