Crystal Particles Research Articles

Preparation and Evaluation of Tetrandrine Nanocrystals to Improve Bioavailability.

Tetrandrine (TET) has multiple pharmacological activities, but its water solubility is poor, which is the main reason for its low bioavailability. The purpose of this study was to prepare TET nanocrystals (TET-NCs) using a grinding method to enhance the dissolution rate and ultimately improve the bioavailability of TET. TET-NCs were synthesized via media milling, employing Poloxam 407 (P407) as surface stabilizer and mannitol as a cryoprotectant during freeze-drying. The crystal structure, particle diameter, and zeta potential were characterized using differential scanning calorimetry (DSC), Fouriertransform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The in vitro release behavior and pharmacokinetics of TET-NCs were assessed. The cytotoxicity of TET and TET-NCS on RAW264.7 cells was determined by the CCK-8 method. The particle size of TET-NCs was 360.0±7.03 nm, PDI was 0.26±0.03, and zeta potential was 6.64±0.22 mV. The cumulative dissolution within 60 minutes was 96.40±2.31%. The pharmacokinetic study showed that AUC0-72 h and Cmax of TET-NCs were significantly enhanced by 3.07 and 2.57 times, respectively, compared with TET (p<0.01). TET-NCs significantly increased the cell inhibition on RAW264.7 cells compared to the TET (P<0.01). The preparation of TET-NCs enhanced dissolution rate and bioavailability significantly, and it also improved the inhibition effect of RAW264.7 cells.

The in situ green synthesis of metal organic framework (HKUST-1)/cellulose/chitosan composite aerogel (CSGA/HKUST-1) and its adsorption on tetracycline

Abstract In this work, a strategy of in situ 3D hierarchical porous HKUST-1/cellulose/chitosan (CSGA/HKUST-1) composite aerogels were synthesized using ethylene glycol diglycidyl ether (EGDE) as a cross-linking agent. The effect of EGDE on CSGA/HKUST-1 and the adsorption of tetracycline (TC) was investigated: the composite aerogel (CSGA) was produced by the ring-opening reaction of the epoxy group of EGDE in alkaline solution. The chemical structure of CSGA/HKUST-1 composite aerogel was characterized by FT-IR, XRD and XPS.49.33 % mass loading of CSGA1/HKUST-1 was achieved and N2 adsorption and desorption experiment showed the BET specific surface area reached 694.514 m2 g−1. SEM observed the CSGA/HKUST-1 composite aerogel pores were filled with a large number of octahedral HKUST-1 crystal particles. CSGA/HKUST-1 composite aerogel has excellent tetracycline adsorption capacity (285.7 mg g−1), and the removal efficiency remained at 92.7 % after five cycles of adsorption–desorption. The pseudo-second-order kinetic model and Langmuir model adsorption mechanism was successfully concluded. This study can provide ideas for in situ synthesis of MOFs on 3D composite aerogel to prepare adsorption materials, improve the mass loading rate of MOFs and prevent MOFs from falling off, etc., and enrich the application of MOFs materials in the treatment of antibiotic pollutants.

Efficient Dye Contaminant Elimination and Simultaneous Electricity Production via a Carbon Quantum Dots/TiO2 Photocatalytic Fuel Cell

Conventional wastewater treatment methods do not fully utilize the energy in wastewater. This study uses a photocatalytic fuel cell (PFC) to remove dye impurities and generate electricity with that energy. Pt serves as the PFC’s cathode, while the carbon quantum dots (CQDs)/anatase TiO2 (A-TiO2) serve as its photoanode. The visible light absorption range of A-TiO2 can be increased by combining CQDs with A-TiO2. The composite of CQD and A-TiO2 broadens the absorption edge from 364 nm to 538 nm. TiO2’s different crystal structures and particle sizes impact the PFC’s power generation and dye contaminant removal. The 30 min photodegradation rate of methylene blue by the 20 nm A-TiO2 was 97.3%, higher than that of the 5 nm A-TiO2 (75%), 100 nm A-TiO2 (92.1%), and A-TiO2 (93%). The photocurrent density of the 20 nm A-TiO2 can reach 4.41 mA/cm2, exceeding that of R-TiO2 (0.64 mA/cm2), 5 nm A-TiO2 (1.97 mA/cm2), and 100 nm A-TiO2 (3.58 mA/cm2). The photodegradative and electrochemical test results show that the 20 nm A-TiO2 delivers a better degradation and electrochemical performance than other samples. When the 20 nm A-TiO2 was used in the PFC photoanode, the photocurrent density, open-circuit voltage, and maximum power density of the PFC were found to be 0.6 mA/cm2, 0.41 V, and 0.1 mW/cm2, respectively. The PFC prepared in this study shows a good level of performance compared to recent similar systems.

