Phase Identification Research Articles

Disappearance of Odd-Even Effects at the Substrate Interface of n-Alkanes.

The physical and chemical properties of organic compounds having alkyl chains are frequently influenced by the parity of the chain length, which is known as the odd-even effect. Understanding the molecular origin of this phenomenon is particularly important for designing materials used in organic thin-film devices. In this work, we focus on thin films of n-alkanes as the simplest model to study the odd-even effect at the substrate interface and analyze the aggregation structure using p-polarized multiple-angle incidence resolution spectrometry in combination with grazing incidence X-ray diffraction. The spectroscopic analysis shows a pronounced odd-even alternation of the molecular tilt angles in the multilayer films. In addition, high-resolution Brewster-angle transmission spectroscopy reveals that the conformation of the methyl group highly depends on whether the carbon number is even or odd. In contrast to the multilayer films, the odd-even effects do not appear in the monolayer films. We demonstrate that, in other words, the interlayer interactions of the molecules are responsible for the odd-even effects. This study also highlights the first identification of the monolayer phase of n-alkanes by using grazing incidence X-ray diffraction in combination with high-resolution infrared spectroscopy. These results not only reveal the molecular origin for the odd-even effect of n-alkanes but also provide analytical techniques for discussing the monolayer structure of various alkylated compounds on a functional group basis.

Atom probe tomography of deuterium-charged optimised ZIRLO

AbstractThis study investigates the morphology and composition of hydrides in Optimized ZIRLO following electrochemical deuterium charging. Both ZrO and ZrDx phases were formed upon charging. The interfaces between these phases are investigated by using atom probe tomography aided by cryogenic sample transfer. The Ga and Sn have formed a “net”-like structure at the original atom probe specimen surface, which is assumed to be associated with the boundaries between individual hydride laths/needles, as it thought to have formed as these species were excluded from the hydrides. Calculation of the D/Zr ratio throughout the sample allows for identification of the ZrDx phases, revealing the specimen consists of a complex arrangement of different hydride phases. In some areas there is small excess of D in the hydride, i.e. ZrD2+y. This result is interpreted as deuterium which was “frozen” as it was passing through the hydride during electrochemical charging. The observed microstructural changes and interfacial phenomena contribute valuable insights that may prove useful for improving the performance and safety of Zr alloys.

Synthesis, characterisations and applications of boron nitride based hybrid metal matrix composites

ABSTRACT This study focuses on how reinforcements impact the base material (specifically AA 6082) regarding its microstructure, mechanical behaviour& corrosion behaviour. Boron nitride (BN) & molybdenum disulphide (MoS2) employed as reinforcing materials ranged from 1% to 3% of BN & 1% to Constant MoS2. The composite materials were produced utilising the stir casting technique. X-ray diffraction (XRD), scanning electron microscope (SEM) with Energy Dispersive spectroscopy (EDAX) & an optical microscope (OM) were used to examine microstructural phase identification analysis. Tensile, compressive, impact, density& porosity fracture mechanisms were investigated by mechanical testing. BN & MoS2 reinforced particles’ presence in the samples is confirmed by XRD and microstructural pictures showing consistent matrix reinforcement distribution. According to the findings, incorporating BN & MoS2 reinforcements improved the mechanical & corrosion properties but slightly reduced the impact strength. The fractured samples revealed micro cuts, micro ploughing, cracks, trans-granular cleavage facets, dimples in the tensile & impact tests. Reduction in Corrosion rate was achieved gradually by adding reinforcement particles for the composites.AA6082, 3 wt: % BN, & 1 wt.% MoS2 composites have shown a decrease in corrosion current density by 1.901 mA/cm2 & an increase in charge transfer resistance by 99.934 Ω cm-2, attributed to passivation.

