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Chemical durability of lanthanide zirconates (A2Zr2O7) (A = La-Yb) under near-field environments is important for evaluating their application as potential nuclear waste forms. In this work, A2Zr2O7 (A = La-Yb) are synthesized by spark plasma sintering with controlled microstructure and their chemical durability are evaluated in a nitric acid solution (pH = 1). Scanning transmission electron microscopy analysis reveals an amorphous passivation film either enriched with Zr or lanthanide. The complex chemistry of the passivation films can be correlated with a transition in corrosion mechanisms from a preferential release of lanthanide in La2Zr2O7 to a preferential release of Zr in Er2Zr2O7 and Yb2Zr2O7. These results suggest a dominant mechanism of incongruent dissolution and surface reorganization for the formation of passivation films. Strong correlations are identified between the leaching rates and cation ionic size, ionic potential, electronegativity differences between A-site cation and Zr, and bonding valence sum of oxygen, suggesting important impacts of structural and bonding characteristics in controlling chemical durability of lanthanide zirconates.

The information on the compatibility of lead–boron–silicate glass of various compositions and ruthenium(IV) oxide compounds is systematized. The chemical processes occurring between them are established in terms of the theory of the acid-base interaction. The informative indicators that determine the direction of such interaction are the acidity, ionic potential, or orbital electronegativity of the components included in the composite materials. The established regularities can be used for selecting the composition of lead- and cadmium-free glass in the development of advanced ruthenium resistors and ruthenium-containing materials.

PEDOT PSS has been studied as a silicon-based binder due to its inherent superior electricity and electrochemical stability. However, it cannot effectively alleviate the huge volume changes of silicon during lithiation/delithiation due to its linear structure, resulting in poor cycling stability. Ion-cross-linking is a usual method to cross-link linear polymers into 3D structures. In this paper, multivalent cations of the 5th period and Group 2 cross-linked PEDOT:PSS were applied as silicon anode binders and studied systematically. It was found that the variation trend of viscosity and conductivity of PEDOT:PSS after cross-linking was consistent with that of ionic potential and softness parameters of multivalent cations. The mesostructure of a binder after cross-linking is influenced by the solubility product constant of sulfites or hydroxides of cations and the growth characteristics of crystals. An Sn4+-cross-linked binder displayed increased viscosity and electrical conductivity and higher reduced modulus and hardness due to its positive softness parameter and higher ion potential. The Si electrode with the Sn4+-cross-linked binder showed improved cycling stability (1876.4 mAh g-1 compared with 1068.4 mAh g-1 of the electrode with the pure PEDOT:PSS binder after 100 cycles) and superior rate capability (∼800 mAh g-1 at an ultrahigh current density of 8.0 A g-1).

The impact of the chemical structure on ion transport, nanoscale morphology, and dynamics in polymerized imidazolium-based ionic liquids is investigated by broadband dielectric spectroscopy and X-ray scattering, complemented with atomistic molecular dynamics simulations. Anion volume is found to correlate strongly with Tg-independent ionic conductivities spanning more than 3 orders of magnitude. In addition, a systematic increase in alkyl side chain length results in about one decade decrease in Tg-independent ionic conductivity correlating with an increase in the characteristic backbone-to-backbone distances found from scattering and simulations. The quantitative comparison between ion sizes, morphology, and ionic conductivity underscores the need for polymerized ionic liquids with small counterions and short alkyl side chain length in order to obtain polymer electrolytes with higher ionic conductivity.

Ultrafast tunnel ionization enables femtosecond time-resolved dynamic measurements of the retro-Diels–Alder reactions of positively charged cyclohexene, norbornene, and dicyclopentadiene. Unlike the reaction times of 500–600 ps that are observed following UV excitation of neutral species, on the ionic potential energy surfaces, these reactions occur on a single picosecond timescale and, in some cases, exhibit vibrational coherence. In the case of norbornene, a 270 cm−1 vibrational mode is found to modulate the retro-Diels–Alder reaction.

Lithium-salt-based deep eutectic solvents, where the only cation is Li+, are promising candidates as electrolytes in electrochemical energy-storage devices like batteries. We have performed broadband dielectric spectroscopy on three such systems, covering a broad temperature and dynamic range that extends from the low-viscosity liquid around room temperature down to the glassy state approaching the glass-transition temperature. We detect a relaxational process that can be ascribed to dipolar reorientational dynamics and exhibits the clear signatures of glassy freezing. We find that the temperature dependence of the ionic dc conductivity and its room-temperature value also are governed by the glassy dynamics of these systems, depending, e.g., on the glass-transition temperature and fragility. Compared to the previously investigated corresponding systems, containing choline chloride instead of a lithium salt, both the reorientational and ionic dynamics are significantly reduced due to variations of the glass-transition temperature and the higher ionic potential of the lithium ions. These lithium-based deep eutectic solvents partly exhibit significant decoupling of the dipolar reorientational and the ionic translational dynamics and approximately follow a fractional Debye-Stokes-Einstein relation, leading to an enhancement of the dc conductivity, especially at low temperatures. The presented results clearly reveal the importance of decoupling effects and of the typical glass-forming properties of these systems for the technically relevant room-temperature conductivity., Comment: 12 pages, 8 figures. Revised version as accepted for publication in J. Chem. Phys

Despite the fact that aluminum is one of the most commonly-used elements, experimental results on the value of its surface tension are largely scattered due to the high sensitivity of aluminum to the atmospheric conditions, leading to huge experimental challenges. In this study, the surface tension of pure Al and Al-O systems was studied in detail using Molecular Dynamics (MD) simulations. A force field that includes embedded atoms method and charge transfer ionic potential was applied to account for interatomic interactions. Simulations were performed at different temperatures (1000-2200 K) with different initial oxygen contents. The simulations allowed us to elucidate the effects of well-controlled atmospheric conditions on surface tension. Our results show that the surface tension of aluminum is sensitive to the amount of oxygen content at the surface, which depends on the total oxygen content and the temperature. At different temperatures, different amounts of oxygen atoms are needed to saturate the aluminum surface ( XSAT0 ). A relationship between XSAT0 and temperature was derived. Due to the scattered data in the literature, a new experiment was performed to measure the surface tension of pure aluminum at two different temperatures. Our MD simulations show a good agreement with these experimental results. We believe that this study can shed light on the underlying mechanisms controlling surface tension of aluminum and could offer routes to better engineer the surface properties of this liquid metal.

