Activation Energy For Conduction Research Articles

Enhancing sintering behavior and conductivity of YSZ electrolyte by co-doping of ZnO and MnO2

This study aimed to enhance the sinterability and conductivity of yttria fully stabilized zirconia electrolyte through co-doping by 2 mol% of ZnO and different contents of MnO2 (0, 0.5, 1, 1.5 mol%) at two sintering temperatures of 1300 and 1400 °C. Phase composition identification, density, microstructure, and conductivity of the samples were evaluated using X-ray diffraction (XRD), Archimedes' method, field emission scanning electron microscopy (FESEM), and electrochemical impedance spectroscopy (EIS), respectively. The XRD results revealed that ZnO and MnO2 are successfully doped in the fluorite structure of YSZ sintered at 1400 °C, and the cubic structure is completely preserved. However, at a sintering temperature of 1300 °C, the (111) peaks of doped samples were slightly split, which implied a slight phase transformation of YSZ from cubic to a tetragonal structure. The co-doped samples, at both sintering temperatures, showed higher relative density and grain size compared with pure YSZ. The addition of 2 mol% of ZnO and 0.5 mol% of MnO2 at 1400 °C increased the relative density of YSZ from 81.6% to 95.1%. The increase in relative density and grain size, while maintaining the cubic structure, caused an increase in the conductivity of the mentioned sample. Compared with pure YSZ, the sample's total conductivity increased from 7.37 to 10.03 S m−1 at 800 °C. The proposed composition showed better sintering behavior, lower activation energy of grain conductivity, and higher conductivity than pure YSZ. This behavior is thought to be due to the facilitating rearrangement of atoms during sintering and an increase in oxygen ion vacancy concentration due to co-doping with the appropriate amount of ZnO and MnO2.

Enhanced mechanical, electrical, thermal, and optical properties of poly(methyl methacrylate)/copper oxide nanocomposites for flexible optoelectronic devices via in‐situ polymerization technique

AbstractPolymethyl methacrylate (PMMA) with varied compositions of copper oxide (CuO) nanoparticles was synthesized using in‐situ free radical polymerization. UV–visible, FT‐IR, XRD, FE‐SEM, DSC, and TGA were employed to examine their structure, morphology, and thermal properties. The broadening and intensification of UV absorption, as well as the shift in IR peaks of PMMA with the addition of CuO, confirm their interactions. The reduction in optical bandgap values with the reinforcement of nanofillers confirms the existence of intermediate energy bands in nanocomposites. XRD indicated that polymerization with CuO reduced the amorphous nature of PMMA. The FE‐SEM image revealed that the dispersion of CuO altered the nonporous, rough surface of PMMA into a homogeneous shape. The reinforcement of CuO enhanced the thermal stability and glass transition temperature of PMMA. The mechanical strength, modulus, impact strength, and rigidity of PMMA were significantly improved through in‐situ polymerization. The electrical property analysis revealed that the AC conductivity increased with frequency, temperature, and filler content. The reduction in activation energy of AC conductivity with temperature points toward their semiconducting nature. PMMA/CuO nanocomposites with higher tensile strength, lower bandgap energy, higher conductivity, and thermal properties can be used to make flexible optoelectronic devices.Highlights A series of PMMA/CuO nanocomposites were synthesized and characterized. Enhanced optical property, thermal stability, and glass transition temperature. Possess excellent dielectric constant and AC conductivity. Mechanical strength and impact resistance of PMMA were greatly enhanced. A promising material for flexible optoelectronic and power storage applications.

Effect of Donor Nb(V) Doping on the Surface Reactivity, Electrical, Optical and Photocatalytic Properties of Nanocrystalline TiO2.

In this work, we primarily aimed to study the Nb(V) doping effect on the surface activity and optical and electrical properties of nanocrystalline TiO2 obtained through flame-spray pyrolysis. Materials were characterized using X-ray diffraction, Raman spectroscopy and IR, UV and visible spectroscopy. The mechanism of surface reaction with acetone was studied using in situ DRIFTs. It was found that the TiO2-Nb-4 material demonstrated a higher conversion of acetone at a temperature of 300 °C than pure TiO2, which was due to the presence of more active forms of chemisorbed oxygen, as well as higher Lewis acidity of the surface. Conduction activation energies (Eact) were calculated for thin films based on TiO2-Nb materials. The results of the MB photobleaching experiment showed a non-monotonic change in the photocatalytic properties of materials with an increase in Nb(V) content, which was caused by a combination of factors, such as specific surface area, phase composition, concentration of charge carriers as well as their recombination due to lattice point defects.

