Positive Temperature Dependence of Quadrupole Splittings in Mössbauer Spectra of Fe_1.33Nb_2.67Se₁₀

Abstract

The Mössbauer effect in the low-dimensional compound Fe 1 33 Nb 2 67 Se 10 has been examined between 78 and 414 K. An anusual positive temperature dependence of the quadrupole splittings was found above 250 K. As a possible origin a mechanism due to bonding is suggested.

A sheet structured MOF magnet: Poly[(1,10-phenanthroline)tetrakis(imidazolato)diiron(II)]

“…The temperature dependence of the quadrupolar splitting can be attributed to thermal averaging of the electron configuration at higher temperatures and/or changes in the orientation of the electric field gradient (EFG) tensor. [36][37] The three spectra ( Figures 5A, 5B and 5C) are consistent with the absence of any structural phase transitions from ambient temperature down to 12K. This is in sharp contrast to the situation observed for the bipy analogue, 2, where spectral changes consistent with transitions from α to β to γ phases were clearly observed over this temperature range.…”