We performed a density functional theory (DFT) study on X-ray photoelectron (XPS) and absorption (XAS) spectra of graphitic carbon nitride (g-C3N4) nanosheets at the N and C K-edges. A combined cluster-periodic approach was employed to calculate XPS spectra, in which the core ionic potential (IP) of the solid 2D material was computed by subtracting the work function (obtained with periodic conditions) from the gas phase IP (obtained with large cluster models). With amino-terminated supermolecules of different sizes, we obtained convergent spectra and provide new assignments for 5 nitrogen [1 sp2; 4 sp3 (bridging, tertiary, and primary/secondary amino nitrogens)] and 4 carbon (all bonded with three nitrogens) local structures. A good agreement with experiments was obtained, with the N1s (C1s) main peak position differing by 0.1-0.2 eV (0.5-0.8 eV). Our simulations show that N1s XPS of pure g-C3N4 contains only two major features at 398.6 and 401.2 eV, contributed from sp2-N and sp3-N, respectively. The chemical shifts of all sp3-N are so close (deviating by 0.3-0.6 eV) that terminal amino groups -NHx (x = 1, 2) will only be distinguished in high-resolution measurements. In C1s XPS, all carbons show similar (deviation < 0.2 eV) IPs, as determined by the same nearest neighbors. We further excluded the effect of shake-up satellites that may change our XPS interpretations by equivalent core hole time-dependent DFT (ECH-TDDFT) simulations. The effect of vibronic coupling is small (redistribution is only 0.1-0.3 eV to the higher-energy region) in the N1s edge as estimated from the asymmetric main peak shape, and negligible in the C1s edge. Quicker size convergence was found in XAS than XPS. In N1s XAS, we identified a weak π* spectral feature at 400-401 eV for both -NHx and tertiary nitrogens. Our study provides a clear theoretical reference for X-ray spectral fingerprints of different local structures, which is useful for analysis of g-C3N4 based materials with various designed or unavoidable structural modifications. We also highlight our combined cluster-periodic approach in calculating the K-edge XPS spectra of general 2D materials which predicts accurate absolute values.

We have successfully synthesized four fused hybrid diimide and diamide arrays with different effective conjugation lengths of perylene diimides and isoindigos. These arrays with varying numbers of amides and imides are an efficient strategy to fine-tune the opto-electronic properties, conformation, energy levels and device performance. It is shown that additional fused isoindigos lead to much lower electron affinity with no influence on the ionic potential. The impact of adding different additional central electron deficient isoindigos to the fused arrays has also been investigated systemically. PDI-BDOPV-PDI incorporating a strong electron deficient BDOPV unit with enforced coplanarity exhibits a very low lowest unoccupied molecular orbital (LUMO) level of −4.11 eV, and the absorption spectrum of PDI-DPN-PDI was even extended to 1000 nm. Thin film transistors were fabricated with these arrays as the semiconductor layers, the fused arrays display electron transport behaviors.

Three transition metal ions (Ni2+, Fe2+ and Cu2+)were chosen as dopants to fabricate PPy/M2+ (M:Ni2+, Fe2+ and Cu2+) electrodes by cyclic voltammetry on the stainless steel wire mesh. Fourier transform infrared, X-ray diffraction, Scanning electron microscopy and X-ray photoelectron spectroscopy techniques were employed to characterize the structure and morphology of PPy/M2+. The results prove that there are some changes in microstructure and valence of transition metal ions. Cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy tests in 1.0 mol L−1 HNO3 electrolyte in three-electrode system exhibit that the larger specific capacitance of PPy/M2+ electrodes are 517, 679 and 764 F g−1 at a current density of 5 mA cm−2 and the capacitance’ retention is 80.5, 82.7 and 83.8% after 1000 cycles. Besides, it was found that the different electrochemical properties of PPy/M2+ electrodes related to different ionic nature, such as ionic potential and ionic radius.

The utility of multivalent metal ions with aqueous electrolyte increases the electrochemical performances of supercapacitors. These compounds are non- toxic, low cost and provide accessible ionic potential towards the application’s scenario. Herein, we report a facile and effective combination of magnesium and iron layered double hydroxides (L-MFH) synthesized by industrially applicable electrodeposition technique. As of now, the bulky compositions between the metals, poor ionic conductivity and deteriorated nanostructure limits the innovation in supercapacitors. Interestingly, L-MFH dendritic structure delivers high specific capacity, 610 Cg−1 at 10 mV/s in 1 M NaOH electrolyte. The derived material retains 80% specific capacity over 3000 cycles, further the asymmetric device through the combination of L-MFH//ACC (activated carbon cloth) delivered a high energy and power densities of 39.86 Whkg−1 and 1206.03 Wkg−1, respectively. Our prescribed methodology encourages the reliability of electrode preparations, which promotes high performances of many hybrid devices.

Despite the fact that aluminum is one of the most commonly-used elements, experimental results on the value of its surface tension are largely scattered due to the high sensitivity of aluminum to the atmospheric conditions, leading to huge experimental challenges. In this study, the surface tension of pure Al and Al-O systems was studied thoroughly using Molecular Dynamics (MD) simulations. A force field that includes embedded atoms method and charge transfer ionic potential was applied to account for interatomic interactions. To complement and validate the numerical approach, the surface tension of pure aluminum at two different temperatures was also measured. A good agreement was obtained between the measured and predicted surface tension. Simulations were then performed at different temperatures (1000–2200 K) with different initial oxygen contents to elucidate the effects of well-controlled atmospheric conditions on surface tension. Our results also show that the surface tension of aluminum is sensitive to the amount of oxygen content at the surface, which depends on the total oxygen content and the temperature. At various temperatures, different amounts of oxygen atoms are needed to saturate the aluminum surface ( X O Sat . ) . A relationship between X O Sat . and temperature was derived. We believe that this study can shed light on the underlying mechanisms controlling surface tension of aluminum and could offer routes to better engineer the surface properties of this liquid metal.

