posted on 2024-02-06, 14:04authored byHenry
J. Hamann, Metin Örnek, Chi-Chin Wu, Scott D. Walck, Steven F. Son, P. Veeraraghavan Ramachandran
The
favorable properties of aluminum nanoparticles have led to
their application in areas ranging from propellants and explosives
to plasmonics. In the area of energetics research, where the heating
of aluminum (Al) nanoparticles (nAl) is involved, producing materials
that maximize heat flow with a low onset temperature is a sought-after
goal. This study examined the ability of gallium (Ga) to increase
the reactivity of nAl. Three Al/Ga composite nanoparticles were formed
by the addition of Ga salt (GaCl3) at different time points
during the nAl synthesis. The timing of Ga addition was found to correlate
with the quantity of Ga present in the resulting composite with earlier
addition yielding a higher Ga concentration. The thermal behavior
of the Al/Ga composites was assessed by using thermogravimetric analysis
(TGA) and differential scanning calorimetry (DSC). The Al/Ga composite
material produced with early Ga addition produced particles with a
TGA trace showing an early onset exothermic peak near 480 °C.
This coincided with a peak seen at this temperature in the DSC trace
for Ga nanoparticles (nGa). Complete oxidization of this material
was achieved below 600 °C, while achieving a higher maximum heat
flow, a significant improvement over that of pure nAl. Experiments
suggest the reduction of gallium (Ga3+) to neutral metal
Ga0, whose presence was detected spectroscopically in the
resulting product concentrated between the active Al core and the
exterior aluminum oxide shell.