Samarium compounds change

Figures 20A and B show the PL spectra, recorded at 290 K, at 600 nm, and as a function of pressure, for Cs9(SmW10O36) and SmWi0O36-LDH, respectively (Park et al., 2002). For the sake of comparison, the line shapes are normalized and displaced along the vertical axis. In both cases, the peak position is red-shifted by 4—5 nm when the hydrostatic pressure increases from 1 bar to 61 kbar. It was shown that the red-shift from A to A lies solely in the deformation of the samarium complexes by the uniaxial stress exerted by the host layers, whereas the shift from B to B is also influenced by the change in the cation environment. Under the same conditions, B is not at the same position for the non-intercalated (HN (n -b u t y 1) 3) 9 (SmW10O3e) and Cs9(SmWi0O36) compounds (Park et al., 2002). Thus only peak A is available to measure the unixial stress. This observation can be used to determine the uniaxial stress, when the external pressure is zero. For the SmW10O36—LDH system, the uniaxial stress varies significantly from 75 at 28 K to 140 kbar at 290 K (Park et al., 2002).

The 5-nitro-2-anthranilates of lanthanum(III), samarium(III), terbium(III), erbium(III) and lutetium(III) were obtained as hydrates having 2.5 mol of water molecules per 1 mol of compound [167]. The compounds are isostructural. The processes of dehydration and rehydration were investigated. The first step of dehydration does not cause a change of crystal structure. The entire dehydration gives anhydrous compounds wifii different structures to the structures of hydrates. The dehydration of the La, Sm, Tb and Br compounds was reversible and rehydration gives complexes having the same crystal structures as the initial compounds. 

The nature of 4f electrons in lanthanides and their compounds, either localized or itinerant, is responsible for most of their physical and chemical properties. Localized states corresponding to tightly bound electron shells or to narrow bands of correlated electrons near the Fermi level are observed for all lanthanides. Pressure has a striking effect on the electronic structure, which, in turn, induces structural changes. For instance, crystal structure transitions from hexagonal closed packed (hep) samarium type double... 

Structural transition has a drastic effect on the electrical behavior of these indides (abrupt change in the slope), but no observable effect on the magnetic data (table 20). The samarium and ytterbium compoimd show non-Ciuie-Weiss behavior. Specific heat data revealed a high y coefficient of 130 mJ/molK for the cerium compound (Pleger et al., 1987). 

---