Modulated hydrogen beam study of adsorption-induced desorption of deuterium from Si(100)-3×1:D surfaces

We have studied the kinetic mechanism of the adsorption-induced-desorption (AID) reaction, H + D/Si(100)D2. Using a modulated atomic hydrogen beam, two different types of AID reaction are revealed: one is the fast AID reaction occurring only at the beam on-cycles and the other the slow AID reaction occurring even at the beam off-cycles. Both the fast and slow AID reactions show the different dependence on surface temperature Ts, suggesting that their kinetic mechanisms are different. The fast AID reaction overwhelms the slow one in the desorption yield for 300 KTs650 K. It proceeds along a first-order kinetics with respect to the incident H flux. Based on the experimental results, both two AID reactions are suggested to occur only on the 3×1 dihydride phase accumulated during surface exposure to H atoms. Possible mechanisms for the AID reactions are discussed

Modeling of hysteretic Schottky diode-like conduction in Pt/BiFeO3/SrRuO3 switches

The hysteresis current-voltage (I-V) loops in Pt/BiFeO3/SrRuO3 structures are simulated using a Schottky diode-like conduction model with sigmoidally varying parameters, including series resistance correction and barrier lowering. The evolution of the system is represented by a vector in a 3D parameter space describing a closed trajectory with stationary states. It is shown that the hysteretic behavior is not only the result of a Schottky barrier height (SBH) variation arising from the BiFeO3 polarization reversal but also a consequence of the potential drop distribution across the device. The SBH modulation is found to be remarkably lower (0.5 eV). It is also shown that the p-type semiconducting nature of BiFeO3 can explain the large ideality factors (>6) required to simulate the I-V curves as well as the highly asymmetric set and reset voltages (4.7 V and 1.9 V) exhibited by our devices

Novel bis(fluorosulfonyl)imide-based and ether-functionalized ionic liquids for lithium batteries with improved cycling properties

Novel ionic liquids (ILs), which were functionalized with ether oxygens to suppress crystallization and with bis(fluorosulfonyl)imide (FSI) anions to improve ionic conductivity, were synthesized and compared. Electrolyte mixtures were prepared by adding LiFSI to N-ethoxyethyl-N-methylpiperidinium FSI ([P 1,2O2 ][FSI]) and N-ethoxyethyl-N-methylmorpholinium FSI ([M 1,2O2 ][FSI]) in ratio of 1:9 (mol/mol). The electrolyte mixtures were found to exhibit a glass transition temperature between −71 and −93 °C and a decomposition temperature higher than 266 °C. Between these temperatures, the electrolytes were ion conductive and thermally stable liquids. [P 1,2O2 ][FSI]-LiFSI exhibited a wider electrochemical stability window and possessed an ability to form solid electrolyte interfaces having a lower resistance compared to [M 1,2O2 ][FSI]-LiFSI. Based on these results, the Li | LiFePO 4 cells containing [P 1,2O2 ][FSI]-LiFSI as electrolytes were assembled and found to possess a high capacity, reaching to the nominal capacity 150 mAh g −1 at C/10. Moreover, the cell retained flat potential profiles throughout 50 cycles

Preparation of epoxy resins derived from lignin solubilized in tetrabutylphosphonium hydroxide aqueous solutions

Organic onium hydroxide aqueous solutions (OHAS) are demonstrated to be potential solvents for the dissolution of lignin and its epoxidation. A series of OHAS has been assessed in terms of the solubility of soda lignin (SL) and Klason lignin (KL), which are moderately and rarely soluble in NaOH aq. soln., respectively. Tetrabutylphosphonium hydroxide ([P 4444 ]OH) aqueous solution was found to exhibit a highest solubility, specifically 40 wt% of SL and 3.0 wt% of KL. The superior solubility of OHAS is comprehended to be due to weak interactions between OH anions and phosphonium cations, and hence OH anions interact effectively with lignin. Epoxidation of SL was achieved by simply adding epichlorohydrin to [P 4444 ]OH aq. dissolving SL. Films of epoxidized SL were prepared by thermal curing with the aid of a crosslinking agent, and the films were found to possess high thermal stability of >250 °C and excellent ductility. The thermal and mechanical properties were controllable by the concentration of [P 4444 ]Cl as an additive

Polymerized ionic liquids as durable antistatic agents for polyether-based polyurethanes

Ionic liquid (IL) fillers, which are composed of polymerized [2-(methacryloyloxy)ethyl]trimethylammonium bis(trifluoromethanesulfonyl)imide, were applied as antistatic agents for polyether-based polyurethane (PU). Surface and volume resistivities of 10 10 Ω sq −1 and 10 8 Ω cm, which are hundred times smaller than those of pristine PU and also are desired values for realizing antistatic effects, were achieved at the concentration of fillers of only 1000 ppm. The fillers exhibited excellent antistatic effect, equivalent to the effect caused by conventional ILs, even though the fillers are solid particles. Temperature dependence of ionic conductivity of the intrinsic fillers was found to follow the Arrhenius model, while that of the filler-PU composites followed the Vogel–Fulcher–Tammann model. This suggests that IL units of the fillers are effectively dissociated in the polyether matrix, and migration of the dissociated ions occurs associated with the relaxation of polyether chains. Employing the polymerized ILs, the reduced resistivity was retained also after ultrasonication treatment of films in methanol. The polymerized IL fillers are concluded to be promising additives for the sustainable and durable antistatic treatment of polyurethanes

Ionic liquids and their derivatives for lithium batteries: role, design strategy, and perspectives

Lithium-ion batteries (LIBs) are the predominant power source for portable electronic devices, and in recent years, their use has extended to higher-energy and larger devices. However, to satisfy the stringent requirements of safety and energy density, further material advancements are required. Due to the inherent flammability and incompatibility of organic solvent-based liquid electrolytes with materials utilized in high energy devices, it is necessary to transition to alternative conductive mediums. The focus is shifting from molecular materials to a class of materials based on ions, including ionic liquids (ILs) and their derivatives such as zwitterionic ILs, polymerized ILs, and solvated ILs, which possess high levels of safety, stability, compatibility, and the ability to rationally design ILs for specific applications. Ion design is crucial to achieve superior control of electrode/electrolyte interphases (EEIs) both on anode and cathode surfaces to realize safer and higher-energy lithium-metal batteries (LMBs). This review summarizes the different uses of ILs in electrolytes (both liquid and solids) for LMBs, reporting the most promising results obtained during the last years and highlighting their role in the formation of suitable EEIs. Furthermore, a discussion on the use of deep-eutectic solvents is also provided, which is a class of material with similar properties to ILs and an important alternative from the viewpoint of sustainability. Lastly, future prospects for the optimization of IL-based electrolytes are summarized, ranging from the functional design of ionic structures to the realization of nanophases with specific features