Secondary Ion Mass Spectroscopy Research Articles

Thermal degradation comparison of delta-doped GaAs tunnel junctions using Si and Te n-type dopants

Tunnel junctions (TJs) are essential for high-performance multijunction solar cells to act as transparent low resistance paths for carriers to travel between adjacent cells. However, TJs typically exhibit highly degraded tunneling performance due to unwanted dopant out-diffusion during top cell growth. In this study, GaAs TJs with Si and Te delta-doping (δ-doping) were grown via solid source molecular beam epitaxy to investigate the tunneling performance and thermal stability. While Si δ-doped TJs exhibited typical tunneling characteristics with an Esaki peak current density of 173 A/cm2, Te δ-doped TJs revealed 1.5 A/cm2 at Vbias = 100 mV without negative resistance. It was found that the performance degradation after annealing at 600 °C for 90 min was significantly higher for TJs with Si δ-doping than for Te. Secondary ion mass spectroscopy measurements reveal that Te shows no clear signs of dopant diffusion while Si exhibited significant out-diffusion in the active TJ layer after thermal annealing. The superior thermal stability of Te compared to Si proves to be advantageous as an alternative n-type dopant for high temperature and long duration grown multi-junction solar cells.

Continuous Si doping in (010) and (001) β-Ga2O3 films by plasma-assisted molecular beam epitaxy

We report the continuous Si doping in β-Ga2O3 epitaxial films grown by plasma-assisted molecular beam epitaxy through the use of a valved effusion cell for the Si source. Secondary ion mass spectroscopy results exhibit that the Si doping profiles in β-Ga2O3 are flat and have sharp turn-on/off depth profiles. The Si doping concentration was able to be controlled by either varying the cell temperatures or changing the aperture of the valve of the Si effusion cell. High crystal quality and smooth surface morphologies were confirmed on Si-doped β-Ga2O3 epitaxial films grown on (010) and (001) substrates. The electronic properties of Si-doped (001) β-Ga2O3 epitaxial film showed an electron mobility of 67 cm2/Vs at the Hall concentration of 3 × 1018 cm−3.

Lipid Deposition Profiles Influence Foreign Body Responses.

Fibrosis remains a significant cause of failure in implanted biomedical devices and early absorption of proteins on implant surfaces has been shown to be a key instigating factor. However, lipids can also regulate immune activity and their presence may also contribute to biomaterial-induced foreign body responses (FBR) and fibrosis. Here it is demonstrated that the surface presentation of lipids on implant affects FBR by influencing reactions of immune cells to materials as well as their resultant inflammatory/suppressive polarization. Time-of-flight secondary ion mass spectroscopy (ToF-SIMS) is employed to characterize lipid deposition on implants that are surface-modified chemically with immunomodulatory small molecules. Multiple immunosuppressive phospholipids (phosphatidylcholine, phosphatidylinositol, phosphatidylethanolamine, and sphingomyelin) are all found to deposit preferentially on implants with anti-FBR surface modifications in mice. Significantly, a set of 11 fatty acids is enriched on unmodified implanted devices that failed in both mice and humans, highlighting relevance across species. Phospholipid deposition is also found to upregulate the transcription of anti-inflammatory genes in murine macrophages, while fatty acid deposition stimulated the expression of pro-inflammatory genes. These results provide further insights into how to improve the design of biomaterials and medical devices to mitigate biomaterial material-induced FBR and fibrosis.

Investigation on photovoltaic performance of Cu2SnS3 thin film solar cells fabricated by RF-sputtered In2S3 buffer layer

A two-step process was used to prepare Cu2SnS3 films in this study: first, precursor stacks were deposited using a magnetron sputtering technique, and then the stacks were annealed in sulfur-containing atmosphere at various times. Utilizing a variety of characterization techniques, it was thoroughly examined how sulfurization time affected the films’ structural, morphological, optical, and electrical characteristics. X-ray diffraction and Raman spectroscopy measurements indicated that two structural polymorphs (tetragonal and monoclinic) of Cu2SnS3 co-existed in the films. Surface and cross-sectional images obtained by scanning electron microscopy showed that the microstructures of the films were entirely changed to well-grown crystal structures at 30 min and 40 min sulfurization times. In2S3/Cu2SnS3 stacks were prepared by the deposition of In2S3 films on the absorber layers sulfurized for 30 and 40 min by RF magnetron sputtering method. The fabrication of Ni/Al/Ni/AZO/i:ZnO/In2S3/Cu2SnS3/Mo/SLG-structured devices was done using both thermally annealed and non-annealed In2S3/Cu2SnS3 stacks. Secondary ion mass spectroscopy studies of the devices revealed that the indium diffused from In2S3 layer into the Cu2SnS3 absorber to a certain depth. The efficiency values of the devices were found to have been slightly enhanced with the annealing of the In2S3/Cu2SnS3 stacks. The solar cell with the maximum efficiency (η) of 3.12 %, open-circuit voltage (VOC) of 0.265 mV, short-circuit current (JSC) of 37.90 mA/cm2, and fill factor (FF) of 0.31 was produced by thermally annealed In2S3/Cu2SnS3 stack with an absorber layer sulfurized for 40 min.

