11 research outputs found
Photoconductive CdSe Nanowire Arrays, Serpentines, and Loops Formed by Electrodeposition on Self-Organized Carbon Nanotubes
Semiconducting nanowires frequently have enhanced properties
and
unique functionality compared to their bulk counterparts. Controlling
the geometry of nanowires is crucial for their integration into nanoscale
devices because the shape of a device component can dictate its functionality,
such as in the case of a mechanical spring or an antenna. We demonstrate
a novel synthetic method for making polycrystalline CdSe nanowires
with controlled geometries by using self-organized single-walled carbon
nanotubes as a template for the selective electrodeposition of nanowires.
Nanowires of up to hundreds of micrometers in length are formed as
high-density straight arrays, as well as in the shape of serpentines
and loops. These nanowires exhibit significant photoluminescence and
photoconductivity applicable to photodetectors and respond to illumination
up to 2 orders of magnitude faster than single crystalline CdSe
Microstructure versus Flaw: Mechanisms of Failure and Strength in Nanostructures
Understanding failure in nanomaterials
is critical for the design
of reliable structural materials and small-scale devices with nanoscale
components. No consensus exists on the effect of flaws on fracture
at the nanoscale, but proposed theories include nanoscale flaw tolerance
and maintaining macroscopic fracture relationships at the nanoscale
with scarce experimental support. We explore fracture in nanomaterials
using nanocrystalline Pt nanocylinders with prefabricated surface
notches created using a “paused” electroplating method.
In situ scanning electron microscopy (SEM) tension tests demonstrate
that the majority of these samples failed at the notches, but that
tensile failure strength is independent of whether failure occurred
at or away from the flaw. Molecular dynamics simulations verify these
findings and show that local plasticity is able to reduce stress concentration
ahead of the notch to levels comparable with the strengths of microstructural
features (e.g., grain boundaries). Thus, failure occurs at the stress
concentration with the highest local stress whether this is at the
notch or a microstructural feature
Microstructure versus Flaw: Mechanisms of Failure and Strength in Nanostructures
Understanding failure in nanomaterials
is critical for the design
of reliable structural materials and small-scale devices with nanoscale
components. No consensus exists on the effect of flaws on fracture
at the nanoscale, but proposed theories include nanoscale flaw tolerance
and maintaining macroscopic fracture relationships at the nanoscale
with scarce experimental support. We explore fracture in nanomaterials
using nanocrystalline Pt nanocylinders with prefabricated surface
notches created using a “paused” electroplating method.
In situ scanning electron microscopy (SEM) tension tests demonstrate
that the majority of these samples failed at the notches, but that
tensile failure strength is independent of whether failure occurred
at or away from the flaw. Molecular dynamics simulations verify these
findings and show that local plasticity is able to reduce stress concentration
ahead of the notch to levels comparable with the strengths of microstructural
features (e.g., grain boundaries). Thus, failure occurs at the stress
concentration with the highest local stress whether this is at the
notch or a microstructural feature
Microstructure versus Flaw: Mechanisms of Failure and Strength in Nanostructures
Understanding failure in nanomaterials
is critical for the design
of reliable structural materials and small-scale devices with nanoscale
components. No consensus exists on the effect of flaws on fracture
at the nanoscale, but proposed theories include nanoscale flaw tolerance
and maintaining macroscopic fracture relationships at the nanoscale
with scarce experimental support. We explore fracture in nanomaterials
using nanocrystalline Pt nanocylinders with prefabricated surface
notches created using a “paused” electroplating method.
In situ scanning electron microscopy (SEM) tension tests demonstrate
that the majority of these samples failed at the notches, but that
tensile failure strength is independent of whether failure occurred
at or away from the flaw. Molecular dynamics simulations verify these
findings and show that local plasticity is able to reduce stress concentration
ahead of the notch to levels comparable with the strengths of microstructural
features (e.g., grain boundaries). Thus, failure occurs at the stress
concentration with the highest local stress whether this is at the
notch or a microstructural feature
Microstructure versus Flaw: Mechanisms of Failure and Strength in Nanostructures
Understanding failure in nanomaterials
is critical for the design
of reliable structural materials and small-scale devices with nanoscale
components. No consensus exists on the effect of flaws on fracture
at the nanoscale, but proposed theories include nanoscale flaw tolerance
and maintaining macroscopic fracture relationships at the nanoscale
with scarce experimental support. We explore fracture in nanomaterials
using nanocrystalline Pt nanocylinders with prefabricated surface
notches created using a “paused” electroplating method.
In situ scanning electron microscopy (SEM) tension tests demonstrate
that the majority of these samples failed at the notches, but that
tensile failure strength is independent of whether failure occurred
at or away from the flaw. Molecular dynamics simulations verify these
findings and show that local plasticity is able to reduce stress concentration
ahead of the notch to levels comparable with the strengths of microstructural
features (e.g., grain boundaries). Thus, failure occurs at the stress
concentration with the highest local stress whether this is at the
notch or a microstructural feature
Microstructure versus Flaw: Mechanisms of Failure and Strength in Nanostructures
Understanding failure in nanomaterials
is critical for the design
of reliable structural materials and small-scale devices with nanoscale
components. No consensus exists on the effect of flaws on fracture
at the nanoscale, but proposed theories include nanoscale flaw tolerance
and maintaining macroscopic fracture relationships at the nanoscale
with scarce experimental support. We explore fracture in nanomaterials
using nanocrystalline Pt nanocylinders with prefabricated surface
notches created using a “paused” electroplating method.
