X-ray absorption fine structure studies of Mn coordination in doped perovskite SrTiO3

abstract

The coordination of Mn in doped SrTiO3 ceramics having nominal compositions SrTi0.98Mn0.02O3 and Sr0.98Mn0.02TiO3 was analyzed using x-ray absorption fine structure (XAFS) measurements. As expected, Mn4+ substitution for Ti4+ leads to Mn occupancy of the octahedral B-sites of ABO(3) perovskite lattice with a Mn-O bond distance of 1.902 A degrees (compared to 1.953 A degrees for Ti-O) and no significant local distortions around the Mn atoms. In contrast, for the composition Sr0.98Mn0.02TiO3, Mn segregates to both the A-sites (as Mn2+) and the B-sites (predominantly as Mn4+). Extended XAFS confirms strong (approximate to 0.77 A degrees) displacements of Mn2+ cations off the ideal A-site positions along << 001 >> directions with a significant distortion of several coordination shells around the dopant atoms.

keywords

STRONTIUM-TITANATE CERAMICS; SPECTRA

subject category

Physics

authors

Levin, I; Krayzman, V; Woicik, JC; Tkach, A; Vilarinho, PM

our authors

acknowledgements

Use of the National Synchrotron Light Source, Brookhaven National Laboratory, was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886.

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