Rare earths paramagnetic

In nearly all cases of rare-earth paramagnetic hyperfine structure the long relaxation time necessary for observation is associated with a highly anisotropic hyperfine tensor. For general symmetry this is of the form 3F — AzSzIz I- i- 4iriS /+... 

This phenomenon is appropriate to the paramagnetic hyperfine spectra of magnetically dilute iron phases, and contrasts with the magnetically concentrated rare-earth paramagnetic hyperfine spectra where the effective-field approximation holds. However, it is possible to revert to the former situation by magnetic dilution. This has been shown in erbium ethyl sulphate diluted with the corresponding yttrium salt [138]. The hyperfine tensor was already known from e.s.r. data to be less anisotropic than usual, and the spec-... 

Verdet Constants of Rare-Earth Paramagnetic Crystals ... 

The valences of the rare-earth metals are calculated from their magnetic properties, as reported by Klemm and Bommer.14 It is from the fine work of these investigators that the lattice constants of the rare-earth metals have in the main been taken. The metals lutecium and ytterbium have only a very small paramagnetism, indicating a completed 4/ subshell and hence the valences 3 and 2, respectively (with not over 3% of trivalent ytterbium present in the metal). The observed paramagnetism of cerium at room temperature corresponds to about 20% Ce4+ and 80% Ce3+, that of praseodymium and that of neodymium to about 10% of the quadripositive ion in each case, and that of samarium to about 20% of the bipositive ion in equilibrium with the tripositive ion. 

Moreover, the analysis of the optical spectra of transition metal and rare earth ions is very illnstrative, as they present qnite different features due to their particular electronic configurations transition metal ions have optically active unfilled outer 3d shells, while rare earth ions have unfilled optically active 4f electrons screened by outer electroiuc filled shells. Because of these unfilled shells, both kind of ion are usually called paramagnetic ions. 

Paramagnetic rare-earth porphyrins, TPPErOH (TPP 5,10,15,20-tetraphenylporphin) and TPPEr(dpm) (dpm 2,2,6,6-tetramethyl-3,5-heptanedionate), emit not only but also S2 fluorescence even if a sequence of the... 

Some metals are diamagnetic because the conduction electron spin susceptibility is smaller than the induced diamagnetic susceptibility component. On the other hand, various rare earth metals display very strong paramagnetism because of unpaired / electrons that remain associated with individual atoms rather than entering into energy bands. 

Paramagnetism Positive Small X = constant Alkali and transition metals, rare earth elements... 

Paramagnetism results from unpaired electrons. As a result, most compounds containing transition, rare-earth, and actinide elements, including oxides, nitrides, carbides, and borides, exhibit paramagnetism. Such ceramics are generally not of importance due to their paramagnetism alone, since they often exhibit other types of magnetism, as well. 

Fig. 13.3. The phase diagram of Ao.33A o.67Mn03 (A = divalent cation, A = rare earth) as a function of temperature and the global instability index of the idealized perovskite structure. The points show the observed transition temperatures in various compounds. FMM = ferromagnetic metal, PMI = paramagnetic insulator, FMI = ferromagnetic insulator (from Rao et al. 1998).

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