Pyrochlore-structure type and its derivative in a general formula A2B2O7 (A = rare earth elements and actinides; B = Ti, Sn, Zr, Hf, Pb, Si, etc.) display excellent structural flexibility and rich crystal chemistry as promising nuclear waste form materials capable of immobilizing actinides and fission products. It is essential to understand these materials’ chemical durability and element release of radionuclides in order to evaluate their performance in near-field environment. However, it is a formidable grand technological challenge to experimentally perform durability testing across hundreds of thousands of possibilities resulting from their extreme compositional complexities due to cation substitutions at both A and B-sites. In this work, we demonstrate a machine learning approach to determine the key materials parameters and structural characteristics governing the leaching behaviors from a small set of selected compositions as model systems, enabling a science-based prediction of their chemical durability that can be extended to a wide range of chemical compositions. The combination of four key structural characteristics and materials parameters, including ionic radius size difference r A - B , ionic potential difference E B - A , electronegativity difference χ B - A , and lattice parameter α , creates features an optimized prediction of the chemical durability. Two machine learning models, linear regression and Kernel ridge regression models, are trained on the randomly-split training dataset derived from the experimentally-determined elemental release rates, and subsequently tested on the testing dataset. The predicted leaching rates from both machine learning models show an excellent agreement with the experimental data, demonstrating the feasibility of rapidly evaluating the material properties of new compositions. These results highlight the immense potential of synergizing informatics through machine learning-based models and well-controlled experiments of selected model systems to accelerate materials design and discovery with optimized compositions and performance of promising materials for effective nuclear waste management.

This work focuses on the effect of ionic radius of dopant cations on the structural and electrical properties of different rare earth doped ceria based nanoparticles. The lattice parameter of the doped samples increases linearly with dopant ionic radius. The Gd3 + doped ceria shows minimum r.m.s. strain among the others. The conductivity and activation energy of the samples are significantly affected by the dopant ionic radius. The Gd3 + doped ceria shows highest conductivity and lowest activation energies among the other rare earth doped ceria. The conductivity decreases and activation energy increases for the dopants having ionic radii higher and lower with respect to Gd3 +. The ion movements at grain and grain boundary are also found to depend on the ionic radius of the dopants. Scaling of frequency dependent modulus spectra reveals the temperature and ionic radius independent relaxation mechanism. The dielectric constant shows that the stability of defect associates is higher for the samples having ionic radius lower and higher than the ionic radius of Gd3 + ions. The conductivity values are well supported by the VRH model.

IL@MOF (IL = ionic liquid; MOF = metal organic framework) as a new type hybrid ionic conductor has attracted research interest. Ionic liquids incorporated within MOFs not only promote the ionic conductivity of ILs, but also mediate the working temperature. In our report, 1-Ethyl-3-methylimidazolium Chloride (EMIMCl) was introduced into the pores of UiO-67(Zr) MOF by taking simple strategy basing on capillary action through specific grinding and diffusing in heating process. The working temperature of EMIMCl@UiO-67 is up to 200 °C. And it shows high ionic conductivity (1.67 × 10 − 3 S·cm − 1 at 200 °C). The activation energy was estimated to be 0.37 eV. It is noteworthy that the hybrid material can be regarded as a fast-ion conductor based on the value of high conduction and low E a . The high-temperature and humidity-independent ion conduction as well as low activation energy make this material potentially useful for electrochemical devices.

This paper proposes a coupled analysis method to deal with ion generation and ion drift in the air. Electric discharge is utilized in various products, and it is very important to clarify not only how much ion is generated but also where ion drifts in the air. The proposed method, which modeled interactions between electric field and ion behavior, including ion generation, ion drift, and charging of a dielectric body, has succeeded in calculating charge removal of a metallic target, which was tens of millimeters away from a pin electrode as a source of generated ion. The calculated results show that the amount of generated ion is drastically changed because electric field is affected by electric charge of ion in the air and charging of a dielectric body. This paper also reports a comparison of measured and calculated results of charge removal time of a metallic target, which were found to be in good agreement.

Tantalum, tantalum oxide and their hetero-interfaces are of tremendous technological interest in several applications spanning electronics, thermal management, catalysis and biochemistry. For example, local oxygen stoichiometry variation in TaOx memristors comprising of metallic (Ta) and insulating oxide (Ta2O5) have been shown to result in fast switching on the sub-nanosecond timescale over a billion cycles, relevant to neuromorphic computation. Despite its broad importance, an atomistic scale understanding of oxygen stoichiometry variation across Ta/TaOx hetero-interfaces, such as during early stages of oxidation and oxide growth, is not well understood. This is mainly due to the lack of a variable charge interatomic potential model for tantalum oxides that can accurately describe the ionic interactions in the metallic (Ta) and oxide (TaOx) environment as well as at their interfaces. To address this challenge, we introduce a charge transfer ionic potential (CTIP) model for Ta/Ta-oxide system by training against lattice parameters, cohesive energies, equations of state, and elastic properties of various experimentally observed Ta2O5 polymorphs. The best set of CTIP parameters are determined by employing a single-objective global optimization scheme driven by genetic algorithms followed by local Simplex optimization. Our newly developed CTIP potential accurately predicts structure, thermodynamics, energetic ordering of polymorphs, as well as elastic and surface properties of both Ta and Ta2O5, in excellent agreement with DFT calculations and experiments. We employ our newly parameterized CTIP potential to investigate the early stages of oxidation of Ta at different temperatures and atomic/molecular nature of the oxidizing species.

International audience; Flash sintering of oxide powders is associated with dissipated power in the narrow range 10–50 W·cm−3 irrespective of their composition. By analysis and normalization of the experimental results from literature to constant particle size (100 nm) and applied electric field (500 V cm−1), we show that the relative flash sintering temperature is dictated by the oxide crystal-type and its cation ionic potential resulting from its chemical composition. The expected flash onset temperature increases with the increase in fusion enthalpy and confirm the formation of liquid at the particle contacts as a mechanism for the powder densification.