Dopant profiling of ion-implanted GaAs by terahertz time-domain spectroscopy

We investigate terahertz time-domain spectroscopy (THz-TDS) as a non-destructive and non-contact technique for depth profiling of dopants in semiconductors. THz temporal waveforms transmitted through silicon-ion-implanted semi-insulating gallium arsenide substrates, as-implanted or post-annealed by rapid thermal annealing, were analyzed by assuming a multi-layered Gaussian refractive index profile in the ∼sub-micrometer-thick implantation region. The implantation energy and dosages in this work were 200 KeV, 1014, 5 × 1014, and 1015 ions/cm2, respectively. The average values of real (n) and imaginary (κ) parts of refractive indices of an as-implanted sample in the depth range of 0–800 nm are 5.8 and 0.7, respectively, at 0.5 THz and are 6.2 and 0.2, respectively, at 1 THz. On the other hand, the refractive index profile of the post-annealed samples displays a prominent Gaussian-like form, and peak refractive indices (n ∼ 25 and κ ∼ 32.7 at 0.5 THz and n, κ ∼17 at 1 THz) were found to be at the depth of 210 nm. Reconstructed dopant profiles in as-implanted, implanted, and post-annealed substrates were found to be in good agreement with measurements by secondary ion mass spectroscopy as well as simulation by the Monte Carlo method. We were also able to determine accurately the projected range (Rp), straggle (Rs), and concentration of dopants by the analysis of THz-TDS data. The spatial resolution, along the depth direction, of the THz-TDS technique for depth profiling of dopants was estimated to be as small as 8-nm. This work suggests the feasibility of using THz-TDS for nondestructive and non-contact diagnostics for profiling dopants in semiconductors.

Non‐Destructive X‐Ray Imaging of Patterned Delta‐Layer Devices in Silicon

AbstractThe progress of miniaturization in integrated electronics has led to atomic and nanometer‐sized dopant devices in silicon. Such structures can be fabricated routinely by hydrogen resist lithography, using various dopants such as P and As. However, the ability to non‐destructively obtain atomic‐species‐specific images of the final structure, which would be an indispensable tool for building more complex nano‐scale devices, such as quantum co‐processors, remains an unresolved challenge. Here, X‐ray fluorescence is exploited to create an element‐specific image of As dopants in Si, with dopant densities in absolute units and a resolution limited by the beam focal size (here ≈1 µm), without affecting the device's low temperature electronic properties. The As densities provided by the X‐ray data are compared to those derived from Hall effect measurements as well as the standard non‐repeatable, scanning tunneling microscopy and secondary ion mass spectroscopy, techniques. Before and after the X‐ray experiments, we also measured the magneto‐conductance, which is dominated by weak localization, a quantum interference effect extremely sensitive to sample dimensions and disorder. Notwithstanding the 1.5 × 1010 Sv (1.5 × 1016 Rad cm−2) exposure of the device to X‐rays, all transport data are unchanged to within experimental errors, corresponding to upper bounds of 0.2 Angstroms for the radiation‐induced motion of the typical As atom and 3% for the loss of activated, carrier‐contributing dopants. With next generation synchrotron radiation sources and more advanced optics, the authors foresee that it will be possible to obtain X‐ray images of single dopant atoms within resolved radii of 5 nm.

