Chemical Reduction of Nd1.85Ce0.15CuO4-delta Powders in Supercritical Sodium Ammonia Solutions

摘要

Nd1.85Ce0.15CuO4-delta powders are chemically reduced in supercritical sodium ammonia solutions from room temperature to 350 degrees C. The crystallographic structure of the reduced powders is investigated from Rietveld refinement of X-ray powder diffraction. The atomic positions are maintained constant within experimental errors while temperature factors of all atoms increase significantly after the chemical treatments, especially of Nd/Ce atoms. The ammonothermally reduced Nd1.85Ce0.15CuO4-delta powders show diamagnetic below 24 K which is contributed to the lower oxygen content and higher temperature factors of atoms in the treated compound. The ammonothermal method paves a new way to reduce oxides in supercritical solutions near room temperature.