Researchers produced magnesium, magnesium oxide (MgO), and magnesium hydride (MgH2) nanostructures using rapid thermal processing (RTP) to evaluate it as a scalable synthesis method. Electron energy loss spectroscopy (EELS) and X-ray energy dispersive spectroscopy (EDS) confirmed the presence of MgO and possibly MgH2 in the samples. The temperature and atmosphere during RTP affected the morphology and composition of the resulting nanostructures. Higher temperatures produced nanostructures with well-defined facets, while longer hold times allowed structures to fully form. Future work will optimize shape, composition reproducibility, and determine the growth mechanism.

1. Magnesium-Based NanostructuresMagnesium-Based Nanostructures
Produced by Rapid Thermal ProcessingProduced by Rapid Thermal Processing
Leland Lam1, Jean L. Lee1 , Tev Kuykendall2 , Jeff Urban2Leland Lam1, Jean L. Lee1 , Tev Kuykendall2 , Jeff Urban2
1California Polytechnic University San Luis Obispo, 2 Lawrence Berkeley National Laboratory1California Polytechnic University San Luis Obispo, 2 Lawrence Berkeley National Laboratory
Abstract Research Question Traces of MgH
A variety of magnesium, magnesium oxide (MgO), and How do the parameters used during rapid thermal processing affect the
Abstract Research Question Traces of MgH2
Hydrogen MgO Element Atomic %
A variety of magnesium, magnesium oxide (MgO), and
magnesium hydride (MgH2) nanostructures were
produced via rapid thermal processing (RTP) to evaluate
How do the parameters used during rapid thermal processing affect the
structure and composition of the resulting nanostructures? 1600
1800
2000
Hydrogen
~13.6 eV
MgO
~22 eV Mg
Element Atomic %
O K 24.35
Mg K 33.47
Cu K 42.18
produced via rapid thermal processing (RTP) to evaluate
it as a scalable synthesis method. The thermal cycle and
atmosphere composition during processing were
structure and composition of the resulting nanostructures?
Observed Structures
800
1000
1200
1400
1600
Intensity
Cu
O
Cu
RTP in H2
atmosphere composition during processing were
hypothesized as key factors determining the types of
nanostructures produced. Electron energy loss
spectroscopy (EELS) and X-ray energy dispersive 0
200
400
600
800
Intensity
Cu
Cu
650
spectroscopy (EELS) and X-ray energy dispersive
spectroscopy (EDS) support the existence of both MgO
and MgH in the samples. Nanoscale morphology
0
0 5 10 15 20 25 30 35 40 45
Energy (eV)
650
and MgH2 in the samples. Nanoscale morphology
appears to be more strongly dependent on temperature
than time. Facets were more apparent on nanostructures
A network of MgO nanocubes were deposited onto a
transmission electron microscopy (TEM) copper grid in a
hydrogen atmosphere and imaged using TEM (right inset).°C)than time. Facets were more apparent on nanostructures
grown at high temperatures. These facets and the
agglomeration observed of the MgO nanoparticles
hydrogen atmosphere and imaged using TEM (right inset).
The peak at 22 eV in the EELS spectrum (left) and the
presence of oxygen and magnesium in the X-ray energy
Shells (50 – 100 μm) Prism (15-60 μm)Sphere (6- 25 μm)Facetted Cluster (10-25μm)
HoldTemperature(°
agglomeration observed of the MgO nanoparticles
suggest that minimizing surface energy determines
structure shape. Future work aims to increase
reproducibility and determine the mechanism of growth
presence of oxygen and magnesium in the X-ray energy
dispersive spectrum (EDS) (right) confirm the presence of
MgO. The slight hydrogen peak at 13.6 eV in the EELS
spectrum and the non-stoichiometric ratio of oxygen to
HoldTemperature(
600
reproducibility and determine the mechanism of growth
of the observed structures.
spectrum and the non-stoichiometric ratio of oxygen to
magnesium suggest the possible presence of MgH2 .
