Nickel magnetic properties

Within the periodic Hartree-Fock approach it is possible to incorporate many of the variants that we have discussed, such as LFHF or RHF. Density functional theory can also be used. I his makes it possible to compare the results obtained from these variants. Whilst density functional theory is more widely used for solid-state applications, there are certain types of problem that are currently more amenable to the Hartree-Fock method. Of particular ii. Icvance here are systems containing unpaired electrons, two recent examples being the clci tronic and magnetic properties of nickel oxide and alkaline earth oxides doped with alkali metal ions (Li in CaO) [Dovesi et al. 2000]. 

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... 

Electronic Spectra and Magnetic Properties of Complexes of Nickel(II) ... 

Nickel(ll) is the only common d ion and its spectroscopic and magnetic properties have accordingly been extensively studied. 

In addition to nickel alloys, nickel also forms an important alloying element in stainless steels and in cast irons, in both of which it confers additional corrosion resistance and improved mechanical and engineering properties, and in Fe-Ni alloys for obtaining controlled physical and magnetic properties (see Chapter 3). With non-ferrous metals nickel also forms important types of alloys, especially with copper, i.e. cupro-nickels and nickel silvers these are dealt with in Section 4.2. 

The specific heats of solids at low temperatures are appreciably less than at higher temperatures. A maximum specific heat has been observed in the case of iron at 740° and nickel at 320° (Lecher, 1908). Since these are the temperatures at which recalescence and loss of magnetic properties occur, the close relation of specific heat to molecular structure is evident. 

Cobalt and Nickel.—The discussion of the magnetic properties of cobalt... 

The magnetic properties of electrons arise from a property called spin, which we describe in more detail in Chapter 8. All electrons have spin of the same magnitude, but electron spin can respond to a magnet in two different ways. Most magnetic effects associated with atoms are caused by the spins of their electrons. Iron and nickel are permanent magnets because of the cooperative effect of many electrons. 

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... 

Nickel-azide coordination chemistry has received particular attention with respect to magnetic properties and molecular magnetism. Therefore, Nin/N3 systems are covered in a separate section (Section 6.3.4.13.1). 

Since the octahedral and tetrahedral configurations have the same number of unpaired electrons (that is, 2 unpaired electrons), we cannot use magnetic properties to determine whether the ammine complex of nickel(II) is Octahedral or tetrahedral. But we can determine if the complex is square planar, since the square planar complex is diamagnetic with zero unpaired electrons. 

Physics of Nickel Clusters. 2. Electronic Structure and Magnetic Properties. 

Breeder etal. (Ill) have carried out S.P. and magnetization experiments to distinguish between ionic and covalent bonding for the adsorption of H2 and O2 on Ni. Nickel contains 9.4 electrons, 0.6 hole, and 0.6 unpaired electron spin per atom in the d band, the latter being responsible for the magnetic properties of the metal. The S.P. measurements were made on an evaporated Ni film and the magnetization studies on a nickel-silica catalyst, the properties of which were regarded as strictly comparable with the metal film. 

Evidence for the square configuration for [Ni(CN)4]— and other complexes of quadriligated nickel(II) was provided in 1931 only by the magnetic properties of salts containing this ion and by the observed... 

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