Surface proton hopping conduction mechanism dominant polymer electrolytes created by self-assembly of bicontinuous cubic liquid crystals.

For the development of the next generation of fuel cells, it is essential to create an innovative design principle of polymer electrolytes that is beyond extension of the existing strategy. In the present study, we focused on the surface hopping proton conduction mechanism where an activation energy for proton conduction is greatly reduced by decreasing the distance between SO3- groups. Our gyroid nanostructured polymer film (Film-G), with a hydrophilic surface where the SO3- groups are aligned densely and precisely, shows high proton conductivity of the order of 10-2 S cm-1 when the water content is about 15 wt%. We reveal that the high proton conductivity of Film-G is attributed to the exhibition of an extremely-fast surface hopping conduction mechanism due to the reduced activation energy barrier along the gyroid minimal surface. This finding should introduce a game-changing novel opportunity in polymer electrolyte design.

Unraveling fundamental characteristics of Na2Mg3Cl8 as a solid-state electrolyte for Na-ion batteries.

In this theoretical study, we harnessed advanced atomistic computations to unravel several features of Na2Mg3Cl8, an unexplored but promising chloride compound for solid-state electrolytes in Na-batteries. First, Na2Mg3Cl8 exhibits an insulating behavior, characterized by an energy gap of ∼5 eV, arising from the hybridization of [NaCl] trigonal prismatic and [MgCl6] octahedral units. Second, the compound possesses mechanical stability and ductility, which render it suitable for practical fabrication. Improved electrolyte/electrode contact can reduce resistance and enhance battery performance. The electrochemical performance of Na2Mg3Cl8 involves an open cell voltage of 1.2 V and a theoretical capacity of 133 mA h g-1. Finally, its transport characteristics include low activation energy for diffusion and conduction as well as a remarkable room-temperature conductivity of 1.26 mS cm-1, comparable to those of current superionic conductors.

Sodium halide solid state electrolyte of Na3YBr6 with low activation energy.

Halide solid-state electrolytes (SSEs) are considered promising candidates for practical applications in all-solid-state batteries (ASSBs), due to their outstanding high voltage stability and compatibility with electrode materials. However, Na+ halide SSEs suffer from low ionic conductivity and high activation energy, which limit their applications in sodium all-solid-state batteries. Here, sodium yttrium bromide solid-state electrolytes (Na3YBr6) with a low activation energy of 0.15 eV is prepared via solid state reaction. Structure characterization using X-ray diffraction reveals a monoclinic structure (P21/c) of Na3YBr6. First principle calculations reveal that the low migration activation energy comes from the larger size and vibration of Br- anions, both of which expand the Na+ ion migration channel and reduce its activation energy. The electrochemical window of Na3YBr6 is determined to be 1.43 to 3.35 V vs. Na/Na+, which is slightly narrower than chlorides. This work indicates bromides are a good catholyte candidate for sodium all solid-state batteries, due to their low ion migration activation energy and relatively high oxidation stability.

High conductivity characteristics of phosphorus-doped nanocrystalline silicon thin films by KrF pulsed excimer laser irradiation method.

The microstructure and high conductivity properties of phosphorus-doped nanocrystalline silicon films were investigated on samples prepared by a plasma-enhanced chemical vapor deposition technique and the KrF pulsed excimer laser irradiation method. The results of Fourier transform infrared spectroscopy and Raman spectroscopy show that Si nanocrystallites with an average diameter of 2 nm to 3 nm are formed in the film. The degree of crystallinity increases with the increase of laser radiation intensity, while the content of hydrogen decreases gradually. More phosphorus atoms are substitutionally incorporated into the nc-Si dots under higher laser irradiation fluence, which is responsible for the high dark conductivity. By controlling the laser fluence at 1.0 J cm-2, the dark conductivity as high as 25.7 S cm-1 can be obtained. Based on the measurements of temperature-dependent conductivity, the carrier transport processes are discussed. The phosphorus doping and the increase of electron concentration are considered to be the reason for high dark conductivity and extremely low conductivity activation energy.

