Crystal Surface Research Articles

Crystal orientation enabling rapid Zn2+ migration for advanced zinc-ion hybrid capacitors

Aqueous zinc-ion hybrid capacitors (AZIHCs) are promising for large-scale energy storage given their superiority in cost and safety, whereas dendrite growth on zinc anodes limits their viability. Metal-organic frameworks (MOFs) exhibit the potential to inhibit dendrite growth due to their unique structure, but the suppression mechanism on different crystalline planes has always been overlooked. Herein, inspired by theoretical simulations, (110) crystal surfaces exhibit unique Z-type channels in ZIF-8, which significantly reduces the migration energy barrier of Zn2+ from 1.2 eV to 0.2 eV compared to the (100) crystalline surface, enabling homogeneous zinc ion deposition. Conversely, (100) surfaces hindered zinc ion transport due to their smaller pore diameter. As predicted, the lifetime of symmetric cells with as-prepared ZIF-8–110@Zn was about 18 times than that of ZIF-8–100@Zn cells at 1 mA cm-2. In-situ optical microscopy also revealed uniform zinc ion deposition with ZIF-8–110@Zn, whereas dendrite growth occurred in bare zinc and ZIF-8–100@Zn anode. Assembling it with activated carbon (AC) cathode for AZIHCs deliver a long cycle life of 3500. This pioneering study not only provides a strategy for further enhancing electrochemical performance by tuning the dominant facets of MOFs, but also provides novel insights into the mechanism of zinc anode protection.

Theoretical investigation of the sm-BiVO4 of different surfaces for photocatalytic properties

The photocatalytic performance of a semiconductor photocatalyst mainly depends on the exposure degree of the crystal surface with high catalytic performance. The research focused on sm-BiVO4, which exhibits superior photocatalytic performance, as the subject of the study. Based on Density Functional Theory (DFT), the stability, electrical properties, optical properties, adsorption properties and surface activity of 7 low-index faces and one easily formed (112) crystal face of monoclinic clinobisvanite bismuth scheelite (sm-BiVO4) were investigated. The results show that the (001) crystal faces of sm-BiVO4 have the highest stability compared to other crystal faces. Bi atoms have the highest number of electrons from VO43−, the highest light absorption efficiency and the highest surface activity. This work not only contributes to the understanding of sm-BiVO4 but also demonstrates that the (001) crystal faces of sm-BiVO4 has great potential for photocatalytic applications.

Tailoring crystal plane of short-process regenerated LiFePO4 towards enhanced rate properties

Captured by the environmental and economic value, the recycling of spent lithium iron phosphate (LFP) batteries has attracted numerous attentions. However, hydrometallurgical method still suffers from complex process, and hydrothermal method is limited by morphology control, ascribed to the strong polarity of water. Herein, supported by ethanol as crystal surface modifier, the regular (010) orientation and short b-axis are effectively tailored for regenerated LFP. As Li-storage cathode, the capacities of as-optimized LFP could reach up to 157.07 mA h g−1 at 1 C, and the stable capacity of 150.50 mA h g−1 could be remained with retention of 93.48% after 400 cycles at 1 C. Even at 10 C, their capacity could be still kept about 119.3 mA h g−1. Assisted by the detail analysis of adsorption energy, the clear growth mechanism is proposed, the lowest adsorbing energy (−4.66 eV) of ethanol on (010) crystal plane renders the ordered growth along (010) crystal plane. Given this, the work is expected to shed light on the tailoring mechanism of internal plane about regenerated materials, whilst providing effective strategies for high-performance regenerated LFP.