In situ scanning electron microscopy (SEM) tension tests demonstrate
that the majority of these samples failed at the notches, but that
tensile failure strength is independent of whether failure occurred
at or away from the flaw. Molecular dynamics simulations verify these
findings and show that local plasticity is able to reduce stress concentration
ahead of the notch to levels comparable with the strengths of microstructural
features (e.g., grain boundaries). Thus, failure occurs at the stress
concentration with the highest local stress whether this is at the
notch or a microstructural feature
Microstructure versus Flaw: Mechanisms of Failure and Strength in Nanostructures
Understanding failure in nanomaterials
is critical for the design
of reliable structural materials and small-scale devices with nanoscale
components. No consensus exists on the effect of flaws on fracture
at the nanoscale, but proposed theories include nanoscale flaw tolerance
and maintaining macroscopic fracture relationships at the nanoscale
with scarce experimental support. We explore fracture in nanomaterials
using nanocrystalline Pt nanocylinders with prefabricated surface
notches created using a “paused” electroplating method.
In situ scanning electron microscopy (SEM) tension tests demonstrate
that the majority of these samples failed at the notches, but that
tensile failure strength is independent of whether failure occurred
at or away from the flaw. Molecular dynamics simulations verify these
findings and show that local plasticity is able to reduce stress concentration
ahead of the notch to levels comparable with the strengths of microstructural
features (e.g., grain boundaries). Thus, failure occurs at the stress
concentration with the highest local stress whether this is at the
notch or a microstructural feature
Microstructure versus Flaw: Mechanisms of Failure and Strength in Nanostructures
Understanding failure in nanomaterials
is critical for the design
of reliable structural materials and small-scale devices with nanoscale
components. No consensus exists on the effect of flaws on fracture
at the nanoscale, but proposed theories include nanoscale flaw tolerance
and maintaining macroscopic fracture relationships at the nanoscale
with scarce experimental support. We explore fracture in nanomaterials
using nanocrystalline Pt nanocylinders with prefabricated surface
notches created using a “paused” electroplating method.
In situ scanning electron microscopy (SEM) tension tests demonstrate
that the majority of these samples failed at the notches, but that
tensile failure strength is independent of whether failure occurred
at or away from the flaw. Molecular dynamics simulations verify these
findings and show that local plasticity is able to reduce stress concentration
ahead of the notch to levels comparable with the strengths of microstructural
features (e.g., grain boundaries). Thus, failure occurs at the stress
concentration with the highest local stress whether this is at the
notch or a microstructural feature
Microstructure versus Flaw: Mechanisms of Failure and Strength in Nanostructures
Understanding failure in nanomaterials
is critical for the design
of reliable structural materials and small-scale devices with nanoscale
components. No consensus exists on the effect of flaws on fracture
at the nanoscale, but proposed theories include nanoscale flaw tolerance
and maintaining macroscopic fracture relationships at the nanoscale
with scarce experimental support. We explore fracture in nanomaterials
using nanocrystalline Pt nanocylinders with prefabricated surface
notches created using a “paused” electroplating method.
In situ scanning electron microscopy (SEM) tension tests demonstrate
that the majority of these samples failed at the notches, but that
tensile failure strength is independent of whether failure occurred
at or away from the flaw. Molecular dynamics simulations verify these
findings and show that local plasticity is able to reduce stress concentration
ahead of the notch to levels comparable with the strengths of microstructural
features (e.g., grain boundaries). Thus, failure occurs at the stress
concentration with the highest local stress whether this is at the
notch or a microstructural feature
Effects of Helium Implantation on the Tensile Properties and Microstructure of Ni<sub>73</sub>P<sub>27</sub> Metallic Glass Nanostructures
We report fabrication and nanomechanical
tension experiments on
as-fabricated and helium-implanted ∼130 nm diameter Ni<sub>73</sub>P<sub>27</sub> metallic glass nanocylinders. The nanocylinders
were fabricated by a templated electroplating process and implanted
with He<sup>+</sup> at energies of 50, 100, 150, and 200 keV to create
a uniform helium concentration of ∼3 atom % throughout the
nanocylinders. Transmission electron microscopy imaging and through-focus
analysis reveal that the specimens contained ∼2 nm helium bubbles
distributed uniformly throughout the nanocylinder volume. In situ
tensile experiments indicate that helium-implanted specimens exhibit
enhanced ductility as evidenced by a 2-fold increase in plastic strain
over as-fabricated specimens with no sacrifice in yield and ultimate
tensile strengths. This improvement in mechanical properties suggests
that metallic glasses may actually exhibit a favorable response to
high levels of helium implantation