Optical absorption spectra of prepared undoped zinc phosphate glass together with samples containing additional Bi2O3 (2.5, 5, 10, 15%) were measured within the range 200–1100 nm before and after gamma irradiation. The spectrum of the undoped glass reveals strong UV absorption which is related to the presence of trace ferric ions (Fe 3+) present as unaviodable impurities within theraw materials. Bi2O3-containing glasses show an additional broad band near the visible band centered at about 464 nm which is attributed to the absorption of Bi 3+ ions. Gamma irradiation is observed to cause extension of the UV absorption of the undoped and the sample containing low 2.5% Bi2O3. The broad visible band due to Bi 3+ is not affected by gamma irradiation indicating some shielding behavior due to the presence of heavy massive Bi 3+ ions. Infrared absorption spectra of the studied glasses reveal vibrational bands due mainly to metaphosphate groups which show interference with the vibrations due to the introduction of Bi–O bonding groups (as BiO6, BiO3 or P–O–Bi) specially with the increase of Bi2O3. The crystallization behavior is discussed in relation to the phase separation concept and ionic potential of the Zn 2+ ions together with the depolymerization effect of Bi2O3 to convert metaphosphate to pyrophospahte and the formation of a crystalline bismuth phosphate phase.

To investigate the correlation between ash flow temperature (FT) and its average mole ionic potential (Iaverage), the FT of ten coals were tested by ash fusion temperature analyzer, and ash compositions were analyzed on an X-ray fluorescence spectrometry. An approximately linear relationship between the FT and its Iaverage was found: FT = 509.12 + 17.98 I average , and its R-squared value was 0.9054. The experimental FTs were all consistent with the linear relationship in the range of measuring error. The correlation might be more accurate among low sulfur and low calcium coal.

Molar volumes and refractive indexes of molten NaNO2–NaNO3 and NaOH–NaNO3 systems were measured by dilatometry and goniometry, respectively. The molar volumes of both systems increased with increasing temperature. Refractive indexes decreased with a rise of temperature or with increasing wavelength of the incident visible light. Assuming that the electronic polarisability is inherent in an ion, the electronic polarisability of a OH－ ion in the melt was estimated from the Lorentz–Lorenz equation to be 1.26×10−30 m3, being comparable with that in the crystal. The effective ionic radius of a OH－ ion was evaluated from the obtained electronic polarisability to be 1.34×10−10 m, using the correlation between the third power of the ionic radius and the electronic polarisability of an ion so far reported. The effective ionic radius obtained in this work was in good agreement with that assigned by Shannon.

Nb-doped Zinc tin oxide (NZTO) channel materials have been prepared by solution process in combination with the spin-coating method. All NZTO thin film transistors (TFTs) are n-type enhancement-mode devices, either without or with Nb additives. High-valence niobium ion (ionic charge = +5) has a larger ionic potential and similar ionic radius to Zn 2+ and Sn 4+ ions. As compared with the pure ZTO device, introducing Nb 5+ ions into the ZTO channel layers can improve the electrical properties and bias stability of TFTs because of the reduction of the oxygen vacancies. This study discusses the connection among the material properties of the NZTO films and the electrical performance and bias stability of NZTO TFTs and how they are influenced by the Nb/(Nb + Sn) molar ratios of NZTO films.

Three different tungsten precursors were used for TiO 2 modification: H 2 WO 4 , WO 2 , and ammonium m-tungstate. It was proved that modification of TiO 2 with tungsten compounds enhanced its photocatalytic activity through the improvement of charge separation. This effect was obtained by coating of TiO 2 particles with tungsten compound, which changed their surficial electrokinetical potential from positive onto negative. The most efficient tungsten compound, which caused enhanced separation of free carriers was ammonium m-tungstate (AMT). Two dyes with different ionic potential were used for the photocatalytic decomposition. It appeared that cationic dye—Methylene Blue was highly adsorbed on the negatively charged surface of TiO 2 modified by AMT and decomposed, however this photocatalyst was quickly deactivated whereas anionic dye—acid red was better adsorbed on the less acidic surface of TiO 2 and was rapidly decomposed with almost the same rate in the five following cycles.

Urea infiltration is the most extensively and ubiquitous method for depositing the multi-cation oxide catalyst layer on the electrode backbone in the SOFC area. The stoichiometry and composition are the two vital parameters for deposited multi-cation oxide nanocatalyst layer on which the catalytic activity and selectivity depend. However, the understanding behind the mechanism of multi-cation oxide nanocatalyst by urea infiltration is still missing, which restricts the reproducibility of this infiltration approach. The infiltration technique of Sm0.5Sr0.5CoO3-δ (SSC) nanoparticle by urea method is highly irreproducible due to the intermediate phase’s formation. This may result from the varying cation stoichiometry being formed along with the final product, and it is assumed to arise mainly due to the difference in precipitation tendency of cations present in the urea precursor solution. We investigate the influence of variation in the urea concentration effect on the stoichiometry of SSC nanoparticles. The difference in several parameters, such as electronegativity, ionic potential, cationic charge, and hydroxylation tendency, brings a competitive reaction within the three cations inside the urea infiltrated precursor solution. Thus, a different instrumental analysis was used to interpret the internal composition and heterostructure of the SSC nanoparticles. By applying, transmission electron microscopy with X-ray powder diffraction, the crystal structure of synthesized SSC nanoparticle was confirmed with the appropriate stoichiometry, and a comprehensive understanding of the mechanism was done for further improving the present urea syntheses protocol with proper reproducibility.

