Research

12 pages, 5793 KiB

Open AccessArticle

Functionalization of the Implant Surface Made of NiTi Shape Memory Alloy

by Karolina Dudek, Tomasz Goryczka, Mateusz Dulski, Bronisław Psiuk, Agnieszka Szurko and Zdzisław Lekston

Materials 2023, 16(4), 1609; https://doi.org/10.3390/ma16041609 - 15 Feb 2023

Cited by 2 | Viewed by 1166

Abstract

To functionalize and improve the biocompatibility of the surface of a medical implant made of NiTi shape memory alloy and used in practice, a clamp, multifunctional layers composed of amorphous TiO₂ interlayer, and a hydroxyapatite coating were produced. Electrophoresis, as an efficient [...] Read more.

To functionalize and improve the biocompatibility of the surface of a medical implant made of NiTi shape memory alloy and used in practice, a clamp, multifunctional layers composed of amorphous TiO₂ interlayer, and a hydroxyapatite coating were produced. Electrophoresis, as an efficient method of surface modification, resulted in the formation of a uniform coating under a voltage of 60 V and deposition time of 30 s over the entire volume of the implant. The applied heat treatment (800 °C/2 h) let toa dense, crack-free, well-adhered HAp coating with a thickness of ca. 1.5 μm. and a high crack resistance to deformation associated with the induction of the shape memory effect in the in the deformation range similar to the real implant work after implantation. Moreover, the obtained coating featured a hydrophilic (CA = 59.4 ± 0.3°) and high biocompatibility. Full article

(This article belongs to the Special Issue Nanoparticles and Nanotechnology: From the Synthesis to Application)

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15 pages, 6944 KiB

Open AccessArticle

Experimental Identification of the Roles of Fe, Ni and Attapulgite in Nitroreduction and Dechlorination of p-Chloronitrobenzene by Attapulgite-Supported Fe/Ni Nanoparticles

by Jing Liang, Junwen Wang, Hong Liu, Emmanuella Anang and Xianyuan Fan

Materials 2022, 15(3), 1254; https://doi.org/10.3390/ma15031254 - 08 Feb 2022

Cited by 3 | Viewed by 1626

Abstract

The porous-material loading and noble-metal doping of nanoscale zero-valent iron (nFe) have been widely used as countermeasures to overcome its limitations. However, few studies focused on the experimental identification of the roles of Fe, the carrier and the doped metal in the application [...] Read more.

The porous-material loading and noble-metal doping of nanoscale zero-valent iron (nFe) have been widely used as countermeasures to overcome its limitations. However, few studies focused on the experimental identification of the roles of Fe, the carrier and the doped metal in the application of nFe. In this study, the nitroreduction and dechlorination of p-chloronitrobenzene (p-CNB) by attapulgite-supported Fe/Ni nanoparticles (ATP-nFe/Ni) were investigated and the roles of Fe, Ni and attapulgite were examined. The contributions of Ni are alleviating the oxidization of Fe, acting as a catalyst to trigger the conversion of H₂ to H*(active hydrogen atom) and promoting electron transfer of Fe. The action mechanisms of Fe in reduction of -NO₂ to -NH₂ were confirmed to be electron transfer and to produce H₂ via corrosion. When H₂ is catalyzed to H* by Ni, the production H* leads to the nitroreduction. In additon, H* is also responsible for the dechlorination of p-CNB and its nitro-reduced product, p-chloroaniline. Another corrosion product of Fe, Fe²⁺, is incapable of acting in the nitroreduction and dechlorination of p-CNB. The roles of attapulgite includes providing an anoxic environment for nFe, decreasing nFe agglomeration and increasing reaction sites. The results indicate that the roles of Fe, Ni and attapulgite in nitroreduction and dechlorination of p-CNB by ATP-nFe/Ni are crucial to the application of iron-based technology. Full article

(This article belongs to the Special Issue Nanoparticles and Nanotechnology: From the Synthesis to Application)

