Magnesium–carbon hydrogen storage hybrid materials produced by reactive ball milling in hydrogen

Time-resolved studies uncovered kinetics and mechanism of Mg–hydrogen interactions during High energy reactive ball milling in hydrogen (HRBM) in presence of various types of carbon, including graphite (G), activated carbon (AC), multi-wall carbon nanotubes (MWCNT), expandable (EG) and thermally-expanded (TEG) graphite. Introduction of carbon significantly changes the hydrogenation behaviour, which becomes strongly dependent on the nature and amount of carbon additive. For the materials containing 1 wt.% AC or TEG, and 5 wt.% MWCNT, the hydrogenation becomes superior to that for the individual magnesium and finishes within 1 h. Analysis of the data indicates that carbon acts as a carrier of the ‘‘activated’’ hydrogen by a mechanism of spill-over. For Mg–G the hydrogenation starts from an incubation period and proceeds slower. An increase in the content of EG and TEG above 1 wt.% results in the deterioration of the hydrogenation kinetics. The effect of carbon additives has roots in their destruction during the HRBM to form graphene layers encapsulating the MgH2 nanoparticles and preventing the grain growth. This results in an increase of absorption–desorption cycle stability and a decrease of the MgH2 crystallite size in the re-hydrogenated Mg–C hybrid materials (40–125 nm) as compared to Mg alone (180 nm).Web of Scienc

Моделювання основних характеристик сонячних елементів на основі гетеропереходів n-ZnS/p-CdTe і n-CdS/p-CdTe

В роботі з використанням програмного середовища SCAPS-3200 проведено моделювання темнових та світлових ВАХ, а також спектральних розподілів квантової ефективності плівкових сонячних елементів (СЕ) на основі ідеальних гетеропереходів n-ZnS/p-CdTe і n-CdS/p-CdTe. Показано, що заміна традиційного матеріалу віконного шару фотоперетворювачів CdS на більш широкозонний матеріал ZnS приводить до зростання ККД. Встановлені конструктивні параметри СЕ на основі багатошарової системи n-ZnS/p-CdTe, які забезпечують їх максимальну ефективність. Вироблені рекомендації щодо оптимізації технології створення реальних дешевих та високоефективних плівкових перетворювачів сонячної енергії. При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/33899В работе с использованием программной среды SCAPS-3200 проведено моделирование темновых и световых ВАХ, а также спектральных распределений квантовой эффективности пленочных солнечных элементов (СЕ) на основе идеальных гетеропереходов n-ZnS/p-CdTe и n-CdS/p-CdTe. Показано, что замена традиционного материала оконного слоя фотопреобразователей CdS на более широкозонный материал ZnS приводит к росту их КПД. Установлены конструктивные параметры СЕ на основе многослойной системы n-ZnS/p-CdTe, обеспечивающие их максимальную эффективность. Выработаны рекомендации по оптимизации технологии создания реальных дешевых и высокоэффективных пленочных преобразователей солнечной энергии. При цитировании документа, используйте ссылку http://essuir.sumdu.edu.ua/handle/123456789/33899Modeling of dark and light I-V characteristics and spectral response of quantum efficiency of solar cell films on the basis of ideal n-ZnS/p-CdTe and n-CdS/p-CdTe heterojunctions with the use of SCAPS-3200 software environment is held in this work. It is shown that the replacement of traditional material of window layer of photovoltaic devices with more wide area ZnS material leads to increase of their efficiency. The constructive parameters of solar cells on the basis of multilayer n-ZnS/p-CdTe system which provide their maximal efficiency were established. It makes possible to optimize the technology of obtaining real cheap and highly effective thin film solar energy transformers. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3389

New CeMgCo₄ and Ce₂MgCo₉ compounds: Hydrogenation properties and crystal structure of hydrides

Two new ternary intermetallic compounds, CeMgCo4 (C15b pseudo-Laves phase, MgCu4Sn type) and Ce2MgCo9 (substitution derivative of PuNi3 type) were synthesized by mechanical alloying method. The structural and hydrogenation properties of these compounds were studied by X-ray diffraction and Pressure–Composition–Temperature measurements. Both compounds absorb hydrogen at room temperature and pressures below 10 MPa forming hydrides with maximum compositions CeMgCo4H6 and Ce2MgCo9H12. Single plateau behavior was observed in P–C isotherm during hydrogen absorption/desorption by Ce2MgCo9 alloy. The CeMgCo4–H2 system is characterized by the presence of two absorption/desorption plateaus corresponding to formation of β-CeMgCo4H4 and γ-CeMgCo4H6 hydride phases. The structure of β-hydride CeMgCo4H(D)4 was determined from X-ray and neutron powder diffraction data. In this structure initial cubic symmetry of CeMgCo4 is preserved and hydrogen atoms fill only one type of interstitial sites, triangular MgCo2 faces. These positions are occupied by 70% and form octahedron around Mg atom with Mg–D bond distances 1.84 Å

Crystal structure of the novel Mg₃MnNi₂D_3−x interstitial deuteride

A novel low-temperature hydride, Mg3MnNi2D3−x with filled Ti2Ni-type structure has been synthesised and its crystal structure has been studied in detail by powder neutron diffraction. Refinement of the structures of β-Mg3MnNi2D1.83 and α-Mg3MnNi2D0.23 deuteride phases showed that D atoms partially fill 16d Mg6 octahedral and 32e Mg3Ni tetrahedral interstices in the cubic metal matrix (sp.gr. View the MathML sourceFd3¯m). The β-hydride was found to be rather unstable, during storage in air it transforms into α-hydride

Y6Mg9Co2 and Y9Mg30Co2: Novel magnesium-rich compounds representing new structure types

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