MnO , structure

Non-volatile MNOS and MNS memory structures with an embedded sheet of Si nanocrystals have been prepared by low pressure chemical vapour deposition using a S13N4 control layer and SiO2 or S13N4 tunnel layers. Si nanocrystals improved the charging behaviour of the MNOS structures. Memory window width of 1.3 V and 2.0 V was achieved for charging pulses of 9 V and 10 V, 100 ms, respectively. 

The results of memory window measurements as a function of writing/erasing pulse amplitude with pulse width of 400 ms are presented in Fig. 1 for both MNS and MNOS structures with and without middle NC layer deposition. Memory window measurements performed by charging pulse width of 100 ms yielded similar results. 

Although no Si NCs were detected at the oxide-nitride interface by XTEM measurements [6], the deposition conditions (introduction of SiH2Cl2 with gas flow rate of 100 seem for 30 s before nitride deposition) affected the charging behaviour of the structures. The charging behaviour of MNOS structures with Si NC deposition became better than that without Si NC deposition. Thus, we suggest the presence of Si NCs at the oxide-nitride interface. Howeve, they are probably too small to be observable by XTEM measurements. 

Fall 1996 Meeting of the Electrochemical Society among the ca. 100 papers on Li cells that were presented, many discussed Li - MnO, structures [8]. 

Katz, R.H. et al. 1989. Disk system architectures for high performance computing. Proc. IEEE 77(12). Lundstrom, K.I. and Svensson, C.M. 1972. Properties of MNOS structures. IEEE Trans. Elec. Dev. ED-19 826. 

An additional problem is encountered when the isolated solid is non-stoichiometric. For example, precipitating Mn + as Mn(OH)2, followed by heating to produce the oxide, frequently produces a solid with a stoichiometry of MnO ) where x varies between 1 and 2. In this case the nonstoichiometric product results from the formation of a mixture of several oxides that differ in the oxidation state of manganese. Other nonstoichiometric compounds form as a result of lattice defects in the crystal structure. ... 

Also of interest are the octacyano complexes, (M(CN)g] (M = Mo, W), whieh are commonly prepared by oxidation of the M" analogues (using MnO,) or Ce" ) and whose structures apparently vary, aceording to the environment and counter cation, between the energetically similar square-antiprismatic and dodecahedral forms. 

Although it is important that no water should exist in the cathode materials of nonaqueous batteries, the presence of a little water is unavoidable when Mn02 is used as the active material. It is believed that this water is bound in the crystal structure, and that it has no effect on the storage characteristics, as shown in Fig. 27, where the relationship of the MnO,... 

Figure 7. Crystal structures of (a) hollandite, (b) romanechite (psilomelane), and (c) todorokite. The structures arc shown as three-dimensional arrangements of the MnO() octahedra (the tunnel-tilling cations and water molecules, respectively, are not shown in these plots) and as projections along the short axis. Small, medium, and large circles represenl the manganese atoms, oxygen atoms, and the foreign cations or water molecules, respectively. Open circles, height z. = 0 fdled circles, height z = Vi.

Figure 2. The structure of 0.15 Li20 Mn02. The lithium and oxygen sites within the (2 X 2) channel of the a - MnO, framework are partially occupied.

Figure 4. The structure of Na0 44MnO2. Hatched regions represent MnOft octahedra and MnOs square pyramids. The circles show the positions of the sodium ions (after Ref. f35J).

The slow step of this reaction corresponds to removal of hydride from an anion and finds several counterparts in oxidations of organic compounds by MnO. The anion may have the structure... 

Our DFT calculations revealed that coordination of nitric oxide to the series of intrazeolite TMI leads to the formation of the bent MNO adducts of various spin states exhibiting generally the Cs microsymmetry with mirror plane defined by the M-N-0 moiety. Optimized structures of some representative mononitrosyl complexes are depicted in Figure 2.8, and their selected geometric parameters and molecular properties are listed in Table 2.4. 

Zener appears to have been the first to consider this problem to some depth in his theoretical work on ferromagnetic crystals of the type l.a. Ca.MnO, (Zener 1951). For x = 0 one has LainMnin03 but for x > 0 some of the Mn will be 4+, and so we have the structure I. a " / a " Mn "(Mn CL in which some Mn-Mn pairs will be mixed valence, that is, MiF Mnj) or MnJ) Mn . Mnm is 3d4 (S = 2) and MnIV is 3d3 (S = 3/2), and Zener proposed that the excess electron (also called itinerant electron or Zener electron) on Mn111 can travel to the MnIV via a doubly-occupied p-orbital of... 

Some results are given in Figure 1 for [MnC ]", and related ones have been obtained for [ReS ]", [MoS ]2" and [WS ]2" (J -7), for each of which the lowest electric-dipole-allowed transition (1t2 Uj) is clearly vibronically structured (a situation which is brought about by the fact that ouj > r). The best fit 6 value derived for each ion (0.05-0.09 %) indicates that, in the T2 state, the change undergone is rather larger than that typical of a one-electron reduction of the ion e.g. 0.03 A for [MnO (8). 

Figure 4.43 The optimized structure of the hexaaquomanganese(II) ion (spin i MnO = 2.220 A). Note that the bond sticks between Mn and O are merely to aid visualization.

This structure is commonly adopted by oxides, nitrides halides, and sulfides MX, including the nonstoichiometric 3d transition-metal oxides TiO, VO, MnO, FeO, CoO, and NiO. 

---