Y//?-MnO

Figure 5. Calibration curve for the determination of the pyrolusite concentration of orthorhombically indexed y - MnO, samples by comparison of the calculated with the observed 4m0) value.

Figure 3. Four step discharge curves of Mn02 2J 100 mg of EMD was discharged continuously in 9 mol L1 KOH (A) and the discharged Mn02 was stored at the 12 mAh (B), 16 mAh (C), and 20 mAh (D) stages for 96 h. Three cells containing 100 mg of y - MnO, were discharged at 23 °C at ImAh to 12, 16 and 20mAh. The cells were kept on open circuit at the temperature shown for 96 h, then the discharge was continued at 1 ma at 23 "C. The cathode potential for the cells stored at 0 C and 23 °C recovered to point "a" but that of the cell stored at 45 °C decreased to point "b".

Corannulene, C2oH10, dibenzo y/ /, mno] fluoranthene, shown in Fig. 1(a), is a bowl-shaped PAH with 5-fold symmetry [6], and has a one-third skeleton of C60 (see Figs 1(c) and (d)). Recently, convenient synthesis for corannulene [7,8] has been developed. On the other hand, coronene, C24H12, hexabenzobenzene, shown in Fig. 1(b), has a flat structure with a 6-fold symmetry axis. 

Manganese(lV) oxide exists in many modifications. The only modification which approaches a stoichiometric composition is p-MnOy (e.g. the mineral pyrolusite) and it is the least reactive. All the other modifications contain additional cations, such as Na+, K", Ca- and Ba ", anions, such as OH, and water. The average valency stale of the manganese is also less than 4 (down to, 1.4). The almost amorphous y-MnO (the mineral nsutite) is particularly reactive. 

Manganese(IV) oxide minerals are thermally decomposed to manganese(Ill) oxide (see Section 3.5.1.3.2), which disproportionates when reacted with hot concentrated sulfuric acid to manganese(II) sulfate tnd battery active y-MnOs ... 

The method of Marti gives y-MnO(OH) with a well-defined x-ray pattern. A solution of 2.2 g. of MnSO 4HgO (10 mmoles)... 

Careful dehydration of y-MnO(OH) (vacuum, 250 °C) yields y-MusOa. y-MnO(OH) occurs in nature as manganite. 

A soln. of codeine methyl ether in tetrahydrofuran shaken vigorously for 24 hrs. under Ng with y-MnO (added in several portions) thebaine. Y 80%. R. B. Barber and H. Rapoport, J. Med. Chem. IS, 1074 (1975). 

It is well known that in mtile-hke structures the planes [0 1 1] and [0 3 1] are twinning planes. Hence, Chabre and Pannetier concluded that twinning faults in the planes [0 2 1] and [0 61] (the equivalent planes in the ramsdellite doubled unit cell) are the explanation for some features in the diflraction patterns of y-MnO for example, the lineshift of the (1 1 0) reflection toward lower angles or the merging of the reflection groups (h 2l)f(h 4 0) and (h 6l)/(H 0 2). 

Manganese Oxides. Manganese(IV) dioxide rarely corresponds to the expected stoichiometric composition of Mn02, but is more reahsticaHy represented by the formula MnO y 2 q, because invariably contains varying percentages of lower valent manganese. It also exists in a number of different crystal forms, in various states of hydration, and with a variety of contents of foreign ions. 

Fig. 6.18 Mossbauer spectra of Mno.25Zno.75Fe204, obtained at the indicated temperatures in a magnetic field of 6 T, applied parallel to the y-ray direction. The lines show fits to three sextets as discussed in the text. (Reprinted with permission from [84] copyright 2003 by Elsevier)...

Correlation between Co and Fe contents in Israeli arid soils. Correlation between Cu and MnO contents in Israeli arid soils. Effects of soil pH on the Zn amount bound to the Fe oxide fraction (amorphous/crystalline Fe oxide and overall Fe oxide bound fractions) in soils from China with pH 3.73 - 8.1 and 0 -14.7% CaC03 (after Han et al., 1995. Reprinted from Geoderma, 66, Han F.X., Hu A.T., Qi H.Y., Transformation and distribution of forms of zinc in acid, neutral and calcareous soils of China, p 128, Copyright (1995), with permission from Elsevier). 

It is interesting to note that the large difference in covalency parameters for the Mn2+—0 bond in MnO Nathans et al., 1964) vs the Mn2+—O bond in MnCC>3 (Lindgard and Marshall, 1969) agrees well with the spin transfer anticipated from Rv and R. This covalency difference for an M—0 bond in ternary oxides M Y Oz, which is dependent on the nature of the Y—0 bonds [in this case (Mn—O)—Mn for MnO and (Mn—0)-C for MnCOs], was also shown to exist for other oxides (see Table 4). 

It occurs in seawater where some species of seaweed and kelp accumulate the element in their cells. It is also recovered from deep brine wells found in Chile, Indonesia, Japan, and Michigan, Arkansas, and Oklahoma in the United States. The iodine is recovered from cremated ashes of seaweed. The ashes are leached with water to remove the unwanted salts. Finally, manganese dioxide (MnO ) is added to oxidize the iodine ions (1 ) to produce elemental diatomic iodine (y. The following reaction takes place 41 " + MnO —> Mnl + I. + 202-... 

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