1,5-Dimethyl-2,3,3,4-Tetrachloro-1,5-Diaza-2,4-Diphosphorinan-6-One and some derivatives

A synthesis of C-chlorinated analogues of 1,5-diaza-2,4-diphosphorinan-6-ones is described. The P-chlorophosphine 3 , a key compound for all reported substitution reactions, reacts in an unusual way with N,N′-dimethyl-N,N′-bis(trimethylsilyl)urea to give the unsymmetrical product 5 , the formation of which is accounted for by a silatropy of the intermediate compound 4 . Compound 5 is stable in solution but rearranges quantitatively into isomer 6 without solvent at room temperature. Compound 3 , its fluoro derivative 9 , and the alkoxy derivatives 10a–d exist as cis-and trans-isomers. Some stereochemical aspects, as well as the possibility of 1,2-chlorotropy, are discussed.     

Photoemission on a Cu-Zr glassy metal

In this paper we present a study of XPS, UPS and magnetic susceptibility on Cu₆₀·Zr₄₀ glassy metal. Our results can be understood in a band structure where the zirconium “d” levels lie close to the Fermi level meanwhile copper “d” levels are at higher binding energies; the density of states at the Fermi level is comparable to that of pure zirconium.     

Surface effects on Sm valence in amorphous Sm alloys

We present the results of XPS and X-ray absorption measurements performed on the amorphous Sm Au and La Sm Au compounds. The XPS Sm 3d$\text{5}\text{2}$ core level spectra in these compounds reveal that at the surface (5 ? 7 Å) the samarium ions present both the Sm²⁺ (4f⁶) and Sm³⁺ (4f⁵) configurations. When the concentration in samarium decreases it is shown that the Sm²⁺ configuration is strongly enhanced at the surface whereas the X-ray absorption measurements indicate on the contrary that in the bulk only the Sm³⁺ configuration is present. Comparison is made with similar findings in pure crystalline Sm and various crystalline rare earth compounds.     

Size-dependent grain-growth kinetics observed in nanocrystalline Fe

Measurements of grain growth in nanocrystalline Fe reveal a linear dependence of the grain size on annealing time, contradicting studies in coarser-grained materials, which find a parabolic (or power-law) dependence. When the grain size exceeds approximately 150 nm, a smooth transition from linear to nonlinear growth kinetics occurs, suggesting that the rate-controlling mechanism for grain growth depends on the grain size. The linear-stage growth rate agrees quantitatively with a model in which boundary migration is controlled by the redistribution of excess volume localized in the boundary cores.