Manganese p-

P-manganese(IV) oxide [14854-26-3] Mn02 black to gray crystal sohd tetragonal D14 Ah 5.026 535 insol H2O... 

Kozawa, A. Powers, R.A. Cathodic reduction of p-manganese dioxide and y-manganese dioxide in ammonium chloride and potassium hydroxide electrolytes. Electrochem. Technol. 1967, 5, 535 The manganese dioxide electrode in alkaline electrolyte the electron-proton mechanism for the discharge process from Mn02 to MnOxt- J- Electrochem. Soc., 1966, 113, 870. 

The best-known electron compounds are the Hume-Rothery phases which have the cubic B2 structure, e.g. P-brass at high temperatures and the transition-metal alu-minides FeAl, NiAl and CoAl, or the complex cubic A13 structure (P-manganese-type), e.g. ZujCo, CusSi, or the close-packed hexagonal A3 structure, e.g. CUjGa, AgjAl, for the valence electron concentration VEC = 3/2, the complex... 

There are several families of ternary carbide phases with transition metals and main group elements several of them being of structural interest such as the H-phases, the filled P manganese type carbides and the k carbides. Of technical importance are however only phases which are used as hard constituents in cemented carbides... 

The rate of adsorption of calcium ions onto p manganese dioxides... 

Yachandra, V.K., Sauer, K., and Klein, M.P., Manganese cluster in photosynthesis where plants oxidize water to dioxygen, Chem. Rev., 96, 2927,1996. 

Other organo-metallic structures (based on manganese in particular), based on the chemistry of -rr complexes with aromatic structures, can also be used to improve the octane number (Guibet, 1987, p. 276). 

By reference to the outline periodic table shown on p. (i) we see that the metals and non-metals occupy fairly distinct regions of the table. The metals can be further sub-divided into (a) soft metals, which are easily deformed and commonly used in moulding, for example, aluminium, lead, mercury, (b) the engineering metals, for example iron, manganese and chromium, many of which are transition elements, and (c) the light metals which have low densities and are found in Groups lA and IIA. 

Fused potassium nitrate is a powerful oxidising agent (cf. the oxidation of manganese compounds, p.. IS6 ... 

Fusion of a manganese compound with sodium carbonate and potassium nitrate (on porcelain) gives a green manganate(VI) (p.. 86)... 

Fig. 4.18 Plot of log (.x/(mg g" )) against log (p°/p) for the adsorption of nitrogen at 77 K on the samples of manganese dioxide referred to in Fig. 4.16. Outgassing temperature (A) room (B) 393 K (C)443 K (D) 493 K. For the points denoted by V in Curve A, a sample was outgassed at 493 K and charged with nonane before the final outgassing at room temperature. (Courtesy Lee and Newnham.)...

One of the problems with early hydride systems was decrepitation of the alloy. Each time the metal hydride storage tank was recharged the particles would break down and eventually the particles became so small that they began to pass through the 5-p.m sintered metal filter which kept the hydride inside the tank. Addition of 0.5% manganese, which caused the decrepitation process to cease once the particles reached a size of about 10 p.m, solved this problem. 

Another principal use of ketene is in the production of sorbic acid [110-44-1] (80,81). In this process, which requires an acidic or manganese(II) catalyst, ketene adds to crotonaldehyde [123-73-9] (8) with subsequent conversion of the P-lactone and the polyester to sorbic acid (qv) (9). 

Tables 1 and 2, respectively, Hst the properties of manganese and its aHotropic forms. The a- and P-forms are brittle. The ductile y-form is unstable and quickly reverses to the a-form unless it is kept at low temperature. This form when quenched shows tensile strength 500 MPa (72,500 psi), yield strength 250 MPa (34,800 psi), elongation 40%, hardness 35 Rockwell C (see Hardness). The y-phase may be stabilized usiag small amounts of copper and nickel. Additional compilations of properties and phase diagrams are given ia References 1 and 2.

J. H. Downing, Elec. Fum. Proc. 44 (1986) J. P. Eaunce andJ. Y. Welsh, "The Production of Manganese Metal," presented at 105th MnnualMeeting... 

P. L. Dancoisne, "Past and Present Evolution of the Manganese Demand," presented at 4th lEMFMMBM Ferroalloy Congress, Salvador de Bahia,... 

The crystal stmcture of ramsdeUite [12032-73-4] is similar to that of P Mn02 except that double chains of MnO octahedra are cross-Unked to adjacent double chains through the sharing of oxygen atoms located at the corners. RamsdeUite and pyrolusite are the only manganese dioxide phases where the composition approaches the stoichiometric Mn02 formula. Heating ramsdeUite to 250°C transforms it to pyrolusite. 

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