The MoO3/CuO binary oxides were selected as the potential high temperature lubricants in this work based on the ionic potential and cation polarizability approach correlated to the lubricity of solid oxides. The NiAl composite coatings with addition of 10, 30, and 50 wt% of MoO3/CuO (1:1) were fabricated via atmospheric plasma spraying (APS) technology. The tribological properties of these NiAl-MoO3/CuO composite coatings were evaluated from room temperature to 800 °C, and the basic wear mechanisms were investigated as well. The results show that, at 800 °C, the composite coating with 30 wt% of MoO3/CuO led to the lowest friction coefficient (approximately 0.16) and wear rate (3.7 × 10−5 mm3 N−1 m−1). These superior tribological outcomes were attributed to the synergistic lubricating effect of MoO3, CuO, NiO and NiMoO4 which formed on the worn surfaces via tribo-chemical reactions. Meanwhile, the decomposition of CuMoO4 formed by tribo-chemical reaction and worked synergistically to reduce the friction coefficient and wear rate at high temperatures. Meanwhile, the decomposition of CuMoO4 formed via tribo-chemical reaction of MoO3 and CuO at high temperature was observed at 800 °C sliding.

The Yb 2 O 3 –SiO 2 system is a promising coating material for silicon-based ceramics and composites in combustion environments due to the low silica activity in this silicate system. These activities lead to lower reactivity with the water vapor component of a combustion environment and hence less formation of Si(OH) 4 (g). In this study the silica activities in the Yb 2 O 3 –SiO 2 system are measured via a vapor pressure technique. Reducing agents are used to increase the vapor pressure of SiO(g) so that it is measureable in the temperature range of interest. The measured SiO(g) pressures are then used to calculated the silica activities. Activities are reported as a function of temperature for the Yb 2 O 3 + Yb 2 SiO 5 and Yb 2 SiO 5 + Yb 2 Si 2 O 7 biphasic fields. Combining the results of this work with those reported earlier, it was found that the flux of silicon tetra-hydroxide and the thermodynamic activity of silica are lower in the biphasic fields of yttrium silicates and yttrium oxide than the biphasic field consisting of ytterbium silicates and ytterbium oxide. This difference has been attributed to the smaller ionic potential of yttrium and higher optical basicity of yttrium silicates when compared to the bigger ionic potential of ytterbium and smaller optical basicity of ytterbium silicates in these systems. The measured activities are then used to calculate some representative Si(OH) 4 (g) fluxes from Yb 2 O 3 –SiO 2 compounds in a typical laboratory test furnace and compared to literature values.

An ionic polymer microactuator driven by an organic photoelectric proton pump transducer is described in this paper. The light responsive transducer is fabricated by using molecular self-assembly to immobilize oriented bacteriorhodopsin purple membrane (PM) patches on a bio-functionalized porous anodic alumina (PAA) substrate. When exposed to visible light, the PM proton pumps produce a unidirectional flow of ions through the structure’s nano-pores and alter the pH of the working solution in a microfluidic device. The change in pH is sufficient to generate an osmotic pressure difference across a hydroxyethyl methacrylate-acrylic acid (HEMA-AA) actuator shell and induce volume expansion or contraction. Experiments show that the transducer can generate an ionic gradient of 2.5 μM and ionic potential of 25 mV, producing a pH increase of 0.42 in the working solution. The ΔpH is sufficient to increase the volume of the HEMA-AA microactuator by 80%. The volumetric transformation of the hydrogel can be used as a valve to close a fluid transport micro-channel or apply minute force to a mechanically flexible microcantilever beam.

PVC-supported strontium tungstate composite membrane was prepared by the cast die frame of membrane preparation. The strontium tungstate material was qualitatively synthesized by sol-gel method of material synthesis. The membrane was characterized by SEM, XRD, FTIR, and simultaneous TGA/DTA studies. These characterizations demonstrated the material nature, functional groups, surface texture, porosity, thermal stability, ion-exchange property etc. The electrochemical properties have been studied by TMS theoretical approach which easily determines the important parameters of membranes like transport number, mobility ratio, charge density, charge effectiveness etc. The theoretical and observed electrolyte potential calculations get the values of charge density. The observed ionic potential and graphical fixed-charge density of both the membranes follows CaCl2 MgCl2 > BeCl2 order, respectively.

This manuscript presents micro-scale experimental diagnostics and nano-scale resolution X-ray imaging applied to the study of proton conduction in non-precious metal catalyst (NPMC) fuel cell cathodes. NPMC’s have the potential to reduce the cost of the fuel cell for multiple applications. However, NPMC electrodes are inherently thick compared to the convention Pt/C electrode due to the lower volumetric activity. Thus, the electric potential drop through the Nafion across the electrode thickness can yield significant performance loss. Ionomer distributions in the NPMC electrodes with different ionomer loading are extracted from morphological data using nanoscale X-ray computed tomography (nano-XCT) imaging of the cathode. Microstructured electrode scaffold (MES) diagnostics are used to measure the electrolyte potential at discrete points across the thickness of the catalyst layer. Using that apparatus, the electrolyte potential drop, the through-thickness reaction distribution, and the proton conductivity are measured and correlated with the corresponding Nafion morphology and cell performance.

Energetic electrons directed toward an insulating target material penetrate to the interior where they progressively loose their energy through multiple atomic collisions and eventually come to rest. They therefore cause an internal charge deposition with spatial distribution largely associated with their entrance energy. An investigation of the charge deposition caused by 2 MeV incident energy electrons implanted into polymethylmethacrylate (PMMA) in air at room temperature was made by measurement of the internal charges accumulated according to the applied implantation doses, up to 500 Gy. The internal charges were measured using the electrically stimulated acoustic wave (ESAW) method and initial volume charges were 90% of the applied charge implant, and were very persistent in some cases taking months to decay. Charge transport models were compared to measured charge decay and two processes, conduction and charge drift, appear to be active simultaneously. However implantation also caused changes in the material conductivity as observed by an increase in net charge decay rates according to increased implantation levels. Because of the well-defined charge deposition process in PMMA and slow decay rates, charge accumulation can be used as a diagnostic for electron radiation exposure.

