Size-dependent melting point of noble metals

Jiang, Q.; Zhang, S; Zhao, Ming-Chun

doi:10.1016/s0254-0584(03)00201-3

Cited by 175 publications

(107 citation statements)

References 14 publications

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“…The lower melting point compared to the bulk material is due to the large surface-to-volume ratio, which results in an increase in the surface free energy of the particles [17]. Several calculations were made to determine the melting point of nanoparticles with different size and shape [13,14,[18][19][20]. For bulk gold the melting point is at 1064 °C [21], whereas for gold nanoparticles it can be found below this value.…”

Section: Introductionmentioning

confidence: 99%

Thermal stability of mesoporous silica-coated gold nanorods with different aspect ratios

Gergely-Fülöp

Zámbó

Deák

2014

Materials Chemistry and Physics

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The effect of different temperatures (up to 900 °C) on the morphology of mesoporous silicacoated gold nanorods was systematically investigated. Gold nanorods with different aspect ratios (AR ranging from 2.5 to 4.3) were coated with a 15 nm thick mesoporous silica shell.Silicon supported monolayers of the particles were annealed in the temperature range of 300-900 °C. The resulting changes in particle morphology were investigated using scanning electron microscopy and visible wavelength extinction spectroscopy. The silica coating generally improved the stability of the nanorods from ca. 250 °C by several hundreds degree Celsius. For nanorods with AR<3 the shape and the aspect ratio change is only moderate up to 700 °C. At 900 °C these nanorods became spherical. For nanorods with AR>3, lower stability was found as the aspect ratio decrease was more significant and they transformed into spherical particles already at 700 °C. It was confirmed by investigating empty silica shells that the observed conformal change of the shell material when annealing core/shell particles is dictated by the deformation of the core particle. This also implies that a significant mechanical stress is exerted on the shell upon core deformation. In accordance with this, for the highest aspect ratio (AR~4) nanorod the shell breaks up at 900 °C and the gold cores were partially released and coalesced into large spherical particles.

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Section: Introductionmentioning

confidence: 99%

Thermal stability of mesoporous silica-coated gold nanorods with different aspect ratios

Gergely-Fülöp

Zámbó

Deák

2014

Materials Chemistry and Physics

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“…This shift is due to melting and subsequent movement of extremely small Au NCs during anneal. Although Au NC anneal temperature is significantly lower than the bulk melting point of Au, due to their small size, the melting point of the NCs is much lower than that of the bulk material [21], [22]. Due to the size-dependent melting temperature, it is possible to melt the smallest Au NCs during NC anneal step, causing them to coalesce together.…”

Section: A Physical Characterizationmentioning

confidence: 99%

“…EDX taken at the center of NC (position 3) is also shown for comparison. Lower melting point of Au NC [21], [22] compared to bulk Au metal causes diffusion of metal atoms into the gate dielectric during NC anneal. Post (Al 2 O 3 ) deposition anneal is also suspected to cause the diffusion of the metal atoms in the film, but the effect is significantly smaller.…”

Section: Physical Failure Mechanismmentioning

confidence: 99%

Performance and Reliability of Au and Pt Single-Layer Metal Nanocrystal Flash Memory Under nand (FN/FN) Operation

Singh

Hofmann

Singh

et al. 2009

IEEE Trans. Electron Devices

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Abstract-In this paper, we report on the fabrication and reliability characterization of gold (Au) and platinum (Pt) single-layer nanocrystal (NC)-based Flash memory devices for NAND application. The devices are fabricated using a CMOS-compatible process flow with high-quality (low leakage and large breakdown) Al 2 O 3 as the control dielectric. The impact of processing conditions on the NC size, area coverage, and number density is also investigated. Large memory window (∼7.5 V for Au and ∼10 V for Pt) and good retention are observed for both Au and Pt NC devices. Excellent postcycling retention is also noted for Pt NC devices. Endurance characteristics are found to be of concern as maximum of only 1 × 10 3 and 4 × 10 3 cycles can be obtained for Au and Pt devices, respectively. Anneal-temperature-dependent gate leakage is observed in Au devices and is investigated using analytical methods. Diffusion of Au atoms from the NC into the gate dielectrics is seen which correlates to the electrical measurements. Postcycling retention and program/erase of Pt NC devices are shown to be good.Index Terms-Cycling endurance, Flash memory, memory window, metal nanocrystals (NCs), reliability failure, retention, transmission electron microscopy (TEM)/electron diffraction (EDX).

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“…Commercial silver pastes and inks generally provide thin film conductivity up to 2000 S cm À1 , even with annealing temperatures as high as 4200 C [2]. Since the melting points of metal particles drops drastically in the nanometer regime (520 nm), it would thus be possible to significantly lower the annealing temperature of Ag-NPs by reducing their particle size [3,4]. However, the preparation of stabilised Ag-NPs in the sub-10 nm range necessary to enable low-temperature coalescences to conductive elements remains a synthetic challenge.…”

Section: Introductionmentioning

confidence: 99%

Facile chemical synthesis of nano-silver powders for printable electronics applications

Sahoo

Kamal

Shankar

et al. 2012

Journal of Experimental Nanoscience

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In this article, a simple and reproducible technique for the synthesis of silver nanoparticles in organic phase without using external reducing agents is reported. The organic phase contains silver acetate as precursor, oleic acid and oleyl amine as capping molecules and diphenyl ether as solvent. Monodispersed silver nanoparticles with an average size of 5 nm could be easily synthesised at large scale and it was possible to isolate the particles suitable for electronics applications. The formation of silver nanoparticles has been characterised in terms of optical absorption, transmission electron microscopy images and smallangle X-ray scattering. Recovered silver nanoparticles reveal X-ray diffraction of a well grown-up fcc-Ag lattice. Chemical and thermal characterisations of silver nanopowders were carried out using X-ray photoelectron spectroscopy and thermogravimetric analysis, respectively. For the latter purpose, concentrated dispersions of silver nanoparticles were prepared and used for depositing uniform thin layers. Thin films were sintered at low temperature to obtain conductive films and the films were characterised using scanning electron microscope. Electrical conductivity of the conductive films was in the range 2-3 Â 10 4 S cm À1 .

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Size-dependent melting point of noble metals

Cited by 175 publications

References 14 publications

Thermal stability of mesoporous silica-coated gold nanorods with different aspect ratios

Thermal stability of mesoporous silica-coated gold nanorods with different aspect ratios

Performance and Reliability of Au and Pt Single-Layer Metal Nanocrystal Flash Memory Under nand (FN/FN) Operation

Facile chemical synthesis of nano-silver powders for printable electronics applications

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