Efficient purification and utilization of pyrite cinder for carbon-coated lithium iron phosphate synthesis

Nonferrous impurities such as Cu, Zn, and Co, along with inert materials such as gangue and silica in pyrite cinder (PyC), significantly limit its direct use as an iron source for battery-grade ferric phosphate (FP) or lithium iron phosphate (LFP). To address this issue, a new process using alkali excitation, mechanical activation, and aging to remove impurities from PyC was developed. Additionally, a novel method for preparing carbon-coated lithium iron phosphate (LFP@C) using purified PyC (p-PyC) as the iron source was explored. With 20% NaOH, 3h of ball milling activation, and aging at 200 ℃ for 4h, the Fe content in PyC increased to 55.14%, with a recovery rate of 95.43%. Compared with those in untreated PyC, the Fe leaching rate in p-PyC reached 98.25%, and the levels of Al, Cu, Zn, Co, and Si in the acid-leaching liquor were reduced by 96.62%, 96.67%, 99.85%, 75.96%, and 99.99%, respectively. The LFP@C cathode material was directly prepared via carbothermal reduction using acid-leaching liquor from p-PyC as the iron source. The LFP@C-30% crystal particles were well connected, and the surface was effectively coated with a carbon layer to form a conductive layer. At 0.1C, the specific capacity was 159.09 mAh·g−1, with 95.63% capacity retention after 100 cycles. LFP@C-30% presented the lowest charge transfer resistance and an apparent diffusion coefficient (DLi) of 2.33×10−11 cm2·s−1. This study offers a simple and effective method for removing impurities from PyC and presents a new approach for converting PyC into high-demand FPs or LFPs.

Particle size control and performance analysis of the ammonium perchlorate-based molecular perovskite energetic material

To solve the problem of high mechanical sensitivity and difficulty in coating caused by large crystal particles of ammonium perchlorate-based molecular perovskite energetic material (H2dabco)[NH4(ClO4)3] (DAP-4), we conducted research on the particle size regulation and performance of it. Firstly, we determined the solubility of DAP-4 in six commonly used organic solvents using a static method. And based on this data, an UDAP-4 (D50 = 6.19 μm) was successfully prepared. The characterization results of UDAP-4 revealed that UDAP-4 exhibits a decrease in thermal decomposition peak temperature (Tp) by 19 °C compared to the raw material, along with an 87.92kJ/mol reduction in activation energy (Ea). The studies on different particle sizes indicate that UDAP-4 maintains good thermal stability while significantly enhancing safety performance. UDAP-4 shows an over 20J increase in impact sensitivity, and a 12N increase in minimum frictional load. And the smaller the particle size, the lower the sensitivity. These findings provide a reference for further secure applications of DAP-4 in an academic context.

Dolomite-derived catalyst-free dual function materials pellets for integrating calcium-looping and reverse–water–gas–shift reaction

Integrated CO2 capture and utilization via reverse water–gas shift reaction (ICCU-RWGS) for syngas production is a promising step contributing to carbon neutrality. Naturally occurring Ca-rich ores are potential candidates of dual function materials (DFMs) for ICCU-RWGS, while the practical circulating operation in twin fluidized-bed reactors necessitates DFMs pellets with high reactivity and good mechanical properties, to overcome powder elutriation and to withstand particle attrition. Dolomite (DM)-derived catalyst-free DFMs pellets are synthesized via the extrusion-spheronization (ES) and graphite-casting (GC) methods. Pelletization will result in pore structure blockage while the decline in textural properties has been remedied to some extent, due to the decomposition of CaMg(CO3)2. The hydration activation of Ca species in molding has benefited the DFMs pellets with uniform dispersion of CaO with smaller grain size. The dolomite-derived DFMs pellets outperform the pristine dolomite and the calcined dolomite DFMs regarding the ICCU-RWGS performance. Promoters such as Al2O3, ZrO2 or aluminate cement (AC) are incorporated to enhance the mechanical strength of the DM-GC pellets. The formed Ca3Al2O6, CaAl2O4, CaZrO3, and Ca2Al2SiO7 due to the interaction between CaO and the promoter, act as supporting skeleton for reinforced mechanical strength and physical barrier for retarding crystal sintering and particle agglomeration. Upon doping 10 wt% ZrO2, the compressive strength of the DM-GC pellets increases remarkably from 0.13 to 1.35 MPa. The desired DM-GC-Zr5 DFMs pellets exhibit excellent ICCU-RWGS performance with high and stabilized CO2 capture capacity (6.01 mmol CO2/g) and CO yield (5.01 mmol CO/g) within 10 cycles, demonstrating as a good DFMs candidate for cost-effective CO2 capture and conversion.