Gamma-Ray Burst Interaction with the Circumburst Medium: The CBM Phase Following the Prompt Phase in GRBs

Progenitor stars of long gamma-ray bursts (GRBs) could be surrounded by a significant and complex nebula structure lying at a parsec-scale distance. After the initial release of energy from the GRB jet, the jet will interact with this nebula environment. We show here that for a large, plausible parameter space region, the interaction between the jet blast wave and the wind termination (reverse) shock is expected to be weak, and may be associated with a precursor emission. As the jet blast wave encounters the contact discontinuity separating the shocked wind and the shocked interstellar medium, we find that a bright flash of synchrotron emission from the newly formed reverse shock is produced. This flash is expected to be observed at around ∼100 s after the initial explosion and precursor. Such a delayed emission thus constitutes a circumburst medium (CBM) phase in a GRB, having a physically distinct origin from the preceding prompt phase and the succeeding afterglow phase. The CBM phase emission may thus provide a natural explanation for bursts observed to have a precursor followed by an intense, synchrotron-dominated main episode that is found in a substantial minority, ∼10% of GRBs. A correct identification of the emission phase is thus required to infer the properties of the flow and of the immediate environment around GRB progenitors.

The Role of Ce3+ Co-doping in the Luminescent Enhancement of Bi3+ Emission and Bi3+→Bi2+ Conversion in LiLaP4O12 Host

This work investigates the luminescent versatility of the LiLa(1-x-y)BixCeyP4O12 system as a scintillator material capable of displaying emission in a range from the blue to the red region depending on the Ce3+ concentration. The LiLaP4O12 host has been proven to be useful as a scintillator material when doped with some rare earths and with bismuth ions. However, the process of bismuth valence change induced by X-rays, when inserted in the LiLaP4O12 matrix, is not known to date, as well as whether this can be controlled and used to enhance the luminescence emission. To determine the mechanism of interaction between the Ce3+ and Bi3+ ions in the LiLaP4O12 host, doped and co-doped samples were synthesized and investigated. Identification of crystalline phase was carried out with X-Ray Powder Diffraction. The luminescent properties were studied via photoluminescence emission and excitation using synchrotron radiation. Scintillator features were studied through radioluminescence emission spectrum. The results indicate that Ce3+ transfers either energy or electrons to Bi3+ when excited with UV (5.2 eV) or X-rays, respectively. In the first case, the overall white luminescence is improved, while in the latter, enhanced red luminescence from Bi2+ was observed, indicating the valence change of Bi ions, assisted by Ce co-dopant. A luminescent mechanism, based on the vacuum-referred binding energy model applied to the experimental data, was proposed to explain the Bi2+ emission, deepening the understanding of the Bi emission mechanism and opening the possibility of tailoring the Bi2+/Bi3+ proportion varying the Ce-co-doping concentration.

Effects of the surface properties and particle size of hydrated lime on desulfurization

In the gas treatment center in smelters, hydrogen fluoride (HF) is separated from the outlet gases of electrolysis cells, which are used to produce aluminum from alumina. However, SO2 largely remains in the effluent gas. Another method has to be developed to separate this gas which is harmful to the environment. In this study, semi-dry desulfurization of a SO2 containing gas was performed at low SO2 concentrations using hydrated lime [Ca(OH)2] as a catalytic desulfurizer under specific humidity conditions. The low reaction temperature of 100 °C and minimal use of the Ca-based desulfurizer under 17 % relative humidity achieved more than 95 % removal of SO2. The morphological changes and presence of sulfur in different lime samples were analyzed by scanning electron microscopy and energy-dispersive X-ray spectroscopy. Brunauer–Emmett–Teller (BET) analysis showed changes in the surface properties of hydrated lime after desulfurization. X-ray photoelectron spectroscopy (XPS) analysis provided the phase and composition identification of the sulfur species on hydrated lime and the CaSO3/CaSO4 product ratio. Based on the experimental results, the optimum catalyst surface area with a specific particle size is critical to the effective conversion of Ca(OH)2 into CaSO3 and CaSO4. The practicality of a Ca-based desulfurizer and its ability to convert into the required product may be the key to reducing the overall cost of desulfurization in aluminum industry.

