Nanoscale Oxide Research Articles

Ti40Zr10Cu36Pd14 bulk metallic glass as oral implant material

The application of highly biocompatible advanced materials leads to fewer complications and more successful medical treatments. This study proposes Ti40Zr10Cu36Pd14 bulk metallic glass (BMG) as an oral implant material and provides insights into its possible processing routes, where high-temperature compression molding via an optimized process is adopted to both evaluate the thermoplastic net-shaping kinetics and tune the specific properties of the alloy. We present processed BMGs and BMG composites of the same composition with improved thermomechanical stability, from which high strength retention at temperatures, compared to the cast glass, by above 100 K higher is registered via dynamic mechanical analysis. ∼100 nm thin surface layers comprised of Ti, Cu, and Zr oxides form at the surface of the alloys, as identified by high-resolution transmission microscopy. Also, ∼4 orders of magnitude lower passivation current density along with ∼2 orders of magnitude lower corrosion current density of the processed glass compared to the values of the as-cast state confirms an extremely high stability in a 0.9 wt% saline environment which can be linked to surface hydrophobicity. Cytocompatibility analysis conducted by seeding human gingival fibroblast cells directly onto the thermoplastically formed Ti40Zr10Cu36Pd14 BMG reveals no adverse effect on cytocompatibility. On the other hand, the formation of a nanoscale oxide layer on the thermoplastically formed samples leads to significantly higher cell attachments on the surface.

An in-situ oxide-dispersion-strengthened AlCoCrFeNiY high-entropy alloy composite coating prepared by AC-HVAF with superior oxidation and spallation resistance

We report an in-situ oxide-dispersion-strengthened AlCoCrFeNiY high-entropy alloy composite coating (ODS-HEA composite coating) with exceptional oxidation and spallation resistance at 1100 °C and 1150 °C. The coating is manufactured by activated combustion-high velocity air fuel (AC-HVAF) and has an ultrafine-grained microstructure that comprises γ, β and nanoscale oxide particles (Al2O3, Cr2O3 and Y2O3) formed in-situ in coating processing. The thermally grown oxides (TGOs) on the coating at 1100 °C and 1150 °C are exclusively α-Al2O3 with a columnar grain structure. The parabolic rate constant of the coating is about half of that of the conventional NiCoCrAlY coating (CNA coating) at both 1100 °C and 1150 °C, respectively. The lower TGO growth rate is primarily attributed to its coarser TGO grains that reduce the efficient oxygen diffusivity. Compared to the CNA coating, a higher TGO/coating interfacial toughness is achieved via inhibiting the formation of interfacial pores for ODS-HEA composite coating. The low TGO growth rate decreases the driving force for TGO spallation and the high interfacial toughness increases the TGO adhesion, thus contributing to the strong spallation resistance for the ODS-HEA composite coating. The superior oxidation and spallation resistance of the ODS-HEA composite coating at 1100 °C and 1150 °C make it a candidate bond coat for advanced thermal barrier coatings.

Hydrothermal Synthesis of Mixed Oxide Compositions of Cobalt‐Zirconium and their Catalytic Activity in the Decomposition of Hydrogen Peroxide

AbstractThe article presents the results of research on the hydrothermal synthesis of nanoscale oxide of cobalt and zirconium and their mixed oxide compositions. The synthesized samples have been characterized by the X‐ray phase, scanning electron microscopy and nitrogen adsorption‐desorption methods; the composition of the samples has been determined by chemical analysis methods, and their catalytic activity in the decomposition of hydrogen peroxide has been studied. It has been shown that during synthesis, highly dispersed cobalt and zirconium oxide are formed, and the sample of the composition (mol %): Co3O4(88)−ZrO2(12) has the highest specific surface area (181.2 m2/g) and the highest activity (K=6.18 ⋅ 10−2 s−1) against the decomposition of hydrogen peroxide. The increasing of the ZrO2 content in oxide compositions reduces their catalytic activity. The particle size in the synthesized samples is 7–38 nm.

A Comparison of Solidification Structures and Submicroscale Cellular Segregation in Rapidly Solidified Stainless Steels Produced via Two-Piston Splat Quenching and Laser Powder Bed Fusion.

