Elastic properties and Mossbauer spectra of Fe1+xNb3−xSe10

Abstract We have measured 57 Fe Mossbauer spectra, Young's modulus, and internal friction of Fe 1+x Nb 3−x Se 10 as functions of temperature. Two quadrupole doublets observed in the Mossbauer spectrum at 300K coalesce into one doublet near 170K, suggesting either that the disorder in the cation sites present at room temperature is removed or that there is an ordering of the distorted octahedral Se cages. A broad minimum in modulus is observed at 50K, with a large peak in internal friction below this at 30K. These are attributed to changes in the charge density wave domain configuration caused by the increasing potential of the competing superlattice.