Solid Diffusion Research Articles

Strategy for building training set for neural-network potentials for ionic diffusion in solids: example for hydride-ion diffusion in LaHO

Strategy for building training set for neural-network potentials for ionic diffusion in solids: example for hydride-ion diffusion in LaHO

Non-Contact and Self-Calibrated Photopyroelectric Method for Complete Thermal Characterization of Porous Materials.

A general theory of a photopyroelectric (PPE) configuration, based on an opaque sample and transparent pyroelectric sensor, backing and coupling fluids is developed. A combined back-front detection investigation, based on a frequency scan of the phase of the PPE signals, followed by a self-normalization of the phases' behavior, leads to the possibility of simultaneously measuring both thermal effusivity and diffusivity of a solid sample. A particular case of this configuration, with no coupling fluid at the sample/backing interface and air instead of coupling fluid at the sample/sensor interface (non-contact method) is suitable for simultaneous measurement ofboth thermal diffusivity and effusivity (in fact complete thermal characterization) of porous solids. Compared with the already proposed configurations for investigations of porous materials, this novel configuration makes use of a fitting procedure with only one fitting parameter, in order to guarantee the uniqueness of the solution. The porous solids belong to a class of materials which are by far not easy to be investigated using PPE. To the best of our knowledge, porous materials represent the only type of compounds, belonging to condensed matter, which were not taken into consideration (until recently) as potential samples for PPE calorimetric investigations. Consequently, the method proposed in this paper complete the area of applications of the PPE method. Applications on some porous building materials and cellulose-based samples validate the theory.

Dissipation and diffusion in one-dimensional solids

Dissipation and diffusion in one-dimensional solids

MRI appearances of stage IA ovarian carcinoma.

To analyze the MRI findings of stage IA ovarian cancer. The data on age distribution, clinical symptoms at onset, CA125 detection, MRI findings, including tumor volume, structure, diffusion-weighted imaging (DWI), apparent diffusion coefficient (ADC) and enhancement, etc., of the patients with stage IA ovarian cancer, who were admitted to Nantong tumor Hospital between 2013 and 2020 were analyzed retrospectively. Only 11 cases of stage IA ovarian cancer were recorded. The age of patients was 30-67 (average 52) years. The initial symptoms were mostly lower abdominal distension and abdominal pain. CA125 was 90% positive. MRI features 1. Large pelvic mass with a volume range of 23-2,009 cm3 (average 669 cm3). 2. Five cases of cyst type (with plaque-like, papillary, or mural nodule vegetations), two cases of cystic-solid mixed type (with thickened septum or wall), and four cases of solid type. 3. DWI diffusion was limited, and ADC was reduced on all solid portions (vegetation, septa, and cyst wall). 4. The solid parts were significantly enhanced on T1-enhanced MRI. 5. There was no metastasis in the pelvic cavity, and a few ascites (negative tumor cells) in three patients. MRI characteristics of stage IA ovarian carcinomas were large tumors, cystic, cystic-solid, or solid; solid portion limited diffusion on DWI and low ADC; enhancement of the cyst wall, vegetation, and septa; no pelvic metastasis.

Effect of the TiB reinforcement phase on the vacuum diffusion bonding of TA15 alloy: Interfacial microstructure and mechanical properties

The present study successfully bonded a TiBw/TA15 composite with a novel network architecture via a solid diffusion bonding (DB) technique. The effects of bonding time and TiB reinforcement phase on the evolution of the bonding interface were evaluated at 950 °C under a vacuum environment. Experimental results indicate that the interface bonding rate increased with the bonding time by reducing the interface voids and could well be bonded at 80 min. However, the TiB reinforcement phase was pernicious for the bonding process due to its low bonding strength with the sample matrix. Shear tests were also performed on the DB interface, and a maximum shear strength of 785 MPa was obtained when the sample was bonded at 2 MPa–950 °C–80 min.

