We report here for the first time a fabrication of betavoltaic battery prototype consisting of 200 single conversion cells based on Schottky barrier diamond diodes which have been vertically stacked ...with ~24% 63Ni radioactive isotope. The maximum electrical output power of about 0.93 μW was obtained in total volume of 5 × 5 × 3.5 mm3. We used the ion-beam assisted lift-off technique to obtain conversion cells of minimal thickness comparable with the characteristic penetration length of beta-particles emitted by 63Ni isotope. The obtained value of 15 μm was limited by the mechanical strength of produced structures and process reliability. To check the performance of thin diamond based conversion cells we carried out IV-curves measurements at electron beam irradiation in SEM. We found that the sacrificial layer for the splitting of such thin conversion cell from HPHT diamond substrate did not cause a considerable degradation of device charge collection efficiency. As a result, the fabricated prototype provided the output power density of about 10 μW/cm3, that is the best known value for nuclear batteries based on 63Ni radioisotope. Moreover, the long half-life of 63Ni isotope gives the battery specific energy of about 3300 mWh/g that is an order of magnitude higher than the typical value of commercial chemical cells.
Display omitted
•We successfully used ion-beam assisted lift-off technique to fabricate 15 μm thick diamond-based energy conversion cells.•The energy conversion efficiency (~5-6 %) of produced cells was limited by relatively low open-circuit voltage (~1.1 V).•For produced conversion cells the charge collection efficiency >90% was demonstrated.•Compact (~90 mm3, 0.35 g) ~1 μW nuclear battery was developed and fabricated by using of 200 cells combined with ~24% 63Ni foil.•The battery power density of 10 μW/cm3 and specific energy of 3300 mWh/g were achieved due to cell thickness decreasing.
Investigation is carried out to experimentally study concentration of microwave radiation with a wavelength ranging from 2.46 to 3.55 cm in a compact subwavelength region by a spherical resonator ...consisting of a dielectric sphere with a waveguide branch 1.15, 2, or 2.26 mm in diameter connected to the sphere tangentially to its surface or normally along its radius. The microwave radiation with a frequency ranging from 8.45 to 12.2 GHz excites Mie resonance oscillations in the spherical resonator with the attached waveguide branch. Frequency dependences of radiation from the waveguide branches show that the radiation intensity at the Mie resonance is almost two orders of magnitude higher than the intensity of the radiation exciting the resonant sphere.
The features of creating supercapacitors based on anodic titanium-oxide nanotubes modified with a layer of a conducting polymer, i.e., the emeraldine form of polyaniline, are considered. Multilayer ...solid-state capacitive systems are formed based on nanostructured electrodes obtained by the anodic treatment of a titanium substrate in a solution of ethylene glycol and ammonium fluoride, followed by the deposition of a layer of polyaniline. Based on the analysis of voltammograms, the capacitance of nanostructured systems is determined to be 4.38 mF/cm2. The features of the influence of the structure of the anodic-formed oxide on the capacitance characteristics of the system are considered. It is established that as a result of the polymorphic transformation of amorphous anodic titanium oxide into crystalline titanium oxide during isothermal annealing, the voltammogram of the systems under study takes on a shape close to an ideal rectangular one, and the capacitance increases by a factor of 2. Based on the impedance-spectroscopy data of the studied samples, an equivalent circuit is constructed and the resistance and capacitance characteristics of the formed supercapacitors are determined.
Electron microscopy is used to study samples of an aluminum matrix composite material with multiwalled carbon nanotubes (MWCNTs). The features of microstructure changes occurring during the ...preparation of a composite in a spark plasma sintering (SPS) setup are identified. The results of the simulation of the SPS process are presented taking into account the high electro- and heat-conducting properties of MWCNTs, which qualitatively explain the differences in the sintering processes of pure aluminum and composite samples.
Oxygen-containing plasma termination of the surface of diamond detectors of the time of flight of high-energy protons for leakage-current reduction is investigated. To this end, platinum electrical ...contacts with a complex shape are made on the surface of diamond using sputtering and explosive photolithography, and their current–voltage characteristics are analyzed. Dark leakage currents via, presumably, the surface states of diamond, which form because of violation of surface termination, are studied. Methods for reducing leakage currents by 2 to 3 orders of magnitude using surface treatment in oxygen-containing plasma (without high-temperature annealing) are developed. After treatment, the leakage currents of all fabricated detectors do not exceed 200 pA at a voltage up to ±850 V, which corresponds to the requirements imposed on detectors of this type.
The regulatory effect of two oxyderivatives of unsaturated fatty acids (oxylipins), 18-hydroxy(9Z,12Z)-octadecadienoic acid (18-HODE) and 18-(9Z,12Z,15Z)-octadecatrienoic acid (18-HOTrE), on the ...sexual and asexual sporulation of wild-type Neurospora crassa strains and wc-1 and wc-2 mutants was studied. In the wild-type strain, 18-HODE, unlike 18-HOTrE, stimulated protoperithecia formation in the dark and in the light. In the same strain, the studied oxylipins influenced conidiogenesis only under illumination. 18-HODE stimulated and 18-HOTrE inhibited the conidia formation. Oxylipins had no effect on protoperithecia formation in photoreceptor complex mutants, which apparently indicated its involvement in signal transduction in N. crassa. The stimulating action of the studied oxylipins on conidiagenesis in wc-1 and the lack of action in wc-2 may indicate alternative signaling pathways of oxylipins in this process.
Southern Ural is a unique region in Eurasia with a high variety of flora and vegetation. Mountain relief predominates in the steppe and forest-steppe landscapes. Stony habitats and petrophytic ...vegetation are widespread here. It is characterized by a high diversity of flora and numerous endemic, rare, and endangered plants. The dataset of 3614 relevés of forb and shrub communities from the territory of Southern Ural and adjacent regions is analyzed. Formalized methods of cluster analysis, an assessment of moistening using the ecological indices of plants, and the definition of indicator species are used. Patterns of changes in the species composition of petrophytic communities along the moistening gradient are determined. It is found that, with an increase in moisture, the number and cover of petrophytic species in communities on rocky habitats decreases. On the contrary, the role of indifferent species is growing. Five groups of species indicating different gradient segments are determined. Based on the results of cluster analysis, four large units of petrophytic vegetation are identified. Desert-steppe communities have the greatest floristic originality among vegetation on rocky habitats. Obligate petrophytes predominate in their diagnostic combination, many of which grow on limestone outcrops. These communities are found in the south of Orenburg oblast, mainly in the dry steppe landscapes of Southern Ural. Dwarf subshrub–bunchgrass steppes are widespread within the steppe landscapes and are common in the forest steppe of Ural. Forb–bunchgrass petrophytic steppes are widely represented in the northern part of the steppe zone and in the southern forest-steppe regions, as well as in the forest-steppe landscapes of Middle Ural. Meadow petrophytic steppes are found in forest-steppe and forest landscapes.
The method of molecular dynamics is used to study phase transitions and ion transport phenomena in uranium dioxide nanocrystals. The temperature dependences of uranium and oxygen diffusion ...coefficients in the range from 2280 to 3950
K are calculated separately for surface, near-surface and bulk regions of the crystals. On these dependences we have distinguished temperature intervals, which correspond to crystalline phase, superionic state and melt. The activation energies of diffusion and pre-exponential factors for these intervals are determined. The obtained results are compared with experimental data and calculations of other authors.
PDF
