Structure cristalline de Gaδ

Bosio, L.; Curien, Hubert; Dupont, M.; Rimsky, Alexandre

doi:10.1107/s0567740873002530

Cited by 69 publications

(39 citation statements)

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“…14,15 In our case, as shown in Figs. 2͑a͒ and 2͑b͒, the nanoparticles having a size of 20 nm present a nice trigonal crystalline order with aϭ9.087 Å, cϭ17.02 Å, spatial group R-3m and with 66 atoms for unit cell.…”

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confidence: 89%

Insight into the premelting and melting processes of metal nanoparticles through capacitance measurements

Parravicini

Stella

Tognini

et al. 2003

Applied Physics Letters

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We demonstrate that capacitance measurements on metallic nanosystems (specifically Ga nanoparticles embedded in dielectric matrix) yield information to clarify the complex phenomenon of melting, where different mechanisms may interplay. The technique is proved to be extremely powerful to study the role of surfaces and interfaces on a twofold basis: very short (of the order of a few angstroms) penetration depth of the probing electric field and a strict relationship of capacity with entropy. We show that initial disorder starts to take place ≈65 °C before full melting, with evidence of two regimes in the premelting and melting region.

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mentioning

confidence: 89%

Insight into the premelting and melting processes of metal nanoparticles through capacitance measurements

Parravicini

Stella

Tognini

et al. 2003

Applied Physics Letters

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“…Ga has two other stable phases at high pressure [19], the GaII, a body-centered cubic structure, and the GaIII, a facecentered tetragonal structure. In addition, a number of metastable phases have also been identified at atmospheric pressure and designated as [20], [21], [22], and [23]. The crystal structure of -Ga is monoclinic.…”

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confidence: 98%

“…The crystal structure of -Ga is monoclinic. It is a metasable phase obtained by supercooling the liquid [22] or by heating amorphous Ga [23]. The crystal structure of -Ga is orthorhombic [21].…”

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confidence: 99%

Unusual Freezing and Melting of Gallium Encapsulated in Carbon Nanotubes

et al. 2004

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The freezing and melting behavior of gallium (Ga) encapsulated in carbon nanotubes was investigated through in situ observation in a transmission electron microscope. It is shown that Ga remains liquid up to -80 degrees C when encapsulated in carbon nanotubes. Results of detailed electron diffraction analysis show that the encapsulated Ga can crystallize in either beta phase or gamma phase rather than the common alpha phase upon freezing. Both beta-Ga and gamma-Ga melt at around -20 degrees C. While this is very close to the melting point of bulk beta-Ga (-16 degrees C), it is considerably higher than that of bulk gamma-Ga (-35.6 degrees C). It was observed that upon solidification, Ga has its unique crystallographic orientation relative to the host carbon nanotube.

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“…3 Results and comments Ga is known to aggregate in different solid phases, depending on the growth conditions and size, named α (stable in bulk) and β, γ, δ, ε (metastable) [14,15].…”

Section: Ga Nanoparticlesmentioning

confidence: 99%

New approach to study melting processes in metal nanoparticles: capacitance measurements

Parravicini

Stella

Ungureanu

et al. 2003

Physica Status Solidi (b)

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Dedicated to Professor Jozef T. Devreese on the occasion of his 65th birthday PACS 64.70.Nd, 65.80.+n, 67.57.Np, 77.22.Ej The size reduction of the nanosystems with respect to macroscopic samples (or also in the micrometric size range) necessarily implies a concomitant and substantial increase of the surface to volume ratio. The surface atoms often play a role in determining or affecting basic properties of the samples investigated. As a consequence, the quest for new techniques specialized to the study of the electrical, optical or thermodynamic behavior of the surfaces or interfaces is becoming progressively more important. By means of capacitance measurements on metallic (specifically Ga) nanoparticles, through the relationship between derivative of the dielectric constant with respect to the temperature and the contribution to entropy due to the applied electric field, we show that initial disorder starts to take place ≈ 65 K before full melting. The premelting region is characterized by two regimes, which will be briefly illustrated.1 Introduction This work is motivated by the quest for new techniques, which can give specific information on the properties of surfaces and interfaces with respect to the bulk. This is becoming crucially important in connection with size reduction and miniaturization of the systems investigated toward the nanometer size range. As a matter of fact, in the case of nanoparticles with radii smaller than 1 µm, the atoms on the surface may reach a population which is ≈50% of the total number of atoms.The recent advances in the preparation of nanosystems offer new opportunities to study the crucial role of surfaces and interfaces in determining phenomena, which are strongly influenced by space confinement. For instance it is well established that thermodynamic properties related to melting show appreciable variations with respect to bulk [1−6]. However there are important aspects, which are still to be clarified: especially the interplay of the different mechanisms for melting (expressed e.g. in terms of Lindeman and Born criteria) has been the object of recent debate and theoretical investigations [7−10]. This is particularly relevant in the nano-size scale, where the role of surfaces and interfaces becomes predominant.

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Structure cristalline de Gaδ

Cited by 69 publications

References 0 publications

Insight into the premelting and melting processes of metal nanoparticles through capacitance measurements

Insight into the premelting and melting processes of metal nanoparticles through capacitance measurements

Unusual Freezing and Melting of Gallium Encapsulated in Carbon Nanotubes

New approach to study melting processes in metal nanoparticles: capacitance measurements

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