Raman and infrared spectroscopy of Sr2B'UO6 (B' = Ni; Co) double perovskites

A.F.L. MOREIRA; A.F. GARCÍA-FLORES; E. GRANADO; N.E. MASSA; R.M. PINACCA; J.C. PEDREGOSA; R.E. CARBONIO; A. MUÑOZ; M.J. MARTÍNEZ-LOPE; J.A. ALONSO; L. DEL CAMPO; D. DE SOUSA MENESES; P. ECHEGUT

VIBRATIONAL SPECTROSCOPY

ELSEVIER SCIENCE BV

Lugar: New York; Año: 2010 vol. 54 p. 142 - 147

0924-2031

Temperature dependent normal modes and lattice thermal expansion of Sr2BUO6 (B = Ni, Co) double perovskites were investigated by Raman/infrared spectroscopies and synchrotron X-ray diffraction, respectively. Monoclinic crystal structures with space group P21/n were con.rmed for both compounds, with no clear structural phase transition between 10 and 400 K. As predicted for this structure, the .rstorder Raman and infrared spectra show a plethora of active modes. In addition, the Raman spectra reveal an enhancement of the integrated area of an oxygen stretching mode, which is also observed in higherorder Raman modes, and an anomalous softening of ¡«1cm-1 upon cooling below T*¡«300 K. In contrast, the infrared spectra show conventional temperature dependence. The band pro.le phonon anomalies are possibly related to an unspeci.ed electronic property of Sr2BUO6 (B = Ni, Co).2BUO6 (B = Ni, Co) double perovskites were investigated by Raman/infrared spectroscopies and synchrotron X-ray diffraction, respectively. Monoclinic crystal structures with space group P21/n were con.rmed for both compounds, with no clear structural phase transition between 10 and 400 K. As predicted for this structure, the .rstorder Raman and infrared spectra show a plethora of active modes. In addition, the Raman spectra reveal an enhancement of the integrated area of an oxygen stretching mode, which is also observed in higherorder Raman modes, and an anomalous softening of ¡«1cm-1 upon cooling below T*¡«300 K. In contrast, the infrared spectra show conventional temperature dependence. The band pro.le phonon anomalies are possibly related to an unspeci.ed electronic property of Sr2BUO6 (B = Ni, Co).P21/n were con.rmed for both compounds, with no clear structural phase transition between 10 and 400 K. As predicted for this structure, the .rstorder Raman and infrared spectra show a plethora of active modes. In addition, the Raman spectra reveal an enhancement of the integrated area of an oxygen stretching mode, which is also observed in higherorder Raman modes, and an anomalous softening of ¡«1cm-1 upon cooling below T*¡«300 K. In contrast, the infrared spectra show conventional temperature dependence. The band pro.le phonon anomalies are possibly related to an unspeci.ed electronic property of Sr2BUO6 (B = Ni, Co).¡«1cm-1 upon cooling below T*¡«300 K. In contrast, the infrared spectra show conventional temperature dependence. The band pro.le phonon anomalies are possibly related to an unspeci.ed electronic property of Sr2BUO6 (B = Ni, Co).2BUO6 (B = Ni, Co).