Thermal properties of Ag@Ni core-shell nanoparticles

Vykoukal, Vít; Zelenka, František; Buršı́k, Jiřı́; Kaňa, Tomáš; Kroupa, Aleš; Pinkas, Jiří

doi:10.1016/j.calphad.2020.101741

Cited by 11 publications

(6 citation statements)

References 41 publications

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“…A variety of nanomaterials of noble metals are fabricated and characterized by different routes of synthesis. Nowadays, nanoparticles of noble metals, particularly silver and gold nanoparticles, cumulate more popularity in the area of nanomaterials research because of their large surface area-to-volume ratio, which makes the diffusion process faster, their feasibility at a lower temperature, and unique physicochemical properties such as electrical, , thermal, , and optical , properties. For the preparation of silver and gold nanoparticles, their salts are required.…”

Section: Introductionmentioning

confidence: 99%

Growth Kinetic Study of Tannic Acid Mediated Monodispersed Silver Nanoparticles Synthesized by Chemical Reduction Method and Its Characterization

et al. 2021

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The complex process of nanoparticle formation in an aqueous solution is governed by kinetics and thermodynamic factors. This paper describes a room-temperature growth kinetic study and evaluation of thermodynamic activation parameters of monodispersed silver nanoparticles (AgNPs) synthesized in alkaline medium by chemical reduction method using AgNO 3 as a source of Ag + ions and tannic acid (TA) as a reductant (reducing agent) as well as a capping or stabilizing agent in the absence of any other external stabilizer. A simple and conveniently handled reaction process was monitored spectrophotometrically to study the growth kinetics in an aqueous solution as a function of the concentration of silver ion, hydroxide ion, and TA, respectively. The neutral nucleophilic group donates the electron density via a lone pair of electrons to Ag + ions for the reduction process, i.e., for the nucleation of AgNPs colloid. Also, a few silver ions form a silver oxide, which also facilitates the nucleation center to enhance the growth of AgNPs colloid. The decrease and increase in rate constant on varying the TA concentration showed its adsorption onto the surface of metallic AgNPs and stabilized by polygalloyl units of TA and were the main elements to control the growth kinetics. Consequently, stabilized TA-mediated AgNPs are formed using the electron donated by quinone form of TA followed by a pseudo-first-order reaction. Apart from this, nanoparticles formed were characterized using UV–visible spectrophotometry, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and powder X-ray diffraction techniques to confirm its formation during the present kinetic study.

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Section: Introductionmentioning

confidence: 99%

Growth Kinetic Study of Tannic Acid Mediated Monodispersed Silver Nanoparticles Synthesized by Chemical Reduction Method and Its Characterization

et al. 2021

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“…The energies of studied decahedral nanoclusters and nanoparticles were calculated in two different ways which are both connected with quantum-mechanical Density Functional Theory (DFT) [20,21] calculations. The first method is a phenomenological thermodynamic modeling based on the CALPHAD method when the energy of nanoclusters and nanoparticles is approximated by a sum of relevant energy contributions corresponding (i) to a defect-free bulk material and (ii) surface energies and stresses (related to surfaces of a bulk, not nanoparticles) [22][23][24][25][26]. It is customary now that some or all energy contributions used in CALPHAD approach are computed using quantum-mechanical methods.…”

Section: Methodsmentioning

confidence: 99%

“…The phenomenological thermodynamic approach based on the CALPHAD method is very often used for calculations of the total energy of particles as well as for the prediction of phase diagrams [22][23][24][25][26]43]. The computations use an approximation when bulk variables are applied in the case of nanoparticles but not all properties of the (nano-)particles are included (for example, a structural disorder is sometimes omitted).…”

Section: Phenomenological Thermodynamic Modelingmentioning

confidence: 99%

Quantum-Mechanical Assessment of the Energetics of Silver Decahedron Nanoparticles

et al. 2020

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We present a quantum-mechanical study of silver decahedral nanoclusters and nanoparticles containing from 1 to 181 atoms in their static atomic configurations corresponding to the minimum of the ab initio computed total energies. Our thermodynamic analysis compares T = 0 K excess energies (without any excitations) obtained from a phenomenological approach, which mostly uses bulk-related properties, with excess energies from ab initio calculations of actual nanoclusters/nanoparticles. The phenomenological thermodynamic modeling employs (i) the bulk reference energy, (ii) surface energies obtained for infinite planar (bulk-related) surfaces and (iii) the bulk atomic volume. We show that it can predict the excess energy (per atom) of nanoclusters/nanoparticles containing as few as 7 atoms with the error lower than 3%. The only information related to the nanoclusters/nanoparticles of interest, which enters the phenomenological modeling, is the number of atoms in the nanocluster/nanoparticle, the shape and the crystallographic orientation(s) of facets. The agreement between both approaches is conditioned by computing the bulk-related properties with the same computational parameters as in the case of the nanoclusters/nanoparticles but, importantly, the phenomenological approach is much less computationally demanding. Our work thus indicates that it is possible to substantially reduce computational demands when computing excess energies of nanoclusters and nanoparticles by ab initio methods.Relative to the bulk, the {111} facet exhibits the highest density of atoms and the highest coordination number of surface atoms. The most stable structures of fcc nanoclusters include the icosahedron, cuboctahedron and decahedron [8]. Another energy contribution is that related to strain. The strain energy of the particle can be affected by many factors. As the ratio of surface to volume decreases, the effect of surface stress is more significant and leads to the compression of particles [8].Our study is focused on decahedral particles which have very interesting plasmonic and optical properties [16] as well as catalytic possibilities due to high strain energy [9]. The decahedron and icosahedron are inherently strained due to twinning and unfilled volume [17]. In particular, the decahedral nanoclusters are balancing the surface stability of five tetrahedrons (see Figure 1), which exhibit the {111} facets, against the strain energy related to an internal unfilled gap of 7.35 • and distortion induced by their twinned internal structure [9]. The actual shape of the studied nanoparticles can deviate from a prediction by the Wulff construction due to the influence of the internal strain and strain-associated strain energy (in particular in the case of intermediate states [18,19]).

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“…Due to such a small size, the ratio of the specific surface to the volume increases, which leads to a change in the physicochemical properties (catalytic activity, magnetic abilities, thermal characteristics, etc.) in comparison with the properties of bulk samples of the same material [1][2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Obtaining nickel nanoparticles by the gas-phase method - induction flow levitation

et al. 2023

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In this paper, we consider the possibility of obtaining nickel nanoparticles from a bulk sample by the method of induction flow levitation. This method is based on non-contact heating and holding a metal sample in a state of levitation by a high-frequency electromagnetic field. The generator power was 10 kW and the frequency was 440 kHz. The synthesis took place at a temperature of 1800°C with a feeding rate of 3 g/h. Argon was used as the refrigerant gas, the pressure in the system was maintained at 400 mbar. The resulting nanoparticles were characterized by size using SEM and TEM micrographs, where the average size of the nanoparticles was ~16 nm. XRF and SEM-EDS, the results showed the presence of only metallic nickel and oxygen in the nanoparticles.

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Thermal properties of Ag@Ni core-shell nanoparticles

Cited by 11 publications

References 41 publications

Growth Kinetic Study of Tannic Acid Mediated Monodispersed Silver Nanoparticles Synthesized by Chemical Reduction Method and Its Characterization

Growth Kinetic Study of Tannic Acid Mediated Monodispersed Silver Nanoparticles Synthesized by Chemical Reduction Method and Its Characterization

Quantum-Mechanical Assessment of the Energetics of Silver Decahedron Nanoparticles

Obtaining nickel nanoparticles by the gas-phase method - induction flow levitation

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