XAFS studies of the local structure and charge state of the Pr impurity in SrTi[O.sub.3]

• Published in: Physics of the solid state Vol. 54; no. 5; pp. 975 - 979
• Main Authors: Sluchinskaya, I.A, Lebedev, A.I, Erko, A
• Format: Journal Article
• Language: English
• Published: Springer 01.05.2012
• Subjects: Rare earth metals; Solid solutions
• ISSN: 1063-7834; 1090-6460
• DOI: 10.1134/S1063783412050381

Solid solutions of ([Sr.sub.1-x][Pr.sub.x])Ti[O.sub.3] 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 [greater than or equal to] 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 [Pr.sup.3+] and [Sr.sup.2+]. It has been found that, in the second shell, there occurs a significant repulsion of the [Pr.sup.3+] and [Ti.sup.4+] ions, which is responsible for the weak dependence of the lattice parameter in the solid solution on the praseodymium concentration.