Heat capacity enhancement and thermodynamic properties of nanostructured amorphous SiO2

Wang, Lan; Tan, Zhi‐Cheng; Sun, Meng; Дружинина, А.И.; Varushchenko, Raisa A; Li, Guanghai

doi:10.1016/s0022-3093(01)00902-4

Cited by 39 publications

(33 citation statements)

References 16 publications

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“…The specific heat of metal nanocrystals has been revealed to be enhanced in comparison with the bulk crystals at low temperatures due to the presence of surfaces, interfaces, or grain boundaries [1][2][3][4][5][6][7][8]. The Debye's T 3 law, which is very efficient to describe the specific heat of the three-dimensional high-symmetry bulk crystals, is often applied to explain the enhanced specific heat of nanocrystals [7,8].…”

Section: Introductionmentioning

confidence: 99%

Surface specific heats of metal nanocrystals at low temperatures

Lei

Luo

2015

Nanoscale

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In order to quantitatively explain the enhanced specific heat of metal nanocrystals measured from 4.2 K to 80 K, an analytical expression has been deduced to determine the surface specific heat in nanocrystals, which is proportional to T(2.5) at low temperatures. The consequently calculated specific heat and surface Debye temperature of copper nanocrystals are in good agreement with the experimental data. This explains why the experimental specific heat of copper nanocrystals is enhanced with respect to the bulk and why it exhibits a different feature as a function of temperature from that of the bulk at low temperatures. The first experimental evidence is presented that the spatial dimension of surfaces should be neither pure 2D nor 3D, but between 2D and 3D, due to the effect of atoms in the core of the nanocrystals.

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Section: Introductionmentioning

confidence: 99%

Surface specific heats of metal nanocrystals at low temperatures

Lei

Luo

2015

Nanoscale

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“…enhancement of specific heat at constant pressure, C P . This enhancement has been observed for nanocrystalline, quasicrystalline and amorphous structures [1,2,3]. In this paper, measurements of C P for amorphous, nanocrystalline and fully crystalline Fe 60 Co 18 Nb 6 B 16 alloy are reported.…”

mentioning

confidence: 67%

Nanocrystallization effects on the specific heat of Fe–Co–Nb–B amorphous alloy

Blázquez¹,

Millán²,

Conde³

et al. 2008

Journal of Non-Crystalline Solids

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Specific heat at constant pressure, C P , was measured on amorphous, nanocrystalline and fully crystalline samples of Fe 60 Co 18 Nb 6 B 16 alloy. Magnetic and calorimetric measurements agree, describing a continuously decreasing Curie temperature of the amorphous phase. A clear enhancement of C P over the Dulong-Pettit limit has been observed (from 14 to 25 %).Part of the enhancement is due to magnetic (mainly amorphous phase) and electronic contributions, although an excess volume can be inferred from the high value of the slope of C P versus temperature.

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“…5) which resulted in a value of 11 and 19 % of SiO 2 for the samples with smaller and larger nanocrystallite sizes, respectively, differing only slightly from the value extracted from the PDF refinement (9.6 and 15 %). This deviation occurred because two contributions to the heat capacities at low temperatures were not considered in this fit: the electronic contribution due to a high concentration of dopants, and nanostructuration as previously observed for SiO 2 [36].…”

Section: Influence Of Oxide Impurities On Heat Capacitymentioning

confidence: 98%

Effects of impurities on the lattice dynamics of nanocrystalline silicon for thermoelectric application

et al. 2012

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Doped silicon nanoparticles were exposed to air and sintered to form nanocrystalline silicon. The composition, microstructure, and structural defects were investigated with TEM, XRD, and PDF and the lattice dynamics was evaluated with measurements of the heat capacity, of the elastic constants with resonant ultrasound spectroscopy and of the density of phonon states (DPS) with inelastic neutron scattering. The results were combined and reveal that the samples contain a large amount of silicon dioxide and exhibit properties that deviate from bulk silicon. Both in the reduced DPS and in the heat capacity a Boson peak at low energies, characteristic of amorphous SiO 2 , is observed. The thermal conductivity is strongly reduced due to nanostructuration and the incorporation of impurities.

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Heat capacity enhancement and thermodynamic properties of nanostructured amorphous SiO2

Cited by 39 publications

References 16 publications

Surface specific heats of metal nanocrystals at low temperatures

Surface specific heats of metal nanocrystals at low temperatures

Nanocrystallization effects on the specific heat of Fe–Co–Nb–B amorphous alloy

Effects of impurities on the lattice dynamics of nanocrystalline silicon for thermoelectric application

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