Fusion-based additive manufacturing techniques leverage rapid solidification (RS) conditions to create parts with complex geometries, unique microscale/nanoscale morphological features, and elemental segregation. Three custom composition stainless steel alloys with varying chromium equivalence to nickel equivalence ratio (Creq/Nieq) between 1.53 and 1.95 were processed using laser powder bed fusion (LPBF) and/or two-piston splat quenching (SQ) to produce solidification rates estimated between 0.4 and 0.8 m/s. Both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were utilized to collect high-resolution images, electron backscatter diffraction (EBSD) phase identification, and measure cellular segregation. Similar features were observed in both LPBF and SQ samples including phase and microstructure, nanoscale oxide particles, cell size, and segregation behavior. However, dislocation pileup was observed along the cell boundaries only in the LPBF austenite solidified microstructure. Targeted adjustment of the SQ feedstock Cr and Ni concentrations, within the ASTM A240 specification for 316L resulted in no observable impact on the cell size, oxide particle size, or magnitude of segregation. Also, the amount of Ni segregation in the ferrite solidified microstructures did not significantly differ, regardless of Cr/Nieq or processing technique. SQ is demonstrated as capable of simulating RS rates and microstructures similar to LPBF for use as an alternative screening tool for new RS alloy compositions.

Conjunctive and concentration dependent effects of nanoscale zinc and boron on the physiological, biochemical, nutrient uptake, and translocation processes in peanut (Arachis hypogaea L.)

In the present investigation, different concentrations (150, 200, 300, 400, and 500 mg/L) of nanoscale zinc oxide (ZnO) and boron (B) were applied through foliar spray (pot culture) to evaluate their effects on the growth and biochemical parameters of peanut. Nanoscale zinc oxide and nano boron were prepared using modified oxalate decomposition and encapsulation methods, respectively, and were characterized using techniques such as, X-ray diffraction (XRD), dynamic light scattering (DLS), ultraviolet–visible (UV–vis) spectroscopy, and transmission electron microscopy (TEM). The average size (37.2 nm, 53.6 nm) and zeta potential (−37.7 mV, −28.3 mV) of nano ZnO and nano boron were measured, respectively. Fourier transform infrared spectroscopic (FT-IR) studies revealed the functional groups that are present in the hydrosols. Highest germination percentage (98.7% and 96%), seedling vigor index (2359 and 1325) and total chlorophyll content (3.28 and 2.24 mg g−1) were recorded at 500 mg/L of nano zinc oxide and nano boron. Significantly higher peroxidase, catalase, superoxide dismutase (SOD) enzymatic activities, pod yield (39.76 g pot−1 and 38.14 g pot−1) and haulm yield (49.56 g pot−1 and 47.05 g pot−1) were also recorded with the application of nano ZnO and boron @ 500 mg/L. Translocation of nanoscale nutrients through stomata was clearly observed. Significant nutrient uptake with the foliar application of nanoscale nutrients has been recorded. The performance of groundnut (in terms of yield, quality and nutrient uptake) was significantly enhanced with the application of nanoscale nutrients and this point to achieving the nutrient bio-fortification with the desired levels for the betterment of human health.

Photoluminescent and magnetic characteristics of cobalt and manganese doped nanoscale zinc oxide

Photoluminescent and magnetic characteristics of cobalt and manganese doped nanoscale zinc oxide

Mechanism for the Formation of Nanoscale Oxides in a Medium of Supercritical CO2 Fluid

A possible mechanism is considered for the formation of nanoscale oxides based on titanium and aluminum isopropoxides in a medium of supercritical CO2 fluid. It is shown that because of intermolecular interactions and high pressure in the system, the supercritical fluid acquires the properties of a condensed medium, the main role of which is to restrain processes of hydrolysis. At the first stage of the hydrolysis of titanium isopropoxide, the water molecule is coordinated in the outer sphere of the central atom due to the formation of intermolecular hydrogen bonds. It is then coordinated into the inner sphere with the formation of a five-coordinate transition state and its destruction, creating a product substituted for the hydroxo group. The next steps proceed in a similar way. The described mechanism agrees with experimental findings and produces nanosized X-ray amorphous titanium oxide. (With aluminum isopropoxide, only the hydrolyzed hydroxo form can be produced.) Results suggest the production of nanosized oxides from isopropoxides in a medium of supercritical CO2 fluid is possible for transitional d-elements.

Mechanism for the Formation of Nanoscale Oxides in a Medium of Supercritical CO2 Fluid

Mechanism for the Formation of Nanoscale Oxides in a Medium of Supercritical CO2 Fluid

Biomedical Applications of Biosynthesized Nickel Oxide Nanoparticles.