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21 pages, 3614 KiB

Open AccessArticle

A Comprehensive Study of Pristine and Calcined f-MWCNTs Functionalized by Nitrogen-Containing Functional Groups

by Anna Bajorek, Bogumiła Szostak, Mateusz Dulski, Jean-Marc Greneche, Sabina Lewińska, Barbara Liszka, Mirosława Pawlyta and Anna Ślawska-Waniewska

Materials 2022, 15(3), 977; https://doi.org/10.3390/ma15030977 - 27 Jan 2022

Cited by 8 | Viewed by 1737

Abstract

We present the study of pristine and calcined f-MWCNTs functionalized by nitrogen-containing functional groups. We focus on the structural and microstructural modification tuned by the previous annealing. However, our primary goal was to analyze the electronic structure and magnetic properties in relation to [...] Read more.

We present the study of pristine and calcined f-MWCNTs functionalized by nitrogen-containing functional groups. We focus on the structural and microstructural modification tuned by the previous annealing. However, our primary goal was to analyze the electronic structure and magnetic properties in relation to the structural properties using a multi-technique approach. The studies carried out by X-ray diffraction, XPS, and ⁵⁷Fe Mössbauer spectrometry revealed the presence of γ-Fe nanoparticles, Fe₃C, and α-FeOOH as catalyst residues. XPS analysis based on the deconvolution of core level lines confirmed the presence of various nitrogen-based functional groups due to the purification and functionalization process of the nanotubes. The annealing procedure leads to a structural modification mainly associated with removing surface impurities as purification residues. Magnetic studies confirmed a significant contribution of Fe₃C as evidenced by a Curie temperature estimated at T_C = 452 ± 15 K. A slight change in magnetic properties upon annealing was revealed. The detailed studies performed on nanotubes are extremely important for the further synthesis of composite materials based on f-MWCNTs. Full article

(This article belongs to the Special Issue Nanoparticles and Nanotechnology: From the Synthesis to Application)

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9 pages, 1898 KiB

Open AccessArticle

Structure and Properties of Copper Pyrophosphate by First-Principle Calculations

by Anna Majtyka-Piłat, Marcin Wojtyniak, Łukasz Laskowski and Dariusz Chrobak

Materials 2022, 15(3), 842; https://doi.org/10.3390/ma15030842 - 22 Jan 2022

Cited by 3 | Viewed by 1618

Abstract

Investigated the structural, electronic, and magnetic properties of copper pyrophosphate dihydrate (CuPPD) by the first-principle calculations based on the density functional theory (DFT). Simulations were performed with the generalized gradient approximation (GGA) of the exchange-correlation functional (E_xc) supplemented by an [...] Read more.

Investigated the structural, electronic, and magnetic properties of copper pyrophosphate dihydrate (CuPPD) by the first-principle calculations based on the density functional theory (DFT). Simulations were performed with the generalized gradient approximation (GGA) of the exchange-correlation functional (E_xc) supplemented by an on-site Coulomb self-interaction (U–Hubbard term). It was confirmed that the GGA method did not provide a satisfactory result in predicting the electronic energy band gap width (E_g) of the CuPPD crystals. Simultaneously, we measured the E_g of CuPPD nanocrystal placed inside mesoporous silica using the ultraviolet–visible spectroscopy (UV–VIS) technique. The proposed Hubbard correction for Cu-3d and O-2p states at U = 4.64 eV reproduces the experimental value of E_g = 2.34 eV. The electronic properties presented in this study and the results of UV–VIS investigations likely identify the semiconductor character of CuPPD crystal, which raises the prospect of using it as a component determining functional properties of nanomaterials, including quantum dots. Full article

(This article belongs to the Special Issue Nanoparticles and Nanotechnology: From the Synthesis to Application)

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12 pages, 32800 KiB

Open AccessArticle

Microwave-Assisted Hydrothermal Synthesis of Zinc-Aluminum Spinel ZnAl₂O₄

by Tomasz Strachowski, Ewa Grzanka, Jan Mizeracki, Adrian Chlanda, Magdalena Baran, Marcin Małek and Marlena Niedziałek

Materials 2022, 15(1), 245; https://doi.org/10.3390/ma15010245 - 29 Dec 2021

Cited by 7 | Viewed by 1928

Abstract

The drawback of the hydrothermal technique is driven by the fact that it is a time-consuming operation, which greatly impedes its commercial application. To overcome this issue, conventional hydrothermal synthesis can be improved by the implementation of microwaves, which should result in enhanced [...] Read more.