In Situ Surface-Enhanced Infrared Absorption Spectroscopy to Explore the Stability of Electrolyte in Nonaqueous Lithium Oxygen Batteries

Tetraethylene glycol dimethyl ether (TEGDME) decomposition on the Au electrode surface is studied using in situ attenuated total reflectance surface enhanced infrared absorption spectroscopy (ATR-SEIRAS). Due to the weak solvation of TEGDME, the superoxide intermediate (LiO2/O2−) of the discharge process rapidly gains electrons on the electrode surface to generate Li2O2. Furthermore, alkyl radical, formed by LiO2/O2− extracting hydrogen from ether, undergoes oxidative decomposition reactions to form by-products. During the charge process, amorphous film-like Li2O2 obtained from surface-phase mechanism oxidizes in the low potential range of 3–3.4 V, while the oxidation potential of large-sized crystal Li2O2 particles obtained from solution-phase mechanism is above 3.4 V. Besides, TEGDME is intrinsically unstable and can decompose at 3.8 V even the solution is saturated with argon, indicating that the degradation of ether-based electrolyte is inevitable during the cycling process. This work confirms the feasibility of ATR-SEIRAS in probing the reaction mechanism and electrolyte stability of lithium oxygen batteries, and provides direct spectroscopic evidence for subsequent optimization of electrolyte components.

SECM Study for Surface-Grain-Resolved Hydrogen Oxidation Reaction Activity of Polycrystalline Pt Electrode

Introduction Carbon-supported Pt nanoparticles (Pt/C) are used as anode as well as cathode catalyst for polymer electrolyte fuel cell (PEFC). In general, electrochemical reactions that proceed at electrocatalyst surfaces are strongly depended upon their surface atomic arrangements. Therefore, to develop novel catalyst materials, guidelines of microstructural surface design of the catalysts are indispensable through clarifying various surface properties of the catalysts, such as surface atomic arrangements, size, and shapes and comprehensive understandings of the surface microstructures and catalytic properties should be required. From the above perspectives, fundamental studies for the electrocatalysis by using "well-defined" single crystal surfaces of Pt (Pt(hkl)) have been conducted to date [1]. However, gaps of material’s sizes between the surfaces of millimeter-sized single crystal and nano-sized particles make it difficult to understand practical catalytic properties of the nano-sized particles. To bridge the forementioned gaps, this study aims to clarify the dependences of hydrogen oxidation reaction (HOR) properties on micrometer-sized surface grains of a polycrystalline Pt electrode, through comparing two-dimensional (2D) surface mappings with micrometer resolution of surface grain orientations analyzed by an electron backscatter diffraction (EBSD) method and of hydrogen oxidation reaction (HOR) activities evaluated by a scanning electrochemical microscope (SECM) [2]. We successfully correlate the micrometer-sized surface grains and corresponding HOR properties. Experimental Polycrystalline Pt substrate (10mm × 10mm, 1mm thickness) was pre-annealed at 1000°C for 15 hours in ultra-high vacuum (UHV: ~10-7 Pa). The surface grain orientations of the polycrystalline electrode were analyzed using EBSD in air. For comparison of 2D mapping images of EBSD-analyzed surface grain orientations and SECM-evaluated HOR activities, ten-nanometer-size triangle shapes were marked by a nano indenter (TTX-NHT, Anton Paar) on the Pt substrate surface as signs of the positions. The polycrystalline Pt substrate surface thus prepared was cleaned by three cycles of Ar+ sputtering and annealing at 1000°C for 10 minutes alternately in UHV and, after that, HOR activities of the electrode was performed in 0.01M HCIO4 + 0.1M NaClO4 mixed electrolyte by SECM. 2D mapping image of micrometer-resolved HOR activities was collected by a scanning Pt-made microelectrode (φ = 10μm) with a distance of ca. 7μm between the microelectrode and polycrystalline electrode. Because a possible scanning region of the microelectrode was 200 µm square, a whole 2D mapping image of HOR activities (350µm × 650μm; Fig. 1(a)) was constructed by eight pieces of the 200 µm square images. Finally, by referring to the position markings made by the nano indenter, 2D images of surface grain orientations and HOR activities were combined with micrometer resolution. Results Fig. 1 shows 2D mapping images of (a) the surface grain orientations and of (b) HOR activities for the polycrystalline Pt electrode surface, respectively, where the grains having surface orientations close to (111), (110), and (100) are distinguished in blue, green, and red and purple in (a; right-hand-side invers pole figure) and the iT values of the scanning microelectrode currents that induced by HOR are presented by colors (b; of a right-hand-side indicator). Close correlations are identified between the surface grain orientations and corresponding HOR activities with micrometer resolution. From detailed comparisons of the two 2D mappings, the order of HOR activities is (111) oriented surface grains > (110) > (100). Notably, in the vicinities of specific grain boundaries, HOR activities changed within the same surface grains. In the presentation, we will discuss dependences of the orientations of surface grains, grain boundaries on corresponding HOR activities for the polycrystalline Pt and Ir electrodes. Acknowledgement This study was supported by new energy and industrial technology development organization (NEDO) of Japan and Japan society for the promotion of science (JSPS).Reference[1] K. Hayashi, et al., Phys. Chem. Chem. Phys., 25, 2770-2775, (2023)[2] O. Wipf, et al., J. Electrochem. Soc. 167, 146502, (2020) Figure 1

