Anisotropic plastic deformation by viscous flow in ion tracks

Dillen, T. van; Polman, A.; Onck, Patrick; Giessen, van der Erik

doi:10.1103/physrevb.71.024103

Cited by 62 publications

(82 citation statements)

References 26 publications

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“…We propose that ion irradiation generates biaxial compressive stress in silicon nitride, as it is known to do in other amorphous materials at higher ion energies. 2,3,[9][10][11][12][13][14][15][16][17][18] An analysis of the resulting mechanics provides good agreement with experimentally measured deflection profiles, as well as an explanation for the qualitatively different shapes observed in low-stress and high-stress silicon nitrides.…”

Section: Introductionmentioning

confidence: 57%

“…Differences in the interaction with ion beams for different types of silica have been observed as well, 2 and have been conjectured to be the manifestation of different flow temperatures in the different silicas. 15 A similar explanation for silicon nitride is tenable.…”

Section: ͑14͒mentioning

confidence: 97%

“…10 Comprehensive studies in SiO 2 have afforded a reasonably complete picture of the phenomenon. [11][12][13][14][15][16] Electronic energy loss in the ion track creates a thermal spike accompanied by thermal expansion. Shear stresses relax when the innermost region of the ion track exceeds the "flow temperature;" subsequent thermal contraction during rapid quenching locks in an expansion perpendicular to the ion track.…”

Section: A Simple Mechanical Model For the Membrane Deflectionmentioning

confidence: 99%

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Focused ion beam induced deflections of freestanding thin films

Kim

Chen

Aziz

et al. 2006

Journal of Applied Physics

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Prominent deflections are shown to occur in freestanding silicon nitride thin membranes when exposed to a 50 keV gallium focused ion beam for ion doses between 10 14 and 10 17 ions/ cm 2 . Atomic force microscope topographs were used to quantify elevations on the irradiated side and corresponding depressions of comparable magnitude on the back side, thus indicating that what at first appeared to be protrusions are actually the result of membrane deflections. The shape in high-stress silicon nitride is remarkably flat-topped and differs from that in low-stress silicon nitride. Ion beam induced biaxial compressive stress generation, which is a known deformation mechanism for other amorphous materials at higher ion energies, is hypothesized to be the origin of the deflection. A continuum mechanical model based on this assumption convincingly reproduces the profiles for both low-stress and high-stress membranes and provides a family of unusual shapes that can be created by deflection of freestanding thin films under beam irradiation.

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Section: Introductionmentioning

confidence: 57%

Section: ͑14͒mentioning

confidence: 97%

Section: A Simple Mechanical Model For the Membrane Deflectionmentioning

confidence: 99%

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Focused ion beam induced deflections of freestanding thin films

Kim

Chen

Aziz

et al. 2006

Journal of Applied Physics

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“…Macroscopically, amorphous SiO 2 (a-SiO 2 ) undergoes a volume-conserving anisotropic deformation when subjected to SHII such that thin freestanding layers contract and expand, respectively, in directions parallel and perpendicular to that of the incident ion [1]. The viscoelastic model [2,3], based on a transient thermal effect, successfully explains this so-called ion hammering. Microscopically, energy is deposited along the ion path, from incident ion to matrix electrons, and is then dissipated within a narrow cylinder of material surrounding the ion path.…”

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confidence: 99%

Role of Thermodynamics in the Shape Transformation of Embedded Metal Nanoparticles Induced by Swift Heavy-Ion Irradiation