Investigation of dysprosium oxide substitution on physical, electrical and dielectric properties in sodium borosilicate glass system

Dysprosium oxide doped sodium borosilicate glasses were prepared in this study using a usual melt-quenching process. Further XRD, FTIR, density measurements, electrical conductivity, and dielectric properties were utilized to explore the prepared glassy samples. We found that all produced samples exhibit amorphous nature through X-ray diffraction. Increase in density and molar volume were found when dysprosium oxide concentration increased, which was ascribed to dysprosium oxide's greater molecular weight. Density data was used to calculate and explain several physical characteristics, including rare earth ion concentration (N), polaron radius (rp), internuclear distance (ri), and field strength (F).

Dependence of Proton Diffusivity on Dopant Concentration in Yttrium-Doped Barium Zirconate; First-Principles Study

Yttrium-doped barium zirconate (BaZrO3) has high proton conductivity and thermal stability, attracting attention to apply solid electrolytes to medium-temperature fuel cells. It has been reported that the proton conductivity decreases as the concentration of Y in BaZrO3increases, and it is desired to elucidate its origin. In order to perform a theoretical analysis associated with such a high-concentration solid solution state, it is necessary to consider a solid solution model that simultaneously includes two or more point defect complexes. Though the number of atomic arrangements is huge, only the structures along the path with the lowest activation energy contribute to proton conduction. In this study, we found the structures that contribute to proton conduction by pathfinding based on the combination of first-principles calculations and graph theory. From the structures on the conduction path with the lowest activation energy, we extracted the parameters that contribute to the improvement of proton conduction by performing the feature analysis.The solution models of the 2×2×2 supercell of BaZrO3 with 12.5 and 25 mol% Y were constructed in which one and two atoms of dopant element Y were substituted to Zr sites, respectively, and the same number of protons were introduced. The total energy calculation was performed for all the symmetrically independent structures. The conduction path search based on the graph theory was performed using the obtained energies of structures, and the association and activation energies of conduction in long-range diffusion were evaluated. A feature regression analysis of total energies was conducted to extract the dominant factors of energies of the structures along the conduction path.The association and activation energies were evaluated from the structural energies of the structures along the obtained conduction path. The difference between the highest and lowest energies with protons at the stationary positions along the searched path is considered the association energy and the energy difference between the highest energy on the path and the highest energy with the proton at the stationary positions is considered to correspond to the mobile activation energy of the proton. The mobile activation and association energies were increased with the increase of Y concentration, which is in good agreement with the experiments.To clarify the parameters which affect the mobile activation and association energies, we performed regression analysis for the energy of the Y 25 mol% using the random forest to extract the dominant factor of the structural energy along the diffusion path in the heavily doped system. The regression parameters of rotation and distortion of octahedra were considered as well as direct descriptors of H-Y configurations. Though the parameters such as a distance of H-Y directly related to the configuration of H and Y appeared to be less important, the parameters related to the rotation of Zr(Y)O6 octahedra, are the first and second highest important parameters. They have an almost linear relationship with high negative correlation coefficients around -0.7 for the structures along the searched diffusion path including H at the transition positions. It is suggested that the rotation of octahedra declines the energy and contributes to the stabilization of the structures along the searched diffusion path. To confirm the rotation effect on the structural energy of Y contents, we calculated the energies as a function of octahedron rotation for the Y 12.5 and 25 mol% models. The larger the Y concentration, the larger the energy change concerning octahedron rotation, suggesting that the Y 25 mol% model is stiffer in terms of octahedron rotation than Y 12.5 mol%. This stiffening of octahedron rotation with Y addition is a key factor of mobile activation and association energies, which are dominant in proton conduction.This work was supported by the Japan Science and Technology Agency CREST (JPMJCR18J3) and JSPS KAKENHI (JP22H05146 and JP22K14465). This work was also supported by MEXT Program: Data Creation and Utilization Type Material Research and Development Project Grant Number JPMXP1122683430.

