Thermal conductivity studies of electrophoretically deposited nanodiamond arrays

In this paper, free-standing nanodiamond arrays were fabricated by an electrophoresis deposition method in different electrolytes: acetonitrile (ACN), water, and dimethyl sulfoxide (DMSO). Various types of nanodiamond were used: detonation nanodiamond (DND), sulfur functionalized DND (SDND) and high-pressure high-temperature nanodiamond with nitrogen vacancy center (ND(NV)). Thermal conductivity of the above nanodiamond arrays were measured and ordered as follows: ND(NV) > DND(DMSO) > DND(water) > DND (ACN) > SDND. The origin of thermal conductivity differences was investigated through the array fabrication parameters: size, functional group of nanodiamond and electrolyte. Large particle size without functionalization improves thermal conductivity of diamond nanoarrays. Meanwhile, DMSO increases thermal conductivity because nanoarrays grow from the bottom of the template and thermal resistance on the interface is reduced. This paper provides a physicial understanding of how thermal conductivity is influenced by template-based electrophoretic deposition (EPD) process and intrinsic properties of nanodiamond.