The drawback of the hydrothermal technique is driven by the fact that it is a time-consuming operation, which greatly impedes its commercial application. To overcome this issue, conventional hydrothermal synthesis can be improved by the implementation of microwaves, which should result in enhanced process kinetics and, at the same time, pure-phase and homogeneous products. In this study, nanometric zinc aluminate (ZnAl₂O₄) with a spinel structure was obtained by a hydrothermal method using microwave reactor. The average ZnAl₂O₄ crystallite grain size was calculated from the broadening of XRD lines. In addition, BET analysis was performed to further characterize the as-synthesized particles. The synthesized materials were also subjected to microscopic SEM and TEM observations. Based on the obtained results, we concluded that the grain sizes were in the range of 6–8 nm. The surface areas measured for the samples from the microwave reactor were 215 and 278 m² g⁻¹. Full article

(This article belongs to the Special Issue Nanoparticles and Nanotechnology: From the Synthesis to Application)

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19 pages, 5877 KiB

Open AccessArticle

Template-Assisted Iron Nanowire Formation at Different Electrolyte Temperatures

by Malgorzata Kac, Anna Mis, Beata Dubiel, Kazimierz Kowalski, Arkadiusz Zarzycki and Iwona Dobosz

Materials 2021, 14(15), 4080; https://doi.org/10.3390/ma14154080 - 22 Jul 2021

Cited by 4 | Viewed by 1719

Abstract

We studied the morphology, structure, and magnetic properties of Fe nanowires that were electrodeposited as a function of the electrolyte temperature. The nucleation mechanism followed instantaneous growth. At low temperatures, we observed an increase of the total charge reduced into the templates, thus [...] Read more.

We studied the morphology, structure, and magnetic properties of Fe nanowires that were electrodeposited as a function of the electrolyte temperature. The nucleation mechanism followed instantaneous growth. At low temperatures, we observed an increase of the total charge reduced into the templates, thus suggesting a significant increase in the degree of pore filling. Scanning electron microscopy images revealed smooth nanowires without any characteristic features that would differentiate their morphology as a function of the electrolyte temperature. X-ray photoelectron spectroscopy studies indicated the presence of a polycarbonate coating that covered the nanowires and protected them against oxidation. The X-ray diffraction measurements showed peaks coming from the polycrystalline Fe bcc structure without any traces of the oxide phases. The crystallite size decreased with an increasing electrolyte temperature. The transmission electron microscopy measurements proved the fine-crystalline structure and revealed elongated crystallite shapes with a columnar arrangement along the nanowire. Mössbauer studies indicated a deviation in the magnetization vector from the normal direction, which agrees with the SQUID measurements. An increase in the electrolyte temperature caused a rise in the out of the membrane plane coercivity. The studies showed the oxidation resistance of the Fe nanowires deposited at elevated electrolyte temperatures. Full article

(This article belongs to the Special Issue Nanoparticles and Nanotechnology: From the Synthesis to Application)

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16 pages, 4020 KiB

Open AccessArticle

Microstructure and Properties of Electrodeposited Nanocrystalline Ni-Co-Fe Coatings

by Piotr Ledwig, Malgorzata Kac, Agnieszka Kopia, Jan Falkus and Beata Dubiel

Materials 2021, 14(14), 3886; https://doi.org/10.3390/ma14143886 - 12 Jul 2021

Cited by 19 | Viewed by 2005

Abstract

Materials based on Ni-Co-Fe alloys, due to their excellent magnetic properties, attract great attention in nanotechnology, especially as candidates for high-density magnetic recording media and other applications from spintronic to consumer electronics. In this study, Ni-Co-Fe nanocrystalline coatings were electrodeposited from citrate-sulfate baths [...] Read more.