Data-Driven Analysis of Contributing Factors in Spectra Toward Quantitative Prediction of Photocatalytic Activity of BaTaO₂N

Photocatalytic hydrogen production via water splitting has attracted attention as an energy infrastructure independent of fossil resources. However, it has not yet reached the practical energy conversion efficiency level (5%), necessitating the enhancement of photocatalyst materials. Various crystal characteristics such as crystal shape, surface state, and lattice defects are known to be influencing factors on the performance of photocatalysts. However, their quantitative correlation and synergistic effects of each factor on performance are unclear. Understanding the quantitative correlation of crystal properties with photocatalytic activity would give effective crystal design for improvement. In this study, we aimed to extract crystallographic properties and understand their correlation with photocatalytic water splitting by multivariate analysis. BaTaO2N (BTON), which responds to visible light, was selected as a model material for photocatalysis.First, internal crystal information was collected from X-ray diffraction (XRD) patterns and Ultraviolet-Visible (UV-Vis) absorption spectra. Interpretable feature values, such as intensity ratio and full width at half maximum at the diffraction peak, impurity, absorption edge wavelength and its area were automatically extracted using Python. The factors contributing to water splitting were then identified by using LASSO regression. These feature values were used to depict a two-dimensional dimension reduction diagram (t-SNE diagram), which describe photocatalytic activity as color map. The t-SNE diagram confirmed the clustering of data with similar water splitting activity, indicating that this diagram can be used as an effective guide to explore the crystal properties with high photocatalytic activity. Next, scanning electron microscopy (SEM) was analyzed to extract additional feature values. Image analysis was carried out for the comprehensive extraction of crystal surface information. Gray-Level Co-occurrence Matrix (GLCM) texture analysis was an effective method for detecting boundary parts, thus used to extract abstract crystal surface information. In addition, Variational Autoencoder (VAE) was used to extract specific crystal surfaces. The extracted feature values can contain information about crystal surface structures such as crystal morphology, particle agglomeration, and co-catalyst support state. Correlation analysis between these feature values and photocatalytic activity is now underway and will be reported in the presentation. AcknowledgementThis work was partly supported by the Strategic Innovation Program (SIP) of the Cabinet Office, the NEDO Green Innovation fund projects, and collaborative research with companies.

Rutile TiO2 As a Negative Electrode Material for Proton Rechargeable Batteries

With the increasing importance of rechargeable batteries, the use of monovalent alkali metal ions such as Na and K ions has been actively investigated. However, there have been relatively few research reports on proton rechargeable batteries. When using protons as a carrier ion, there are concerns about irreversible H2 evolution due to the poor electrochemical stability of aqueous electrolytes. If the fast proton conduction originating from Grötthuss mechanism can be utilized, the rechargeable batteries with water-based electrolytes including protons as carrier ions that combine safety and rapid charge–discharge performance is expected.1−3 On the other hand, it is required that negative electrodes operate at a lower potential to improve battery voltages. Although anatase TiO2 have been reported as the host material for protons to show a reversible capacity, H2 evolution remains an unavoidable issue. In this study, we focused on the energy level of the conduction band of rutile TiO2, which is more positively located than anatase TiO2. It is expected that the positively located conduction band reduce irreversible HER and achieve a long-cycle life. The influence of crystal structures and particle sizes on battery performances of rutile, anatase, and brookite TiO2 were systematically examined. To investigate the effect of crystal structure on the electrochemical protonation of TiO2 with as little influence of particle size as possible, TiO2 was synthesized by different preparation methods for each structure (Figure 1a). The electrolyte used in this study is the citric buffer solution consisting of 1 M citric acid and 1 M trisodium citrate. The electrochemical protonation/deprotonation was investigated using three-electrode type cell with the counter electrode of activated carbon and the reference electrode of Ag/AgCl in sat. NaCl.Figure 1b shows galvanostatic charge–discharge properties of several TiO2 synthesized by the hydrothermal method. The reaction potentials of TiO2 with protons are rutile, brookite, and anatase, in that order, reflecting the more positive conduction band level of the rutile. The XRD measurements revealed that the rutile TiO2 uptakes/releases protons while maintaining the parent phase without any phase transitions (Figure 1c). The lattice parameters, a and c reversibly and slightly expanded/contracted (Figure 1d), but did not change as much as during the insertion/extraction of alkali metal ions such as Li+ and Na+.4,5 The fact that lattice expanded and contracted clearly reveals that protons were inserted into the rutile TiO2 bulk. Meanwhile, the larger particles showed little protonation and H2 evolution was dominant regardless of the crystal structures. The particle size is an influential factor, and smaller sizes are advantageous in the electrochemical protonation.6 AcknowledgementThis work was supported by a Grant-in-Aid for Scientific Research (B) (20H02840, 24K01601) from the Japan Society for the Promotion of Science (JSPS).References Wang, Y. Xie, K. Tang, C. Wang, C. Yan, Angew. Chem. Int. Ed., 57 (2018) 11569.B. Mitchell, W. C. Lo, A. Genc, J. LeBeau, V. Augustyn, Chem. Mater., 29 (2017) 3928.Makivić, J.-Y. Cho, K. D. Harris, J.-M. Tarascon, B. Limoges, V. Balland, Chem. Mater., 33 (2021) 3436.Usui, S. Yoshioka, K. Wasada, M. Shimizu, H. Sakaguchi, ACS Appl. Mater. Interfaces, 7 (2015) 6567.Usui, Y. Domi, S. Ohnishi, N. Takamori, S. Izaki, N. Morimoto, K. Yamanaka, K. Kobayashi, H. Sakaguchi, ACS Mater. Lett., 3 (2021) 372.Shimizu, D. Nishida, A. Kikuchi, S. Arai, J. Phys. Chem. C, 127 (2023) 17677. Figure 1

