Saturation magnetization nickel

The pressure sensitivity of the magnetic properties of the Invar alloys is indicated by extensive measurements of the coefficient of saturation magnetization change with pressure M dMJdP for various compositions as shown in Fig. 5.10. The exceedingly large values in the 30%-40% Ni range are evident and much in excess of the values for iron and nickel. The 30-wt% Ni composition in the fee phase is the most sensitive to pressure, whereas this... 

Fig. 5.10. The pressure dependence of saturation magnetization for iron-nickel alloys shows a strong pressure dependence in the neighborhood of the Invar alloys (28.5 to 40-at. % nickel in the fee phase). The shock data shown are in excellent agreement with the static high pressure data (after Wayne [69W01]).

The values for the atomic saturation magnetization at the absolute zero, ferromagnetic metals iron, cobalt, and nickel are 2.22, 1.71, and 0.61 Bohr magnetons per atom, respectively.9 These numbers are the average numbers of unpaired electron spins in the metals (the approximation of the g factor to 2 found in gyromagnetic experiments shows that the orbital moment is nearly completely quenched, as in complex ions containing the transition elements). 

For alloys of iron, cobalt, nickel, and copper the calculated values of saturation magnetic moments agree closely with the observed values in particular, the maximum value of about 2.48 magnetons at electron number about 26.3 is reproduced by the theory. There is, however, only rough agreement between the observed and calculated values of the Curie temperature. 

An obvious refinement of the simple theory for cobalt and nickel and their alloys can be made which leads to a significant increase in the calculated value of the Curie temperature. The foregoing calculation for nickel, for example, is based upon the assumption that the uncoupled valence electrons spend equal amounts of time on the nickel atoms with / = 1 and the nickel atoms with J = 0. However, the stabilizing interaction of the spins of the valence electrons and the parallel atomic moments would cause an increase in the wave function for the valence electrons in the neighborhood of the atoms with / = 1 and the parallel orientation. This effect also produces a change in the shape of the curve of saturation magnetization as a function of temperature. The details of this refined theory will be published later. 

Wang C-P, R Franco, JJG Moura, 1 Moura, EP Day (1992) The nickel site in active Desulfovibrio baculatus [NiFeS] hydrogenase is diamagnetic. Multifield saturation magnetization measurement of the spin state of Ni(II). 7 Sio/ Chem 267 7378-7380. 

For iron, cobalt, nickel, and their alloys, the most sensitive technique for characterizing the particle surface is the measurement of magnetic properties. Thus, we synthesized cobalt nanoparticles of 1.6 nm (ca. 150 atoms), 2 nm (ca. 300 atoms) and 4 nm (a few thousand atoms) mean size. The structure of the particles is hep in the latter case and polytetrahedral in the first two cases. The 4 nm particles display a saturation magnetization equal to that of bulk... 

Recall that the saturation magnetization, Mj, is the maximum possible magnetization in the material, and is simply the prodnct of the net magnetic moment per atom. Pm, and the number of atoms per unit volnme, N. The net magnetic moment, in turn, is related to the electronic structure (paired or unpaired electrons), although a number of other factors come into play. Use this information to calculate the saturation magnetization for nickel. 

Figure 6.60 Saturation magnetization of some nickel alloys. Reprinted, by permission, from C. Kittel, Introduction to Solid State Physics, p. 335. Copyright 1957 by John Wiley Sons, Inc.

Person 1 Calculate the saturation magnetization, Ms, for nickel ferrite, which has a lattice parameter of a = 0.833 nm. 

Metallic nickel has a saturation magnetization of 0.6 Wb/m2 and a lattice parameter of 0.352 nm. What is the magnetic moment per atom in Bohr magnetons ... 

The magnetic properties of supported nickel were also studied. It was found that the saturation magnetization, which... 

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