et al. 2011

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Swift heavy-ion irradiation of elemental metal nanoparticles (NPs) embedded in amorphous SiO 2 induces a spherical to rodlike shape transformation with the direction of NP elongation aligned to that of the incident ion. Large, once-spherical NPs become progressively more rodlike while small NPs below a critical diameter do not elongate but dissolve in the matrix. We examine this shape transformation for ten metals under a common irradiation condition to achieve mechanistic insight into the transformation process. Subtle differences are apparent including the saturation of the elongated NP width at a minimum sustainable, metal-specific value. Elongated NPs of lesser width are unstable and subject to vaporization. Furthermore, we demonstrate the elongation process is governed by the formation of a molten ion-track in amorphous SiO 2 such that upon saturation the elongated NP width never exceeds the molten ion-track diameter. Ion-solid interactions during swift heavy-ion irradiation (SHII) are dominated by inelastic processes in the form of electron excitation and ionization while, in contrast, the influence of elastic processes such as ballistic displacements is negligible. Macroscopically, amorphous SiO 2 (a-SiO 2 ) undergoes a volume-conserving anisotropic deformation when subjected to SHII such that thin freestanding layers contract and expand, respectively, in directions parallel and perpendicular to that of the incident ion [1]. The viscoelastic model [2,3], based on a transient thermal effect, successfully explains this so-called ion hammering. Microscopically, energy is deposited along the ion path, from incident ion to matrix electrons, and is then dissipated within a narrow cylinder of material surrounding the ion path. The heat flow in both the electron and lattice subsystems is well described as functions of time and radial distance by the inelastic thermal spike (i-TS) model [4,5]. When the temperature of the lattice exceeds that required for melting, the material along the ion path is molten and upon quenching an ion track is formed. Recently, we measured the molten ion-track diameter in a-SiO 2 as a function of electronic stopping power [6]. The ion-track radial density distribution consisted of an under-dense core and over-dense shell (relative to unirradiated material), the formation of which was attributed to a quenched-in pressure wave emanating from the ion-track center [6].Elemental metal nanoparticles (NPs) embedded in a-SiO 2 and subjected to SHII can undergo an intriguing shape transformation where once-spherical NPs become progressively more rodlike with the direction of elongation aligned along that of the incident ion. This phenomenon has been reported for several metals under a wide range of SHII conditions, with Refs. [7][8][9][10][11][12][13][14][15][16][17] citing selected examples. Freestanding metallic NPs irradiated under comparable conditions do not change shape, demonstrating the embedding a-SiO 2 matrix must have a role in the shape transformation process [8,17]. An unambiguous ...

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“…According to the thermal spike model [15,22] the anisotropic deformation per unit of deposited energy density can be represented as @A=@S e / a=qC at the same irradiation fluence, where a is the thermal volume expansion coefficient, q is the mass density and C is the specific heat per unit mass. Thus the deformation of PS is larger than for SiO 2 by almost two orders of magnitude [23].…”

Section: Resultsmentioning

confidence: 99%

Anisotropic deformation of polystyrene particles by MeV Au ion irradiation

Liu

Zhao

Chen

et al. 2008

Nuclear Instruments and Methods in Physics Research Section B:

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MeV Au irradiation leads to a shape change of polystyrene (PS) and SiO 2 particles from spherical to ellipsoidal, with an aspect ratio that can be precisely controlled by the ion fluence. Sub-micrometer PS and SiO 2 particles were deposited on copper substrates and irradiated with Au ions at 230 K, using an ion energy and fluence ranging from 2 to 10 MeV and 1 Â 10 14 ions/cm 2 to 1 Â 10 15 ions/cm 2 . The mechanisms of anisotropic deformation of PS and SiO 2 particles are different because of their distinct physical and chemical properties. At the start of irradiation, the volume of PS particles decrease, then the aspect ratio increases with fluence, whereas for SiO 2 particles the volume remains constant.

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Anisotropic plastic deformation by viscous flow in ion tracks

Cited by 62 publications

References 26 publications

Focused ion beam induced deflections of freestanding thin films

Focused ion beam induced deflections of freestanding thin films

Role of Thermodynamics in the Shape Transformation of Embedded Metal Nanoparticles Induced by Swift Heavy-Ion Irradiation

Anisotropic deformation of polystyrene particles by MeV Au ion irradiation

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