The generation of anti-Frenkel pairs (oxygen vacancies and oxygen interstitials) in monoclinic and cubic ${\mathrm{HfO}}_{2}$ under an applied electric field is examined. A thermodynamic model is used to derive an expression for the critical field strength required to generate an anti-Frenkel pair. The critical field strength of ${\mathcal{E}}_{\mathrm{aF}}^{\mathrm{cr}}\ensuremath{\sim}{10}^{1}\phantom{\rule{0.16em}{0ex}}{\mathrm{GVm}}^{\ensuremath{-}1}$ obtained for ${\mathrm{HfO}}_{2}$ exceeds substantially the field strengths routinely employed in the forming and switching operations of resistive switching ${\mathrm{HfO}}_{2}$ devices, suggesting that field-enhanced defect generation is negligible. Atomistic simulations with molecular static (MS) and molecular dynamic (MD) approaches support this finding. The MS calculations indicated a high formation energy of $\mathrm{\ensuremath{\Delta}}{E}_{\mathrm{aF}}\ensuremath{\approx}8\phantom{\rule{0.16em}{0ex}}\mathrm{eV}$ for the infinitely separated anti-Frenkel pair, and only a decrease to $\mathrm{\ensuremath{\Delta}}{E}_{\mathrm{aF}}\ensuremath{\approx}6\phantom{\rule{0.16em}{0ex}}\mathrm{eV}$ for the adjacent anti-Frenkel pair. The MD simulations showed no defect generation in either phase for $\mathcal{E}l3\phantom{\rule{0.16em}{0ex}}{\mathrm{GVm}}^{\ensuremath{-}1}$, and only sporadic defect generation in the monoclinic phase (at $\mathcal{E}=3\phantom{\rule{0.16em}{0ex}}{\mathrm{GVm}}^{\ensuremath{-}1})$ with fast $({t}_{\mathrm{rec}}l4\phantom{\rule{0.16em}{0ex}}\mathrm{ps})$ recombination. At even higher $\mathcal{E}$ but below ${\mathcal{E}}_{\mathrm{aF}}^{\mathrm{cr}}$ both monoclinic and cubic structures became unstable as a result of field-induced deformation of the ionic potential wells. Further MD investigations starting with preexisting anti-Frenkel pairs revealed recombination of all pairs within ${t}_{\mathrm{rec}}l1\phantom{\rule{0.16em}{0ex}}\mathrm{ps}$, even for the case of neutral vacancies and charged interstitials, for which formally there is no electrostatic attraction between the defects. In conclusion, we find no physically reasonable route to generating point-defects in ${\mathrm{HfO}}_{2}$ by an applied field.

Vertical stacks of two-dimensional (2D) materials separated by a van der Waals gap and held together by van der Waals forces are immensely promising for a plethora of nanotechnological applications. Charge control in these stacks may be modeled with use of either a simple electrostatics approach or a detailed atomistic one. In this paper, we compare these approaches for a gated 2D transition-metal dichalcogenide bilayer and show that recently reported electrostatics-based models of this system give large errors in band energy compared with atomistic (density-functional-theory) simulations. These errors are due to the tails of the ionic potentials that reduce the electrical-equivalent van der Waals gap between the 2D layers, and can be corrected by use of the reduced gap in the electrostatic model. For a physical van der Waals gap (defined as the chalcogen-to-chalcogen distance) of 3 angstrom in a 2D bilayer, the electrical-equivalent gap is less than 1 angstrom. For the example of band-to-band-tunneling-based ultra-low-power transistors, this is seen to lead to errors of several hundred millivolts or more in the threshold voltage estimated from electrostatics.

We construct an analytical model to account for the influence of the subnanometer-wide interfacial layer on the differential capacitance and the electro-osmotic mobility of solid–electrolyte interfaces. The interfacial layer is incorporated into the Poisson–Boltzmann and Stokes equations using a box model for the dielectric properties, the viscosity, and the ionic potential of mean force. We calculate the differential capacitance and the electro-osmotic mobility as a function of the surface charge density and the salt concentration, both with and without steric interactions between the ions. We compare the results from our theoretical model with experimental data on a variety of systems (graphite and metallic silver for capacitance and titanium oxide and silver iodide for electro-osmotic data). The differential capacitance of silver as a function of salinity and surface charge density is well reproduced by our theory, using either the width of the interfacial layer or the ionic potential of mean force as the only fitting parameter. The differential capacitance of graphite, however, needs an additional carbon capacitance to explain the experimental data. Our theory yields a power-law dependence of the electro-osmotic mobility on the surface charge density for high surface charges, reproducing the experimental data using both the interfacial parameters extracted from molecular dynamics simulations and fitted interfacial parameters. Finally, we examine different types of hydrodynamic boundary conditions for the power-law behavior of the electro-osmotic mobility, showing that a finite-viscosity layer explains the experimental data better than the usual hydrodynamic slip boundary condition. Our analytical model thus allows us to extract the properties of the subnanometer-wide interfacial layer by fitting to macroscopic experimental data.

We have measured the maximum ionic conduction in distilled water of hydrated compounds based on ZrO2 containing as the second component zirconium phosphate, zirconium phosphomolybdenum acid as well as hydrated aluminum oxide in a maximum saturated form after absorption of Cu(II) ions. The conduction value of ion-exchange materials constitutes 0.01–0.07 S · m−1. Compared were the values of ionic conduction as well as migration mobility of adsorbed Cu(II) ions with properties of the surface of hydrated compounds (charge, volume of pores, radius of pores). It was shown that ionic conduction and mobility of adsorbed ions increase with a decrease of the radius of pores of inorganic polymers.

The formation of capacitive sheath and existence of the transition electric field between sheath edge and bulk plasma in RF-CCP discharge is predicted (PRL 89, 265006 2002); such structures are sensitive to the plasma composition. On the basis of semi-infinite particle-in-cell (PIC) simulation the effect of charge and mass of ionic species on the spatio-temporal evolution of the transient electric field and phase mixing phenomena in linear and weakly nonlinear regime has been explored. As an important feature, the simulation results predict that the maximum amplitude of the transient electric field decreases with increasing ionic mass and charge; further the sheath width increases with increasing ionic mass while follow opposite trend with increasing ionic charge. The excitation of wave like structures in the transition region and efficient energy transport to the bulk region of CCP discharges in a nonlinear regime has also been predicted. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

PVC-based nickel tungstate is a newly synthesized composite material that has been used to make mechanically and thermally well-stable membrane. The composite material was qualitatively synthesized by the sol‐gel method of material preparation. The composite material and prepared membrane have been selected and characterized on the basis of their chemical composition, ion-exchange capacity, and FTIR, TGA, and SEM analysis. It has verified the material nature, functional groups, thermal stability plus the phase transition, surface structure, porosity, ion transportation, etc. For the measurement of ionic potential, KCl, NaCl, and LiCl strong electrolytes are used, which helps to obtain the charge density of the membrane that decided the nature of membrane performance accordingly. Teorell‐Meyer‐Sievers theoretical approach is used to obtain the important parameters of examined membrane that included the transport number, mobility ratio, charge effectiveness, etc.

