Effective Charge in LiNbO3 Films Fabricated by Radio-Frequency Magnetron Sputtering Method

Physics of the Solid State - Amorphous Li–Nb–O films were deposited onto Si substrates by radio-frequency magnetron sputtering method. The fabricated heterostructures demonstrated the...     

Synthesis of composite calcium-phosphate coatings via pulsed photon processing

The phase composition and mechanical properties of coatings generated on a Ti surface via the ion sputtering of a hydroxyapatite (HA) target and a compound (hydroxyapatite and Ti) target with subsequent pulsed photon processing (PPP) with incoherent xenon lamp radiation are investigated. It is found for the first time that pulsed photon processing accelerates the crystallization of amorphous films of Ca–P–O–H and Ca–P–O–H–Ti compositions, during which tricalcium phosphate Ca₃(PO₄)₂, titanium oxide TiO₂ (rutile, anatas), and perovskite CaTiO₃ are formed, depending on the radiation dose and the ratio between Ti and Ca phases (Ti/Ca) with hydroxyapatite structure. It is found that pulsed photon processing of initial amorphous coatings greatly increases their hardness (up to 10.9 GPa) and adhesion (up to 29.0 MPa).     

Olefin polymerization on immobilized zirconocene catalysts containing alkylaluminoxanes synthesized on the support surface

Ethylene and propylene polymerization on immobilized catalysts of composition MMT-H₂O/AlR₃/Zr-cene (MMT = montmorillonite) and on the corresponding homogeneous catalysts of composition Zr-cene-MAO (Zr-cene = rac-Et(Ind)₂ZrCl₂, rac-Me₂Si(Ind)₂ZrCl₂, rac-Me₂Si(2-Me-4-Ph-Ind)₂ZrCl₂, rac-1-(9-η⁵-Flu)2-(5,6-Cp2-Me-1-η⁵-Ind)Et]ZrCl₂) is considered. Here, the activating support for the zirconocenes is montmorillonite containing methylaluminoxane or isobutylaluminoxane synthesized directly on the monmorillonite surface by the partial hydrolysis of an alkylaluminum (AlMe₃, Al(i-Bu)₃, Al(i-Bu)₂H) with the mobile water of the support (MMT-H₂O/AlR₃). The MMT-H₂O/AlR₃ supports are demonstrated to be effective activators for ansa-zirconocenes. The catalytic properties of the immobilized systems (process kinetics and efficiency, the molar mass of the resulting polymer, and the structure of the macromolecules) depend on the activating support and the zirconocene precatalyst. The complexes of the MMT-H₂O/Al(i-Bu)₃ support with all zirconocene precatalysts are more active in propylene polymerization than the same complexes of MMT-H₂O/AlMe₃. The zirconcenes immobilized on MMT-H₂O/AlR₃ afford polyethylene and polypropylene with a higher molar mass than the corresponding homogeneous systems. Furthermore, immobilization causes activesite heterogeneity. As compared to the homogeneous single-site catalysts of composition Zr-cene-MAO, the corresponding catalysts immobilized on MMT-H₂O/AlR₃/Zr-cene are more stereospecific in the case of rac-Me₂Si(Ind)₂ZrCl₂ (C ₂ symmetry) and are less stereospecific in the case of rac-[1-(9-η⁵-Flu)2-(5,6-Cp-2-Me-1-η⁵-Ind)Et]ZrCl₂ (C _s symmetry).     

Spontaneous radiation of a brownian nanoparticle

It is shown that a charged Brownian nanoparticle (or an electron) similar to a two-level atom can generate spontaneous and induced radiation upon switching on an external field. The diffusion mechanism of charging nanoparticles is examined. The radiation process is a macroscopic quantum phenomenon, which can be used in synthetic biology, medicine, and other fields of science and engineering.