Gadolinium oxidation states

Most properties are similar to the rare-earth analog gadolinium that has If electrons. The trivalent oxidation state (Cm3+) is most stable. The metal is reactive, being more electropositive than aluminum. 

As shown in Table I, lanthanum and lutetium oxides have Sq ground states and consequently their heat capacities should be attributed to lattice vibration. Data on these substances may be used to represent the lattice contribution to a first approximation for neighboring isostructural (and nearly so) sesquioxides. Cubic gadolinium oxide provides a midseries lattice heat capacity approximation at relatively high temperatures... 

Gadolinium pyrophosphate Gd4(P207)3, was prepared from gadolinium oxide and sodium pyrophosphate in hydrochloric acid solution. The X-ray pattern showed it to be amorphorous in the vacuum dried state but when heated at 700 and 900°C it became a crystalline solid which indexed in the tetragonal and cubic systems. The presence of the pyrophosphate group in the anhydrous product was confirmed by... 

For these elements, the correspondence of the actinide and the lanthanide series becomes most clearly revealed. The position of curium corresponds to that of gadolinium where the / shell is half-filled. For curium, the +3 oxidation state is the normal state in solution, although, unlike gadolinium, a solid tetrafluoride, CmF4, has been obtained. Berkelium has +3 and +4 oxidation states, as would be expected from its position relative to terbium, but the +4 state of terbium does not exist in solution whereas for Bk it does. 

Cyclooctatetraenyl derivatives of the rare earths were synthesized shortly after the characterization of uranocene first for europium and ytterbium in the oxidation state R by Hayes and Thomas (1969a). But one year later, Mares et al. (1970) prepared complexes of the type K[R(Cj,Hg)2], where R = Ce, Pr, Nd, Sm, and Tb. The corresponding yttrium, lanthanum and gadolinium derivatives are described by Hodgson et al. (1973) and the scandium compound was made by Westerhof and De Liefde Meijer in 1976 ... 

Gadolinium, like other related rare earth metals, is silvery white, has a metallic luster, and is malleable and ductile. The element is relatively stable in dry air but in moist air tarnishes with the formation of a loosely adhering oxide film. The metal reacts slowly with water and is soluble in diluted acid. Gadolinium exhibits a trivalent oxidation state and because of the half-filled 4f level the Gd " " ion is especially stable and unique for its high paramagnetic moment. It has the highest thermal neutron capture cross-section of any known element. 

The removal of 4f electrons is indeed essential in most oxidation states of these elements, which have the tendency of attaining the stable electronic configuration of La or Xe. In the middle of the series, gadolinium is considered rather stable because of the half--filled 4f subshells. It represents, as La and Lu, a sort of reference element for some regular changes in the chemical behaviour, such as an abnormal valency state. As a matter of fact, all three have one 5d electron besides zero, seven and fourteen 4f electrons (which make empty, half-fulled and fully filled the 4f shells, respectively). Therefore, Ln(III) ions correspond to a stable electronic structure 5s p. Lanthanum and lutetium, together with yttrium, could be formally assumed as d elements (see Tab. 2). 

The oxidation state of IV demonstrated by thorium is then analogous to the IV oxidation state of cerium. From the behavior of uranium, neptunium and plutonium it must be deduced that as many as three of the assumed 3f electrons are readily given up, so that the failure of thorium to demonstrate an oxidation state of III is accounted for. On the basis of this hypothesis, elements 95 and 96 should exhibit very stable III states in fact, element 96 should exhibit the III state almost exclusively because, with its seven 3f electrons, it should have an electron structure analogous to that of gadolinium, with its seven 4f electrons. 

The electronic configurations 5f or 4f representing the half-filled f shells of curium and gadolinium, have special stability. Thus, tripositive curium and gadolinium, are especially stable. A consequence of this is that the next element in each case readily loses an extra electron through oxidation, so as to obtain the f structure, with the result that terbium and especially berkelium can be readily oxidized from the III to the IV oxidation state. Another manifestation of this is that europium (and to a lesser extent samarium) -just before gadolinium - tends to favor the 4f structure with a more stable than usual II oxidation state. Similarly, the stable f electronic configuration leads to a more stable than usual II oxidation state in ytterbium (and to a lesser extent in thuUum) just before lutetium (whose tripositive ion has the 4f structure). This leads to the prediction that element 102, the next to the last actinide element, will have an observable II oxidation state. 

Modern CT systems use solid state detectors in general. Each detector element consists of a radiation-sensitive solid-state material (such as cadmium tungstate, gadolinium-oxide or gadolinium oxi-sulfide with suitable dopings), which converts the absorbed X-rays into vis-... 

Maher RC, Cohen LF (2008) Raman spectroscopy as a prohe of hanptuatnre and oxidation state for gadolinium-doped ceria used in soUd oxide fuel cells. J Phys Chem A 112(7) 1497-1501... 

The GdAlgB O QiCe ", Tb " is synthesized by a soHd-state firing of the rare-earth coprecipitated oxide plus boric acid and MgCO at 900° C in a slightly reducing atmosphere. As in the case of the lanthanum phosphate phosphor, a flux is usually used. The synthesis of this phosphor is further comphcated, however, by the fact that it is a ternary system and secondary phases such as gadolinium borate form and must then react to give the final phosphor. 

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