Enabling High-Voltage Stability in Solid-State Battery Cathodes with ALD Coatings

Solid-state batteries (SSBs) promise improved safety and energy density by using solid electrolytes (SEs) and high-voltage cathodes. However, the SEs are unstable at high voltages, leading to oxidative chemical decomposition at the SE/CAM (cathode active material) interface, resulting in the formation of an insulating cathode-electrolyte interface (CEI) on CAM particles [1]. The layered oxide cathodes (LiNixMnyCozO2; NMC), when cycled at elevated voltages (>4.3V), undergo irreversible structural and chemical deformations, including the formation of kinetically less active phases (spinel and rock-salt), oxygen evolution, and mechanical degradation (intergranular or intraparticle cracking) [2]. The instability of the SE, CAM particles, and SE/CAM interface, collectively, results in inferior electrochemical performance, including low initial Coulombic efficiency (CE), increased cell polarization and impedance, reduced rate capability, and capacity fade during extended cycling.Therefore, it is crucial to stabilize the SE/CAM interface and preserve the CAM structure in SSB cathodes, particularly during high-voltage cycling. This is primarily achieved by developing a protective coating on CAM particles. Niobium (Nb)-based coatings are promising to protect the SE/CAM interface, mostly developed by wet chemical and solid-state processing routes that involve high-temperature annealing. On the other hand, atomic layer deposition (ALD) is a powerful technique for coatings, providing precise thickness and composition control [3]. Unfortunately, these coatings may have ‘hot spots’ for local current focusing (crystalline defects, i.e., grain boundaries) and oxygen release (pinholes at particle-particle contacts) [4].In the present study, we developed an Nb-based thin conformal amorphous coating on single crystal NMC CAM particles using ALD equipped with a rotary bed attachment. Unlike traditional stationary ALD reactors, ALD with a rotary bed attachment ensures a pinhole-free continuous coating on CAM powders. The low-temperature ALD process results in an amorphous coating (chemically and structurally isotropic), which is expected to effectively withstand the volumetric changes occurring in CAM particles during repetitive charge/discharge cycling. Comparing the performance of uncoated and coated samples tested at high voltages (≥4.5V) shows that the coated cathodes display significant improvements, including high initial Coulombic efficiency (91% vs. 83%), enhanced rate capability (10x higher accessible capacity at a 2C rate), and improved capacity retention during extended cycling (99.4% after 500 cycles). These enhancements are attributed to reduced cell polarization and interfacial impedance in coated samples. Post-mortem electron microscopy and XRD analysis confirm that the coating remains intact, inhibiting oxygen release from the CAM structure and the formation of inactive phases (spinel and rock-salt), thereby preventing CAM particle cracking. These findings pave the way for stable and high-performance SSBs with high-voltage cathodes.Keywords: Solid-state batteries, composite cathodes, Nb-based coating, atomic layer deposition (ALD), high voltage stability.Reference: Xiao et al. Understanding interface stability in solid-state batteries. Nat. Rev. Mater. 5 (2020) 105.Wang et al. Single crystal cathodes enabling high-performance all-solid-state lithium-ion batteries. Energy Storage Mater. 30 (2020) 98.Koshtyal et al. Applications and Advantages of Atomic Layer Deposition for Lithium-Ion Batteries Cathodes: Review. Batteries 8 (2022) 184.Cheng et al. Materials Design Principles of Amorphous Cathode Coatings for Lithium-Ion Battery Applications. J. Mater. Chem. A 10 (2022) 22245.

