Addenda to “Structural Transition Induced by Charge-Transfer in RbMn[Fe(CN)6

Abstract

We have performed neutron powder diffraction and Rietveld analysis of RbMn[Fe(CN)6] at 300K and 40K, using the Kinken powder diffractometer for high efficiency and high resolution measurements (HERMES) installed at the JRR-3M reactor at the Japan Atomic Energy Research Institute, Tokai, Japan. The room temperature structure (see Table I) determined by neutron diffraction is reasonable, because the Mn–N bond distance (1⁄4 2:195ð3Þ A) and the Fe– C bond distance (1⁄4 1:922ð4Þ A) are comparable with the values of the other transition metal cyanides. The atomic coordinates of the high-temperature phase reported in our previous paper were seriously deviate from the values. Here, note that the neutron structural analysis has clear advantage over the X-ray structural analysis if the neighboring atomic species in the periodic table should be distinguish, like RbMn[Fe(CN)6]. So, we concluded that the previous Rietveld analysis on the X-ray diffraction pattern was trapped a wrong local minimum. Actually, we found a structural solution close to those shown in Table I. We show in Fig. 1 the recalculated lattice constants and bond distances of RbMn[Fe(CN)6] in the warming-run. We confirmed that the bond distances of the low-temperature phase are the same within the experimental errors between the structures determined by the neutron powder diffraction and that reported previously. The cubic-tetragonal transition at 290K accompanies a significant Jahn–Teller distortion of the MnN6 octahedra, and is considered to be driven by the charge-transfer from the Mn2þ site to the Fe3þ site.