Research on gold leaching of carbonaceous pressure-oxidized gold ore via a highly effective, green and low toxic agent trichloroisocyanuric acid

In this work, trichloroisocynauric acid (TCCA) are used for gold leaching with the advantages of fast reaction rate, high leaching efficiency, low toxicity and environmentally friendly. In addition, an important feature is the continuous hydrolysis of TCCA in an aqueous solution to produce oxidants (HClO) while maintaining the effective chlorination concentration at a high level. The various factors affecting TCCA leaching carbonaceous pressure-oxidized gold ore were investigated and the leaching kinetics were established. According to the results of orthogonal experiments, the optimal conditions of TCCA concentration 0.25 mol L−1, NaCl concentration 50 g L−1, pH 5.5, leaching temperature 45 °C and solid-liquid ratio 1:6 could be obtained, and the gold leaching efficiency reached (88.64 ± 0.37) % within 3 h. After the three stages of TCCA leaching, a gold leaching efficiency was increased to 94.39%. Furthermore, TCCA leaching process could be divided into three steps, the findings of kinetic models revealed that in the early leaching step (0–2 h), TCCA leaching was controlled by solid products layer diffusion model, and yet shifted to be controlled by interfacial chemical reaction model in the final step. Importantly, TCCA leaching solution might be converted into a disinfectant with an effective chlorination concentration of 16.075% treated with resin adsorption and alum removal, enabling the secondary utilization of wastewater resources.

A comprehensive study of parallel gap resistance welding joint between Ag foil and front electrode of GaAs solar cell

When space solar cell array is subjected to harsh temperature cycle, such as planet orbit, thermal fatigue cracks in bonding area are easily induced. With the aim of improving bonding quality and elucidating failure mechanism of parallel gap resistance welding (PGRW) joints in temperature cycling environment, the present research investigates the effect of current density on bonding quality and thermal fatigue behavior of PGRW joint between Ag interconnector and front electrode of GaAs solar cell. When current density is set at 417 A/mm2, a solid diffusion bonding is achieved at the Ag/Au interface, which also possesses adequate joint strength as ensured by both pressure and input energy of PGRW. Crack initiation by thermal fatigue is found at joint edge, which subsequently propagates along the interface as the environment temperature cycling continues. Further investigation reveals that the conducted temperature cycling generates serious tensile and compressive stress in the multi-layered joint structure. Since such reciprocating forces directly induce micro-plastic deformation and strain accumulation at joint interface, failure by crack is finally generated at the joining interface.

Evaluation of Antioxidant and Antimicrobial Activity of Saponin Extracts from Different Parts of Argania spinosa L. Skeels

The argan tree is a versatile forest tree (silviculture-fruit-forestry) of great importance for the country both in biological, phytogenetic and ecological biodiversity as well as in economic and social aspects. It has significant medicinal and therapeutic potential. The present study concentrated on saccharide-containing molecules, particularly saponins, for their medicinal properties. Butanol was used to fractionate phytochemical groups from different parts of Argania spinosa (branch, leaf, pulp, shell and seed), which were subsequently precipitated in ether. It was found that solvent fractionation increased the total saponin amount according to the colorimetric test using vanillin and sulfuric acid. The butanol fraction of the argan shell and its precipitate showed the highest levels of triterpene saponins compared to the rest of the plant parts studied. The samples showed antioxidant capacity by DPPH versus ascorbic acid (IC50 = 1.92 µg/mL) and by ABTS using the similar standard (IC50 = 11.31 µg/mL). The antioxidant activity of the samples was significantly improved from the crude shell extract (IC50 = 5.85 µg/mL) to its butanolic fraction (IC50 = 2.94 µg/mL) and its precipitate (IC50 = 1.57 µg/mL) using 2,2-diphenyl-picrylhydrazyl. Indeed, the ABTS test, showed similarity to the core results. Also, the solid disc diffusion method was used to highlight the antimicrobial activity of extracts from different parts of the Argania spinosa plant. The EtOH 70% and Aqueous leaf extracts exhibited the highest antibacterial activity, resulting in an inhibition zone of approximately 13 mm against the growth of Staphylococcus saprophyticus. On the other hand, the extract of saponin filtrate from the pulp part of the plant displayed the lowest antibacterial activity, with an inhibition zone of 9 mm. All studied types of saponin extract from different parts of the plant do not contribute to any antifungal activity against Botrytis cinerea.

