Europium magnetic susceptibility

Table 9. Magnetic susceptibility X atom of europium at different temperatures [160]...

The readers will undoubtedly agree that the elucidations and derivations of the equations 13—15 are beyond the scope of this book, but chemists with some physical inclination may find some satisfaction in reading through Van Vleck s [207] Theory of Electric and Magnetic Susceptibilities to quench their mathemetical thirst. Instead of tabulating the measured magnetic moments of all europium compounds with variations we will mention the magnetic behaviour of the individual compounds as we deal with them. 

In 1939 Klemm and Doll [276] prepared all the halides of divalent europium and studied the magnetic characteristics of these compounds. The magnetic susceptibilities (X g) and effective moments of the fluoride, chloride, bromide and iodide are tabulated in Table 15. Except for the... 

Nine derivatives of 1, [RSb9W2i086]16 (R = La-Gd, Dy, Yb), have been isolated and characterized by elemental analysis, magnetic susceptibility, and infrared spectra. The four-line 183W-NMR spectrum of the lanthanum derivative is consistent with the D3h symmetry of the parent structure, but the emission spectrum of the europium derivative suggests a lower symmetry in the solid state (Liu et al., 1992). No structural determinations of these derivatives have yet been reported. 

Yb -83 at.% ) when present in the tetragonal dicarbide, which was confirmed by magnetic susceptibility measurements (Flahaut 1969), and trivalent in the cubic hypocarbide. In the sesquicarbide, the behavior of europium and ytterbium is anomalous. Ytterbium forms a monoclinic Yb2C3 phase (Haschke and Eick 1970a) while europium forms a tetragonal phase with a Ca2C3-type structure (Pasto and Morgan 1976, Schwetz et al. 1979). 

Grignard type compounds of some lanthanide metals in the oxidation state +2 have been investigated by D.F. Evans et al. (1970, 1971). Europium, samarium and ytterbium react in tetrahydrofuran with alkyl and aryl iodides between —20 and + 30°C forming colored solutions containing mixtures of compounds, which give some Grignard-type reactions. Characterization of the compounds was done only by magnetic susceptibility measurements and some titrimetric analyses. 

In addition to using the lattice parameter(s) of the RM compound to estimate the valence state of europium and ytterbium one can use magnetic susceptibility data (Gschneidner 1969b, Wohlleben 1981) and Lm absorption edges, XPS and UPS (Wohlleben 1981) to distinguish between the 4f" and 4f" configurations and intermediate valences. For europium one can also use Mossbauer isomer shift data (Brix et al. 1964, Clifford 1967, van Steenwijk and Buschow 1977, de Vries et aL 1984). 

The magnetic susceptibility of EuPdIn and YbPdIn has been measured in the temperature range 100 to 1000 K (Cirafici et al., 1985). While the europium atoms in EuPdIn are in a stable divalent oxidation state over the whole temperature range, a continuous increase of... 

The equiatomic compounds EuLiBi and YbLiBi, containing divalent rare earths, are known. EuLiBi, which is extremely moisture-sensitive, was prepared from reaction of Eu, Li, and Bi in a 1 2 1 atomic ratio within Mo crucibles placed in steel ampoules jacketed by silica tubes at 1000 °C for 5-7 d (Prill et al., 2002). Powder X-ray diffraction indicates an orthorhombic TiNiSi-type structure (Pearson symbol oPl2, space group Pntm (No. 62), Z = 4), but atomic positions were not refined (section 5.4, fig. 9a). The presence of divalent europium is supported by Eu Mossbauer spectroscopy (isomer shift of -11 mm/s) and magnetic susceptibility measurements (effective magnetic moment of 8.3 mb, close to that of the free-ion value of 7.94 MB for Eu +). EuLiBi orders antiferromagnetically below 7.5 K. 

The similarity in unit-cell volumes between LaNi5P3 and EuNisP3 with the LaCosP3-type structure suggests that the europium atoms are divalent, which has been confirmed by magnetic susceptibility measurements (Badding and Stacy 1987a,b). 

Lux et al. (1991a) examined the compounds Eui jGdxPtP and Euo.sSro sPtP which have the same structures as a- or P-EuPtP, but do not undergo first-order phase transitions at x>0.05. Their Lm-X-ray absorption and magnetic susceptibility studies have shown a dependence similar to that of EuPtP, but only one magnetic transition was foimd. The temperatures of antiferromagnetic order in these compounds depend on europium content and have the following values 7.5 K (5% Gd), 6.8 K (10% Gd) and 6.4 K (50% Sr). 

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