A lattice dynamical investigation of the Raman and the infrared frequencies of the Dy2Ti2O7 pyrochlore spin ice compound

Synthesis, X-ray Rietveld analysis, infrared and Mössbauer spectroscopy of R 2 FeSbO 7 (R 3+ = Y, Dy, Gd, Bi) pyrochlore solid solution

“…Though seven characteristics IR transmission bands, to be consistent with the theoretical analysis, are usually observed in the range of 100−1000 cm −1 for other pyrochlore compounds [1,9,25], due to our experimental limitation we could not record IR spectra precisely below 420 cm −1 . Only three or four IR active bands are found for the pyrochlores within the phonon wavenumbers range of 400−750 cm −1 [1,[26][27][28][29][30][31], as also recorded in the present study. It is to mention that group theoretical analysis provides the irreducible representation for vibrational mode of each sub-lattice of the unit cell [5].…”

Raman and x-ray absorption spectroscopy study of the phase evolution induced by mechanical milling and thermal treatments inR2Ti2OSanjuán1, Guglieri2, Díaz‐Moreno3 et al. 2011Phys. Rev. B751450View full textAdd to dashboardCite

“…Its high frequency suggests it in some way involves Ti-O bond stretching and O-Ti-O angle bending, which according to the calculations of Gupta et al 20,21 are the internal coordinates with the highest force constants in Ti pyrochlores. A decomposition of the band using lorentzian profiles (Fig.…”

“…The most characteristic features of Ti-pyrochlore spectra are an intense band at ∼ 320 cm −1 , which includes contributions from the E g mode and from a T 2g attributed mostly to (O 2 )-A-(O 2 ) bond bending, and the A 1g band at 520 cm −1 , which involves the modulation of the only free parameter of the crystal structure, x, through the vibration of O 1 along 100 cubic axes. A peculiarity of the pyrochlore structure is that, according to calculations, 20,21 none of the Raman active modes involves to any great extent Ti-O bond stretching, a vibration that is expected to give the highest wavenumbers since it involves the shortest bonds. In addition to the allowed modes, the spectra of all titanate pyrochlores show additional features, which arise from second-order excitations, crystal field transitions, and positional disorder, if present.…”

A lattice dynamical investigation of the Raman and the infrared wavenumbers of Sr2LnTaO6 (Ln=Nd, Gd, Dy, Er, Yb)

“…This model successfully explains the lattice dynamics of many materials studied recently [6][7][8][9][10]. The short range forces are the forces that are effective up to certain neighbors only.…”