Dynamic Monkey Bar Mechanism of Superionic Li‐ion Transport in LiTaCl6

AbstractThe LiTaCl6 solid electrolyte has the lowest activation energy of ionic conduction at ambient conditions (0.165 eV), with a record high ionic conductivity for a ternary compound (11 mS cm−1). However, the mechanism has been unclear. We train machine‐learning force fields (MLFF) on ab initio molecular dynamics (AIMD) data on‐the‐fly and perform MLFF MD simulations of AIMD quality up to the nanosecond scale at the experimental temperatures, which allows us to predict accurate activation energy for Li‐ion diffusion (at 0.164 eV). Detailed analyses of trajectories and vibrational density of states show that the large‐amplitude vibrations of Cl− ions in TaCl6− enable the fast Li‐ion transport by allowing dynamic breaking and reforming of Li−Cl bonds across the space in between the TaCl6− octahedra. We term this process the dynamic‐monkey‐bar mechanism of superionic Li+ transport which could aid the development of new solid electrolytes for all‐solid‐state lithium batteries.

High Performance Protonic Ceramic Electrochemical Cells Operating at

Protonic ceramic electrochemical cells (PCECs) can operate in both fuel cell and steam electrolysis modes for efficient power generation and green hydrogen production. Thanks to the low activation energy of proton conduction, PCECs are uniquely capable of operating at temperatures below 600°C. Although some intriguing demonstrations of intermediate-temperature (500-600°C) PCECs (IT-PCECs) have been made in the last decade, the operating temperature of PCECs is still too high to revolutionize ceramic electrochemical cell technology, which is ascribed to the high ohmic resistance and positive electrode polarization resistance. It has been also recognized the electrode polarization resistance dominates the total resistance at <500°C. These challenges suggest both the electrolyte and positive electrode should be redesigned to lower the PCEC operating temperature.In this work, we present two main approaches to reducing electrolyte ohmic resistance, electrolyte-positive electrode contact resistance, and electrode polarization resistance, which enables PCECs operation at <500°C. First, by using the ultrasonic spray coating system to coat the electrolyte layer on a negative electrode substrate with low Ba-deficiency, a bamboo-structured, ultrathin, and chemically homogeneous electrolyte can be fabricated. Second, a newly in-situ formed composite positive electrode was developed, which enhances the interfacial bonding between the positive electrode and electrolyte, further reducing ASRo , while improving both bulk oxygen-ion diffusion coefficient and surface oxygen exchange coefficientat <500°C.The newly developed LT-PCECs attain outstanding power densities in fuel cell mode (as high as 0.77 W cm-2 at 450°C), and exceptional current densities in electrolysis mode (over -1.28 A cm-2 at 1.4 V and 450°C). Furthermore, reducing the temperature does not sacrifice the fuel flexibility of these ceramic fuel cells. We demonstrated that the PCECs can directly utilize ammonia and methane for power generation at <500°C. Exceptional durability has been also demonstrated in both fuel cell and electrolysis modes at <500°C.These results further emphasize that through the PCEC scalable manufacturing processes and novel positive electrode materials presented here, PCECs can be employed for power generation and H2 production at <500°C, thereby transforming the architectures and removing previous operational constraints of ceramic electrochemical cells for scaled operation. PCECs can therefore be considered as one part of the growing hydrogen economy, while leveraging the existing fossil fuel infrastructure and achieving higher energy efficiency and lower CO2 emissions.

Dynamic Monkey Bar Mechanism of Superionic Li-ion Transport in LiTaCl6.

The LiTaCl6 solid electrolyte has the lowest activation energy of ionic conduction at ambient conditions (0.165 eV), with a record high ionic conductivity for a ternary compound (11 mS cm-1 ). However, the mechanism has been unclear. We train machine-learning force fields (MLFF) on ab initio molecular dynamics (AIMD) data on-the-fly and perform MLFF MD simulations of AIMD quality up to the nanosecond scale at the experimental temperatures, which allows us to predict accurate activation energy for Li-ion diffusion (at 0.164 eV). Detailed analyses of trajectories and vibrational density of states show that the large-amplitude vibrations of Cl- ions in TaCl6 - enable the fast Li-ion transport by allowing dynamic breaking and reforming of Li-Cl bonds across the space in between the TaCl6 - octahedra. We term this process the dynamic-monkey-bar mechanism of superionic Li+ transport which could aid the development of new solid electrolytes for all-solid-state lithium batteries.