Molten Salt Synthesis and Growth Mechanism of Single Crystal Ni-Rich Layered Oxides As Cathode Materials

Responding to the growing demand for high-energy lithium ion batteries (LIBs), it is crucial to develop advanced materials which offer higher energy density than currently available commercial materials. The class of Ni-rich layered oxide has attracted great interest owing to their prime advantage of high reversible capacity.[1] However, conventional polycrystalline cathodes suffer from intergranular cracking that occurs within secondary particles during repeated cycling, leading to the loss of contact between active materials and an increase in the exposed fresh surfaces to further parasitic reactions with electrolytes.[2-3] Consequently, this phenomenon results in a significant impedance rise and rapid deterioration in performance.In response to the challenge of intergranular cracking, the utilization of a single crystal morphology has been proposed as a promising solution. Studies have demonstrated that eliminating grain boundaries allows a single crystal cathode to maintain structural integrity, suppress the formation of intergranular cracks, and ultimately enhance cycle stability.[4-5] Nevertheless, ongoing debates persist regarding gas evolution and rate performances. One reason for this lies in the diverse characteristics of single crystal particles, such as particle size and shape, the degree of agglomeration, and cation disorder, all of which exert a complex influence on their properties. To effectively manage these features, a comprehensive understanding of the synthesis process and the identification of critical factors that affect the properties of single crystal Ni-rich cathodes are necessary.In this study, we elucidated the synthesis mechanism of single crystal LiNi0.95Co0.05O2 (SC95) using the molten salt synthesis (MSS) method, employing a combination of lithium hydroxide (LiOH) and lithium sulfate (Li2SO4) as a salt mixture. Through a comparative analysis of the MSS process against the solid-state synthesis, we closely examined the mechanisms governing crystal growth and morphology evolution during MSS. By conducting a comprehensive analysis, including in situ heating XRD, SEM, and EPMA, we demonstrated that the unique synthesis behavior of MSS stemmed from both the formation process of a layered structure and the grain growth of SC95 proceeded through a liquid-solid phase reaction. The maintenance of the salt mixture in a molten state during the reaction facilitated the uniform coverage of the precursor, resulting in a homogeneous reaction and effective dispersion of SC95. Based on these findings, we successfully prepared discrete micron-sized SC95 particles with monodisperse particle size distribution. The SC95 cathode exhibited superior cyclability over 150 cycles with a capacity retention of 89 % at a 1 C rate. This study provides valuable insights necessary for designing highly dispersed single crystal Ni-rich cathodes.

Direct Conversion from Poly- to Single-Crystal Cathode By Oxygen-Storage Additive

As demand for electric vehicles increases, interest in cathode materials with high energy density continues to increase. Ni-rich layered NCM811 is a cathode material attracting attention because it can realize high energy density. However, currently available NCM cathode materials use secondary particles. In the case of commercial NCM811, which has a secondary particle shape, the cycle-life characteristics rapidly decrease due to the cracks of the primary particles constituting the secondary particles. Single crystallization of NCM cathode materials is used to minimize these particle cracks. Single-crystal cathodes without intergranular cracks have been shown to improve cycling and thermal stability by minimizing surface degradation.In this study, A high-performance single crystal cathode material was synthesized by directly converting commercial NCM811 polycrystal using a crystal growth promoter (Ce0.5Zr0.5O2) during heat treatment. The CeZrO2 additive used in the synthesis was able to grow primary particles significantly at the same temperature compared to when no additive was used or when CeO2 or ZrO2 was used. The performance of single crystal particles synthesized using this method was further improved through cobalt coating. Single crystals synthesized using additives showed very excellent cycle-life performance compared to existing commercial secondary particles or active materials that were heat-treated without additives at the same temperature. The enhanced electrochemical performance is attributed to decreased crack generation, reduced surface reactivity by cobalt coating, which was confirmed through various electrochemical analyses and electrode observations.

Solid-State Synthesis for High-Tetragonality, Small-Particle Barium Titanate.

This study successfully synthesized high-tetragonality barium titanate (BaTiO3) particles with a small particle size by implementing ball milling in the solid-state synthesis of BaTiO3 and utilizing nanoscale raw materials. This study also addressed the issues of impurities and uneven particle size distribution that could exist in the synthesized BaTiO3 particles. The crystal structure, morphology, and particle size of the synthesized BaTiO3 particles have been meticulously analyzed and discussed through the use of techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and the laser particle size analyzer. BaTiO3 has been successfully synthesized, exhibiting a uniform particle size with an average diameter of 170 nm and a high tetragonality value of 1.01022. This new solid-state synthesis method provided insights to avoid the impact of "size effects" during the process of electronic device miniaturization.

