The compressibility of nanocrystalline Pt

Mikheykin, A.S.; Dmitriev, Vladimir; Chagovets, S. V.; Kuriganova, Alexandra B.; Smirnova, N. V.; Leontyev, Igor N.

doi:10.1063/1.4758000

Cited by 15 publications

(14 citation statements)

References 27 publications

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“…The material is composed of particles of twinned grains in the region where the microstrain shows little dependence on the applied external pressure ( figure 6(a)). The nanoparticle meso-structure commonly observed in fcc metals can be divided into two categories: single and twinned nanocrystals [17]. Single crystalline structures bounded by low index facets represent simple polyhedra (cube, octahedron) and their truncated modifications, while the twinned nanocrystals rather assume the forms of decahedra or icosahedra [17,64].…”

Section: Maud Analysismentioning

confidence: 99%

“…It is known that noble metal nanoparticles, such as Ag, Cu, Pd, and Au, at sizes of 10 nm often possess multiply twinned grains that allow them to adopt shapes and atomic structures not existing in bulk materials [64,65]. The properties exhibited by particles with multiply twinned polycrystalline structures are often far different from those of single-crystalline particles or from the bulk [17,64,65], as the observed distinct stiffness in the EOS of n-Au reveals ( figure 3).…”

Section: Maud Analysismentioning

confidence: 99%

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Pressure-induced stiffness of Au nanoparticles to 71 GPa under quasi-hydrostatic loading

Hong

Duffy

Ehm

et al. 2015

J. Phys.: Condens. Matter

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The compressibility of nanocrystalline gold (n-Au, 20 nm) has been studied by x-ray total scattering using high-energy monochromatic x-rays in the diamond anvil cell under quasi-hydrostatic conditions up to 71 GPa. The bulk modulus, K0, of the n-Au obtained from fitting to a Vinet equation of state is ~196(3) GPa, which is about 17% higher than for the corresponding bulk materials (K0: 167 GPa). At low pressures (<7 GPa), the compression behavior of n-Au shows little difference from that of bulk Au. With increasing pressure, the compressive behavior of n-Au gradually deviates from the equation of state (EOS) of bulk gold. Analysis of the pair distribution function, peak broadening and Rietveld refinement reveals that the microstructure of n-Au is nearly a single-grain/domain at ambient conditions, but undergoes substantial pressure-induced reduction in grain size until 10 GPa. The results indicate that the nature of the internal microstructure in n-Au is associated with the observed EOS difference from bulk Au at high pressure. Full-pattern analysis confirms that significant changes in grain size, stacking faults, grain orientation and texture occur in n-Au at high pressure. We have observed direct experimental evidence of a transition in compressional mechanism for n-Au at ~20 GPa, i.e. from a deformation dominated by nucleation and motion of lattice dislocations (dislocation-mediated) to a prominent grain boundary mediated response to external pressure. The internal microstructure inside the nanoparticle (nanocrystallinity) plays a critical role for the macro-mechanical properties of nano-Au.

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Section: Maud Analysismentioning

confidence: 99%

Section: Maud Analysismentioning

confidence: 99%

Pressure-induced stiffness of Au nanoparticles to 71 GPa under quasi-hydrostatic loading

Hong

Duffy

Ehm

et al. 2015

J. Phys.: Condens. Matter

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“…7,8 Due in part to its simple structure, Pt is widely used in high-pressure experiments as a pressure calibrant and laser absorber. 9 Nanoparticles of Pt 10 and other metals 11 have also been observed to have anomalously low compressibility, and this has possible implications for pressure calibration using metal powders. Recently, Pt has also been used as a deviatoric strain marker: the success of laser annealing or pressure media in minimizing deviatoric stresses has been judged by comparison to the strength of Pt as a function of pressure.…”

Section: Introductionmentioning

confidence: 99%

Strength and texture of Pt compressed to 63 GPa

Dorfman

Shieh

Duffy

2015

Journal of Applied Physics

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Angle-and energy-dispersive X-ray diffraction experiments in a radial geometry were performed in the diamond anvil cell on polycrystalline platinum samples at pressures up to 63 GPa. Observed yield strength and texture depend on grain size. For samples with 70-300-nm particle size, the yield strength is 5-6 GPa at $60 GPa. Coarse-grained ($2-lm particles) Pt has a much lower yield strength of 1-1.5 GPa at $60 GPa. Face-centered cubic metals Pt and Au have lower strength to shear modulus ratio than body-centered cubic or hexagonal close-packed metals. While a 300-nm particle sample exhibits the h110i texture expected of face-centered-cubic metals under compression, smaller and larger particles show a weak mixed h110i and h100i texture under compression. Differences in texture development may also occur due to deviations from uniaxial stress under compression in the diamond anvil cell. V

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“…The measured lattice parameters are 3.9230 (1) Å and 3.9225 (1) Å by PDF fit and Rietveld refinement, respectively. The Rietveld value of 3.9225 (1) Å is somewhat larger than the 3.9178 Å for 10.6 nm Pt 27 , but slightly smaller than the bulk Pt of 3.9231 Å (JCPDS 00-004-0802). This implies that there is no significant structural modification due to the nano-size effect in n-Pt (50 nm) compared to bulk Pt.…”

Section: Resultsmentioning

confidence: 76%

“…Because almost all the EOS parameters have been based on Rietveld refinements so far, we then add the offset of 7.57 × 10 −4 Å to the PDF data (solid circles, Figure 4 ), leading to a good agreement with the data of Rietveld refinements. To get rid of the influence of lattice stiffness caused either by size 27 28 or microstructure (nanocrystallinity) 13 , the EOS curve at 12.35–12.70 GPa is normalized to the average value of Rietveld refinement (right axis, Fig. 4 ) for a direct comparison (right axis, Fig.…”

Section: Resultsmentioning

confidence: 99%

High-energy X-ray focusing and applications to pair distribution function investigation of Pt and Au nanoparticles at high pressures

Hong

Ehm

Zhong

et al. 2016

Sci Rep

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We report development of micro-focusing optics for high-energy x-rays by combining a sagittally bent Laue crystal monchromator with Kirkpatrick-Baez (K–B) X-ray focusing mirrors. The optical system is able to provide a clean, high-flux X-ray beam suitable for pair distribution function (PDF) measurements at high pressure using a diamond anvil cell (DAC). A focused beam of moderate size (10–15 μm) has been achieved at energies of 66 and 81 keV. PDF data for nanocrystalline platinum (n-Pt) were collected at 12.5 GPa with a single 5 s X-ray exposure, showing that the in-situ compression, decompression, and relaxation behavior of samples in the DAC can be investigated with this technique. PDFs of n-Pt and nano Au (n-Au) under quasi-hydrostatic loading to as high as 71 GPa indicate the existence of substantial reduction of grain or domain size for Pt and Au nanoparticles at pressures below 10 GPa. The coupling of sagittally bent Laue crystals with K–B mirrors provides a useful means to focus high-energy synchrotron X-rays from a bending magnet or wiggler source.

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The compressibility of nanocrystalline Pt

Cited by 15 publications

References 27 publications

Pressure-induced stiffness of Au nanoparticles to 71 GPa under quasi-hydrostatic loading

Pressure-induced stiffness of Au nanoparticles to 71 GPa under quasi-hydrostatic loading

Strength and texture of Pt compressed to 63 GPa

High-energy X-ray focusing and applications to pair distribution function investigation of Pt and Au nanoparticles at high pressures

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