Application of ion implantation as a tool to study neutron induced morphological changes in HOPG and RBMK-1500 reactor graphite

Based on the RBMK-1500 (rus.: peaктop бoльшoй мoщнocти кaнaльный, PБMК; reaktor bolshoy moshchnosti kanalnyy, “high-power channel-type reactor”) reactor irradiation conditions, ion implantation was used as a tool to study neutron induced morphological changes in both highly oriented pyrolytic graphite (HOPG) and nuclear grade RBMK graphite. Graphite samples were implanted with 180 keV 14N+ ions at the fluences of 1.0 × 1016 ions/cm−2 and 2.5 × 1016 ions/cm−2. To study temperature effects on both ion migration and structural disorder level in the graphite matrix, the implantation procedures were carried out under different temperature conditions – room temperature (RT) and 500 °C. Subsequently, the distribution profiles of the implanted 14N+ ions were obtained by using secondary ion mass spectroscopy (SIMS) technique, while the microstructural properties of the graphite were evaluated by Raman spectroscopy. Implantation induced primary displacement damage profiles and implanted ion profiles were evaluated theoretically by using GEANT4 10.6 and SRIM-2013 codes. The profiles of implanted nitrogen obtained by SIMS technique were found to be in good agreement with theoretical ones. The surfaces of HOPG samples displayed macroscopic damage in form of fractures after 14N+ ion implantation at 500 °C; however, in case of RBMK graphite, the sample surfaces remained without visually observable changes. The Raman spectra showed an increase of sp3-related content and formation of amorphous carbon in both HOPG and RBMK graphite samples; the latter exhibits higher structural disorder at microscopic level and stronger amorphization than HOPG.

ToF-SIMS Depth Profiling to Measure Nanoparticle and Polymer Diffusion in Polymer Melts

We apply time-of-flight secondary ion mass spectroscopy (ToF-SIMS) and cross-sectioned trilayer samples to separately measure nanoparticle (NP) and polymer diffusion on micrometer length scales in polymer melts. We fabricate polymer/diffusing medium/polymer trilayer samples and measure the cross section to extract the NP or deuterated polymer distribution in 3D using ToF-SIMS. After correcting the data for sample tilt, deconvoluting the beam resolution, and integrating the data to extract 1D concentration profiles, we fit the data to extract the diffusion coefficient. These results from cross-sectional ToF-SIMS are in excellent agreement with earlier studies using well-established ion beam methods. This work establishes ToF-SIMS as a reliable tool for measuring NP and polymer diffusion coefficients and opens the door to investigating diffusion in more complex polymer systems and across longer time and length scales.

Advanced characterization techniques for nanostructured materials in biomedical applications

Recent advancements in nanostructured materials have found widespread application across many domains, particularly in the biomedical field. Before using nanostructured materials in clinical applications, many important challenges, especially those related to their uses in biomedicine, must be resolved. Biological activity, compatibility, toxicity, and nano-bio interfacial characteristics are some of the major problems in biomedicine. We may therefore investigate the nanostructured materials for biomedical applications with the aid of modern characterization techniques. This overview article illustrates the present state of nanostructured materials in the biomedical field with uses and the importance of characterization methods through the use of cutting-edge characterization techniques. In this article, the techniques for analysing the topology of nanostructures, including Field Emission Scanning Electron Microscopy (FESEM), Dynamic Light Scattering (DLS), Scanning Probe Microscopy (SPM), Near-field Scanning Optical Microscopy (NSOM), and Confocal microscopy, are described. In addition, the internal structural investigation techniques X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), and Magnetic Resonance Force Microscopy (MRFM) are discussed. In addition, composition analysis techniques such as X-ray Photoelectron Spectroscopy (XPS), Energy Dispersive X-ray spectroscopy (EDS), Auger Electron Spectroscopy (AES), and Secondary Ion Mass Spectroscopy (SIMS) have been discussed. The essence of the nanomaterials as they relate to physics, chemistry, and biology is thoroughly explained in this overview along with characterization techniques through case studies. Additionally, the constraints and difficulties with specimen and analysis that are related to comprehending nanostructured materials have been identified and addressed in this study.

Metrology and Nanometrology at Agricultural/Food/Nutraceutical Interface: An Updated Shot