Nickel oxide nanoparticles have gained tremendous attention recently in a variety of scientific domains thanks to their characteristic chemical, physical, optical, and biological properties. Due to the diversity of applications in various fields, different physicochemical methods have been used to synthesize nickel oxide nanoparticles. However, most conventional methods use hazardous chemicals during synthesis and become liable for potential health risks, while others are expensive and require a lot of energy to synthesize nanoparticles. As a result, the nanoparticles become less biocompatible and biologically inefficient. Biogenic synthesis of nanoparticles is currently proposed as a valuable alternative to the physical and chemical methods, as it is a simple, non-toxic, cheap, green and facile approach. This synthetic method uses biological substrates such as plant extracts, microorganisms, and other biological products to synthesize nickel oxide nanoparticles. The various phytochemicals from plant extracts, enzymes or proteins from microorganisms, and other biological derivatives play as reducing, stabilizing, and capping agents to provide bioactive and biocompatible nickel oxide nanoscale material. This review discusses current findings and trends in the biogenic synthesis of nickel oxide nanoparticles and their biological activities such as antibacterial, antifungal, antileishmanial, and anticancer, with an emphasis on antimicrobial and anticancer activity along with their mechanistic elucidation. Overall, this thorough study provides insight into the possibilities for the future development of green nickel oxide nanoparticles as therapeutic agents for a variety of ailments.

Insights into the selectivity of metallic oxides for arsenic and phosphate from EXAFS and DFT calculations

Phosphate is the biggest competitor for arsenic removal. Nanoscale metal oxides (NMOs) are commonly used to treat arsenic-contaminated water, yet their selective adsorption mechanisms for arsenic and phosphate are poorly understood. We quantified the selectivity of iron oxide (Fe2O3), zinc oxide (ZnO), and titanium dioxide (TiO2) nanosheets for arsenic in systems containing arsenic and phosphate, and determined the interaction of phosphate and arsenate/arsenite on metal oxide surfaces through batch experiments, spectroscopic techniques, and DFT calculations. We found that Fe2O3, TiO2, and ZnO nanosheets exhibit selectivity for arsenate/arsenite in the presence of phosphate, with Fe2O3 the most selective, followed by TiO2 and ZnO. The bonding mechanism on these metallic oxide surfaces dominates the selectivity. The more stable inner-sphere complexes of arsenate on the surfaces of Fe2O3 (bidentate binuclear), TiO2 (bidentate binuclear), and ZnO nanosheets (tridentate trinuclear) contribute to their preference for arsenate over phosphate. This difference in arsenate selectivity can be reflected in the difference in adsorption energy, net electron transfer number, and M − O bond length of the most stable inner sphere complexes. Overall, our study elucidated the selective adsorption mechanisms of arsenate/arsenite on Fe2O3, TiO2, and ZnO surfaces and highlighted the need to consider the competition between arsenate and phosphate during their removal from contaminated water.

A novel method for preparing ODS steel using precursor powder combining with sub-rapid solidification

Due to the expensive cost and challenges of batch mass production, the large-scale industrial application of oxide dispersion strengthened (ODS) steel is restricted. In this work, a novel method for preparing ODS steel using precursor powder combining with sub-rapid solidification was introduced. Herein, an ODS steel based on 316L stainless steel was prepared by this method and aged at 800 °C for 3 h to achieve massive diffuse precipitation of nano-scale oxides. The results indicated that the novel method successfully triggered the co-precipitation of nano-scale TiO2 and Er–Ti composite oxides with a number density of 6.58 × 1023 m−3 in the 316L stainless steel. After further aging at 800 °C for 3 h, a large number of Ti-rich oxide clusters with a size of less than 10 nm precipitated in the strips. With the precipitation of multiscale oxides, the aged 0.25% strip exhibited a yield strength and tensile strength of 411 MPa and 730 MPa, respectively, while maintaining an elongation of 33%. This work provided an alternative method for ODS steel fabrication.

Nanoscale Ni-NiO-ZnO Heterojunctions for Switchable Dehydrogenation and Hydrogenation through Modulation of Active Sites.

Catalysts consisting of metal-metal hydroxide/oxide interfaces are highly in demand for advanced catalytic applications as their multicomponent active sites will enable different reactions to occur in close proximity through synergistic cooperation when a single component fails to promote it. To address this, herein we disclosed a simple, scalable, and affordable method for synthesizing catalysts consisting of nanoscale nickel-nickel oxide-zinc oxide (Ni-NiO-ZnO) heterojunctions by a combination of complexation and pyrolytic reduction. The modulation of active sites of catalysts was achieved by varying the reaction conditions of pyrolysis, controlling the growth, and inhibiting the interlayer interaction and Ostwald ripening through the efficient use of coordinated acetate and amide moieties of Zn-Ni materials (ZN-O), produced by the reaction between hydrazine hydrate and Zn-Ni-acetate complexes. We found that the coordinated organic moieties are crucial for forming heterojunctions and their superior catalytic activity. We analyzed two antagonistic reactions to evaluate the performance of the catalysts and found that while the heterostructure of Ni-NiO-ZnO and their cooperative synergy were crucial for managing the effectiveness and selectivity of the catalyst for dehydrogenation of aryl alkanes/alkenes, they failed to enhance the hydrogenation of nitro arenes. The hydrogenation reaction was influenced by the shape, surface properties, and interaction of the hydroxide and oxide of both zinc and nickel, particularly accessible Ni(0). The catalysts showed functional group tolerance, multiple reusabilities, broad substrate applicability, and good activity for both reactions.

