Role of Li_2B_(12)H_(12) for the Formation and Decomposition of LiBH_4

By in situ X-ray diffraction (XRD) and nuclear magnetic resonance (NMR) spectroscopy, the role of Li_2B_(12)H_(12) for the sorption of LiBH_4 is analyzed. We demonstrate that Li_2B_(12)H_(12) and an amorphous Li_2B_(10)H_(10) phase are formed by the reaction of LiBH_4 with diborane (B_2H_6) at 200 °C. Based on our present results, we propose that the Li -2B - (12)H_(12) formation in the desorption of LiBH_4 can be explained as a result of reaction of diborane and LiBH_4. This reaction of the borohydride with diborane may also be observed for other borohydrides, where B_(12)H_(12) phases are found during decomposition

Hydrogen Dynamics in Lightweight Tetrahydroborates

The high hydrogen content in complex hydrides such as M[AlH4]x and M[BH4]x (M = Li, Na,K, Mg, Ca) stimulated many research activities to utilize them as hydrogen storage materials. An understanding of the dynamical properties on themolecular level is important to understand and to improve the sorption kinetics. Hydrogen dynamics in complex hydrides comprise long range translational diffusion as well as localized motions like vibrations, librations or rotations. All the different motions are characterized by their specific length- and timescales. Within this review we give an introduction to the physical properties of lightweight complex hydrides and illustrate the huge variety of dynamical phenomena on selected example

In situ characterization of the decomposition behavior of Mg(BH4)(2) by X-ray Raman scattering spectroscopy

We present an in situ study of the thermal decomposition of Mg(BH4)(2) in a hydrogen atmosphere of up to 4 bar and up to 500 degrees C using X-ray Raman scattering spectroscopy at the boron K-edge and the magnesium L2,3-edges. The combination of the fingerprinting analysis of both edges yields detailed quantitative information on the reaction products during decomposition, an issue of crucial importance in determining whether Mg(BH4)(2) can be used as a next-generation hydrogen storage material. This work reveals the formation of reaction intermediate(s) at 300 degrees C, accompanied by a significant hydrogen release without the occurrence of stable boron compounds such as amorphous boron or MgB12H12. At temperatures between 300 degrees C and 400 degrees C, further hydrogen release proceeds via the formation of higher boranes and crystalline MgH2. Above 400 degrees C, decomposition into the constituting elements takes place. Therefore, at moderate temperatures, Mg(BH4)(2) is shown to be a promising high-density hydrogen storage material with great potential for reversible energy storage applications.Peer reviewe

АСУ ТП горения жидкого и газообразного топлива на основе бесконтактных оптических техник

В результате выполнения магистерской диссертации разработана автоматизированная система управления горением жидкого и газообразного топлива на основе бесконтактных оптических техник. В процессе выполнения работы был произведен анализ существующих бесконтактных оптических методов. Также были проведены экспериментальные исследования, и произведен выбор схемы регулирования. Разработаны схема структурная, схема функциональная, схема принципиальная электрическая, схема монтажная внешних проводок и сборочный чертеж щита управления со спецификацией на него. Осуществлен выбор технических средств автоматизации и составлена заказная спецификация. Система разработана с учетом технических требований, нормативных документов и исходя из результатов научно-исследовательской работы.As a result of the master's thesis, an automated control system for the combustion of liquid and gaseous fuels based on contactless optical techniques was developed. In the course of the work, the analysis of the existing non-contact optical methods was carried out. Experimental studies were also carried out, and the choice of the control scheme was made. A structural diagram, a functional diagram, an electrical circuit diagram, a wiring diagram of external wiring and an assembly drawing of the control panel with a specification for it are developed. The choice of technical means of automation is carried out and the custom specification is made. The system is developed taking into account technical requirements and research results

Isotope effects in switchable metal-hydride mirrors

Measurements of optical reflectance, transmittance, and electrical resistivity on the switchable mirror systems YHx and YDx show that the absorption of hydrogen induces the same variations as that of deuterium. In both cases there is a weak transparency window for the metallic dihydride (dideuteride) phase and a yellowish transparency in the insulating trihydride (trideuteride) phase. The slightly higher electrical resistivity of the deuterides is related to the lower energy of their optical phonons. The absence of significant isotope effects in the optical properties of YHx(YDx) is at variance with Peierls-like theoretical models. It is, however, compatible with strong electron correlation model

Generation and detection of H electrodiffusion waves

A study was conducted on the generation and detection of H electrodiffusion waves. The applied electric field was used to spatially modulate the H concentration in a thin V film, to drive H pulses and to control the hydrogen uptake of the sample. The migration of H in transition metals was visualized by using the switchable mirror material as an optical hydrogen indicator