High Power Short Wavelength Infrared Photonic Crystal Surface Emitting Lasers

High Power Short Wavelength Infrared Photonic Crystal Surface Emitting Lasers

Amorphous stabilization of BCS II drugs using mesoporous silica

This study aimed to investigate the amorphous stabilization of BCS Class II drugs using mesoporous silica as a carrier to produce amorphous solid dispersions. Ibuprofen, fenofibrate, and budesonide were selected as model drugs to evaluate the impact of molecular weight and partition coefficient on the solid state of drug-loaded mesoporous silica (MS) particles. The model drugs were loaded into three grades of MS, SYLYSIA SY730, SYLYSIA SY430, and SYLYSIA SY350, with pore diameters of 2.5 nm, 17 nm, and 21 nm, respectively, at 1:1, 2:1, and 3:1, carrier to drug ratios, and three different loading concentrations using solvent immersion and spray drying techniques. Differential scanning calorimetry (DSC) thermograms of SY430 and SY350 samples exhibited melting point depressions indicating constricted crystallization inside the pores, whereas SY730 samples with melting points matching the pure API may be a result of surface crystallization. Powder x-ray diffraction (PXRD) diffractograms showed all crystalline samples matched the diffraction patterns of the pure API indicating no polymorphic transitions and all 3:1 ratio samples exhibited amorphous halo profiles. Response surface regression analysis and Classification and Regression Tree (CART) analysis suggest carrier to drug ratios, followed by molecular weight, have the most significant impact on the crystallinity of a drug loaded into MS particles.

Scale inhibition mechanism of calcium sulfate by gum Arabic: Experimental testing, quantum chemical calculations, and molecular dynamics simulations

In this paper, the scale inhibition mechanism of gum arabic (GA) on calcium sulfate fouling is theoretically and experimentally investigated. A combination of experiments, quantum chemical calculations, and molecular dynamics simulations are carried out. The results demonstrated that GA has the potential to inhibit the precipitation process of calcium sulfate fouling significantly. As the concentration of GA increases, the scale inhibition efficiency also increases. Moreover, with a concentration of 6.8 g/L of calcium sulfate in the solution, it is shown that the scale inhibition efficiency of 1 g/L GA is 97.5 %. Additionally, it is noted that the variation in the solution pH does not significantly affect the GA scale inhibition effect. It was highlighted that carboxyl groups, hydroxyl groups, and ether bond oxygens in the GA molecule are the functional groups that exhibit scale inhibition. These groups serve as the low electronegativity regions with strong interactions with calcium ions. In addition, GA can be adsorbed on the active growth sites on the gypsum surfaces to form a dense, self-assembled barrier film. This film aids in inhibiting the calcium sulfate precipitation process. The findings of this study rank the scale inhibition of GA at different crystal surfaces as follows: gypsum (010) > gypsum (-111) > gypsum (120).

Exerting pulling forces in fluids by directional disassembly of microcrystalline fibres

Biomolecular polymerization motors are biochemical systems that use supramolecular (de-)polymerization to convert chemical potential into useful mechanical work. With the intent to explore new chemomechanical transduction strategies, here we show a synthetic molecular system that can generate forces via the controlled disassembly of self-organized molecules in a crystal lattice, as they are freely suspended in a fluid. An amphiphilic monomer self-assembles into rigid, high-aspect-ratio microcrystalline fibres. The assembly process is regulated by a coumarin-based pH switching motif. The microfibre crystal morphology determines the monomer reactivity at the interface, resulting in anisotropic etching. This effect exerts a directional pulling force on microscopic beads adsorbed on the crystal surface through weak multivalent interactions. We use optical-tweezers-based force spectroscopy to extract mechanistic insights into this process, quantifying a stall force of 2.3 pN (±0.1 pN) exerted by the ratcheting mechanism produced by the disassembly of the microfibres.

Green auto-combustion synthesis of SrNiO3/NiO/SrCO3 ferromagnetic-nanocomposites in the presence carbohydrate sugars and their application as photocatalyst for degradation of water-soluble organic-pollutants

This study utilized an environmentally-friendly method to synthesize SrNiO3/NiO/SrCO3 nanocomposites using glucose and lactose as fuels. A variety of fuel concentrations were investigated in order to determine their effects on SrNiO3/NiO/SrCO3 nanocomposites from both a pure and a morphological perspective. Various physiochemical techniques were employed to examine the crystal structure, morphology, optical, magnetic, and surface properties of the synthesized nanoparticles. These techniques included X-ray diffract, scanning electron microscopy, transmission electron microscopy, energy-dispersive spectroscopy (EDS), Fourier-Transform Infrared Spectroscopy (FTIR), vibrating sample magnetometers, and Brunauer-Emmett-Tellers. The band gap of the as-synthesized nanoparticles was determined to be 2.5eV, suggesting that they are capable of acting as a photocatalyst under sunlight-like conditions. The photocatalytic activity of SrNiO3/NiO/SrCO3 nanocomposites was evaluated against Methyl orange (MO) and Methyl violet (MV), and the mechanism of the photocatalyst was investigated using EDTA, benzoic acid, and benzoquinone as scavengers. A comparison of photocatalytic activity in UV and sun-like light showed that maximum degradation (92%) and (84.8%) were related to degradation of MO (20 ppm) and MV in 60min, respectively. The results indicate that SrNiO3/NiO/SrCO3 nanocomposites synthesized using the auto combustion method may serve as a promising photocatalyst for the degradation of organic pollutants in the environment within a short period of time.