In Situ Reactive Formation of Mixed Oxides in Additively Manufactured Cobalt Alloy.

Oxide-dispersion-strengthened (ODS) alloys have long been considered for high temperature turbine, spacecraft, and nuclear reactor components due to their high temperature strength and radiation resistance. Conventional synthesis approaches of ODS alloys involve ball milling of powders and consolidation. In this work, a process-synergistic approach is used to introduce oxide particles during laser powder bed fusion (LPBF). Chromium (III) oxide (Cr2O3) powders are blended with a cobalt-based alloy, Mar-M 509, and exposed to laser irradiation, resulting in reduction-oxidation reactions involving metal (Ta, Ti, Zr) ions from the metal matrix to form mixed oxides of increased thermodynamic stability. A microstructure analysis indicates the formation of nanoscale spherical mixed oxide particles as well as large agglomerates with internal cracks. Chemical analyses confirm the presence of Ta, Ti, and Zr in agglomerated oxides, but primarily Zr in the nanoscale oxides. Mechanical testing reveals that agglomerate particle cracking is detrimental to tensile ductility compared to the base alloy, suggesting the need for improved processing methods to break up oxide particle clusters and promote their uniform dispersion during laser exposure.

Regulating corrosion resistance of Mg alloys via promoting precipitation with trace Zr alloying

Poor corrosion property has been a bottleneck problem during the application of Mg alloys. This work proposes a new way to improve the corrosion resistance of MgNd alloy by micro-alloying Zr, which promotes the precipitation process to rapidly form a protective corrosion layer. The corrosion rate decreases by three orders of magnitude from 32.69 mL/cm2/day to 0.072 mL/cm2/day. The results show Zr tends to form nano-scale oxide clusters on Mg surface, acting as pre-precipitation sites to accelerate the precipitation and facilitate the formation of dense and compact corrosion layer.

A 3D printable alloy designed for extreme environments

Multiprincipal-element alloys are an enabling class of materials owing to their impressive mechanical and oxidation-resistant properties, especially in extreme environments1,2. Here we develop a new oxide-dispersion-strengthened NiCoCr-based alloy using a model-driven alloy design approach and laser-based additive manufacturing. This oxide-dispersion-strengthened alloy, called GRX-810, uses laser powder bed fusion to disperse nanoscale Y2O3 particles throughout the microstructure without the use of resource-intensive processing steps such as mechanical or in situ alloying3,4. We show the successful incorporation and dispersion of nanoscale oxides throughout the GRX-810 build volume via high-resolution characterization of its microstructure. The mechanical results of GRX-810 show a twofold improvement in strength, over 1,000-fold better creep performance and twofold improvement in oxidation resistance compared with the traditional polycrystalline wrought Ni-based alloys used extensively in additive manufacturing at 1,093 °C5,6. The success of this alloy highlights how model-driven alloy designs can provide superior compositions using far fewer resources compared with the ‘trial-and-error’ methods of the past. These results showcase how future alloy development that leverages dispersion strengthening combined with additive manufacturing processing can accelerate the discovery of revolutionary materials.

Upgraded lithium storage performance of defect-rich Si@C anode assisted by Fe2O3-induced pseudocapacitance