Particle Size and Crystal habit Modification of Ammonium Perchlorate Using Cooling Sonocrystallization Process

AbstractAmmonium perchlorate (AP) is a widely used solid oxidizer in solid propellant formulations, with its particle size and crystal habit significantly affecting performance. Since controlling these properties remains challenging, this study employs an intensified crystallization strategy, specifically a cooling sonocrystallization process, to recrystallize AP to control and modify its particle size and crystal habit. The effects of solution concentration, sonication intensity, sonication pulse on/off recipe, and cooling rate on the recrystallization of AP are first investigated using a Taguchi L9 orthogonal array design. By understanding the main effect of these operating parameters, further sonocrystallization experiments are designed for process improvement. Compared with the unprocessed AP, the crystal habit and mean particle size of AP are considerably modified after cooling sonocrystallization, achieving a mean size of approximately 50 µm with a regular habit. Consistency in crystal structure and spectrometric properties between sonocrystallized and unprocessed AP was confirmed. Furthermore, the thermal properties and decomposition behavior of the sonocrystallized AP are analyzed, revealing improved exothermic characteristics. These results prove that cooling sonocrystallization is an efficient tool for producing AP particles and also holds the potential for preparing fine particles of other energetic materials.

Investigating secondary ice production in a deep convective cloud with a 3D bin microphysics model: Part I - Sensitivity study of microphysical processes representations

Secondary ice production (SIP) is a crucial phenomenon for explaining the formation of ice crystal clouds, especially when addressing the discrepancies between observed ice crystal number concentrations and ice nucleating particles (INPs). In this study, we investigate parameterizations of three SIP processes (Hallett-Mossop, fragmentation of freezing drops, and fragmentation due to ice–ice collision) by simulating a deep convective cloud observed during the HAIC/HIWC campaign with the 3D bin microphysics scheme DESCAM (DEtailed SCAvening and Microphysics model). The simulated mean cloud properties, including particle size distributions and ice crystal number concentration are compared with in situ probe observations obtained during the campaign. Simulation excluding SIP shows a large underestimation of small ice crystals (< 1 mm diameter) for temperatures warmer than ‐30∘C. In our results, incorporating Hallett-Mossop and fragmentation due to ice–ice collision processes leads to ice crystal number concentrations close to observed values, thereby reducing discrepancies by two orders of magnitude. Our simulations also indicates that fragmentation of freezing drops affect minimally the properties of the cloud at its mature stage. Furthermore, we investigate the impact of fragments sizes resulting from SIP processes and show that the size of fragments generated from fragmentation due to ice–ice collision significantly influences the shape of ice particle size distribution. Employing various parameterizations of the ice crystal sticking efficiency reveals a notable impact on cloud properties. This study shows that SIP mechanisms are important and have to be considered for cold and mixed-phase clouds. However their parameterization lack reliability, highlighting the need for better quantifying these mechanisms. The companion paper, investigates the effects of SIP processes on the formation and the evolution of the deep convective system.

Electrochemical activation of MnS as an efficient conversion-type Cu2+ storage electrode

Electrochemical activation can turn inactive materials into active materials in situ for energy storage facilely, controllably and efficiently, which makes metal sulfides feasible for Cu2+ storage based on electrochemical activated into CuS. Among common heavy metal sulfides, MnS has the highest solubility product and high Cu2+ adsorption and exchange rate in the copper removal by vulcanization in nickel electrolytic anodic solution. Here, MnS is electrochemical activated in situ in aqueous Cu-ion battery, and the effects of crystal structure and particle size on the electrochemical activation of MnS were revealed. The results show that both α, γ-MnS can be electrochemical activated, and activation cycling number is related to the particle size of MnS. When the MnS particle size is ball-milled small enough (1–2 μm), MnS will be completely transformed into CuS during the first discharge process, and then CuS↔Cu2S will participate in the reversible conversion reaction for copper storage. When the MnS particle size is larger (> 10 μm), the α-MnS electrode capacity gradually increases and becomes stable after 30 cycles, and the capacity remains at 458.6 mAh g–1 after 300 cycles.

