The EXAFS Study on Modified MnO₂ with Bismuth

A short range structure investigation of modified MnO₂ was made using the extend X-ray absorption fine structure method (EXAFS). As it turned out that the coordination mumber of the first shell of the Mn atom decreases upon modification,while no change happens to the second sell, and the Mn-Mn coordination to the thirdshell disappeares. The dopant bismuth exists in the lattice of modified MnO₂. The abeorption spectra of Mn K-edge on line shows that with the electro-discharge reduction,the deeper of the reduction the slower of the process in which the local structure around the Mn atom is transferred into the disorder and the vaguer the change of the coordination number, compared with one of non-modified MnO₂. Furthermore there is no structural rearrangement of Mn atoms during the l-e discharge.