Effect of pH and Boric Acid on Magnetic Properties of Electrodeposited Co Nanowires

Agarwal, Shivani; Khatri, Manvendra Singh

doi:10.1007/s40010-020-00708-7

Cited by 4 publications

(4 citation statements)

References 23 publications

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“…The peaks of sample 2 are dominated by the contribution of the Co-hcp phase, which are oriented along the (100), (002), and (101) directions. Actually, the electrolyte with a low pH (<2.5) favors the Co-fcc formation, and the electrolyte with a higher pH (≥2.5) favors the Co-hcp formation. , Agarwal et al reported that two crystalline phases, (111) Co-fcc and (002) Co-hcp, appear at pH 4, the pH being the same as in our study. Our results strongly support this information. − The diffraction peaks are sharp and narrow, indicating that the nanowires have a preferred orientation.…”

Section: Resultssupporting

confidence: 83%

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High-Coercivity Cobalt Nanowire Arrays: Synthesis and Heat Treatment

Xu,

Yao,

Lou

et al. 2023

Crystal Growth & Design

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An anodic aluminum oxide (AAO) template with a highly ordered structure is prepared and used for the synthesis of Co nanowire arrays. The surface of Co nanowires is smooth and uniform, the diameter is 50 nm, the length is about 20 μm, and the aspect ratio of a Co nanowire is about 400. A large aspect ratio represents a strong shape anisotropy and dipolar interactions, resulting in high coercivity. In addition, the small diameter of the nanowires also contributes to the increased coercivity because the small size hinders the propagation mechanism of the domain walls during magnetic inversion. The magnetic curve in the parallel configuration shows a higher coercivity and remanence than that in the perpendicular configuration, and the rectangle is also more obvious. The shape anisotropy of nanowires tends to be magnetized along the axis, so an easy magnetization axis is parallel to nanowires. In order to investigate the effect of heat treatment on the magnetic properties of nanowires, we treated the samples for different times. The Co 3 O 4 (shell)−Co (core) structure was formed after the surface oxidation of the annealed Co nanowires. The grain size and diameter after heat treatment are twice as large as those without treatment; the thickness of the shell is about 25 nm, and the diameter of the core is about 50 nm. The core−shell interface is clearly distinguishable with increasing roughness. Due to the coexistence of two phases and the increase in grain size, the saturated magnetic moments decrease, and the coercivity and remanence ratio increase with the increase of heat treatment time. There is an exchange interaction between the core and shell magnetic phases, and the magnetic signal is a result of the competing ferromagnetic core and antiferromagnetic shell. The Co 3 O 4 (shell)−Co (core) nanowires are basically in the ferromagnetic state, the coercivity is twice that of Co showing a large magnetocrystalline anisotropy and energy, and the direction parallel to the nanowire axis is easier to be magnetized. The exchange bias effect can persist up to above room temperature, which is directed by the interfacial spin pinning effect, and the coercivity and the shift of the hysteresis loop depend on the contribution of the interfacial surface spins to the magnetization reversal.

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Section: Resultssupporting

confidence: 83%

“…Agarwal et al reported that two crystalline phases, (111) Co-fcc and (002) Co-hcp, appear at pH 4,31 the pH being the same as in our study. Our results strongly support this information.32−34 The diffraction peaks are sharp and narrow, indicating that the nanowires have a preferred orientation.…”

supporting

confidence: 78%

High-Coercivity Cobalt Nanowire Arrays: Synthesis and Heat Treatment

Xu,

Yao,

Lou

et al. 2023

Crystal Growth & Design

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“…An example for the chemical approach is to synthesize MNWs with different compositions or crystal structures [ 83 , 84 , 85 , 86 ]. For instance, it was shown that by varying the pH of the electrolyte during electrodeposition, one can manipulate the crystal structure of cobalt MNWs from hexagonal close-packed (hcp), to a mixture of hcp and face-center-cubic (fcc), to a purely fcc crystal structure [ 85 , 87 ]. Over the last few years, the physical approaches for tailoring the coercivity have been intensively studied.…”