Analysis of Diffusion Coefficients of Iron Monoboride and Diiron Boride Coating Formed on the Surface of AISI 420 Steel by Two Different Models: Experiments and Modelling.

In the present work, two mathematical diffusion models have been used to estimate the growth of the iron monoboride and diiron boride coating formed on AISI 420 steel. The boronizing of the steel was carried out with the solid diffusion packing method at a boronizing temperature of 1123 K-1273 K. Experimental results show the two-coating system consists of an outer monoboride and an inner diiron boride coating with a predominantly planar structure at the propagation front. The depth of the boride coating increases according to temperature and treatment time. A parabolic curve characterizes the propagation of the boride coatings. The two proposed mathematical models of mass transfer diffusion are founded on the solution corresponding to Fick's second fundamental law. The first is based on a linear boron concentration-penetration profile without time dependence, and the second model with time dependence (exact solution). For both models, the theoretical law of parabolic propagation and the average flux of boron atoms (Fick's first fundamental law) at the growth interfaces (monoboride/diiron boride and diiron boride/substrate) are considered to estimate the propagation of the boride coatings (monoboride and diiron boride). To validate the mathematical models, a programming code is written in the MATLAB program (adaptation 7.5) designed to simulate the growth of the boride coatings (monoboride and diiron boride). The following parameters are used as input data for this computer code: (the layer thicknesses of the FeB and Fe2B phases, the operating temperature, the boronizing time, initial formation time of the boride coating, the surface boron concentration limits, FeB/Fe2B and Fe2B/Fe growth interfaces, and the mass transfer diffusion coefficient of boron in the iron monoboride and diiron boride phases). The outputs of the computer code are the constants εFeB and εFe2B. The assessment of activation energies of AISI 420 steel for the two mathematical models of mass transfer is coincident (QFeB=221.9 kJ∙mol-1 and QFe2B=209.1 kJ∙mol-1). A numerical analysis was performed using a standard Taylor series for clarification of the proximity between the two models. SEM micrographs exhibited a strong propensity toward a flat-fronted composition at expansion interfaces of the iron monoboride and diiron boride coating, confirmed by XRD analysis. Tribological characterizations included the Vickers hardness test method, pin-on-disc, and Daimler-Benz Rockwell-C indentation adhesion tests. After thorough analysis, the energies were compared to the existing literature to validate our experiment. We found that our models and experimental results agreed. The diffusion models we utilized were crucial in gaining a deeper understanding of the boronizing behavior of AISI 420 steel, and they also allowed us to predict the thicknesses of the iron monoboride and diiron boride coating. These models provide helpful approaches for predicting the behavior of these steels.

Insight into LIB Diffusion Phenomena Using Analytical Impedance Models

Electrochemical impedance spectroscopy (EIS) is extensively used to characterize the transport properties in porous electrodes of lithium-ion batteries (LIB). In the low-frequency domain (f < 1 Hz), solid diffusion and electrolyte diffusion are competing over similar timescales, which explains why both phenomena are difficult to characterize independently. In which case can the solid diffusion coefficient be correctly extracted from experimental EIS? To answer this question, the linearized P2D-Newman model of a complete cell is solved using a Fourier transform to obtain a physics-based analytical impedance. The solution allows deriving the characteristic frequencies and non-dimensional numbers of the system, and gives the parameters range for which solid diffusion is overwhelming electrolyte transport in the impedance signal. A simple criterion is then given to discriminate electrodes that are properly designed for active materials electrochemical characterization.

