| Abstrakt: |
Nonstoichiometric manganese(III, IV) oxides with the layered birnessite structure were analyzed in terms of the model expressed by the general formula Mn1 - qO,OH)2(Mn,R)2 q(O,OH,H2O)6 q,in which the first part reflects the composition of layers, the second part, the composition of the interlayer spaces of the structure, and q is the coefficient characterizing the relative content of vacant positions in the layers. As R+ (R2 +) ions, Li+, Na+, K+, Rb+, Cs+, Sr2 +, Ba2 +, and Ag+ were taken. The H form of birnessite has a particular composition. Experimental data show that metal ions participate in ion exchange with OH groups in the birnessite structure. The increased content of the Li+ and Ag+ ions in birnessite is attributed to their increased participation in the ion exchange M+ + HO-Mn ρarr; 4 H+ + MO-Mn. As the heat treatment temperature is increased, Mn3 + ions are accumulated in the interlayer spaces of the structure, and, above 350°C, the positions of these ions become regular, with transition from the layered birnessite structure to the tunnel structure. [ABSTRACT FROM AUTHOR] |
Full text from SpringerLink