Effect of alkali metal sulfates on hydration properties of alpha-calcium sulfate hemihydrate for 3D printing

Three-dimensional printing (3DP) technology is an important means of achieving decorative convenience, personalization, and functional integration for future building construction. However, the setting time and hydration process of calcium sulfate hemihydrate (HH) present chanllenges for the 3DP application. This study aims to investigate the accelerating effect of alkali metal sulfates accelerators on the hydration transformation of HH into calcium sulfate dihydrate (DH). The setting time, conductivity, Ca2+ ion concentration, size distribution, and zeta (ζ) potential of gypsum slurries with different accelerators were measured. The results demonstrated that the accelerators significantly enhanced the hydration process of αlpha-calcium sulfate hemihydrate (α-HH). On the effect of accelerators, the setting times of gypsum slurries containing 30 wt% lithium sulfate (LS), sodium sulfate (NS) and potassium sulfate (KS) were accelerated by 82.56 %, 86.06 % and 97.13 %, respectively, compared to the control sample. The crystal particle sizes of hydration products decreased, and the absolute values of ζ potential increased to 1.85 mV, 3.1 mV, and 5.3 mV, respectively. The X-ray photoelectron spectroscopy (XPS) analysis revealed a shift in the peak values of the hardened specimens towards higher electric fields. This was accompanied by improved ion dispersion within the slurry, resulting in enhanced supersaturation of calcium sulfate dihydrate and crystallization of the crystal nuclei. Thus, the suitable accelerators can effectively achieve rapid solidification and hardening of high-fluidity gypsum slurries.

Aircraft observation of aerosol and mixed-phase cloud microphysical over the North China Plain, China: Vertical distribution, size distribution, and effects of cloud seeding in two-layered clouds

Aerosol and clouds are essential to climate effects. Based on an aircraft observation in a mixed-phase cloud in Shijiazhuang, China, on November 21, 2020, analyzing the vertical and size distributions of cloud droplets, and ice crystal particles, and the effects of the similar to a “seeder-feeder” process after cloud seeding on cloud microphysics. The first seeding cloud (CS1) and second seeding cloud (CS2) were at 2600–2800 m and 1500–2300 m, respectively. Before seeding, the average number concentration of cloud droplets (Nc) was 236.91 cm−3 and 152.13 cm−3 in CS1 and CS2 from vertical observation. In CS1, the average number concentration of ice crystals (Ni) was 0.26 L−1 with dendritic ice crystals and graupel, while in CS2, the average Ni was 0.19 L−1, including rimed plate ice crystals, graupel, and needle ice crystals. After seeding, the average Nc decreased from 322.90 to 260.69 cm−3 and the spectrum of Nc broadened from 2.5 to 24 to 45 μm in CS1. The ice microphysics also had different responses in the layered cloud. Ni increased by 421 times in regions with high Nc and low LWC (Nc > 322.90 cm−3, LWC < 0.14 g∙m−3), including spoked and heavily rimed ice crystals and graupel (200–500 μm) in CS1. In CS2, the maximum Ni was 252.03 L−1 and the average Ni increased by 2 magnitudes (from 0.39 to 11.44 L−1). There were rimed needles and columnar ice crystals (200–300 μm) in regions with high Nc and high LWC (Nc > 92.78 cm−3, LWC > 0.13 g∙m−3), and high Nc and low LWC (Nc > 92.78 cm−3, LWC < 0.13 g∙m−3). Seeding in CS1 and CS2 formed a structure similar to the “seeder-feeder” process. Controlled by the downdraft (>1 m/s), these particles descended into the “feeder” region of CS2. Appropriate temperature and rimed crystals contributed to secondary ice crystal production (SIP), resulting in main columns (200–300 μm) observed in CS2. The “feeder” region generated more ice crystals than the “seeder” region.

Prediction of Li-ion conductivity in Ca and Si co-doped LiZr2(PO4)3 using a denoising autoencoder for experimental data

All-solid-state batteries composed of inorganic materials are in high demand as power sources for electric vehicles owing to their improved safety, energy density, and overall lifespan. However, the low ionic conductivity of inorganic solid electrolytes has limited the performance and adoption of inorganic all-solid-state batteries. The solid electrolyte LiZr2(PO4)3 has attracted attention owing to its high Li-ion conductivity. The ionic conductivity of LiZr2(PO4)3 changes with the crystalline phase obtained, which varies based on composition control through elemental substitution and process conditions such as sintering temperature. Traditionally, optimizing such parameters and understanding their relationship to physical properties have relied on researcher experience and intuition. However, a recent use of a materials informatics approach utilizing machine learning shows promise for more efficient property optimization. This study proposes a deep learning model to correlate powder X-ray diffraction (XRD) profiles with the activation energy (Ea) for Li-ion conduction, thereby enhancing the interpretability of the measurement data. XRD profiles, which contain information on crystal structure, lattice strain, and particle size, were used as-is (i.e., without preprocessing) in the deep learning model. An attention mechanism was introduced to the deep learning model that focuses on XRD crystal-structure information and visualization of important factors embedded in the XRD profiles. The highlighted areas in the output of this model successfully predict LiZr2(PO4)3 phases with low Ea (high Li conductivity) and high Ea (low Li conductivity). Moving forward, this deep learning model can offer new insights to materials researchers, potentially contributing to the discovery of new solid electrolyte materials.