Full Parameterization Study of a High-Energy and High-Power Li-Ion Cell for Physicochemical Models

For physicochemical modelling of lithium ion batteries, an extensive parametrization is necessary. These parameters need to be derived cell specifically as they vary with cell design. In this study, two cells from the same manufacturer are investigated which are optimized for high power and high energy applications. After opening the cells under argon atmosphere, the battery materials are extracted to conduct various chemical and physical measurements to define the active material type, microstructure, conductivity and mass loading of the electrodes. Furthermore, laboratory cells were built from the extracted materials to evaluate tortuosity and exchange current density by electrochemical impedance spectroscopy, open circuit voltages and solid diffusion coefficient by galvanostatic intermittent titration technique (GITT). The differences and similarities of these parameters for both cell types are discussed and compared to literature. Main differences are the electrode area, thickness, porosity, and thus, mass loading and areal capacity of the electrodes. Both cells have a NCA cathode, but only the high energy cell has a blend anode consisting of graphite and Si/SiOx whereas the anode active material of the high power cell is only made of graphite. The derived parameters are finally used for the parameterization of a P2D model.

Variability on the Phytochemical Composition, Antioxidant and Antimicrobial Activities of Ruppia cirrhosa Extract Using Two Different Methods of Extraction

Background: Nowadays, there is increasing attention to the discovery of new bioactive substances from marine sources. This research aimed to characterize the phytochemical composition as well as antioxidant and antimicrobial activities of Tunisian Ruppia cirrhosa extracts (RCEs) using two different extraction methods. Methods: RCEs were obtained by two different extraction methods: maceration and successive extraction. The determination of polyphenolic contents and antioxidant activity was made by calorimetric assay, and the effect of RCE was observed against pathogenic bacteria and fungi using the solid diffusion method. Results: The successive extraction of R. cirrhosa extract relatively showed higher total phenol (38.1 mg GAE/g) and condensed tannin (18.07 mg CE/g) contents than the maceration extraction (35.43 mg EAG/g and 12.99 mg CE/g, respectively). However, the total flavonoid amount of RCE was higher in the maceration extraction (33.09 mg CE/g) than in the successive extraction (21.27 mg CE/g). The total antioxidant capacity of RCE indicated a decrease in this activity after fractionation. Indeed, the activity of RCE decreased from 47.8 to 37.83 mg GAE/g, and RCE obtained by the two extraction methods showed moderate antioxidant activity using reducing power (IC50=380-490 µg/mL) and β-carotene bleaching (IC50=110-310 μg/mL) assays. Furthermore, RCEs obtained by maceration had the greatest antibacterial activity against all tested strains (IZ=3.33-9.33 mm) except Salmonella typhimurium (IZ=2 mm), Enterococcus faecalis (IZ=6 mm), and Streptococcus aureus (3.67 mm) as compared to those obtained by successive extraction. The strains of Candida had a sensitivity for R. cirrhosa extracts obtained by maceration. Indeed, R. cirrhosa extracts obtained by successive extraction had higher inhibitory activity against Candida krusei deduced through an inhibition diameter of 6 mm. Conclusion: It can be concluded that R. cirrhosa extract is rich in bioactive molecules, and it has an extremely promising biological potential.

A self-correction single particle model of lithium-ion battery based on multi-population genetic algorithm

At present, the Single Particle (SP) model and the Extended Single Particle (ESP) model become a serious concern because they have real usage potentials for the battery management system. However, utilization of the models relies too much on accurate model parameters. Measuring accurately the parameters is a tough task, since they change with the battery condition during the actual use. In this study, Multi-Population Genetic Algorithm (MPGA), a certain kind of GA's improved algorithm, has been adopted to propose a Self-Correction Single Particle Model (SC-SPM). The SC-SPM can self-correct the measured values by sensing the terminal voltage change, which gives more accurate results for the solid phase diffusion process. To verify the proposed SC-SPM, four groups of simulations are performed, indicating that the SC-SPM is more accurate at observing the solid phase diffusion process when the battery condition changes beyond a certain range, and helping BMS better estimating other battery states. At the same time, the single step calculation time is <0.5 s which can meet the requirement of on-line application.

