RESUMEN
Silver(I) ions have the propensity of undergoing reduction to form metallic silver within olefin/paraffin separation systems when they are subjected to hydrogen at elevated temperatures. Ionic liquids (ILs) are versatile solvents known for their low vapor pressure, high thermal stability, and structural tunability and have been shown to minimize hydrogen-induced reduction of silver(I) ions when employed as solvents. In the development of robust separation platforms that employ silver(I) ions, it is essential to deploy reliable approaches capable of measuring and assessing the factors that lower the overall separation performance. In this study, silver(I) ions dissolved in an imidazolium-based IL are subjected to mixed gas streams composed of hydrogen, nitrogen, and methane under varying temperatures. Using inverse gas chromatography, a total of 44 columns with stationary phases containing four different concentrations of silver(I) bis[(trifluoromethyl)sulfonyl]imide ([Ag+][NTf2 -]) dissolved in the 1-decyl-3-methylimidazolium ([C10MIM+]) [NTf2 -] IL were used to measure partition coefficients of olefins and paraffins, as well as aromatics, esters, and ketones. Upon exposing the stationary phases to mixed gases at elevated temperatures, olefin partitioning between the silver(I) ion pseudophase and the two other phases (i.e., carrier gas and IL stationary phase) was observed to decrease over time, while partitioning between the IL stationary phase and carrier gas remained unchanged. It was found that exposure gases composed of 5.0 to 85.0 mol % hydrogen and temperatures ranging from 95 to 130 °C resulted in a remarkable acceleration of silver(I) ion reduction and an approximate 36.4-61.3% decrease in olefin partitioning between the silver(I) ion pseudophase and both the carrier gas and IL stationary phase after 60 h. While binary mixtures of hydrogen and nitrogen resulted in a continuous decrease in silver(I) ion-olefin complexation capability, a ternary gas mixture produced varied silver(I) ion reduction kinetics.
RESUMEN
We investigated the atomic structure of inclined threading edge dislocation (TED) typically observed in GaN grown on Si(111) through (scanning) transmission electron microscopy. Atomic observations verified that the inclined TED consisted of two partial dislocations. These results imply that the inclined TED possesses a Ga-Ga atomic configuration that is energetically unfavorable. However, the introduction of such structures is considered unavoidable because the TEDs should climb regularly to mediate the applied stress or the increasing surface due to the buffer layer. This Ga-Ga configuration is highly likely to form metallic bonds and appears to be the primary reason for the inferior efficacy of a GaN light-emitting diode grown on Si(111).