Sulfate cellulose nanocrystal (CNC) dispersions always present specific self-assembled cholesteric mesophases which is easily affected by the inherent properties of particle size, surface charge, and repulsion or affinity interaction, and external field force generated from ionic potential of added electrolytes, magnetic or electric field, and mechanical shearing or stretching. Aiming at understanding the liquid crystal orientation and fiber alignment under high-voltage electric field, randomly distributed, uniform-aligned, or core-sheath nanofibrous mats involving charged CNCs and PVA were electrospun; and among them, specific straight arrayed fine nanofibers with average diameter of 270 nm were manufactured by using a simple and versatile gap collector. Moreover, arrayed composite nanofibers regularly aligned along the vertical direction of gap plates and selectively reflected frequent and continuous birefringence which was regarded as nematic phases of CNCs induced by the uniaxial stretching under high-voltage electric field. As a synergic effect of rigidness of nanocrystals and stretching orientation of nematic phases, the aligned nanofibrous arrays exhibited a higher tensile strength and strain than the randomly oriented or core-sheath nanofibrous mats at the same loading of CNCs. By contrast, mesophase transition of CNCs from cholesteric to nematic occurred in the coaxially spun core-sheath nanofibers at a loss of long-ranged chiral twist. Hence, the structure-effect relationship between liquid crystal orientation of charged nanorods in polymer-based fine nanofibers and the flexibility or mechanical integrity of the aligned fiber array will be favorable for strategic development of functional liquid crystal fabrics.

PVC based MP composite membrane has been prepared by the sol–gel method of material synthesis. This composite material as well as membrane has been characterized by SEM, XRD, FTIR, TGA, and LCR studies which are used to show the mechanical, chemical, and thermal properties. By the above characterizations, it is clear that the membrane has smooth, porous, and cracks free surface as well as it also verified the material nature, functional groups, thermal stability, phase transition, ion transportation etc. Some strong electrolytes are used to obtain the ionic potential and charge density of membrane which decided the nature of charge present on membrane. TMS theoretical approach is used to obtain the other parameters of membrane like transport number, mobility ratio, charge effectiveness etc. The observed ionic potential and charge density of used electrolytes are following the KCl NaCl > LiCl order, respectively.

The bond length, average binding energy, magnetic moment per atom and the ionic potential of Nin(2-13) clusters were calculated in detail. The variations of magnetic moment per atom and the ionic potential agree well with experimental data. Theoretical results show that BPW91/Lanl2dz method is the best method and basis set for nickel clusters research, respectively. The ground state configurations and electronic structure properties of Nin(2-13) clusters were investigated using the BPW91/LanL2DZ level of DFT method. Through the molecular orbital, we could explain the paramagnetic and diamagnetic to the influence of the magnetic moment after different nickel cluster molecular hybridization.

An In-rich chalcopyrite single crystal of the Cu–Ag–In–Se (CAIS) system shows a mixed ionic and electronic conduction. To study the influence of the ionic motion in the I – V relations, three slices of this single crystal with different composition have been chosen, and an electrode/CAIS/electrode solid state device has been formed with each one. The current, I , and the potential drop across the sample have been measured as a function of time for different external applied voltages. The I ( t ) curves can be only fully understood by using a three mobile ion framework. The ionic diffusion coefficients have been computed from σ (1 /t ) curves and assigned to A g Cu x , Cu Cu x and In Cu • . The I – V relations shows non-linear shapes and hysteresis effects associated with the presence of a remaining voltage at the CAIS/electrode interface due to the ionic accumulation from previous analysis. In addition, the I – V relations are not reproducible, since the initial sample state is not fully recovered by ionic redistribution after 20 days of recovering time. To fully explain the results, the number of available vacancies, the Ag/Cu atomic ratio and/or the apparition or disappearance of (In Cu • + V Cu / ) defect pairs must be taken into account. A relation between the sample stoichiometry and the net ionic charge accumulated at the CAIS/electrode interface and its remaining time upon removing the electric field has been established. The remaining interface potential has been calculated. It shows a linear dependence with the sample potential drop. The ionic motion could produce stoichiometric deviations along the active film of the solar cell that would vary its resistivity. Likewise, the interface potential could be responsible of the significant benefit reported in the literature on CuInSe 2 /Cu-poor solar cells.

The electro-osmotic flow of an aqueous solution of NaCl between two parallel silicon walls is studied through a molecular dynamics simulation. The objective here is to examine the dependency of the electro-osmotic flow on the surface charge density by considering the changes made in the structural properties of the electric double layer (EDL). The ion concentration, velocity profiles, and electric charge density of the electrolyte solution are investigated. Due to the partially charged atoms of the water molecules, water concentration is of a layered type near the wall. The obtained profiles revealed that an increase in the surface charge density, at low surface charges where the governing electrostatic coupling regime is Debye–Huckel, increases both the electro-osmotic velocity and the EDL thickness; whereas, a decreasing trend is observed in these two parameters in the intermediate regime. For high values of surface charge density, due to the charge inversion phenomenon, the reversed electro-osmotic flow will be generated in the channel. Results indicate that the absolute value of the reversed electro-osmotic velocity rises with an increase in the surface charge density.

