Broadband microwave measurements of nanodiamond

Microwave complex permittivity measurements of different nanodiamond powders were measured (in the range of 10nm to 1µm). We have developed a low resolution, high accuracy broadband measurement system using our cylindrical cavity resonator consisting of 6 transverse magnetic (TM) modes ranging from 2.49GHz to 9.43GHz. The particle sizes were also measured using scanning electron microscopy. Surface impurities were found in the powder with the smaller particle sizes using Raman spectroscopy. We observed higher dielectric losses in the powder with impurities. Our broadband measurement system shows that the frequency dependence of the losses were minimal and thus the impurity has a dielectric loss mechanism which is most likely not due to free electron conduction.