Section: Why Magnetic Nanowires For Nanobarcodes?mentioning

confidence: 99%

Magnetic Nanowires for Nanobarcoding and Beyond

Kouhpanji

Stadler

2021

Sensors

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Multifunctional magnetic nanowires (MNWs) have been studied intensively over the last decades, in diverse applications. Numerous MNW-based systems have been introduced, initially for fundamental studies and later for sensing applications such as biolabeling and nanobarcoding. Remote sensing of MNWs for authentication and/or anti-counterfeiting is not only limited to engineering their properties, but also requires reliable sensing and decoding platforms. We review the latest progress in designing MNWs that have been, and are being, introduced as nanobarcodes, along with the pros and cons of the proposed sensing and decoding methods. Based on our review, we determine fundamental challenges and suggest future directions for research that will unleash the full potential of MNWs for nanobarcoding applications.

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“…Contrary to Ni, Fe and alloyed NWs, it is well known that electrodeposited Co NWs can exhibit the hexagonal close packed (hcp) crystalline texture, responsible for the appearance of an additional MC anisotropy contribution that superposes to the magnetostatic (MS) contribution. Indeed, the hcp texture of Co NWs can be tailored by controlling electrochemical parameters like the electrolytic bath acidity [2][3][4][5][6], temperature [7,8], current density [9], deposition potential [10,11], boric acid concentration [6], or geometrical parameters of the NWs like their diameter [12,13], and aspect ratio [14,15]. Furthermore, previous works have shown that Co NWs synthesized using electrolytes with pH values in the range 2.0-2.6 have preferred face centered cubic (fcc)-like texture without any MC anisotropy contribution, whereas they present the hcp texture when they are electrodeposited using electrolytes with pH values between 3.5 and 6.6.…”

Section: Introductionmentioning

confidence: 99%

Crystalline texture of cobalt nanowire arrays probed by the switching field distribution and FORC diagrams

Guerrero

Encinas

Palomo

et al. 2023

J. Phys. D: Appl. Phys.

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The crystalline texture of arrays of low diameter Co nanowires (NWs) synthesized by electrodeposition using electrolytes with different acidities (pH in the range 2.0 to 6.6) was studied by the switching field distribution (SFD) and first order reversal curve (FORC) diagrams. Particularly, the SFD determined as the derivative dM/dH of the descending part of the major hysteresis loop (MHL) has proven to be a reliable and powerful method for the identification of different crystalline textures in the NWs and the quantification of their corresponding texture percentages. The presence of the fcc-like texture at low pH values and hcp textures with the c-axis perpendicular and parallel to the NWs axis at higher pH values have been identified by performing multiple Gaussian fits to the SFD by virtue of their different magnetic behavior observed during reversal of the magnetization. The field position and size of each curve in the multiple Gaussian fit provide information about the corresponding magnetic contribution and volumetric texture percentage of each crystalline texture in the NWs, respectively. The analysis of the SFD has been complemented and validated with FORC diagram measurements, showing that the width of the coercive field distribution (CFD) is in good agreement with the width of the SFD. Also, it has been found that the different branches observed in the FORC diagrams along the interaction axis provide further insight on the interaction between magnetocrystalline fields. This work provides a novel methodology for the use of magnetometry as a reliable technique for the study of the interplay between the microstructure and magnetic behavior of arrays of NWs.

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Effect of pH and Boric Acid on Magnetic Properties of Electrodeposited Co Nanowires

Cited by 4 publications

References 23 publications

High-Coercivity Cobalt Nanowire Arrays: Synthesis and Heat Treatment

High-Coercivity Cobalt Nanowire Arrays: Synthesis and Heat Treatment

Magnetic Nanowires for Nanobarcoding and Beyond

Crystalline texture of cobalt nanowire arrays probed by the switching field distribution and FORC diagrams

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