Metallic conductivity transition of carbon nanotube yarns coated with silver particles

Dry spun carbon nanotube yarns made from vertically aligned multiwalled carbon nanotube forests possess high mechanical strength and behave like semiconductors with electrical conductivity of the order of 4 x 10(4) S m(-1). Coating a submicron-thick film of silver particle-filled polymer on the surface increased the electrical conductivity of the carbon nanotube yarn by 60-fold without significantly sacrificing its mechanical strength. The transitional characteristics of the silver-coated carbon nanotube yarn were investigated by varying the take-up ratio of the silver coating. A step change in conductivity was observed when the silver content in the coated yarn was between 7 and 10 wt% as a result of the formation of connected silver particle networks on the carbon nanotube yarn surface.