Electrochemical characteristics of simple nitrate + amide melts at ambient temperatures

The electroreduction of Co͑II͒ and Co͑II͒ + Sm͑III͒ in urea-acetamide-NaBr-MCl x melts were investigated by cyclic volatmmetry and chronoamperometry. The reduction of Co͑II͒ is an irreversible process. Sm͑III͒ cannot be reduced alone, but Sm-Co can be codeposited by induced deposition. The mechanism may involve a polynuclear complex containing Co͑II͒ and Sm͑III͒. An amorphous Sm-Co film comprised of nanoagglomerates has been synthesized. SEM shows that most of the agglomerates fall within a size range of 20-35 nm with a few agglomerates in the 50-90 nm range. The Sm content in the films varies from 7.9 to 79.16 wt % with the applied potential and the molar ratio of Sm͑III͒/Co͑II͒ in melt. The film could be crystallized by heattreatment at 900°C. Large crystal grains appeared after heat-treatment and their phase was confirmed as Sm 2 Co 17 . In addition, crystalline nanoparticles with the size of 10 nm were found on these large crystal grains. The magnetic properties of the Sm-Co films were determined using hysteresis loops, the coercive field H c of Sm ͑79.16 wt %͒-Co amorphous film is 2300 Oe at 5 K; and the remanent magnetization M R and the saturation magnetization M S are 0.536 and 1.429 emu g −1 , respectively.Rare earth ͑RE͒-transition metal ͑TM͒ alloys have excellent magnetic, optical, and electric properties and have been used to fabricate functional materials. Sm-Co alloys are widely used in permanent magnet applications because of their high-performance intrinsic magnetic properties such as very high Curie temperatures, high anisotropy fields, and relatively high saturation magnetizations. SmCo 5 alloy with the anisotropy larger than 10 8 erg cm −3 is expected to be a potential material for high-density recording media. 1 Permanent magnet materials based on Sm 2 Co 17 compound are the best candidates among all known materials for high-temperature applications. 2 Since the 1990s great progress has been made in the field of magnetic materials through the development of amorphous and nanocrystalline magnetic alloys, for example, the Finemet alloy and Nanoperm alloy which have proven to be excellent soft magnetic materials. 3,4 The amorphous RE-TM alloys, which are generally ferrimagnetic, have been intensively studied because of their potential practical applications. They can be used as magneto-optic recording media 5 because the crystallographic structure of amorphous alloys consists of a random array of atoms with very short-range correlations, leading to randomly distributed local anisotropy directions. 6 An amorphous phase may be used as a precursor to prepare a nanocrystalline structure upon crystallization. 7,8 When a certain amount of nanocrystalline phase is grown within the amorphous phase by annealing, the nanocomposite exhibits some peculiar characteristics which interest both materials scientists and engineers. 9,10 For instance, the exchange-spring magnet is prepared by the novel nanoassembly of known magnetic materials to create a composite with new and improved properties. They are based on...

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“…25 Figure 2 presents the CVs obtained using a Pt working electrode in urea-acetamide-NaBr-CoCl 2 at different scan rates.…”

Section: Resultsmentioning

confidence: 99%

Induced Codeposition of Sm–Co Amorphous Films in Urea Melt and Their Magnetism

Liu

Yang

et al. 2006

J. Electrochem. Soc.

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“…In pure molten urea, only the bulk current is observed, as previously reported. 25 According to, 8,26 the bulk electroreduction of molten urea molecules proceeds through the Eq. 3:…”

Section: Possible Impurities Inducing Peaks C 2 /A 2 -mentioning

confidence: 99%

Voltammetric Response of Water in Deep Eutectic Solvent Based on Choline Chloride and Urea

Bučko¹,

Roy

Valverde-Armas

et al. 2018

J. Electrochem. Soc.

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This work investigates the electrochemical role of water in the research of deep eutectic solvent (DES) based on urea and choline chloride. The motivation comes from the growing use of this DES, and on reports where a characteristic voltammetric cathodic pre-wave is observed. However, there has been no direct study to verify if such interpretation of the pre-wave is appropriate. In this regard, cyclic voltammetry has been used in this paper to interrogate the reactions inducing the appearance of the pre-wave. These experiments have been carried out using reline (the eutectic mixture of urea and choline chloride) melts containing different amounts of water, compounds which can be incorporated as impurities from air, or as decomposition products of reline. The analyses showed that a pre-wave in voltammograms in reline originates from water electroreduction accompanied with a subsequent choline hydroxide formation. In this sense, reline behaves like a typical mixture of organic solvent + alkali cation salt + water. The voltammetric signal depends on water content in reline. Importantly, this offers a possibility for in-situ electrochemical determination of water content in reline, provided that a calibration curve is constructed.

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“…Manganese(1r) chloride was early reported to be highly dissociated in acetamide solution including the original water of hydratioq2 ' and later a 1 : 2 complex was observed to form on direct reaction in refluxing benzene or carbon tetrachloride, the light pink crystals (m.p. 188 "C) 142 having infrared and Raman spectra indicative of oxygen coordination., 5 3 The heat of formation has been calculated from solution data.254…”

Section: ' ~-' ~~mentioning

confidence: 99%

The chemistry of molten acetamide and acetamide complexes

Kerridge¹

1988

Chem. Soc. Rev.

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Electrochemical characteristics of simple nitrate + amide melts at ambient temperatures

Cited by 33 publications

References 9 publications

Induced Codeposition of Sm–Co Amorphous Films in Urea Melt and Their Magnetism

Induced Codeposition of Sm–Co Amorphous Films in Urea Melt and Their Magnetism

Voltammetric Response of Water in Deep Eutectic Solvent Based on Choline Chloride and Urea

The chemistry of molten acetamide and acetamide complexes

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