Characterization of the charge ordering state by maximum entropy method

摘要

In this work we introduce the use of a combined Rietveld refinement and Maximum Entropy Method (MEM), as a helpful new tool to gain insight into the charge ordering pattern present in CO-transition metal compounds. In particular we show the study made on two CO oxyborates A_2OBO_3 (A = Mn and Fe): (a) the Mn-oxyborate, that exhibits a strong charge lattice coupling, and whose charge ordering pattern had been previously satisfactory established from BVS analysis of single crystal X-ray diffraction data and that we have used as a test to confirm the validity of the new method; (b) the weakly charge-lattice coupled Fe-oxyborate, a compound not suitable for the BVS approach and for which nevertheless this method gives evidence for a new charge ordering pattern.