Determination of the average oxidation degree of manganese in single crystals of manganites

A procedure has been developed for the determination of the average oxidation degree of manganese in manganites of rare-earth elements. It is shown that potassium periodate in a mixture of conc. HNO3and H3PO4quantitatively oxidizes manganites to permanganic acid at a temperature of ∼90°C. This allows total manganese in a test sample to be determined by photometry. The procedure involves two independent steps at which the average oxidation degree of manganese in manganites is determined by photometry and iodometry with a confidence interval of 0.02.