Abstract: Nanometrology has been considered as a key to the future of nanotechnology since recently. It is particularly important for nanoparticle market development that is commonly applied in dif-ferent areas of science. The adoption of nanotechnologies in food and agrochemical industries represents a new frontier, with particular regard to plant defence against pathogen agents. Na-nometrology deals with a broad range of measurements, as well as chemical and structural characterization, electronic, thermal, and mechanical properties, fabrication and monitoring of nanodevices, and theoretical modelling of nanomaterials properties. Besides the scientific and technological values of a global standard offered by nanometrology, there are also several in-dustry-related values. In this paper, the most common the areas of science emphasized on the most frequently applied methods by the example of techniques/tools that have been described from a metrological standpoint at a nano size scale. Therefore, at the microscopic scale may be widely applied: optical techniques, for example, X-ray Photoelectron Spectroscopy (XPS), or op-tical transmission. Moreover, Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX) can be used for microscopic characterization, while Scanning Probe Micros-copy (SPM), consisting of Scanning-Tunnelling Microscopy (STM) and Atomic Force Microscopy (AFM), as well as Transmission-Electron Microscopy (TEM), can be employed at the nanoscopic scale. The review has also mentioned about Secondary Ion Mass Spectroscopy (SIMS) to analyze secondary ions using a mass spectrometer. In addition, Electron Energy Loss Spectroscopy (EELS) using high-energy electrons from sample penetration or Fourier Transform Infrared Spectroscopy (FTIR) to obtain the infrared spectrum of a sample were also presented. Particle size analysis can be analyzed by performing Small-/Wide-Angle X-ray Scattering (SAXS/WAXS) and Dynamic Light Scattering (DLS) techniques. A specific metrology approach is required for most nanoparticle-based products, that is, the way nanometrology is significant for production quality control and for toxicology studies. This review wants to give an updated shot on the metrological approaches and applications, with particular attention to nanometrology for dif-ferent areas of scientific research, i.e., food, agricultural, nutraceutical, biological and medical ones. The novelty character of this paper is to discuss the application of nanotechnologies under metrological principles and approach at the interface of different integrated, multipurpose and multidisciplinary application fields. The following topics are here explored: i) metrology: defi-nitions, principles, and main features; ii) calibration methods and techniques; iii) measurement methods and systems; iv) proficiency testing; v) nanometrology. Particularly, nanometrology was highlighted in the following directions: significance of the nanodimension, nanometrology in chemical research, nanometrology for the characterization of nanoparticles, nanometrology in biological and medical sciences, mechanical nanometrology, electrical nanometrology and applications of nanometrology in agriculture and food industry.

New Level of Development of Secondary Ion Mass Spectroscopy for Materials Science

New Level of Development of Secondary Ion Mass Spectroscopy for Materials Science

Critical role of hydrogen for superconductivity in nickelates.

The newly discovered nickelate superconductors so far only exist in epitaxial thin films synthesized by a topotactic reaction with metal hydrides1. This method changes the nickelates from the perovskite to an infinite-layer structure by deintercalation of apical oxygens1-3. Such a chemical reaction may introduce hydrogen (H), influencing the physical properties of the end materials4-9. Unfortunately, H is insensitive to most characterization techniques and is difficult to detect because of its light weight. Here, in optimally Sr doped Nd0.8Sr0.2NiO2H epitaxial films, secondary-ion mass spectroscopy shows abundant H existing in the form of Nd0.8Sr0.2NiO2Hx (x ≅ 0.2-0.5). Zero resistivity is found within a very narrow H-doping window of 0.22 ≤ x ≤ 0.28, showing unequivocally the critical role of H in superconductivity. Resonant inelastic X-ray scattering demonstrates the existence of itinerant interstitial s (IIS) orbitals originating from apical oxygen deintercalation. Density functional theory calculations show that electronegative H- occupies the apical oxygen sites annihilating IIS orbitals, reducing the IIS-Ni 3d orbital hybridization. This leads the electronic structure of H-doped Nd0.8Sr0.2NiO2Hx to be more two-dimensional-like, which might be relevant for the observed superconductivity. We highlight that H is an important ingredient for superconductivity in epitaxial infinite-layer nickelates.

Characterization of unintentional doping in localized epitaxial GaN layers on Si wafers by scanning spreading resistance microscopy

Localized epitaxy of gallium nitride (GaN) on silicon (Si) is studied, with the aim of achieving material compatible with 1200 V vertical devices, in particular an unintentional doping level <1 × 1016 cm−3, which is essential to have high quality devices. In this study, three mask materials (SiN, SiO2, Al2O3) are examined and the unintentional doping concentration in GaN layers grown by metal organic vapor phase epitaxy (MOVPE) is investigated by scanning spreading resistance microscopy (SSRM). The results from SSRM are verified by secondary ions mass spectroscopy (SIMS) and show that an unintentional doping concentration lower than 1016 cm−3 is achieved when Al2O3 is used as the mask material. This value is lower than any previous studies of localized GaN growth, and in addition, this is the first time that SSRM has been used to observe such low doping concentrations in GaN.

