Synthesis, growth and characterization of L-Leucine Magnesium Nitrate Hexahydrate crystal

L-Leucine Magnesium Nitrate HexaHydrate ([Formula: see text]) crystal is a nonlinear optical (NLO) material of semiorganic type. It has grown using a slow evaporation solution growth (SEST) technique at elevated temperature (40∘C) by dissolving LL+MNHH in double distilled water. It was crystalized and recrystalized from a supersaturated solution by stirring it for several hours to get high optical perfection. The X-ray diffraction studies confirmed the presence of the intermixed compound in the [Formula: see text] crystal and possess monoclinic structure. Fourier transform infrared spectroscopy (FTIR) spectrum identified the functional groups of the grown crystal. The crystal has very good optical absorption and transparency in the UV–Vis region. The thermal analysis revealed the thermal stability of the crystal. The dielectric study shows that dielectric constant and dielectric loss decrease at higher frequencies. The crystal showed nonlinear property by second-harmonic generation (SHG) study. This type of material with fair nonlinearity is useful in optoelectronics application devices.

Experimental Research of the Heat Storage Performance of a Magnesium Nitrate Hexahydrate-Based Phase Change Material for Building Heating

Phase change heat storage material is a preferred material in solar building heating or off-peak electric-heat storage heating technology and is the research focus. A compact phase change thermal storage device has been designed and experimentally studied for improving heating system load in this work. A new type, magnesium nitrate hexahydrate-based phase change material has been studied to improve the cooling degree and crystallization difficulty. The focus of this study is on the heat charging and discharging characteristics of this new phase change material. The heat storage device has two groups of coils, the inner side which carries water and the outer side which is the phase change material. A testing system was built up to value the thermal cycling performance of the heat storage device. The measurement data include phase change material temperature field, water inlet and water outlet mean temperature, heat charging and heat discharging depth, and flow rates over the operating period. The results show the phase change material has a quick response with the operating temperature range of 20–99 °C. Its latent heat is 151.3 J/g at 91.8 °C. The heat storage density of this phase change material is about 420 MJ/m3. The thermal performance degradation is about 1.8% after 800 operation cycles. The phase change thermal storage device shows flexibility and a great potential to improve the capacity and economy of heating systems.

Applications of a simultaneous differential scanning calorimetry–thermomicroscopy system

A simultaneous DSC–thermomicroscopy system (DSC450 Linkam Scientific) was applied to the study of phase transitions in rubidium nitrate and silver iodide, the oxidation of polyethylene, the thermal degradation of polylactic acid and magnesium nitrate hexahydrate, and the reversible transitions in thermochromic inks. The results demonstrated the benefits of obtaining simultaneous optical data, both images and light intensity measurements, with DSC, particularly in the interpretation of complex processes and the detection of events with small changes in enthalpy.

Influence of the exchange current density and overpotential for hydrogen evolution reaction on the shape of electrolytically produced disperse forms - Review

In this study, comprehensive survey of formation of disperse forms by the electrolysis from aqueous electrolytes and molten salt electrolysis has been presented. The shape of electrolitically formed disperse forms primarily depends on the nature of metals, determined by the exchange current density (j0) and overpotential for hydrogen evolution reaction as a parallel reaction to metal electrolysis. The decrease of the j0 value leads to a change of shape of dendrites from the needle-like and the 2D fern-like dendrites (metals characterized by high j0 values) to the 3D pine-like dendrites (metals characterized by medium j0 values). The appearing of a strong hydrogen evolution leads to formation of cauliflower-like and spongy-like forms (metals characterized by medium and low j0 values). The other disperse forms, such as regular and irregular crystals, granules, cobweb-like, filaments, mossy and boulders, usually feature metals characterized by the high j0 values. The globules and the carrot-like forms are a characteristic of metals with the medium j0 values. The very long needles were a product of molten salt electrolysis of magnesium nitrate hexahydrate. Depending on the shape of the disperse forms, i.e. whether they are formed without and with vigorous hydrogen evolution, formation of all disperse forms can be explained by either application of the general theory of disperse deposits formation or the concept of "effective overpotential". With the decrease of j0 value, the preferred orientation of the disperse forms changed from the strong (111) in the needle-like and the fern-like dendrites to randomly oriented crystallites in the 3D pine-like dendrites and the cauliflower-like and the spongy-like forms.