E. Preisler
Jul 1, 1976
Citations
0
Influential Citations
35
Citations
Journal
Journal of Applied Electrochemistry
Abstract
Manganese dioxide, prepared by the anodic oxidation of hot sulphuric acid-containing manganese sulphate solutions, is a polycrystalline material with a random distribution of the lattice orientations of the micro crystals. Electrodeposited manganese dioxide precipitating under similar conditions from acidic solutions of manganese chloride, nitrate, or perchlorate exhibit clearly a fibrous structure, the axes of the single fibres being parallel with the direction of growth. X-ray diffraction shows a marked texture of growth. All the fibrous forms of manganese dioxide that have been described are of theγ-variety. They can easily be cleft in planes parallel to the direction of their growth.Even the manganese dioxide crystallizing from sulphate solutions often has a growth texture which, though less marked, is still detectable by X-ray analysis. Sometimes the crystal orientation is so pronounced that this material can also be cleft.In the hot spent electrolyte of the technical process, manganese dioxide of theγ-variety is deposited on non-polarized surfaces, possibly by a very slow hydrolysis of manganese(III)ions. This manganese dioxide has a bulk density of 4.5 g cm−3 and its crystals, too, are oriented with regard to the direction of their growth.