Enhancing the electron mobility in Si-doped (010) β-Ga2O3 films with low-temperature buffer layers

We demonstrate a new substrate cleaning and buffer growth scheme in β-Ga2O3 epitaxial thin films using metal–organic vapor phase epitaxy (MOVPE). For the channel structure, a low-temperature (LT, 600 °C) un-doped Ga2O3 buffer was grown, followed by a transition layer to a high-temperature (HT, 810 °C) Si-doped Ga2O3 channel layers without growth interruption. The (010) Ga2O3 Fe-doped substrate cleaning uses solvent cleaning, followed by additional hydrofluoric acid (49% in water) treatment for 30 min before the epilayer growth. This step is shown to compensate the parasitic Si channel at the epilayer–substrate interface that originates from the substrate polishing process or contamination from the ambient. From secondary ion mass spectroscopy (SIMS) analysis, the Si peak atomic density at the substrate interface is found to be several times lower than the Fe atomic density in the substrate—indicating full compensation. The elimination of the parasitic electron channel at the epi–substrate interface was also verified by electrical (capacitance–voltage profiling) measurements. In the LT-grown (600 °C) buffer layers, it is seen that the Fe forward decay tail from the substrate is very sharp, with a decay rate of ∼9 nm/dec. X-ray off-axis rocking curve ω-scans show very narrow full width at half maximum (FWHM) values, similar to the as-received substrates. These channels show record high electron mobility in the range of 196–85 cm2/V⋅s in unintentionally doped and Si-doped films in the doping range of 2 × 1016–1 × 1020 cm−3. Si delta-doped channels were also grown utilizing this substrate cleaning and the hybrid LT buffers. Record high electron Hall mobility of 110 cm2/V⋅s was measured for sheet charge density of 9.2 × 1012 cm−2. This substrate cleaning, combined with the LT buffer scheme, shows the potential of designing Si-doped β-Ga2O3 channels with exceptional transport properties for high-performance Ga2O3-based electron devices.

Activation of Dolomite Flotation by Ferrous Hydroxide and Carbonate

The major problem with Carlin-type gold deposit flotation is that the high dolomite content in the concentrate decreases the quality of gold. Further, the activation mechanisms involved in dolomite flotation are still not fully understood. Herein, the correlation of Fe2+ conversion with xanthate adsorption and dolomite flotation was investigated to reveal the effect of dolomite embedded with pyrite. Flotation tests suggested that Fe2+ rather than Fe3+ improved the floatability of dolomite from 20% to 45%. Contact angles and thermodynamic tests indicated that the hydrophobicity of Fe2+-modified dolomite corresponds to the adsorption of xanthate. Importantly, time-of-flight secondary ion mass spectroscopy (Tof-SIMS) and x-ray photoelectron spectroscopy (XPS) attributed the activation of dolomite flotation to the formation of Fe(OH)2 and FeCO3. The coordination model of flotation successfully elucidated the selective adsorption of xanthate between Fe(OH)2, FeCO3 and FeOOH surfaces. The density function theory (DFT) simulation calculation was performed to identify the reaction rate at the atomic level, and the density of states (DOS) was also conducted to verify the conclusions at the electronic level. This study presents important surface chemistry evidence for understanding and regulating the poor selectivity in the flotation of Carlin-type gold deposits.

Formation of Type II Silicon Clathrate with Lithium Guests through Thermal Diffusion.

At low guest atom concentrations, Si clathrates can be viewed as semiconductors, with the guest atoms acting as dopants, potentially creating alternatives to diamond Si with exciting optoelectronic and spin properties. Studying Si clathrates with different guest atoms would not only provide insights into the electronic structure of the Si clathrates but also give insights into the unique properties that each guest can bring to the Si clathrate structure. However, the synthesis of Si clathrates with guests other than Na is challenging. In this study, we have developed an alternative approach, using thermal diffusion into type II Si clathrate with an extremely low Na concentration, to create Si clathrate with Li guests. Using time-of-flight secondary-ion mass spectroscopy, X-ray diffraction, and Raman scattering, thermal diffusion of Li into the nearly empty Si clathrate framework is detected and characterized as a function of the diffusion temperature and time. Interestingly, the Si clathrate exhibits reduced structural stability in the presence of Li, converting to polycrystalline or disordered phases for anneals at temperatures where the starting Na guest Si clathrate is quite stable. The Li atoms inserted into the Si clathrate lattice contribute free carriers, which can be detected in Raman scattering through their effect on the strength of Si-Si bonds in the framework. These carriers can also be observed in electron paramagnetic resonance (EPR). EPR shows, however, that Li guests are not simple analogues of Na guests. In particular, our results suggest that Li atoms, with their smaller size, tend to doubly occupy cages, forming "molecular-like" pairs with other Li or Na atoms. Results of this work provide a deeper insight into Li guest atoms in Si clathrate. These findings are also relevant to understanding how Li moves through and interacts with Si clathrate anodes in Li-ion batteries. Additionally, techniques presented in this work demonstrate a new method for filling the Si clathrate cages, enabling studies of a broad range of other guests in Si clathrates.