A room temperature chemical process for homogeneous mixing of precursor phases for low temperature tetracalcium phoshate preparation

The aim of this study was to prepare phase pure tetracalcium phosphate (TTCP) from the precursor phase mixtures homogeneous at the nano/microscale level at lower heat treatment temperatures in much shorter dwell times.Two different precursor powder mixtures were prepared by reacting CaCO3 with H3PO4 in ethanol or water. The resultant precursor powder mixtures were heat treated at temperatures in the 1200–1350 °C range for 2 and 5 h. Phase structures of the powders were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopy analysis. Scanning electron microscopy (SEM) was used for the investigation of powder particle sizes and morphology. Powders synthesized by the heat treatment of both of the starting powder mixtures prepared in ethanol or water with 2 and 5 h of dwell times at 1350 °C were determined to be phase pure TTCP. SEM analysis along with the phase identification showed that the precursor powder prepared in ethanol had micron sized plates formed by aggregation of sub-micron sized thin CaHPO4 plates covering CaCO3 particles. The precursor powder prepared in water contained large aggregates of sub-micron sized CaCO3 particles whose surface was covered by precipitated nano-sized hydroxyapatite. TTCP powders were composed of large irregularly shaped particles formed by sintering of smaller equiaxed grains. Average grain and particles sizes of the TTCP powders synthesized from the precursor powder prepared in ethanol were 3.2–3.9 and 8.1–8.4 μm, respectively. Average grain and particle sizes of the TTCP powders synthesized from the precursor powder prepared in water however were measured to be 3.3–5.1 and 11.2–11.6 μm, respectively.The TTCP preparation method presented in this study provides homogeneous and well-mixed precursor powders prepared from cheap and commonly available precursors without milling and decreases the heat treatment time to 2 h at 1350 °C.

In-situ grown hexagonal rod-like ZIF-L(Zn/Co) variant on reduced graphene oxide (rGO) for the enhanced electrochemical sensing of acetaminophen

Graphene – one of the most regarded materials in the world of Flatland has a substantial role in sensing applications due to its exceptional properties. Combining graphene with MOF can effectively mitigate the limitations of MOF while synergistically enhancing their unique properties. In this research work, we present a new hybrid composite of Zeolite Imidazolate Framework-L made composite with reduced graphene oxide, ZIF-L(Zn/Co)/rGO (ZLG) and applied its electrocatalytic performance in the sensitive detection of acetaminophen (AP). The mixture was prepared via a simple in-situ solvothermal method whose physico-chemical nature was investigated in detail. The ZIF-L phase identification, morphological change of ZIF, confirmation of rGO incorporation, and chemical composition analysis were established using the XRD, SEM, Raman and XPS respectively. Additionally, the kinetics of electron transfer was studied by EIS. Thereafter, proper optimization of various sensor parameters such as pH, scan rate and analytical performance were executed. Preliminary sensing studies carried out by cyclic voltammetry revealed an enhancement in peak current from 0.48µA to 1.05µA upon incorporation of rGO into the ZIF-L(Zn/Co) hybrid. Compared with reported studies along a similar vein, from the differential voltammetric analysis the ZLG-modified GCE displays a high selectivity towards AP with a broad linear range of 1 µM – 2060 µM exhibiting a sensitivity and LOD of 8.145 µA/mM and 162 nM respectively. The real-time validation of the sensor in paracetamol tablets and biological samples of human blood and urine exhibited recovery values in the range of ∼ 94 % − 102 %. Hence, this suggests a reliable practical applicability of the sensor owing to the high catalytic, large surface area and increased conductivity of the nanocomposite.

Enhancing the Mechanical Properties of Co-Cr Dental Alloys Fabricated by Laser Powder Bed Fusion: Evaluation of Quenching and Annealing as Heat Treatment Methods.

Residual stresses and anisotropic structures characterize laser powder bed fusion (L-PBF) products due to rapid thermal changes during fabrication, potentially leading to microcracking and lower strength. Post-heat treatments are crucial for enhancing mechanical properties. Numerous dental technology laboratories worldwide are adopting the new technologies but must invest considerable time and resources to refine them for specific requirements. Our research can assist researchers in identifying thermal processes that enhance the mechanical properties of dental Co-Cr alloys. In this study, high cooling rates (quenching) and annealing after quenching were evaluated for L-PBF Co-Cr dental alloys. Cast samples (standard manufacturing method) were tested as a second reference material. Tensile strength, Vickers hardness, microstructure characterization, and phase identification were performed. Significant differences were found among the L-PBF groups and the cast samples. The lowest tensile strength (707 MPa) and hardness (345 HV) were observed for cast Starbond COS. The highest mechanical properties (1389 MPa, 535 HV) were observed for the samples subjected to the water quenching and reheating methods. XRD analysis revealed that the face-centered cubic (FCC) and hexagonal close-packed (HCP) phases are influenced by the composition and heat treatment. Annealing after quenching improved the microstructure homogeneity and increased the HCP content. L-PBF techniques yielded superior mechanical properties compared to traditional casting methods, offering efficiency and precision. Future research should focus on fatigue properties.

