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Disorder of Fe(2)O5 bipyramids and spin-phonon coupling in SrFe12O19 nanoparticles

2019; Elsevier BV; Volume: 45; Issue: 10 Linguagem: Inglês

10.1016/j.ceramint.2019.03.214

1873-3956

M.A.P. Buzinaro, M.A. Macêdo, B. F. O. Costa, Nilson S. Ferreira,

Advanced Condensed Matter Physics

The local structure of SrFe12O19 nanoparticles was investigated by a combined synchrotron pair distribution function (PDF), Raman and 57Fe-Mössbauer spectroscopic analysis. The PDF and 57Fe-Mössbauer spectroscopy results indicate that SrFe12O19 nanoparticles exist in an M-type hexagonal phase (∼10 nm), with a dynamically disordered trigonal bipyramidal Fe(2) site (2b). We determine that at 300 K, the timescale dynamics of Fe3+ ions near the 2b positions are between 10−15 and 10− s. The Raman spectra show anomalous shifts in all active phonon wavenumbers above TN ≈ 720 K, indicating the presence of spin-phonon coupling. The Fe3+(2b) dynamic regime motion was interpreted by taking into account changes in the electric polarization at T = TN, which discontinuously drops to zero at this temperature.