Structural modification on heat treatment of γ-MnO2

Surface characterization of heat-treated electrolytic manganese dioxide

“…6 contains a comparison of their XRD patterns. The data in the latter figure are consistent with previous studies in this area by, for example, Petit et al [11], Tedjar et al [12], and Chabre and Pannetier [9]. Essentially, as the heat treatment temperature increases from ambient to 450 • C, there is a progressive transformation of the γ -MnO 2 structure to β-MnO 2 [13], while at 500 • C there is a conversion of β-MnO 2 to Mn 2 O 3 [14].…”

“…This is reflected in the increase in x in MnO x from 1.96 for the starting EMD to 2.00 for the sample heat-treated at 450 • C. The smaller and more highly charged Mn 4+ ion would tend to draw electron density from the O-H bond in the hydroxyl group, effectively making the Mn-O bond stronger. A number of previous reports [9,11,12] dealing with the heat treatment of EMD have also shown that other defects such as cation vacancies are annealed out of the structure as the heat-treatment temperature increases. Overall, the removal of these cation vacancies would again lead to a strengthening of the Mn-O bond simply because there is a higher proportion of Mn-O bonds in the structure.…”

The mechanism of foaming and thermal conductivity of glasses foamed with MnO 2

“…Increasing the temperature further, the sample mass becomes stable again at 990 K. This indicates that the reduction of MnO 2 to Mn 2 O 3 is completed. Increasing the temperature even further (T N 1173 K), Mn 2 O 3 reduces to Mn 3 O 4 [22,28,29].…”

“Urban Mine” A Modern Source of Materials: Part I Battery Recycling

“…For the environment and recycling rate issues, battery recycling was subject of intense research for non-thermal processes [10,[20][21][22][23][24].…”

“…Indeed if the process allows recovering steel and zinc, unfortunately manganese is lots in slag while carbon graphite is lost as CO2 during thermal process. A mechanochemistry route was investigated and patent in 1994 [10] leading to the recovery of 1) Steel after shredding and magnetic separation 2) Graphite carbon in first acid leaching step 3) Zinc metal and manganese dioxide by double electro wining after purification leaching solution (Figure 4) The analysis of zinc metal shows a purity of 98.8% while the X-Ray diffraction analysis shows that the recovered product has a same fingerprint than a market production EMD (Electrolytic Manganese Dioxide).…”