Effect of the Intaglio Surface Treatment and Thickness of Different Types of Yttria-Stabilized Tetragonal Zirconia Polycrystalline Materials on the Flexural Strength: In-Vitro Study.

Surface treatment of the intaglio surface of zirconia is important for bonding. However, it could affect the strength of the materials. The purpose of this study is to compare the effect of laser, etching, and air abrasion surface treatment methods to a control group on the flexural strength of three zirconia materials with two different thicknesses. (1) Methods: A total of 120 disks were divided into three groups according to the type of zirconia and the ceramic thickness. Then, according to the surface treatment method, the groups were divided into four subdivisions. The change in the microstructure of the ceramic material was investigated through Scanning Electron Microscope (EVO LS10, Carl Zeiss SMT Ltd. Oberkochen, Germany). Phase identification was performed using an X-ray diffraction device (XRD; Ultimate IV X-ray Diffractometer, Rigaku Inc., Tokyo, Japan). The flexural strength was assessed with a biaxial flexural strength test in a universal testing machine. Data were analyzed using SPSS Software (SPSS version 26.0.Armonk, NY: IBM Corp). A three-way ANOVA and a post hoc Dunnett T3 test were employed to evaluate the effect of the yttria concentration, thickness, and surface treatment on the flexural strength of zirconia (α = 0.05). (2) Results: At 0.8 mm thickness, air abrasion significantly increased the flexural strength of 3Y-TZP (1130.6 ± 171.3 MPa) and 4Y-TZP (872 ± 108.6 MPa). However, air abrasion significantly decreased the flexural strength of 5Y-TZP materials (373 ± 46.8 MPa). Laser irradiation significantly decreased the flexural strength of 5Y-TZP (347 ± 50.3 MPa), while etching significantly decreased the flexural strength of both 3Y-TZP (530 ± 48.8) and 4Y-TZP (457.1 ± 57.3). When the thickness increased to 1 mm, air abrasion continued to significantly decrease the flexural strength of 5Y-TZP materials. (3) Conclusions: There was a negative effect of surface treatment on the flexural strength at 0.8 mm thickness rather than at 1 mm thickness. Air abrasion enhances the flexural strength of 3Y-TZP and 4Y-TZP materials but significantly reduces the flexural strength of 5Y-TZP materials. Zircos-E etching and Er:YAG surface treatment methods did not significantly reduce the flexural strength of 5Y-TZP materials at 1 mm thickness and can be recommended as an alternative surface treatment for 5Y-TZP materials.

Plants-extracts mediated CuS nanoparticles: An effective antibacterial agent

Antibacterial activity of plant-mediated synthesized CuS nanoparticles against gram-positive Bacillus subtilis and gram negative Pseudomonas putida is studied in this presented work. A facile hydrothermal approach was followed to synthesize spherical shaped CuS nanoparticles using flowers extract of Tagetes patula (S1), leaves extract of Azadirachta indica (S2), and bark extract of Terminalia arjuna (S3). Crystal phase identification, average crystallites size, surface morphology, absorbance spectra and energy band gap analyses of samples were further determined using XRD, SEM, and UV-DRS spectroscopy respectively. Furthermore, under irradiation of visible light, antibacterial activity of marigold flowers mediated (S1), neem leaves mediated (S2), and arjuna bark mediated (S3) CuS samples were studied. XRD data confirmed the marigold mediated CuS sample has relatively smaller crystallites size of 10.67 nm. The estimated band gap energies for respective S1, S2, and S3 samples are 174 eV, 175 eV, and 177 eV. The antibacterial analysis of S1 sample displays its excellent antibacterial activity with the formation of relatively large inhibition zones of 29 mm and 30 mm diameters, against Bacillus subtilis and Pseudomonas putida respectively. The demonstrated antibacterial activity of biocompatible CuS nanoparticles suggests their potential use in biomedical applications.

