Discrete Periodic Melting Point Observations for Nanostructure Ensembles

Efremov, Mikhail Yu.; Schiettekatte, F.; Zhang, M.; Olson, E. A.; Kwan, A. T.; Berry, R. Stephen; Allen, L. H.

doi:10.1103/physrevlett.85.3560

Cited by 130 publications

(73 citation statements)

References 28 publications

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“…Allen and co-workers developed a suitable experimental technique to study the calorimetry of the melting process in nanoparticles and found that both the melting temperature and the latent heat of fusion depend on the particle size. [38][39][40] Here we calculate the molar heat of fusion and molar entropy of fusion for Ag nanoparticles, and the results are shown in Fig. 9.…”

Section: Silver Nanoparticlesmentioning

confidence: 99%

Thermodynamic Properties of Nano-Silver and Alloy Particles

Hu¹,

Xiao²,

Deng³

et al. 2010

Silver Nanoparticles

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In this chapter, the analytical embedded atom method and calculating Gibbs free energy method are introduced briefly. Combining these methods with molecular dynamic and Monte Carlo techniques, thermodynamics of nano-silver and alloy particles have been studied systematically. For silver nanoparticles, calculations for melting temperature, molar heat of fusion, molar entropy of fusion, and temperature dependences of entropy and specific heat capacity indicate that these thermodynamic properties can be divided into two parts: bulk quantity and surface quantity, and surface atoms are dominant for the size effect on the thermodynamic properties of nanoparticles. Isothermal grain growth behaviors of nanocrystalline Ag shows that the small grain size and high temperature accelerate the grain growth. The grain growth processes of nanocrystalline Ag are well characterized by a power-law growth curve, followed by a linear relaxation stage. Beside grain boundary migration and grain rotation mechanisms, the dislocations serve as the intermediate role in the grain growth process. The isothermal melting in nanocrystalline Ag and crystallization from supercooled liquid indicate that melting at a fixed temperature in nanocrystalline materials is a continuous process, which originates from the grain boundary network. The crystallization from supercooled liquid is characterized by three characteristic stages: nucleation, rapid growth of nucleus, and slow structural relaxation. The homogeneous nucleation occurs at a larger supercooling temperature, which has an important effect on the process of crystallization and the subsequent crystalline texture. The kinetics of transition from liquid to solid is well described by the Johnson-Mehl-Avrami equation. By extrapolating the mean grain size of nanocrystal to an infinitesimal value, we have obtained amorphous model from Voronoi construction. From nanocrystal to amorphous state, the curve of melting temperature exhibits three characteristic regions. As mean grain size above about 3.8 nm for Ag, the melting temperatures decrease linearly with the reciprocal of grain size. With further decreasing grain size, the melting temperatures almost keep a constant. This is because the dominant factor on melting temperature of nanocrystal shifts from grain phase to grain boundary one. As a result of fundamental difference in structure, the amorphous has a much lower solid-to-liquid transformation temperature than that of nanocrystal.

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Section: Silver Nanoparticlesmentioning

confidence: 99%

Thermodynamic Properties of Nano-Silver and Alloy Particles

Hu¹,

Xiao²,

Deng³

et al. 2010

Silver Nanoparticles

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show abstract

“…Due to the small thermal mass of the sensors, very fast heating rates can be achieved that minimize heat loss to the environment. For instance, the nanocalorimetry sensor originally developed by Allen and coworkers can attain heating rates as large as 10 5 K/s and has been used to perform very precise heat capacity measurements on nanoparticles 3,4 and ultrathin polymer films. [5][6][7] Schick et al have developed a different sensor that can operate under non-adiabatic conditions with controlled heating and cooling rates in the range of 10 3 K/s.…”

Section: Introductionmentioning

confidence: 99%

Scanning AC nanocalorimetry combined with in-situ x-ray diffraction

Xiao

Gregoire

McCluskey

et al. 2013

Journal of Applied Physics

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Micromachined nanocalorimetry sensors have shown excellent performance for high-temperature and high-scanning rate calorimetry measurements. Here, we combine scanning AC nanocalorimetry with in-situ x-ray diffraction (XRD) to facilitate interpretation of the calorimetry measurements. Time-resolved XRD during in-situ operation of nanocalorimetry sensors using intense, high-energy synchrotron radiation allows unprecedented characterization of thermal and structural material properties. We demonstrate this experiment with detailed characterization of the melting and solidification of elemental Bi, In, and Sn thin-film samples, using heating and cooling rates up to 300 K/s. Our experiments show that the solidification process is distinctly different for each of the three samples. The experiments are performed using a combinatorial device that contains an array of individually addressable nanocalorimetry sensors. Combined with XRD, this device creates a new platform for high-throughput mapping of the composition dependence of solid-state reactions and phase transformations. V C 2013 AIP Publishing LLC.

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“…This type of sensor has the capability of measuring incremental changes in sample thickness of the order of 0.004 nm [12]. It should be noted that in previous nanocalorimetry experiments involving thin metal films, [9][10][11][12], the thickness of the membrane was about 30-50 nm. The sensors used in this work have a 10-fold increase of membrane thickness.…”

Section: Methodsmentioning

confidence: 99%

“…The operation and fabrication of the nanocalorimetry device and technique are described in detail elsewhere [7][8][9][10][11][12]. Here we give an abridged description of the technique.…”

Section: Methodsmentioning

confidence: 99%

Glass transition of thin films of poly(2-vinyl pyridine) and poly(methyl methacrylate): nanocalorimetry measurements

et al. 2003

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Glass transitions were observed in thin films of poly(2-vinyl pyridine) (P2VP) and poly(methyl methacrylate) (PMMA) using a scanning nanocalorimetry technique which has both high sensitivity (10 −9 J/K) and high scan rates (10 4 -10 5 K/s). Samples were deposited by the spin-cast method. The thickness of samples was 100-400 nm. Glass transition temperature, obtained by nanocalorimetry, is shifted toward higher temperatures by 10-20 K and activation enthalpy of glass transition is shifted to lower values by factor of 2-4. The glass transition characteristics of both polymers are discussed in terms of the standard Tool-Narayanaswamy-Moynihan (TNM) multi-parameter model.

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Discrete Periodic Melting Point Observations for Nanostructure Ensembles

Cited by 130 publications

References 28 publications

Thermodynamic Properties of Nano-Silver and Alloy Particles

Thermodynamic Properties of Nano-Silver and Alloy Particles

Scanning AC nanocalorimetry combined with in-situ x-ray diffraction

Glass transition of thin films of poly(2-vinyl pyridine) and poly(methyl methacrylate): nanocalorimetry measurements

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