Non-Arrhenius Ionic Conductivity Behaviour in Antiperovskite Solid Electrolytes for Sodium Metal Batteries

Solid-state sodium metal batteries have been proposed as an alternative to lithium-ion batteries (LIBs) for next-generation applications due to the high abundance and wide distribution of sodium resources.1 Sodium antiperovskites (Na3OX, X = Cl, Br, or BH4) have recently attracted great interest as solid electrolyte candidates due to the relatively low processing temperature (<500 oC), reasonable ionic conductivity (up to 4.4 x 10-3 S cm-1 at room temperature), and great chemical stability against sodium metal anodes.2,3 Typical solid-state ionic conductors have temperature-dependent ionic conductivity that follows Arrhenius behaviour over a broad range of temperatures, corresponding to a constant activation energy Ea. However, this is not the case in Na3OBr, and instead a phenomenon resulting in a higher ionic conductivity and lower activation energy is observed to occur at 255 oC. Similar non-Arrhenius ionic conductivity phenomenon has also been reported in the potassium antiperovskite K3OI. It has been proposed that this behaviour originated from anion disordering, but conclusive experimental evidence to support this claim has not been reported.4 An understanding of the origin of this behaviour could enable the synthesis route to be optimised such that higher ionic conductivities could be achieved.In this work, we combined temperature-resolved bulk and local characterisation methods including Pawley and Rietveld refinements of synchrotron x-ray diffraction (XRD), pair distribution function (PDF), solid-state nuclear magnetic resonance (NMR) spectroscopy, and electrochemical impedance spectroscopy (EIS) to gain an insight into the origin of this non-Arrhenius behaviour. We found that this phenomenon does not originate from anion disordering, as previously speculated, because the lattice parameter of Na3OBr changed linearly with temperature and no major intensity changes were observed in the Na-Br and Na-O signals in the PDF patterns. Other supporting findings that lead us to this conclusion will be discussed in the presentation.References Wang, X. et al. Ultra-stable all-solid-state sodium metal batteries enabled by perfluoropolyether-based electrolytes. Nat. Mater. 21, 1057–1066 (2022).Zheng, J., Perry, B. & Wu, Y. Antiperovskite Superionic Conductors: A Critical Review. ACS Mater. Au 1, 92–106 (2021).Sun, Y. et al. Rotational Cluster Anion Enabling Superionic Conductivity in Sodium-Rich Antiperovskite Na3OBH4. J. Am. Chem. Soc. 141, 5640–5644 (2019).Zheng, J. et al. Antiperovskite K3OI for K-Ion Solid State Electrolyte. J. Phys. Chem. Lett. 12, 7120–7126 (2021).

Improvement of Ionic Conductivity in Li7La3Zr2O12 (LLZO) Solid Electrolyte By Doping with Aluminum/Tungsten

Recently, there has been increasing interest in solid electrolytes, which are the most important materials in all-solid-state lithium-ion batteries. Among all solid electrolytes, garnet-type Li7La3Zr2O12 (LLZO) has been proven to be one of the most promising electrolytes due to its high Li+ conductivity, wide potential window, and electrochemical stability towards metallic lithium anode. In particular, cubic garnet-type LLZO solid electrolytes have received a lot of attention for the development of high-performance all-solid-state batteries with safety, energy density, and long cycle life. In this study, we synthesized LLZO solid electrolyte powders with garnet structure and determined the optimal composition and sintering temperature by adding Al/W to form a stable cubic phase.In this study, Al or W-doped LLZO were prepared by a post-doping method. In this process, LLZO powder was first prepared, and then mixed with Al2O3 or WO3 powders to produce doped LLZO ceramic electrolytes, respectively. During this process, the doped ions entered the LLZO lattice, increasing the lithium ion transport channels and promoting lithium ion conductivity. The sintering time, crucible, and sintering temperature were adjusted to investigate the optimal process conditions of the post-doping method. As a result, the doped solid electrolyte exhibited high lithium ion conductivity and low activation energy. Using the high lithium ion conductivity and broad electrochemical stability window of the Al or W doped LLZO SSE, the (NCM622)/(Al or W doped-LLZO) cell delivered a steady cycle for 100 cycles at 0.1C. The Al or W doped-LLZO prepared in this study showed advantages of high conductivity, simple preparation process, high reproducibility, and low cost, which provides technical support and reference for further application of garnet-type SSEs in solid-state batteries with high energy density.