The Stability of Manganese Oxides Under Laser Irradiation During Raman Analyses: I. Compact Versus Channel Structures

ABSTRACTManganese oxides/oxyhydroxides (MnOx) are based on Mnn+O6 and Mnn+O4 polyhedra arranged such as to form compact, channel or layered structures. In geology, they are precious archives of past redox conditions for palaeoclimatic reconstructions; in material sciences, they are used for a variety of applications, from pigments to environmental remediation and energy storage. Thus, the fast, remote and non‐destructive identification of MnOx is critical in several disciplines. Micro‐Raman spectroscopy is often used for this purpose, although a systematic characterization of their stability under the laser beam is still lacking. In this work, we present our results on the behaviour of the most common MnOx having compact and channel structures when a 532‐nm laser with intensity between ~23 μW/μm2 and ~36.8 mW/μm2 is used. The compact structures of manganosite (NaCl‐like) and hausmannite (spinel‐like) are stable up to ~36.8 mW/μm2. The stability of oxides with channel structures depends on channel size, charge of channel cations and valence state of Mn. Hausmannite is the final degradation product of all MnOx with channel structures, irrespective of the starting phase. Pyrolusite, manganite, hollandite and romanéchite are relatively stable under the laser beam, and the transition to the spinel structure occurs above 2.5 mW/μm2 while the degradation of cryptomelane and todorokite starts ~226 μW/μm2. The analysis of MnOx thus needs very accurate experimental conditions to avoid misleading and incorrect phase identifications. Based on our data, we propose an analytical protocol for a proper characterization of these minerals via Raman spectroscopy.

A Recurrent Deep Network for Gait Phase Identification from EMG Signals During Exoskeleton-Assisted Walking

Lower limb exoskeletons represent a relevant tool for rehabilitating gait in patients with lower limb movement disorders. Partial assistance exoskeletons adaptively provide the joint torque needed, on top of that produced by the patient, for a correct and stable gait, helping the patient to recover an autonomous gait. Thus, the device needs to identify the different phases of the gait cycle to produce precisely timed commands that drive its joint motors appropriately. In this study, EMG signals have been used for gait phase detection considering that EMG activations lead limb kinematics by at least 120 ms. We propose a deep learning model based on bidirectional LSTM to identify stance and swing gait phases from EMG data. We built a dataset of EMG signals recorded at 1500 Hz from four muscles from the dominant leg in a population of 26 healthy subjects walking overground (WO) and walking on a treadmill (WT) using a lower limb exoskeleton. The data were labeled with the corresponding stance or swing gait phase based on limb kinematics provided by inertial motion sensors. The model was studied in three different scenarios, and we explored its generalization abilities and evaluated its applicability to the online processing of EMG data. The training was always conducted on 500-sample sequences from WO recordings of 23 subjects. Testing always involved WO and WT sequences from the remaining three subjects. First, the model was trained and tested on 500 Hz EMG data, obtaining an overall accuracy on the WO and WT test datasets of 92.43% and 91.16%, respectively. The simulation of online operation required 127 ms to preprocess and classify one sequence. Second, the trained model was evaluated against a test set built on 1500 Hz EMG data. The accuracies were lower, yet the processing times were 11 ms faster. Third, we partially retrained the model on a subset of the 1500 Hz training dataset, achieving 87.17% and 89.64% accuracy on the 1500 Hz WO and WT test sets, respectively. Overall, the proposed deep learning model appears to be a valuable candidate for entering the control pipeline of a lower limb rehabilitation exoskeleton in terms of both the achieved accuracy and processing times.

Mutability of Nucleation Particles in Reactive Salt Hydrate Phase Change Materials.