Electrolyte engineering and material modification for graphite‐based lithium‐ion batteries operated at low temperature

AbstractGraphite offers several advantages as an anode material, including its low cost, high theoretical capacity, extended lifespan, and low Li+‐intercalation potential. However, the performance of graphite‐based lithium‐ion batteries (LIBs) is limited at low temperatures due to several critical challenges, such as the decreased ionic conductivity of liquid electrolyte, sluggish Li+ desolvation process, poor Li+ diffusivity across the interphase layer and bulk graphite materials. Various approaches have therefore been explored to address these challenges. On the basis of graphite anode and corresponding LIBs, this review herein offers a comprehensive analysis of the latest advances in electrolyte engineering and electrode modification. First, electrolyte engineering is discussed in detail, highlighting the design of new electrolyte formula with broad liquid temperature range, optimized solvation structure, and well‐performed inorganic‐rich solid electrolyte interface. The advances in material modification have been then depicted with the view of improving the solid bulk diffusion rate to show general strategies with excellent performance at low temperatures. Finally, the corresponding challenges and opportunities have also been outlined to shed light on viable strategies for developing efficient and reliable graphite anode and graphite‐based LIBs under low‐temperature scenarios.

Construction of electrochemical model for high C-rate conditions in lithium-ion battery based on experimental analogy method

Lithium-ion batteries (LIBs) modeling is critical for the safe and efficient operation of electric vehicles (EVs) and energy storage systems (BESSs). Most electrochemical models are mainly suitable for normal temperature or low C-rate conditions (≤2 C). Meanwhile, the electrochemical model parameters are usually obtained by the half-cell testing method. This method has difficulty in disassembling batteries and obtaining model parameters quickly. To solve this problem, the internal electrochemical behavior of LIBs under high-C rate conditions is first studied in this paper. Through the above theoretical analysis, the relationship between the solid phase diffusion coefficient, the reaction rate constant and temperature/concentration must be considered under high C-rate conditions. Then a fast calibration method for electrochemical model parameters is proposed, and a variable parameter high C-rate model is established. Finally, the variable parameter high C-rate model is validated at different rates of 5 °C, 25 °C and 55 °C. The results show that the mean absolute errors (MAE) of the variable parameter high C-rate model are within 13 mV under low C-rate conditions. Under the high C-rate condition (≤6 C), the MAEs of the model are within 50 mV.

Variational formulation of Cahn–Hilliard-type diffusion coupled with crystal plasticity

This article presents a relatively general framework for the description of the Cahn–Hilliard-type diffusion in solids undergoing infinitesimal elastic and plastic deformations. The coupled chemo-mechanical problem, characterised by phenomena such as phase segregation, microstructure coarsening and swelling, is treated using the variational framework which is governed by continuous-time, discrete-time and discrete-space–time incremental variational principles. It is shown that the governing equations of the coupled problem can be derived as Euler equations of minimisation and saddle point principles. A point of departure from the existing works is the coupling of crystal plasticity to the problem of diffusion and optimising the potential with respect to the plastic variables such that they are solved locally at the integration points. This is done using a return map algorithm which results in a reduced global problem. The variational framework results in a system of symmetric non-linear algebraic equations that are solved by Newton–Raphson-type iterative methods. This is a novel and attractive feature with respect to numerical implementation, as models resulting from the proposed variational framework are computationally less expensive in comparison with non-symmetric formulations. The numerical simulations presented at the end predict the applicability of models resulting from the proposed variational framework for multiple scenarios.