High-Spatial-Resolution Quantitative Chemomechanical Mapping of Organic Composite Cathodes for Sulfide-Based Solid-State Batteries

Understanding the chemomechanical behaviors of electrodes, particularly at electrode/electrolyte interfaces, is critical for improving the performance of all-solid-state batteries. However, due to the instability of electrolyte materials under ambient conditions, such characterizations are challenging, particularly for sulfide-based all-solid-state batteries. Herein, by combining time-of-flight secondary-ion mass spectroscopy (ToF-SIMS) and in-SEM nanoindentation measurements, a systematic quantitative investigation of the chemomechanical behaviors of pyrene-4,5,9,10-tetraone (PTO)/Li6PS5Cl composite cathodes is carried out. Chemical and quantitative mechanical information on the composite cathode was collected with high spatial resolution after developing and implementing an air-free characterization protocol. By directly connecting the Young’s modulus and hardness with the Li distribution in the composite cathode, a comprehensive chemomechanical mapping of the PTO/Li6PS5Cl composite cathode has been established. This work improves our knowledge of the critical chemomechanical phenomena that occur at the cathode/electrolyte interfaces in all-solid-state batteries.

Excitonic luminescence of iodine-intercalated HfS2

Photoluminescence from bulk HfS2 grown by the chemical vapor transport method is reported. A series of emission lines is apparent at low temperature in the energy range of 1.4–1.5 eV. Two groups of the observed excitonic transitions followed by their replicas involving acoustic and optical phonons are distinguished using classical intensity correlation analysis. The emission is attributed to the recombination of excitons bound to iodine (I2) molecules intercalated between layers of HfS2. The I2 molecules are introduced to the crystal during the growth as halogen transport agents in the growth process. Their presence in the crystal is confirmed by secondary ion mass spectroscopy.

Effects of Ageing in Disinfectant Solution on the Corrosion Resistance and Antimicrobial Behavior of Copper Alloys.

This work studies two copper-based alloys as potential antimicrobial weapons for sectors where surface hygiene is essential. Effects of different alloying elements addition at the same Cu content (92.5% by weight) on the corrosion resistance and the antibacterial performance of two copper alloys were studied in an aerated disinfectant solution (0.25% v/v Aniosurf Premium (D)) by electrochemical corrosion, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectroscopy (ToF-SIMS) and antibacterial tests. Results showed that the nature of the alloying elements had a clear influence on the corrosion resistance and antibacterial performance. Electrochemical impedance results and surface analyses demonstrate the presence of organic compounds bound on the substrate and that a film covers part of the total active surface and may act as a protective barrier by preventing the interaction between metal and solution, decreasing the antimicrobial performance of copper-based materials. Low zinc and silicon contents in copper alloys allows for better aging behavior in D solution while maintaining good antibacterial performance. The XPS and ToF-SIMS results indicated that artificial aging in disinfectant enhanced Cu enrichment in the organic film formed, which could effectively stimulate the release of Cu ions from the surface.

Super-stable conductive colloidal dispersions stabilized by nanoparticle-type emulsifying agents

We were able to replace most of the solvent phases of conductive Nickel paste with water through emulsification technique for oil-in-water (O/W) Pickering emulsion. Hydrophobic nickel paste (in hexylacetate) met with excess water as it was prepared, and BaTiO3 (BT) nanoparticle agents (d = 17.2 nm) introduced in the process were strongly adsorbed on the boundary between the hexylacetate phase and the water phase to form very stable emulsion paste. The morphology and structure of BT nanoparticles and their components were identified transmission electron microscopy, thermogravimetric analysis, Time-of-flight secondary ion mass spectroscopy, Fourier transform Infrared, X-ray photoelectron spectra. It was confirmed that the emulsion paste, in which nanoparticles acted as emulsifying agents, maintained its initial stability for 5000 h and had significantly higher stability even at high temperatures of 150 ℃.