Gadolinium radius

The key features in a normalized REE distribution plot are (I) the absolute magnitude of the concentrations (2) the differentiation of the lighter REEs from each other in going from the radius of La " (1.14 A) to Sm (1.00 A) (3) the differentiation of the heavier REEs as the size decreases from Gd (0.97 A) to Lu " (0.85 A) and (4) the difference between the europium concentration measured and that predicted by a smooth variation in normalized concentrations between samarium and gadolinium. Because the REE distribution curves are... 

As reported by Smith et al. (see reference 3 on page 581), pure gadolinium silicide, GdsSi4, has the following unit cell dimensions a = 7.45, b = 14.67, c = 7.73 A. The reduction of lattice parameters, when compared to the germanide, is expected given the smaller effective radius of Si in comparison with that of Ge. 

Based on simple electrostatic theory one would predict a more or less direct relationship between the formation constants and say the atomic numbers or the ionic radii of the lanthanides, as the ionic radii varies more or less monotonically along the series and do not show (Fig. 4) any strong gadolinium break (12). However, as we have seen from the plots in Fig. 3 that the variation of the formation constants are no simple function of the atomic numbers or the ionic radii. Thus Grenthe (19) writes The experimental results proved that there was no simple variation of the measured properties with the crystallographic ionic radius - on the contrary a double series was observed. The author feels that at this point some comments on the practice of plotting the formation constants vs. the ionic radii or any function of the ionic radii (polarizability) should be made. 

The lanthanide or rare earth elements (atomic numbers 57 through 71) typically add electrons to the 4f orbitals as the atomic number increases, but lanthanum (4f°) is usually considered a lanthanide. Scandium and yttrium are also chemically similar to lanthanides. Lanthanide chemistry is typically that of + 3 cations, and as the atomic number increases, there is a decrease in radius for each lanthanide, known as the lanthanide contraction. Because bonding within the lanthanide series is usually predominantly ionic, the lanthanide contraction often determines the differences in properties of lanthanide compounds and ions. Lanthanide compounds often have high coordination numbers between 6 and 12. see also Cerium Dysprosium Erbium Europium Gadolinium Holmium Lanthanum Lutetium Praseodymium Promethium Samarium Terbium Thulium Ytterbium. 

Hambright et al. (1988) have also studied the kinetics of displacement of the Gd " ion from the gadolinium(III) complex of TSPP by ethylenediaminetetraacetate (EDTA) giving Gd(EDTA) and H2(TSPP) as the main products. This represents the first example of metal removal from a metalloporphyrin by a chelating ligand. A mechanism has been proposed to account for the kinetic data. The water-soluble lanthanide complexes of TMPyP also undergo demetallation in the presence of EDTA (Haye and Hambright 1991). Similar to the acid solvolysis reactions, a linear relationship between log k and the ionic radius of the metal center can be established, and complexes with smaller metal center are more stable toward demetallation by EDTA. 

In our computations, we find the magnetic ordering tendencies of gadolinium to change as the lattice parameters are altered away from their equilibrium values. On changing the c/a ratio over the range 1.54-1.66, with the WS-radius fixed at the... 

Plutonium Concentration (g/litre) Gadolinium Concentration (g/litre) Infinite Cylinder Radius (cm) Infinite Slab Thickness (cm)... 

The lattice contributions to the heat capacities of molten GdQ2 and TbCl2 were obtained on the assumption of their linear dependence upon the ionic radius. This estimate was made because it was accepted in this work that gadolinium and terbium dihalides have SrBr2-type structures with CN = 8. The smoothed crystal radii of Eu +, Gd +, Tb and E)y used in our calculations were taken from Chervonnyi and Chervormaya (2005c). 

It is well known that the ionic conductivity of aliovalent-doped ceria solutions show a maximum at a certain dopant concentration and cation radius. Compared to divalent cation doping, however, trivalent dopants are observed to contribute higher conductivity values in ceria. Among trivalent rare earth metals, samarium and gadolinium are accepted as the most effective dopants. Therefore, we have selected a cermet made up of nickel and 20 at% samarium-doped ceria (SDC) as the anode material in our standard cells [12-14]. 

---