Materials based on Ni-Co-Fe alloys, due to their excellent magnetic properties, attract great attention in nanotechnology, especially as candidates for high-density magnetic recording media and other applications from spintronic to consumer electronics. In this study, Ni-Co-Fe nanocrystalline coatings were electrodeposited from citrate-sulfate baths with the Ni²⁺:Co²⁺:Fe²⁺ ion concentration ratios equal to 15:1:1, 15:2:1, and 15:4:1. The effect of the composition of the bath on the morphology, microstructure, chemical composition, microhardness, and magnetic properties of the coatings was examined. Scanning (SEM) and transmission (TEM) electron microscopy, X-ray diffractometry (XRD), and energy dispersive X-ray spectroscopy (EDS) were used to study surface morphology, microstructure, chemical, and phase composition. Isothermal cross-sections of the Ni-Co-Fe ternary equilibrium system for the temperature of 50 °C and 600 °C were generated using the FactSage package. Magnetic properties were analyzed by a superconducting quantum interference device magnetometer (SQUID). All the coatings were composed of a single phase being face-centered cubic (fcc) solid solution. They were characterized by a smooth surface with globular morphology and a nanocrystalline structure of grain diameter below 30 nm. It was determined that Ni-Co-Fe coatings exhibit high hardness above 4.2 GPa. The measurements of hysteresis loops showed a significant value of magnetization saturation and small coercivity. The microstructure and properties of the obtained nanocrystalline coatings are interesting in terms of their future use in micromechanical devices (MEMS). Full article

(This article belongs to the Special Issue Nanoparticles and Nanotechnology: From the Synthesis to Application)

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16 pages, 6033 KiB

Open AccessArticle

Heterostructural Mixed Oxides Prepared via ZnAlLa LDH or ex-ZnAl LDH Precursors—Effect of La Content and Its Incorporation Route

by Katarzyna Antoniak-Jurak, Paweł Kowalik, Wiesław Próchniak, Robert Bicki and Grzegorz Słowik

Materials 2021, 14(8), 2082; https://doi.org/10.3390/ma14082082 - 20 Apr 2021

Cited by 4 | Viewed by 2183

Abstract

The effect of La content and its incorporation route on physicochemical properties of ZnO/Zn(Al,La)₂O₄ or La₂O₃–ZnO/ZnAl₂O₄ mixed oxides with a spinel structure obtained from ZnAlLa Layered double hydroxides (LDHs) or ex-ZnAl LDH materials [...] Read more.

The effect of La content and its incorporation route on physicochemical properties of ZnO/Zn(Al,La)₂O₄ or La₂O₃–ZnO/ZnAl₂O₄ mixed oxides with a spinel structure obtained from ZnAlLa Layered double hydroxides (LDHs) or ex-ZnAl LDH materials was investigated. The heterostructural nanocomposites with the similar Zn/Al molar ratio and varied La content were prepared by two techniques: via co-precipitation and thermal treatment of ZnAlLa LDHs at 500 °C or via incipient wetness impregnation of ex-ZnAl LDHs with aqueous solutions of lanthanum nitrate and subsequent thermal treatment. The obtained series of materials were characterized by the following techniques: X-ray fluorescence (XRF), N₂ adsorption (BET), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis with evolved gas analysis (TG/DTG/EGA), scanning transmission electron microscopy (STEM) energy-dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM) and Fourier-transform infrared spectroscopy (FFT). The evaluation of activity toward the high-temperature water gas shift (HT-WGS) within the temperature range of 350–420 °C was carried out on the basis of rate constant measurements in the kinetic mode using a differential reactor. The co-precipitation technique allowed for a better distribution of La in bulk and on the spinel surface than in case of lanthanum incorporation via impregnation. ZnO/Zn(Al,La)₂O₄ or La₂O₃–ZnO/ZnAl₂O₄ mixed oxides were characterized by moderate activity in the HT-WGS reaction. The results reveal that introduction of lanthanum oxide over 2.4–2.8 wt% induces the phase separation of the ZnAl₂O₄ spinel, forming ZnO on the ZnAl₂O₄ spinel surface. Full article

(This article belongs to the Special Issue Nanoparticles and Nanotechnology: From the Synthesis to Application)

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