Following a flowsheet comprised of a hydrothermal reaction and a dehydration/carbonization, Si-xFe/O@C anodes featured with Fe-doping and carbon encapsulation were assembled. Comparing with pure Si, Si disseminated with in situ generated nano-scaled ferric oxide (Fe2O3) particulates displays remarkably improved cyclic performance. Fe2O3 may induce amorphization and optimize electrical conductivity, by enhancing the formation of Fe and Li2O amidst charging-discharging cycles. The as-derived Fe phase benefits the transport and storage of lithium-ion and electrons. Meanwhile, numerous tiny interfaces can be constructed between Fe granules and adjacent LixSi or Li2O, and generate pseudocapacitance. After the carbonization of resorcinol-formaldehyde resin encapsulated on Si granules, core-shell structured Si-xFe/O@C particulates can be assembled. Owing to the synergism of defect-rich structure, carbon layer well-wrapped thereon and interfacial pseudocapacitance, these nanocomposite anode materials exhibit long cyclic and upgraded rate performance. After 200 cycles, Si-0.42Fe/O@C anode retains a capacity of 929 mAh·g−1 at 1 A·g−1 and 735 mAh·g−1 at 2 A·g−1. In the rate performance test operated at 5 A·g−1, a high current density, 844 mAh·g−1 could be released. Si-0.42Fe/O@C can be charged with a specific capacity exceeding 250 mAh·g−1 over the potential range of 0.75-3 V at various current densities, demonstrating the contribution of nano-Fe pseudocapacitance effect to the energy storage of Si anodes.

Continuous Hot‐Dip Galvanizing of Medium‐Manganese Third‐Generation Advanced High‐Strength Steels

The effects of process atmosphere oxygen partial pressure (pO2) on the preimmersion surface structures, interfacial reactive wetting products, and reactive wetting mechanisms of two prototype (0.15–0.20)C–(5.6–5.9)Mn–(0.4–1.9)Al–(1.1–1.5)Si–(0–0.6)Cr (wt%) third‐generation advanced high‐strength steels during continuous hot‐dip galvanizing are determined. In this study, the two‐stage thermal processing routes employed comprise an austenitization anneal followed by flash pickling and an intercritical anneal. All annealing treatments are conducted in a N2–5 vol% H2 process atmosphere with a controlled dew point. The substrates are austenitized at dew points of –30 or –10 °C, intercritically annealed at a dew point of –30, –10, or +5 °C, and then galvanized using a conventional 0.2 wt% Al (dissolved) bath. The preimmersion surfaces comprise a near‐pure Fe layer with dispersed nanoscaled oxide nodules. The primary reactive wetting mechanism is the direct wetting of the surface Fe, while oxide wetting, oxide cracking and liftoff, and oxide bridging by the liquid metal bath are secondary reactive wetting mechanisms. Zn ingress into the substrate via pores in the oxide network from selective dissolution during flash pickling is also noted. A well‐developed Fe2Al5–xZnx interfacial layer is observed for all metallic coating conditions. The resultant coatings show outstanding adherence after ASTM three‐point bend testing.

High electrochemical stability and low-agglomeration of defective Co3O4 nanoparticles supported on N-doped graphitic carbon nano-spheres for oxygen evolution reaction

The design of hybrid electrocatalysts with abundant active sites and long term stability is crucial for efficient oxygen evolution reaction (OER) application. Cobalt oxide is considered as one of the most promising electrocatalysts to replace noble metal due to its low cost, availability, and electrocatalytic activity towards the oxygen evolution reaction in alkaline media. However, nano-scale cobalt oxide suffers from severe surface self-agglomeration during the OER process, so that leading to poor activity and durability. Herein, ultra-small cobalt oxide nanoparticles are anchored on the surface of nitrogen doped porous 3D graphitic carbon nano-spheres (N-ACS@Co3O4) to increase the amount of exposed active site and avoid the self-agglomeration. The obtained electrocatalyst (N-ACS@Co3O4) is enriched with abundant oxygen vacancies and exhibits a superior OER activity (Overpotential of 237 mV at 10 mA.cm−2) and exceptional stability for at least 30 h in alkaline electrolyte (1 M KOH). The DFT calculations demonstrate that the strong adsorption of Co3O4 on N-doped graphene can prevent its agglomeration, and therefore improves the stability of Co3O4 nanoparticles during OER process in line with the experimental results.

Unraveling the origin of the excellent high-temperature oxidation resistance of an AlCrFeNiTi complex concentrated alloy

Oxidation behavior of Al8Cr13.3Fe63.5Ni11.2Ti4 complex concentrated alloy was studied in the air at 800 °C. Results show that the oxidation kinetics does not obey a parabola relationship. The oxidation process was divided into two distinct stages, transforming from an approximately parabolic law to a quasi-linear law at 10 h. This alloy exhibits excellent oxidation resistance with only 0.41 mg/cm2 of specific mass gain after 100 h oxidation, ascribed to the compact outer CrTi2O5 +TiO2 and inner Cr2O3 +nano-scale CrTi2O5 oxide layers. However, this oxide scale does not prevent the N from diffusion inward, forming the TiN and AlN in internal oxidation zone.

Nanoparticle toxicity may cause testicular dysfunction

Nanoparticle toxicity may cause testicular dysfunction