Evaluation of the effect of oxygen addition on charge carrier transport properties in single-crystal diamond growth

The effects of oxygen addition during single-crystal diamond growth by microwave plasma CVD method on crystal surface morphology and charge carrier transport properties were evaluated. Diamond single-crystals were homoepitaxially grown on (001) surface of high-pressure and high-temperature (HPHT) synthesized type IIa single-crystal diamond substrates with a fixed methane concentration of 1 % and oxygen concentrations of 0–0.8 %. Inverted pyramid-shaped pits were generated as the oxygen concentration increased. The free exciton recombination emission intensity in the cathodoluminescence spectrum reached a maximum at oxygen concentration of 0.5 %. The samples with oxygen concentrations of 0.5 % and 0.8 % showed excellent charge collection efficiency and energy resolution. On the other hand, the mobility-lifetime (μτ) product was only (7.1 ± 1.7) × 10−5 cm2/V, which is approximately 1/4 of that of the sample with 0.2 % methane and no oxygen addition.

Double-edge scan wavefront metrology and its application in crystal diffraction wavefront measurements.

Achieving diffraction-limited performance in fourth-generation synchrotron radiation sources demands monochromator crystals that can preserve the wavefront across an unprecedented extensive range. There is an urgent need for techniques of absolute crystal diffraction wavefront measurement. At the Beijing Synchrotron Radiation Facility (BSRF), a novel edge scan wavefront metrology technique has been developed. This technique employs a double-edge tracking method, making diffraction-limited level absolute crystal diffraction wavefront measurement a reality. The results demonstrate an equivalent diffraction surface slope error below 70 nrad (corresponding to a wavefront phase error of 4.57% λ) r.m.s. within a nearly 6 mm range for a flat crystal in the crystal surface coordinate. The double-edge structure contributes to exceptional measurement precision for slope error reproducibility, achieving levels below 15 nrad (phase error reproducibility < λ/100) even at a first-generation synchrotron radiation source. Currently, the measurement termed double-edge scan (DES) has already been regarded as a critical feedback mechanism in the fabrication of next-generation crystals.

Preparation of Al2O3 thin films by RS-ALD and edge passivation application for TOPCon half solar cells

A rotary spatial atomic layer deposition (RS-ALD) method is proposed for the preparation of high-quality Al2O3 thin films and its application to the edge passivation of tunnel-oxide passivated contact (TOPCon) half solar cells. The high- quality Al2O3 thin films were prepared on silicon wafers by optimizing the process conditions with a process pressure of 4 Torr and a trimethylaluminum (TMA, (CH3)3Al) flow rate of 300 sccm. The Al2O3 thin films were annealed to analyse the transformation of the film crystal structure, surface morphology, and passivation properties. Compared to the half solar cells without edge passivation, the efficiency of the cell with only deposited Al2O3 increased by 0.098 %, and the module power increased by 3.08 W. The efficiency of the cell with deposited Al2O3 + annealing increased by a further 0.021–0.119 %, and the module power increased by a further 0.68–3.76 W.

Mo-Doped LaFeO3 Gas Sensors with Enhanced Sensing Performance for Triethylamine Gas.

Triethylamine is a common volatile organic compound (VOC) that plays an important role in areas such as organic solvents, chemical industries, dyestuffs, and leather treatments. However, exposure to triethylamine atmosphere can pose a serious threat to human health. In this study, gas-sensing semiconductor materials of LaFeO3 nano materials with different Mo-doping ratios were synthesized by the sol-gel method. The crystal structures, micro morphologies, and surface states of the prepared samples were characterized by XRD, SEM, and XPS, respectively. The gas-sensing tests showed that the Mo doping enhanced the gas-sensing performance of LaFeO3. Especially, the 4% Mo-doped LaFeO3 exhibited the highest response towards triethylamine (TEA) gas, a value approximately 11 times greater than that of pure LaFeO3. Meantime, the 4% Mo-doped LaFeO3 sensor showed a remarkably robust linear correlation between the response and the concentration (R2 = 0.99736). In addition, the selectivity, stability, response/recovery time, and moisture-proof properties were evaluated. Finally, the gas-sensing mechanism is discussed. This study provides an idea for exploring a new type of efficient and low-cost metal-doped LaFeO3 sensor to monitor the concentration of triethylamine gas for the purpose of safeguarding human health and safety.