High-performance gradient Fe-Si alloy thin sheets fabricated by solid powder siliconizing and diffusion annealing

High-performance gradient Fe-Si alloy thin sheets fabricated by solid powder siliconizing and diffusion annealing

Sub-10 nm Mixing and Alloying of Cu-Ag and Cu-Ni via Accelerated Solid Diffusion.

Development of nanoscale multicomponent solid inorganic materials is often hindered by slow solid diffusion kinetics and poor precursor mixing in conventional solid-state synthesis. These shortcomings can be alleviated by combining nanosized precursor mixtures and low temperature reaction, which could reduce crystal growth and accelerate the solid diffusion at the same time. However, high throughput production of nanoparticle mixtures with tunable composition via conventional synthesis is very challenging. In this work, we demonstrate that ∼10 nm homogeneous mixing of sub-10 nm nanoparticles can be achieved via spark nanomixing at room temperature and pressure. Kinetically driven Spark Plasma Discharge nanoparticle generation and ambient processing conditions limit particle coarsening and agglomeration, resulting in sub-10 nm primary particles of as-deposited films. The intimate mixing of these nanosized precursor particles enables intraparticle diffusion and formation of Cu/Ni nanoalloy during subsequent low temperature annealing at 100 °C. We also discovered that cross-particle diffusion is promoted during the low-temperature sulfurization of Cu/Ag which tends to phase-segregate, eventually leading to the growth of sulfide nanocrystals and improved homogeneity. High elemental homogeneity, small diffusion path lengths, and high diffusibility synergically contribute to faster diffusion kinetics of sub-10 nm nanoparticle mixtures. The combination of ∼10 nm homogeneous precursors via spark nanomixing, low-temperature annealing, and a wide range of potentially compatible materials makes our approach a good candidate as a general platform toward accelerated solid state synthesis of nanomaterials.

Pore-scale lattice Boltzmann simulation of CO2-CH4 displacement in shale matrix

This study couples the Navier-Stokes and multicomponent advection-diffusion equations within the lattice Boltzmann method (LBM) to innovatively simulate the CO2–CH4 displacement in nanoporous shale matrix. In the LBM simulations of CO2 injection into heterogenous CH4-saturated nanoporous media, gas movements are modeled by two separate advection-diffusion lattices driven by the velocity solved from the third Navier-Stokes lattice. Langmuir adsorption kinetics is employed at the fluid-solid interfaces to simulate the mass exchange between the bulk free space and the solid matrix. Mass transfer inside the solid matrix is considered with adsorption and diffusion parameters obtained from molecular dynamics studies. CO2 adsorption and CH4 desorption are simulated simultaneously. The coupling scheme is successfully validated for advection, diffusion, and surface adsorption. Results show that the global mass transfer process is sensitive to intra-matrix diffusion. When the solid diffusion rate is ∼10−4 of the bulk one, selectivity can significantly impact the outflux concentration. Changing the CO2 adsorption rate constant 0.1–10 times nearly has no impact on gas adsorption in the solids. In comparison, the CH4 desorption rate constant strongly correlates to the CH4 desorption pathway. Increasing the particle size under a given porosity may benefit advection and lead to fast adsorption/desorption in the solids.

Solidification Path Calculation of ternary Al-Cu-Mg alloys in Al rich corner

ABSTRACT The liquid solidification paths of ternary eutectic and quasiperitectic Al-Cu-Mg alloys in Al-rich corner were calculated using an extended microsegregation model. The user’s programs were coupled with CALPHAD software for calculating the thermodynamic data of the investigated alloys. The influences of initial composition, average solidification rate, assumption of dendrite morphology, diffusion coefficient and the united solid back diffusion (SBD) parameter Фn on solidification paths were investigated. It was found that differences of the above parameters could greatly affect the liquid solidification path, types and quantities of the precipitated phases, and concentration of solutes in liquid phase. Solidification experiments were carried out with four Al-Cu-Mg alloys to verify the accuracy of the calculation, and reasonable agreements were obtained between the predicted solidification paths and the experiment results.