Nucleation particles, solid phases dispersed throughout a medium to decrease the energy barrier for solidification or other reversible phase transitions, are generally selected on the basis of structural or interfacial energy considerations between the host phase and the solid phase that is crystallizing. However, the existence of chemical reactions between the nucleation particles and the host phase can obscure these underlying relationships, thereby complicating the process of selection of active nucleation particle phases. Here, we reveal the origin of nucleation activity of barium-based nucleation particles in the salt hydrate calcium chloride hexahydrate (CCH), a candidate for near room temperature thermal energy storage. We demonstrate that these compounds undergo a series of cation exchange and secondary precipitation reactions, resulting in an assemblage of solid precipitates with some degree of limited solid solution, which collectively dramatically reduce undercooling in CCH, but which obscure the identification of a single crystalline phase primarily responsible for the nucleation of crystalline CCH from the liquid. Importantly, this result illustrates a pathway to harness in situ chemical reactions to generate stable active nucleation particles in reactive phase change materials, which may not be readily synthesized by alternative methods, or which may not be active or remain stable when added in isolation.

An experimental insight into a promising novel organic nonlinear optical single crystal Guanidinium 2,4-dichlorobenzoate (G24DCB)

Guanidinium 2,4-dichlorobenzoate (G24DCB), a new chloro substituted benzoic acid based organic single crystal is synthesized, grown and added to the guanidinium family of single crystals. Such G24DCB crystal was obtained by a versatile slow evaporation solution growth technique. The analysis of single crystal X-ray diffraction examined the phase identification and determination of lattice parameters for the synthesized compound. The G24DCB crystal has monoclinic system and adopts space group P21/c. Powder X-ray diffraction explores the studied crystal's crystalline characteristics. The study of Fourier Transform-Infrared (FTIR) spectroscopy examined the necessary vibrational assignments for the formation of the structure of G24DCB. The UV–Visible-NIR analysis entails the determination of the cut-off wavelength of the G24DCB compound from its transmittance spectrum and the computation of other related optical parameter values. Photoluminescence analysis was employed to investigate the studied crystal's emission characteristics. The thermal stability of the G24DCB crystal was examined through thermogravimetric analysis and differential thermal analysis. The laser-induced damage threshold of the crystal was determined using a Nd:YAG laser. The various mechanical attributes exhibited by the synthesized compound were elucidated by microhardness studies and it corresponds to a soft material type. The various third order nonlinear optical characteristics were probed by Z scan study. The positive results of the aforementioned studies suggest the emerging significance possessed by the novel title crystal Guanidinium 2,4-dichlorobenzoate in nonlinear optical applications.

Deep learning assisted characterization of bubble behavior in a gas-solid fluidized bed with binary particle mixtures

Gas-solid fluidized beds are widely applied as chemical reactors, and the fluidization quality in the bed is closely related to bubble behavior. Digital image processing is a commonly used non-invasive method for bubble behavior analysis, but it is usually constrained by experimental conditions such as lighting, making identification of bubble and emulsion phases still challenging. Herein, deep learning is applied in this study to optimize traditional digital image processing techniques. By evaluating different deep learning models (FCN, DeepLab V3, U-Net), rapid and accurate identification and segmentation of bubble images can be achieved, and the U-Net model performs best, achieving an identification accuracy of 99.05 %. Further application of U-Net to analyze bubble behavior demonstrates that deep learning methods enable efficient and accurate identification of bubbles and real-time analysis of bubble behavior, highlighting the significant potential application of deep learning in the field of complex hydrodynamics in fluidized beds.

Microstructural evolution of diamond thin film grown on a silicon substrate via a surface-wave plasma system: Identification of intermediated phase

Diamond thin films are promising for diverse applications because of their exceptional properties. Understanding the interface between diamond films and substrates is crucial for optimizing the film quality and functionality. In this study, a diamond thin film was grown on a Si(100) substrate using a microwave-based surface-wave plasma system and subjected to transmission electron microscopy (TEM) and electron energy-loss spectroscopy (EELS). The formation of a SiC interlayer was identified at the interface between the diamond thin film and Si substrate through cross-sectional TEM and EELS. Analysis of the atomic structure and crystalline properties indicated that the interlayer was β-SiC and that the orientation relationships [110]β-SiC//[110]Si and (111)β-SiC//(111)Si existed at the β-SiC/Si interface. The β-SiC interlayer exhibited the {111} extra half-planes, because they were more easily formed by the {111} planes than the {110} extra half-planes generated on {001} planes through 60° misfit dislocations. Many stacking faults and microtwins were observed in the diamond grains; such planar defects were likely attributed to strain behavior and complex contrasts at the nanoscale.