Optimization of Pulsed Laser Energy Density for the Preparation of MoS2 Film and Its Device by Pulsed Laser Deposition.

This article aims to explore the most optimal pulsed laser energy density when using the pulsed laser deposition (PLD) process to prepare the MoS2 films. We gradually increased the pulsed laser energy density from 70 mJ·cm-2 to 110 mJ·cm-2 and finally determined that 100 mJ·cm-2 was the best-pulsed laser energy density for MoS2 films by PLD. The surface morphology and crystallization of the MoS2 films prepared under this condition are the best. The films consist of a high-crystallized 2H-MoS2 phase with strong (002) preferential orientation, and their direct optical band gap (Eg) is 1.614 eV. At the same time, the Si/MoS2 heterojunction prepared under the optimal pulsed laser energy density shows an opening voltage of 0.61 V and a rectification ratio of 457.0.

Straight sections of step edges on a NiAl(110) curved single crystal surface used to calculate an approximation of step formation energy

Curved crystals may feature a smooth transition between different vicinal surfaces. Using one curved single crystal to study different vicinal surfaces requires less experimental time than using several single flat crystals. Here, we study step distributions on the (110) plane of a curved NiAl single-crystal surface, which consists of alternating Ni and Al atom rows. We use scanning tunneling microscopy under UHV conditions at room temperature and our home-built Python-based analysis script to obtain statistical information on kink and straight sections along step-edge distributions from STM images. We perform this analysis mainly to study this single crystal’s kink distributions and step termination We propose a new method to estimate the step formation energy based on step edge analysis and statistical mechanics. With this method, we find an approximation of the step formation energy for NiAl(110).

Magnetic Nitrogen-Doped Fe&lt;sub&gt;3&lt;/sub&gt;C@ c Catalysts for Efficient Activation of Peroxymonosulfate for Degradation of Organic Pollutants

Recoverable and stable nanocatalysts are essential for peroxymonosulfate - based advanced oxidation processes (AOPs) in wastewater purification treatment. In this paper, Fe3C nanorods @ nitrogen-doped carbon composites (N-Fe3C@C) with core-shell architecture were fabricated by the co-precipitation and calcination methods, and characterized and analyzed in terms of their crystal structure, microscopic morphology, and surface chemical elements. In addition, N-Fe3C@C-4 degraded 85.36% of tetracycline in 10 min under PMS, which was much higher than the catalytic ability of Fe3O4 (42.03% in 10 min). Both the active radical trapping and EPR experiments verified that 1O2 played a key role for degradation of organic dyes in PMS system. The investigation on the degradation mechanism revealed that the presence of the carbon layer facilitated to adsorb TC, accelerate free radical generation and promote the redox cycle of Fe2+/Fe3+ in the nanocatalyst. This study offers novel ideas for multifunctional catalysts for advanced wastewater purification treatment.

Crystal facet‐controlled CeO2 as surface decoration on nanosheet‐type SnO2 for sensing ultralow concentration gases

AbstractImproving the gas‐sensing properties of sensors is important for the detection of ultralow‐concentration gases. As sensor signals are generated from the reactions on the surface of the sensor material, improving the surface structure of the sensor material can enhance the sensing properties. In this study, nanosheet‐type tin oxide with a metastable (101) crystal facet surface was used as the gas sensor material. To enhance the sensing properties, crystal facet‐controlled cerium oxide with superior oxygen storage capacity at moderate temperatures was decorated on the surface of the nanosheet‐type tin oxide material. An investigation of the sensor properties revealed that the decorated sensor exhibited improved gas selectivity and enhanced sensitivity to all tested gases. Prior to decoration, selectivity was observed for acetone and ethanol, whereas the decorated sensor exhibited high selectivity for acetaldehyde. The limits of detection of the decorated sensors were 245, 459, and 934 ppt for acetone, ethanol, and acetaldehyde, respectively. Thus, the proposed material can effectively enhance the sensing of extremely low‐concentration gases.

