Magnetic properties molar susceptibility

The magnetic moment, m, is a term used to quantify the magnetic properties of a substance. It is not measured directly, but is obtained from the measured molar susceptibility to which it is related, i. e. 

Exchange constants for low-dimensional magnets are most commonly obtained via comparison of experimental data to the predicted behavior of a thermodynamic property for a given model, usually the magnetic susceptibility. Johnston et al. showed that the molar susceptibility xm of the uniform chain can be expressed as a ratio of polynomials in powers ofthe reduced temperature t t = hgT/ 2J ). The coefficients N and D are listed in Table 1. 

The technique of principal component analysis was applied to a set of 12 characteristics associated with aromaticity, including the two above, using a variety of heterocyclic compounds <89JA7>. Three principal components, were found that accounted for most of the variance of the data. Characteristics associated with classical aromaticity, such as the two mentioned above, were dominated by the first component and those associated with magnetic properties, such as the molar susceptibility, were dominated by the second. The In score for oxazole was low, of 16 compounds, only furan was lower. On the other hand, the ii2 score was one of the higher scores. 

Magnetic properties will be discussed, and a new correlation for the molar diamagnetic susceptibility will be presented, in Chapter 10. 

The magnetic properties were studied in the temperature range of 2-1100 K (Hiebl et al. 1987). The compounds in which the transition-metal component is from the same column of the Periodic Table display a similar behaviour. A temperature-independent exchange-enhanced susceptibility was observed for T = Fe, Ru, and Os. In the case of Co, Rh, and Ir, the molar susceptibility is somewhat lower, but a broad maximum in the temperature dependence of x around 600 K, observed in all three compounds, is reminiscent of spin fluctuators. Antiferromagnetic ordering, indicated for T = Ni, Pd, and Pt by sharp cusps in the x versus T curves, was confirmed by the observation of linear magnetization curves at low temperatures. MCW behaviour is found above the antiferromagnetic transition. 

For the magnetic and electrical properties of paper sheets, the mass susceptibility X, c.g.s.] and AC conductivity (a ohm cm ] of paper samples were measured and recorded in Table 7.15. It was observed that this investigated CMC-Fe[III]-based beater additive Improved to less extent the semiconductor property of produced paper sheets however, the trend was reversed for the case of HEC-Fe(III] and CMC-Zn[II] complexes. These observations are probably related to the magnetic moment, molar conductivity and electrical conductivity of metal and metal complexes [19,49]. 

The most common way to ascertain the magnetic properties of materials is to measure their molar magnetic susceptibility, The magnetic susceptibility is related to the effective magnetic moment according to Equation (15.10) and is mea-sured using either a Gouy balance or an Evans balance. 

The magnetic properties of the individual molecules or ions within the crystal are expressed in terms of three principal molecular susceptibilities Ki, K, which arc defined with respect to an orthogonal system of axes. In compounds where the orientations of the molecules in the unit cell arc known from X-ray diffraction studies. Kj. K, and may be determined from the principal molar susceptibilities of the crystal and the molecular direction cosines. The relationships between these quantities arc again different for different crystal systems and different molecular symmetries. Therefore, only the most important relations can be given here. For more details the reader is referred to the work of Lonsdale and Krishnan [157,158] or to Mitra [11],... 

Molar susceptibility is a macroscopic property that reflects the magnetic moment, x, a microscopic property of electrons. The general relationship between and jx is... 

Confirmation of CFT comes from a consideration of the magnetic properties of coordination compounds. Molar susceptibilities, derived from measurements on a Guoy balance, can be related to the magnetic moment of the complex. A comparison of this experimentally derived magnetic moment with spin-only moments yields a measure of the number of unpaired electrons in the compound. The results derived from a consideration of magnetic properties are consistent with CFT. 

This chapter is intended to recall the principles of magnetism, the definition of magnetic induction and of magnetic induction in a vacuum which is referred to as magnetic field. Readers may not recollect that the molar magnetic susceptibility is expressed in cubic meters per mol Some properties of electron and nuclear spins are reviewed and finally some basic concepts of the magnetic resonance experiments are refreshed. In summary, this chapter should introduce the readers into the language used by the authors. 

Only the diamagnetic susceptibility and the second moment of the nuclear magnetic resonance show additive molar properties. 

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