The temperature dependence of charge order in Fe2OBO3 was investigated by
resistivity and differential scanning calorimetry measurements, Mossbauer
spectroscopy, and synchrotron x-ray scattering, revealing an intermediate phase
between room temperature and 340 K, characterized by coexisting mobile and
immobile carriers, and by incommensurate superstructure modulations with
temperature-dependent propagation vector (1/2,0,tau). The incommensurate
modulations arise from specific anti-phase boundaries with low energy cost due
to geometrical charge frustration.Comment: 4 p., 5 fig.; v2: slightly expanded introduction + minor changes. PRL
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