Non-monotonic dependence of high-temperature stability of stone wool fibres on pre-oxidation time and temperature

Stone wool is a sustainable, fire-safe insulation material, and its fire-safety depends on its high-temperature stability (HTS). It is known that the HTS of stone wool fibres can be enhanced by pre-oxidation (i.e., heat treatment in air) at temperatures below or at its glass transition temperature (Tg). However, so far, a quantitative trend of HTS with varying pre-oxidation temperature (Tpre-ox) and time (tpre-ox) remains unknown. In this study, we quantified the change of HTS of stone wool fibres with a Tg of 677 °C as functions of both Tpre-ox and tpre-ox through a hot-stage microscope. The derived results revealed striking non-monotonic trends in the HTS of stone wool fibres. The HTS first increased with Tpre-ox from 500 to 630 °C for tpre-ox of 15 minutes, but declined beyond 630 °C. The HTS was significantly improved upon pre-oxidation for merely 2 minutes, at 677 °C, then dropped with extending tpre-ox to 16 hours, and finally increased again with tpre-ox up to 16 days. The origin of the non-monotonic trend was explored by characterizing the crystallization behaviour, thermal expansion, surface composition, and surface morphology in stone wool fibres after pre-oxidation.

Interplay between charge and spin noise in the near-surface theory of decoherence and relaxation of C3v symmetry qutrit spin-1 centers

Decoherence and relaxation of solid-state defect qutrits near a crystal surface, where they are commonly used as quantum sensors, originate from charge and magnetic field noise. A complete theory requires a formalism for decoherence and relaxation that includes all Hamiltonian terms allowed by the defect's point-group symmetry. This formalism, presented here for the C3v symmetry of a spin-1 defect in a diamond, silicon carbide, or similar host, relies on a Lindblad dynamical equation and clarifies the relative contributions of charge and spin noise to relaxation and decoherence, along with their dependence on the defect spin's depth and resonant frequencies. The calculations agree with the experimental measurements of Sangtawesin [], and corroborate the importance of charge noise. Published by the American Physical Society 2024

Strong Magnetic p-n Heterojunction Fe3O4-FeWO4 for Photo-Fenton Degradation of Tetracycline Hydrochloride

With the abuse of antibiotics, its pollution poses an increasing threat to the environment and human health. Effective degradation of organic pollutants in water bodies is urgent. Compared to traditional treatment methods, advanced oxidation processes that have developed rapidly in recent years are more environmentally friendly, efficient and applicable to a wider range of organic compounds. FeWO4 was used in this study as the iron-based semiconductor material to modify and optimize the material design. Fe3O4/FeWO4 composites were prepared by a two-step hydrothermal method. The crystal structure, surface morphology, electrochemical properties and separability of the composite semiconductor were analyzed by XRD, XPS, UV-vis, SEM, EDS and Mott-Schottky. The results showed that, when the initial contaminant concentration was 30 mg/L, the initial solution pH was 4, the dosage of the catalyst was 25 mg and the dosage of hydrogen peroxide was 30 μL, the degradation efficiency of tetracycline hydrochloride (TCH) could reach 91% within 60 min, which was significantly improved compared to the performance of the single semiconductors Fe3O4 and FeWO4. In addition, the catalyst prepared in this experiment can be easily recovered by magnetic separation technology in practical application, which will not affect the turbidity of water while reducing the cost of catalyst separation and recovery.

Step height measurement of monoatomic silicon crystal lattice steps with a commercial atomic force microscope

Abstract Precise control of advanced materials relies on accurate dimensional metrology at the sub-nanometre scale. At this scale, the accuracy of scanning probe microscopy (SPM) has been limited by the lack of traceable transfer standard artefacts with calibration structures of suitable dimensions. With the adoption in 2019 of the silicon crystal lattice spacing as a secondary realization of the metre in the International System of Units (SI), SPM users have direct access to a realization of the SI metre at the sub-nanometre level by means of the step height of self-assembled monatomic lattice steps that can form on the surface of silicon crystals. A key challenge of successfully adopting this pathway is establishing the need for established protocols to minimize measurement errors and artifacts in routine laboratory use.&amp;#xD;In this study, step height measurements of monoatomic lattice steps in an ordinal/staircase structure on a Si(111) crystal surface have been derived from images acquired with a commercially available, research-level atomic force microscope (AFM). Measurement results derived from AFM images using three different SPM image processing and analysis software packages are compared. Significant sources of measurement uncertainty are identified; principally the contribution from the dependence on scan direction. The calibration of the&amp;#xD;AFM derived from this measurment was used to traceably measure the sub-nanometre lattice steps on a silicon carbide crystal surface to demonstrate the viability of this calibration pathway.&amp;#xD;