HoldTemperature(
MgO nanoparticles can be used for carbon capture and
Background Possible MgO Self-AssemblyFacettedCluster
Agglomeration(10-30μm)Sphere (8 – 25 μm)
HoldTemperature(
MgO nanoparticles can be used for carbon capture and
catalysis. MgH2 with its relatively high hydrogen capacity
has potential in hydrogen storage devices. Before the
550
has potential in hydrogen storage devices. Before the
benefits of these and other nanoparticles can be
realized, scalable synthesis methods must be in place.realized, scalable synthesis methods must be in place.
Processes that can produce nanomaterials with consistent
and tunable properties (size, shape, composition) are the
key to commercializing nanomaterials.
Un-facettedClusters(5-8μm) Shells (20 – 100 μm)Partial Prism (1-10 μm)
Un-facetted
Clusters(1-10μm)
20 100 180
Hold Time (s)
and tunable properties (size, shape, composition) are the
key to commercializing nanomaterials.
Rapid Thermal Processing Initial EDS data suggest that the structures grown in the N2Hold Time (s)Rapid Thermal Processing
Implications and Future Work
Initial EDS data suggest that the structures grown in the N2
atmosphere are formed from the MgO nanoparticle network.
RTP in N
The structures formed at higher temperatures appeared to
have more clearly defined facets. These facets are more
Implications and Future WorkRTP in N2
The structures formed at higher temperatures appeared to
have more clearly defined facets. These facets are more
pronounced in nanostructures produced in H2. MgO grown
in N2 display well-defined facets in larger structures. These
Magnesium + silicon
substrates in alumina boat
650
in N2 display well-defined facets in larger structures. These
facets are indicative of the dominance of the
thermodynamically favorable, low index planes of MgO. The
substrates in alumina boat
H2 or N2
650
Un-facettedClustersUn-facetted ClusterAssemblage of MgO
thermodynamically favorable, low index planes of MgO. The
formation of structures with facets occurs at higher
temperatures when diffusion is more likely to occur. MgO
nanoparticle agglomeration into larger structures is
Example RTP Temperature Cycle
1. Ramp to 650
H2 or N2
(°C)
Un-facettedClusters
formingPrism(14-25μm)
Un-facetted Cluster
Agglomeration (5-30 μm)
Assemblage of MgO
Nanoparticles (10-15μm)Disk-like Prisms (5-10 μm)
nanoparticle agglomeration into larger structures is
hypothesized to be driven by a reduction in surface energy.
Increased time simply grows structures which are more fully
Example RTP Temperature Cycle
1. Ramp to 650°C in 60 s
2. Hold at 650°C for 100 s
3. Ambient cool
HoldTemperature(
600
Increased time simply grows structures which are more fully
formed compared to those formed using a shorter hold time.
Future work includes optimizing for shape and composition
3. Ambient cool
HoldTemperature
600
Shells and Fully Future work includes optimizing for shape and composition
reproducibility, testing whether self-assembly occurs by
annealing, and gathering more comprehensive composition
data.
HoldTemperature
Partially Formed Prisms (1-5 μm)Mg Prisms (.5 – 10 μm)
Shells and Fully
Formed Prisms
(dark region)
data.
Acknowledgments
HoldTemperature
550
No reaction
Fully and Partially
Formed Prisms, Spheres
(light blue region)
(dark region)
This work was supported in part by the U.S. Department of
Energy, Office of Science, Office of Workforce Development
Acknowledgments
550
No reaction(light blue region)
MgO Network
(white region)
This work was supported in part by the U.S. Department of
Energy, Office of Science, Office of Workforce Development
for Teachers and Scientists (WDTS) under the Visiting Faculty
Program (VFP) program.20 100 180
Un-facettedClusters(1-10μm)
After processing, rings can be seen on the silicon.
Assemblage of MgO
Nanoparticles (5-15 μm)
(white region)
NoReaction
Program (VFP) program.20 100 180
Hold Time (s)
After processing, rings can be seen on the silicon.
These rings are related to different structures.