The effect of roughness and top layer in solid particle impingement erosion of multilayer nanostructured nitride PVD coatings

The effect of the surface roughness of the coating and the composition of the upper layer on the solid particle erosion of multilayer nanostructured coatings applied via cathodic arc evaporation (CAEPVD) method was investigated. CrN/TiN nanostructured multilayer coating (TiN as the upper layer) and TiN/CrN nanostructured multilayer coating (CrN as the upper layer) were applied on 410 stainless steel through the CAEPVD method with the following architecture. 1) a bottom layer of Cr and CrN deposited on the substrate, 2) nanolayers of TiN and CrN deposited on the bottom layer alternately and 3) an upper layer of CrN or TiN deposited on the nanolayers. After applying the coating, half of the samples were polished to obtain smooth surfaces, while the other half remained unpolished, resulting in rough surfaces. Surface morphology, phases identification, adhesion, mechanical, and erosion behavior of the coatings were characterized using SEM, XRD, Rockwell adhesion measurements, nanoindentation test, and solid particle impingement, respectively. The nano-scale indentation results demonstrated that the hardness, Young's modulus, H/E, and H3/E2 of the CrN/TiN coating were 5.57, 1.42, 3.86, and 85.39 times larger than those of the substrate. For the TiN/CrN coating, the values were 4.04, 1.13, 3.53 and 51.68 times greater than those of the substrate. The results of the erosion test showed that the erosion mass loss for the CrN/TiN and TiN/CrN coatings decreased up to 73% and 67%, respectively. Additionally, surface smoothing improved erosion resistance by 40% for both coatings. This shows that the smoothed CrN/TiN nanostructured multilayer coating is an excellent candidate for increasing the erosion resistance due to the higher ratios of H/E and H3/E2 and smoother surface.

Identification of the high-pressure phases of α-SnWO4 combining x-ray diffraction and crystal structure prediction

We have characterized the high-pressure behavior of -SnWO4. The compound has been studied up to 30 GPa using a diamond-anvil cell and synchrotron powder X-ray diffraction. We report evidence of two structural phase transitions in the pressure range covered in our study, and we propose a crystal structure for the two high-pressure phases. The first one, observed around 12.9 GPa, has been obtained combining indexation using DICVOL and density-functional theory calculations. The second high-pressure phase, observed around 17.5 GPa, has been determined by using the CALYPSO code, the prediction of which was supported by a Le Bail fit to the experimental X-ray diffraction patterns. The proposed structural sequence involves two successive collapses of the unit-cell volume and an increase in the coordination number of Sn and W atoms. The room-temperature equations of state, the principal axes of compression and their compressibility, the elastic constants, and the elastic moduli are reported for -SnWO4 and for the two high-pressure phases.

Superhydrophobic FeNi3/Al2O3 multifunctional hybrid Janus particles for the catalytic degradation of azo dye, oil/water separation and microplastics removal

Emerging pollutants are causing global health and environmental challenges, necessitating the advancement of methodologies for their efficient removal. In this study, we present the efficacy of superhydrophobic FeNi3/Al2O3 Janus particles in the removal of oils and microplastics from water, combined with the degradation of azo dyes, leveraging their surface properties. Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray Spectroscopy (EDS) revealed the morphology and elemental composition of these particles, which were further complemented by X-ray diffraction (XRD) for phase identification. After surface functionalization of the FeNi3/Al2O3 Janus particles with lauric acid, they exhibited superhydrophobicity (152 ± 1°) and superoleophilicity (0°). High-resolution X-ray photoelectron spectroscopy (HR-XPS) showed that the alumina face was modified with lauric acid, while the intermetallic face remained as FeNi3. Significantly, the alumina face demonstrated 99 % efficiency in separating oils and microplastics, while the FeNi3 face facilitated the complete degradation (100 %) of methyl red within three minutes, as shown by ultraviolet-visible spectrophotometry. These results highlight the multifunctional properties of superhydrophobic FeNi3/Al2O3 Janus particles in removing and degrading various pollutants.