Физико-химические свойства растворов перхлората и тетрафторбората лития в смеси сульфолана и сернистого ангидрида

The temperature dependencies of physical and chemical properties (viscosity, density, electrical conductivity) and the melting temperature of 1M solutions of lithium salts (LiClO4 and LiBF4) in the mixture of sulfolane and sulfurous anhydride (∼1M) were studied. It was shown that the introduction of 1M (5% wt.) of sulfurous anhydride into 1M solutions of LiClO4 and LiBF4 in sulfolane increased the specific and corrected electrical conductivity, densities, activation energy of electrical conductivity and viscous flow of electrolyte solutions; and reduced viscosity and melting temperatures.

Thermal and mass transfer analysis of Casson-Maxwell hybrid nanofluids through an unsteady horizontal cylinder with variable thermal conductivity and Arrhenius activation energy

In this study, the flow, thermal transfer, and mass transport of Casson-Maxwell hybrid nanofluids are explored. The governing PDEs are converted into nonlinear ODEs using similarity transformations and then solved using MATLAB's Bvp4c scheme. Various non-dimensional parameters’ influences on fluid behaviour and transport are investigated. Results indicate that higher curvature parameter values boost velocity, temperature, and concentration fields, enhancing mass and heat transfer as well as fluid motion. The unsteadiness parameter affects velocity profiles and heat/mass transfer processes. Thermal and mass relaxation times, alongside parameters like thermophoresis, Brownian motion, variable thermal conductivity, Arrhenius activation energy, chemical reaction, and temperature difference ratio, significantly shape temperature and concentration profiles and optimise heat and mass transfer rates. Additionally, combining the Casson and Maxwell hybrid nanofluid models shows marked changes in skin friction performance: absolute skin friction rises by 30%, while heat transmission increases by almost 11% compared to the Casson-Maxwell nanofluid model.

Ultrahigh Energy Storage in Tungsten Bronze Dielectric Ceramics Through a Weakly Coupled Relaxor Design.

Dielectric energy-storage capacitors, known for their ultrafast discharge time and high-power density, find widespread applications in high-power pulse devices. However, ceramics featuring a tetragonal tungsten bronze structure (TTBs) have received limited attention due to their lower energy-storage capacity compared to perovskite counterparts. Herein, a TTBs relaxor ferroelectric ceramic based on the Gd0.03 Ba0.47 Sr0.485-1.5 x Smx Nb2 O6 composition, exhibiting an ultrahigh recoverable energy density of 9 J cm-3 and an efficiency of 84% under an electric field of 660kV cm-1 is reported. Notably, the energy storage performance of this ceramic shows remarkable stability against frequency, temperature, and cycling electric field. The introduction of Sm3+ doping is found to create weakly coupled polar nanoregions in the Gd0.03 Ba0.47 Sr0.485 Nb2 O6 ceramic. Structural characterizations reveal that the incommensurability parameter increases with higher Sm3+ content, indicative of a highly disordered A-site structure. Simultaneously, the breakdown strength is also enhanced by raising the conduction activation energy, widening the bandgap, and reducing the electric field-induced strain. This work presents a significant improvement on the energy storage capabilities of TTBs-based capacitors, expanding the material choice for high-power pulse device applications.

