Energetics of 5f- and 4f-orbitals and 5f- and 4f-elements similarity

En se fondant sur la détermination des potentiels d'oxydation Me2+/Me3+ sur l'énergie d'excitation des atomes entre les configurations fn s2 et fn-1 ds2 et sur les énergies de transition d'un ion une fois chargé entre fn s1 et fn+1 s0, on montre qu'il existe une grande similitude entre la première moitié de la série des lanthanides et la seconde moitié de celle des actinides. Cette similitude se manifeste également par une analogie des propriétés chimiques des éléments de ces deux sous-séries.Basing on the determination of oxidation potentials of Me2+/Me3+, of the energy of excitation of atoms from an fn s2 into an fn-1 ds2 state, and of transition energy of a monocharged ion from an electron configuration fn s1 into an fn+l s0 it was established that the maximum similarity of these elements is observed when comparing the first half of the lanthanides with the second one of the actinides. This similarity is also expressed in a likeness in the chemical properties of these subgroups of the elements

Modeling of mass-transportation of tris-(acetylacetonato)chromium(III) at atmospheric pressure

The main requirement to "hot" sources for MO CVD processes is stability of precursor vapor concentration in the area of substrate surface. Establishing the mathematical models of sublimation process of precursor will allow greatly to accelerate a transition from results of the concrete experiment to the "hot" source development with necessary parameters. Possibility of elaborating similar mathematical model taking into account totality of experimental parameters was approved on the example of description of sublimation process of tris-(acetylacetonato)chromium(III) (Cr(acac)3). Modeling of sublimation process of Cr(acac)3 for different conditions of experiment was carried out with using the notions of heat-mass-exchange theory. Criteria dependency satisfactory describing influence of experimental parameters on the rate of sublimation of molecular crystals of volatile Cr(acac)3 was obtained. An empirical correlation, J=Const×T2.18×V0.43×esp(-ΔH/RT)×W1.62×L0.386, is proposed to describe the rate of mass transfer. The W and L-are width and length of sample, accordingly. This model satisfactory describes the whole collection of experimental data and ensures forecasting of sublimation rate under other conditions of the performance of the process