Temperature and Humidity Dependence of Resistance in Nano-Diamond Powder

Abstract: The electrical resistance of detonation nano-diamond powders was measured from liquid nitrogen temperature to room temperature and in relative humidity environments from around 10% to 100%. After sample exposures of several hours at 100% relative humidity at room temperature (around 295 K), when the temperature was reduced, the resistance increased to the upper measurement limit of our apparatus (120 M{\Omega}) at around 240 K. Upon warming, the resistance dropped back to the room temperature value, with some hysteresis. For sample exposures after several hours at 100% relative humidity at room temperature, as the relative humidity was reduced, the sample resistance increased to the upper range limit of the apparatus. As the relative humidity was then increased (all at room temperature), the resistance dropped. For samples exposed to low (~10%) relative humidity for several hours at room temperature, as the humidity was increased (at room temperature), the resistance decreased, and then increased when the humidity was reduced. The temperature behavior was markedly differ from that of powdered graphite and multi-walled carbon nano tubes.