Magnetic moments, effective, uranium

Figure 8 Effective magnetic moment of uranium In original and...

Table 9. Conduction electron polarization effect in uranium ferromagnetic monocompounds conduction electron polarization moment Psai saturation moment from magnetization studies ordered magnetic moment as determined by neutron scattering...

These paramagnetic compounds obey the Curie-Weiss relation down to about 100 K. But the effective magnetic moment of the uranium complex varies from about 3.37 /xb at room temperature to about 2.76 p.B at 87 K. It is always less than the 3.62 /xb expected for simple Russell-Saunders coupling without crystal field effects. 

The general pattern of the UV/vis absorption spectra of all these complexes resembles that of (in perchloric acid), but apparently corresponding peaks are shifted by about 4% in frequency, very much the same as in the red UCU salts. Data on the magnetic susceptibilities and effective magnetic moments for the uranium in these complexes are conflicting. On the one hand, a series of rather low fiets... 

The effective molar paramagnetic moment of USb2TiOy was less than that of the standard uranium-antimony oxide composition (Figure 8) but still significant. As temperature was increased from 4 to 105 K, the effective magnetic moment of the old uranium-antimony oxide catalyst increased to a value corresponding to one unpaired electron which is consistent with At low temperatures the... 

AnAlz (An = U, Np). UAI2 shows no transition into a magnetically ordered state down to temperatures below 1K. An effective paramagnetic moment on the uranium... 

Even though the macroscopic magnetization can be understood, we must not overlook the fact that the paramagnetic moment and the ordered moment are far from the values of the trivalent (or tetravalent) uranium ion. Lam and Ellis (1985) stress in a theoretical paper the importance of the hybridization of the 5f electrons with other electrons in the valence or conduction bands. Only if we accept that such an effect actually reduces the still more or less localized actinide moment are we entitled to use the terminology of localized-moment magnetism. 

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