Arsenic is a highly toxic element and its contamination in water bodies is a worldwide problem. Arsenic adsorption with metal oxides/hydroxides-based adsorbents is an effective approach to remove arsenic species from water for the health of both human beings and the environment. However, no material criterion had been proposed for the selection of potential candidates. Equally puzzling is the fact that no clear explanation was available on the poor arsenic adsorption performance of some commonly used adsorbents, such as active carbon or silica. Furthermore, in-depth examination was also not available for the dramatically different competing adsorption effects of various anions on the arsenic adsorption. Through the arsenic adsorption mechanism study on these highly efficient arsenic adsorbents, we found that ionic potential could be used as a general material criterion for the selection of highly efficient arsenic adsorbents and such a criterion could help us to understand the above questions on arsenic adsorbents. This material criterion could be further applied to the selection of highly efficient adsorbents based on ligand exchange between their surface hydroxyl groups and adsorbates in general, which may be used for the prediction of novel adsorbents for the removal of various contaminations in water.

The surface potential decay (SPD) properties of low-density polyethylene (LDPE) are determined by charge injection and volume charge transport properties. We adopt a bipolar charge transport (BCT) model to investigate the SPD properties of LDPE with the consideration of time dependent charging process. The non-linear charge continuity equation in the BCT model is solved by a finite differential weighted essentially nonoscillatory (WENO) method that is high stable and high order accurate. Poisson’s equation is resolved by Boundary Element method (BEM). We obtain the analytical and numerical SPDs in the case of single charge carrier injection and the agreement of analytical and numerical results is excellent. After analyzing the numerical SPD and space charge results at bipolar charge injection, we find that SPD crossover phenomena occur when the hole injection barrier between the insulator and the grounded electrode is relative low. The SPD crossover occurs when the grid voltage exceeds a threshold value. Moreover, it is also found that the SPD crossover is affected by charge trapping/detrapping properties.

This paper presented the measurement results of space charge distribution and high field conduction in cross-linked polyethylene (XLPE) plate sample at various electric fields for a broad temperature range from 30 to 90 °C. The temperature effect on charge trapping and transport mechanism is discussed based on estimation of threshold characteristic and apparent mobility. It is shown that the threshold field for space charge accumulation apparently decreased with the temperature, probably associated with acceleration of charge injection and ionic dissociation. The apparent mobility of charges showed an exponential dependence on temperature, which indicates enhancement of charge detrapping and transfer rate at higher temperature. The field dependence of the space charge decreases with the temperature, results in more space charge accumulate at room temperature than at high temperature at certain high field. This behavior indicates that the space charge formation rate increases slower than the charge detrapping rate as the temperature increases. Besides, negative charge is always dominant in the sample at the measuring field and temperature range. This is probably due to stronger electron injection at XLPE-aluminum interface or more negative ion formed by dissociation of chemical species.

Thanks to the use of abundant chemical elements, organic chemistry provides great opportunities for discovering innovative electrode materials, which could be prepared (i) from renewable resources (biomass) and (ii) via eco-efficient processes, making the concept of greener and sustainable batteries possible [1]. We are putting a lot of efforts on greener and sustainable organic non-aqueous and aqueous batteries at the IMN. In this communication, we report on novel crystallized organic positive electrode materials for the non-aqueous application of organic batteries. However the synthesis of high-voltage lithiated materials is rather challenging, so very few examples of all-organic Li-ion cells currently exist. Compounds of the Mn+ 2/n-p-DHT (with Mn+ = Li+, Mg2+, Ca2+ and Ba2+) family were studied to better understand the effect of substitution chemistry on the redox properties of the Li-diphenolate cycle of p-DHT. This innovative chemical approach makes it possible to tune the redox potential of lithiated organic electrode materials, by playing on the nature and the ionic potential of a spectator cation in the host structure. Indeed, by adjusting the attractor/donor electron effects in the organic redox-active backbone, it is possible to modify the redox potential of the molecule by inductive effect. We show that substituting magnesium (2,5-dilithium-oxy)-terephthalate for lithium (2,5-dilithium-oxy)-terephthalate enables an outstanding voltage gain of 800 mV, leading to a high operating voltage of 3.4V vs. Li+/Li [2]. This Mg(Li2)-p-DHT compound is the first lithiated organic positive electrode material with an operating potential as high as that of LiFePO4. Based on this finding, full organic Li-ion cells with an output voltage of 2.5V and long cycle life have been achieved, thus making a big step forward the design of high energy green and sustainable organic batteries. References [1] P. Poizot, F. Dolhem, Energy Environ. Sci. 4, 2003 (2011). [2] A. Jouhara, N. Dupré, A.C. Gaillot, D. Guyomard, F. Dolhem, P. Poizot, Nature Commun., 9, 4401 (2018).

We investigate the persistent luminescence in europium-doped strontium pyrophosphate upon codoping with auxiliary rare earth ions. The persistent phosphors are synthesized via solid-state reaction method under flowing N2 + H2. Under UV irradiation, broadband emission persistent luminescence located at 420 nm is observed in all of these phosphors at room temperature. The effects of auxiliary rare earth ions on Sr2P2O7:Eu2+ are discussed according to the decay curves and thermoluminescence spectra. Sr2P2O7:Eu2+,Lu3+ shows the best performance, while and La3+ and Ce3+ codoped samples are the weakest. The influence of auxiliary codopants is discussed in terms of ionic potential and ionic radius. We derive an empirical formula based on the experimental results.

In situ electrochemical dilatometry was used to study, for the first time, the expansion behavior of a porous carbon electrode in a pure ionic liquid, 1-ethyl-3-methyl-imidazolium-tetrafluoroborate. For a single electrode, an applied potential of -2 V and +2 V against the potential of zero charge resulted in maximum strain of 1.8 % and 0.5 %, respectively. During cyclic voltammetry, the characteristic expansion behavior strongly depends on the scan rate, with increased scan rates leading to a decrease of the expansion. Chronoamperometry was used to determine the equilibrium specific capacitance and expansion. The obtained strain versus accumulated charge relationship can be fitted with a simple quadratic function. Cathodic and anodic expansion data collapses on one parabola when normalizing the surface charge by the ratio of ion volume and average pore size. There is also a transient spike in the height change when polarity is switched from positive to negative that is not observed when changing the potential from negative to positive indicating the size and the shape of the ion is influencing the expansion behavior., 10 pages double spaced, 3 figs, Electrochemistry Communications, accepted