Cerium crystal structures

The crystal structures of Hf 2 (OH) 2 (S0O 3 (H2O) i, (14) and Ce2(0H)2(S0i,)3 (H20)it (14) also have been determined and found to be isomorphous to the zirconium compound. The cell constants for this series of four isomorphous compounds reflect the effect of the ionic radii on the dimensions of the unit cell. The values for these cell constants are in Table II. Thus, the cell constants for the zirconium and hafnium compounds are nearly identical and smaller than the cell constants for the cerium and plutonium compounds which are also nearly identical. This trend is exactly that followed by the ionic radii of these elements. 

The crystal structure of the cerium sandwich complex (31) (34) shows it to be similar to that of the related Cclv bis(octaethylporphyrinate) complex (Fig. 7) (83, 84). 

A ternary compound of cerium with copper and antimony of the stoichiometric ratio 3 3 4 was identified and studied by means of X-ray analysis by Skolozdra et al. (1993). Ce3Cu3Sb4 compound was found to have the Y3Au3Sb4 type with the lattice parameters of a = 0.9721 (X-ray powder diffraction). For experimental details, see the Y-Cu-Sb system. At variance with this data, Patil et al. (1996) reported a tetragonal distortion of the cubic crystal structure Y3Cu3Sb4 for the Ce3Cu3Sb4 alloy which was prepared by arc melting the constituent ele-... 

This is the case with fluoro complexes and the crystal structure of (NH CeFd shows the coordination is nearly square antiprismatic with cerium having eight fold coordination [140], However the compounds Cs2NaMF6 and analogous chloride have octahedral coordination [139]. Raman spectra of the chloro compounds of La, Pr, Nd and Er have been obtained [146-148]. Raman spectra along with the far infrared spectra of Nd and Er show the octahedral coordination of the lanthanide ion. For these complexes the location of Aig band is as follows La = 274 cm-1 Pr = 281 cm-1 Nd = 278 cm-1 Er = 289 cm"1. 

The crystal structure of (NH4)Ce(N03)6 shows monoclinic symmetry with each Ce(IV) atom coordinated by six bidentate nitrate groups and the symmetry around the cerium atom approximating closely to Th. The bond lengths and bond angles for Ce(IV) and Ce(III) nitrato complexes are given in Table 4.14 for comparison. 

Figure 1.31 (a) The coordination status of the central cerium ion in NaCe(S04)2-ll20 (h) the crystal structure of NaCe(S04)2-H20 [26], (Reprinted from O. Lindgren, The crystal structure of sodium cerium(III) sulfate hydrate, NaCe(S04)H20, Acta Chemica Scandinavica, A31, 591-594, 1977, with permission from Forlagsforeningen Acta Chemica Scandinavica.)... 

Boussie, T.R., Eisenberg, D.C., Rigsbee, J. et al. (1991) Structures of organo-f-element compounds differing in the oxidation state of the central metal crystal structures of bis([8]annulene) complexes of cerium(lV), ytterbium(III), and uranium(III). Organometallics, 10, 1922. 

A number of crystal structures of derivatives containing the [Eu(dik)4] are available but, at variance with the cerium complexes, the electrochemical investigation of a number... 

Figure 2.t. The crystal structure of CeO> (a) unii celt as cep array of cerium atoms The cep layers are parallel to the [Ml] planes of the fe e. unit cell, (b) and (c) the same stniclure redrawn as a primitive cubic array of oxygens. 

Other oxygen ion conductors that have potential use as solid electrolytes in electrochemical devices are stabilized bismuth and cerium oxides and oxide compounds with the perovskite and pyrochlore crystal structures. The ionic conductivity and related properties of these compounds in comparison with those of the standard yttria-stabilized zirconia (YSZ) electrolyte are briefly described in this section. Many of the powder preparation and ceramic fabrication techniques described above for zirconia-based electrolytes can be adapted to these alternative conductors and are not discussed further. 

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