Microwave Permittivity of Trace sp² Carbon Impurities in Sub-Micron Diamond Powders

Statistics
Metrics and citations
Share
Metadata
Show full item recordDate
2018Department
Ciencia de los Materiales e Ingeniería Metalúrgica y Química InorgánicaSource
ACS Omega 2018,3, 2183-2192Abstract
Microwave dielectric loss tangent measurements
are demonstrated as a method for quantifying trace
sp2-hybridized carbon impurities in sub-micron diamond
powders. Appropriate test samples are prepared by vacuum
annealing at temperatures from 600 to 1200 °C to vary the
sp2/sp3 carbon ratio through partial surface graphitization.
Microwave permittivity measurements are compared with
those obtained using X-ray photoelectron spectroscopy (XPS),
Raman spectroscopy, and electron energy loss spectroscopy
(EELS). The average particle size remains constant (verified
by scanning electron microscopy) to decouple any geometric
dielectric effects from the microwave measurements. After
annealing, a small increase in sp2 carbon was identified from
the XPS C 1s and Auger spectra, the EELS σ* peak in the C 1s
spectra, and the D and G bands in Raman spectroscopy, although a quantifiable diamond to G-band peak ratio was unobtainable.
Surface hydrogenation was also evidenced in the Raman and XPS O 1s data. Microwave cavity perturbation measurements show
that the dielectric loss tangent increases with increasing sp2 bonding, with the most pertinent finding being that these values
correlate with other measurements and that trace concentrations of sp2 carbon as small as 5% can be detected.
Collections
- Artículos Científicos [4846]
- Articulos Científicos CC. Mat. [195]