CENTRO DE QUIMICA INORGANICA "DR. PEDRO J. AYMONINO"
Unidad Ejecutora - UE
congresos y reuniones científicas
Local structure study of multiferroic BiMn2O5 with EXAFS
GILBERTO FABBRIS; GABRIEL ANDREGUETTO; EDUARDO GRANADO; NESTOR MASSA; MARIA JESUS MARTINEZ-LOPE; JOSE ANTONIO ALONSO; GUSTAVO AZEVEDO
Campinas, SP, Brasil
Congreso; International Conference on Synchrotron Radiation on Materials Science SRMS-6; 2008
Ana Lucia Ferreira,Executive Secretariat SRMS-6 , 13083-970 Campinas - SP, email: firstname.lastname@example.org
Temperature-dependent EXAFS measurements were utilized to investigate the local structure of BiMn2O5. Mn K-Edge results reveal a very small temperature dependence of the Debye-Waller factor, suggesting the MnO polyhedra are rigid. Above 125 K, structural distortions in the first coordination shell are observed at the Bi L3 Egde, in qualitative agreement with recent results for TbMn2O5 by Tyson et al. The present results and synchrotron radiation XRD analysis by Granado et al. suggest low energy vibrational modes associated with rigid rotations of the Mn-O polyhedra are operative at low temperatures, which might explain the low temperature linear expansion coefficient verified for this material. Local structural distortions associated with the ferroelectric phase-transition around 40K could not be identified, showing that any local structure change at this transition is very small.