Non-isothermal crystallization kinetics and memory switching properties of Tl-Se-Ge-Sb chalcogenide semiconductor alloy for thermally stable phase change memory applications

Quaternary (Tl20Se70Ge10)0.85Sb0.15 chalcogenide glass was synthesized using melt-quenching and thermal evaporation techniques for bulk and thin film samples, and its amorphous character was confirmed by XRD. Based on different models of non-isothermal crystallization kinetics, the average values of the glass transition and the crystallization activation energies are 121.33 and 82.94 kJ mol−1, respectively. The crystallization mechanism in the examined composition is 2D nucleation growth, according to Avrami exponent Thermal parameters of the studied quaternary glass, like fragility fluctuation free volume reduced glass transition temperature thermal stability and glass formation ability were investigated and indicated that the (Tl20Se70Ge10)0.85Sb0.15 ChG exhibits a good ability of glass formation and thermal stability. The obtained results of the dc electrical conductivity are found to increase with temperature and decrease with film thickness. The electrical conduction activation energy (0.583 ± 0.004 eV) is thickness independent and the predominant conduction mechanism is the hopping of charge carriers in the band tail localized states. The () curves of (Tl20Se70Ge10)0.85Sb0.15 chalcogenide glass film samples were analyzed and shown to be appropriate for a memory switch. The mean value of the threshold voltage decreases exponentially as temperature increases, whereas it increases linearly as film thickness increases. The values of threshold voltage and threshold resistance activation energies are 0.282 ± 0.003 and 0.521 ± 0.004 eV, respectively. The obtained switching characteristics data were discussed in view of the electrothermal model motivated by current channel Joule heating. These findings highlight the suitability of the investigated composition for various optoelectronic applications, such as memory switching devices, optical data storage, phase-change memories and optical fibres sensing devices.

Electrical conductivity and significant radiation shielding properties of B2O3.Pb3O4.ZnO.Y2O3 glasses

The electrical properties and radiation shielding characteristics are investigated for a glass system of the configuration 60% B2O3-35% Pb3O4-(5-x)%ZnO - x%Y2O3 with x from 0 to 3 mol%. Frequencies from 100 Hz to 5 MHz were applied to measure the ac conductivity in a temperature range between 310 and 700K. The values of ac conductivity (σac) are found in the range from 2×10−9 S.cm−1 to 5×10−2 S.cm−1, while the activation energy for ac conductivity (Eac) is found to fluctuate between 0.4 and 1.43 eV. The dc conductivity (σdc) and dc activation energy (Edc) are discussed according to thermal activation and small polaron hopping mechanisms. An alternation from mainly electronic to mainly ionic conduction mechanism is evidenced for the samples greater than 2% mol of the Y2O3. The radiation shielding characteristics are studied in wise of mass attenuation coefficient, μ/ρ, effective atomic number, Zeff, half value layer (HVL), and mean free path (MFP). The values of μ/ρ are obtained experimentally and theoretically by Phy-X/PSD software. The obtained relative deviation between theoretical and experimental results lies in the range from 0 to 3.8%. All the shielding factors demonstrate an inverse reliance on the Y2O3 content in the glasses. The MFP and HVL magnitudes of the glasses are compared with other traditional shielding materials and presented better attenuation ability. The relation between the shielding parameters and the electrical properties is discussed and it is also found that both properties are strongly affected by the interionic separations between the Pb ions in the glasses.

Physical properties of deep eutectic solvents with efficient nitrogen removal capability

The efficient separation of N-compounds from fuel oil is of great significance for environmental protection and the development of sustainable chemical processes. In this work, eight quaternary acidic deep eutectic solvents (DESs) were prepared for the removal of basic N-compounds (pyridine) from simulated oils. Initially, the density, viscosity, conductivity, surface tension and refractive index values of the DESs were determined at 293.15–333.15 K. Based on these data, physical quantities such as molecular volume, standard entropy, lattice energy, activation energy of viscous flow, activation energy of conductivity, surface entropy, surface energy, speed of sound, molar Gibbs free energy, molar polarizability, molar polarizability, and free molar volume have been calculated. The effects of temperature, alkyl chain length of hydrogen bond acceptors (HBAs)/hydrogen bond donors (HBDs), structure of HBDs, and HBAs anion on the physical properties of DESs were systematically investigated. The internal interaction and property change of DESs are further studied. Finally, pyridine was extracted from the simulated oil using the prepared DESs. DESs consisting of tetrabutylammonium bromide and lactic acid had the highest extraction capacity under the same conditions. The extraction efficiency was found to be strongly correlated with the alkyl chain length and the acidity of the HBDs. This work is expected to provide information on the removal of N-compounds from both theoretical and industrial perspectives.