Effect of 10 MeV electron irradiation on the electrical properties of bulk α-In2Se3 crystals.

In this work, the effect of 10 MeV electron irradiation on the structure and electrical properties of bulk α-In2Se3 crystals is studied by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray microanalysis, atomic-force microscopy, and Raman spectroscopy methods. Droplets of 200-500 nm in size were detected on the bulk α-In2Se3 crystal surface. The droplets can be formations with the γ-In2Se3 crystalline phase. The current-voltage characteristics measured by conductive atomic-force microscopy are different on and outside the droplets after electron irradiation. On the droplets, slightly better conductive properties were detected after irradiation with the electron fluence of 1015 cm-2. It is found that local resistance increases significantly for both on and outside the droplets after irradiation with the electron fluence of 1017 cm-2. Our study shows that electron irradiation can contribute to the disappearance of ferroelectric domains in the bulk α-In2Se3 crystals. Also, the distribution of surface potentials measured by Kelvin probe force microscopy becomes more uniform after electron irradiation. The results obtained in the work allow us to calculate the operating time of the device containing α-In2Se3 under conditions of long-term electron irradiation with high-energy electrons. The study shows that α-In2Se3 is a very promising material for applications in the aerospace and nuclear industries.

Multicomponent Domino Cyclization of Ethyl Trifluoropyruvate with Methyl Ketones and Amino Alcohols as A New Way to γ-Lactam Annulated Oxazacycles.

A new route to bicyclic γ-lactams was found, which was proposed as a three-component cyclization of ethyl trifluoropyruvate with methyl ketones and 1,2-, 1,3-amino alcohols. As a result, a series of trifluoromethyl-substituted tetrahydropyrrolo [2,1-b]oxazol-5-ones and tetrahydropyrrolo[2,1-b][1,3]oxazine-6-ones was synthesized, in which the substituent at the nodal carbon atom was varied. The introduction of a twofold excess of ethyl trifluoropyruvate in reactions with amino alcohols and acetone made it possible to obtain the same bicycles, but functionalized with a hydroxyester fragment, which are formed due to four-component interactions of the reagents. Transformations with 2-butanone and aminoethanol lead predominantly to similar bicycles, while an analogous reaction with aminopropanol gives N-hydroxypropyl-2,3-dihydropyrrol-5-one. Almost all bicycles are formed as two diastereomers, the structure of which was determined using 1H, 19F, 13C NMR spectroscopy, including two-dimensional experiments and XRD analysis. A domino mechanism for the formation of tetrahydropyrrolo[2,1-b]oxazacycles was proposed, which was confirmed by their stepwise synthesis through the preliminary preparation of the aldol and bis-aldol from ethyl trifluoropyruvate and methyl ketones.