Application of ultrafine-dispersed diamonds in electroplating

The results obtained upon the electrochemical deposition of composite coatings containing ultrafine-dispersed diamonds produced by detonation synthesis are generalized. The main advantages of such coatings over the well-known composite electrochemical coatings are revealed.     

High-efficiency erbium ion luminescence in silicon nanocrystal systems

The photoluminescence spectra and kinetics of both erbium-doped and undoped multilayer structures of quasi-ordered silicon nanocrystals in a silicon dioxide matrix were studied. It was shown that the optical excitation energy of silicon nanocrystals 2–3 nm in size can be practically completely transferred to Er³⁺ ions in the oxide surrounding the nanocrystals, with its subsequent radiation at 1.5 μm. Possible reasons for the high excitation efficiency of the Er³⁺ ions are discussed, and the conclusion is drawn that the F?rster mechanism is dominant in the energy transfer processes occurring in these structures. __________ Translated from Fizika Tverdogo Tela, Vol. 46, No. 1, 2004, pp. 105–109. Original Russian Text Copyright ? 2004 by Kashkarov, Kamenev, Lisachenko, Shalygina, Timoshenko, Schmidt, Heitmann, Zacharias.     

Modeling of the structure and electronic structure of condensed phases of small fullerenes C<Subscript>28</Subscript> and Zn@C<Subscript>28</Subscript>

A comparative analysis of the stability factors and electronic structure of two possible crystalline forms of small fullerene C₂₈ and endohedral fullerene Zn@C₂₈ with diamond and lonsdaleite structures is performed using a cluster model. Atoms of elements that, when placed inside C₂₈ cages, have no significant effect on the stability of free small-fullerene molecules are shown to be able to dramatically change the electronic properties and reactivity of the C₂₈ skeleton and to be favorable for forming small-fullerene crystalline modifications, which are covalent crystals. In contrast, if the presence of foreign atoms inside C₂₈ cages stabilizes the isolated nanoparticles, then molecular crystals (such as C₆₀ fullerites) are formed due to weak van der Waals forces.     

Calculation of the asymmetry parameters of the angular distribution and of the spin polarization of Auger electrons for open-shell atoms

By means of the multichannel Hartree-Fock-Dirac method, the parameters β and α₂ of the angular distribution of Auger electrons and the parameter β₂ of their spin polarization are calculated for sodium, krypton, xenon, barium, mercury, and excited argon. Relevant Coulomb matrix elements are determined by using orthogonal multielectron initial-and final-state wave functions for intermediate-type coupling in a relativistic approximation. Exchange interaction is taken into account in all calculations. A comparison of the results of calculations performed in the frozen-core approximation and those obtained with orthogonal initial-and final-state wave functions reveals that the relaxation of core orbital processes has only a slight effect on the anisotropy parameters of the angular distribution. The resulting values of the parameters β, α₂, and β₂ are compared with the results of different calculations.     

Amplitude of Elastic Photon Scattering in Scalar Electrodynamics

In the present paper, the probability of creating pairs of scalar particles in an arbitrary plane electromagnetic wave field is calculated. The amplitude of elastic photon scattering in the field of an arbitrary plane electromagnetic wave is calculated by the method of dispersion relations. Special cases of the plane electromagnetic wave field are examined.     

New data on the ternary fission of 252Cf from the Gammasphere facility

Ternary fission of ²⁵²Cf was studied at Gammasphere using eight ΔE×E particle telescopes. Helium, beryllium, boron, and carbon light charged particles (LCPs) emitted with kinetic energy more than 9, 21, 26, and 32 MeV, respectively, were identified. The 3368-keV γ transition from the first 2⁺ excited state in ¹⁰Be was found and the population probability ratio N(2⁺)/N(0⁺) = 0.160 ± 0.025 was estimated. No evidence was found for 3368-keV γ rays emitted from a triple molecular state. For the first time, charge distributions are obtained for ternary fission fragments emitted with helium, beryllium, and carbon LCPs.     

Magnetic structure and properties of a bulk Fe72Al5P10Ga2C6B4Si1 alloy in the amorphous and nanocrystalline states

The structure forming under controlled crystallization of a bulk Fe₇₂Al₅P₁₀Ga₂C₆B₄Si₁ amorphous alloy has been studied using differential scanning calorimetry, transmission electron microscopy, and x-ray diffraction. Crystallization of the alloy was established to result in the formation of a nanocrystalline structure consisting of three phases. The domain structure and magnetic properties of amorphous and nanocrystalline samples were investigated using the magnetooptic indicating film technique (MOIF) and a vibrating-sample magnetometer. The coercive force and the saturation magnetization of the amorphous samples were found to be 1 Oe and 130 emu/g, respectively. It was shown that the formation of the nanocrystalline structure entails a dramatic decrease in domain size (down to 1–4 μm) as compared to an amorphous sample (∼1 mm). Simultaneously, a decrease in the saturation magnetization and a strong increase in the coercive force of the samples were observed. __________ Translated from Fizika Tverdogo Tela, Vol. 46, No. 5, 2004, pp. 858–863. Original Russian Text Copyright ? 2004 by Abrosimova, Aronin, Kabanov, Matveev, Molokanov.     

Crystal and magnetic structure of the Sm0.55Sr0.45MnO3 and (Nd0.545Tb0.455)0.55Sr0.45MnO3 manganites

Neutron diffraction data are presented for the ¹⁵²Sm_0.55Sr_0.45MnO₃ (SSM) and (Nd_0.545Tb_0.455)_0.55Sr_0.45MnO₃ (NTSM) manganites. The Nd and Tb contents in the latter composition are such that the average radius of the A cation 〈r _A 〉 in these two compounds is the same. The difference in local tolerance factor fluctuations was about 10%. It was found that replacement of a rare-earth cation with leaving 〈r _A 〉 unchanged has practically no effect on the structural and transport properties; indeed, both compounds are metals at low temperatures, have the same crystal structure from liquid-helium to room temperature, and exhibit the same pattern of structural distortions at the onset of magnetic ordering. Magnetic moments of Mn ions in both compositions are ferromagnetically ordered at low temperatures, with T _C =122 and 90 K for the SSM and NTSM, respectively. Below 80 K, the rare-earth cation moments in NTSM undergo additional ordering. In contrast to compositions that are close in Sr concentration (x _Sr=0.4, 0.5), which feature a phase-separated state with a mixture of the ferromagnetic metallic and antiferromagnetic insulator phases, the ground state of both studied compositions with x _Sr=0.45 is uniformly ferromagnetic and metallic. __________ Translated from Fizika Tverdogo Tela, Vol. 46, No. 9, 2004, pp. 1650–1656. Original Russian Text Copyright ? 2004 by Kurbakov, Trounov, Balagurov, Pomyakushin, Sheptyakov, Gorbenko, Kaul.