Thermal conductivity of cold compacted bismuth nanowires

•The thermal conductivity of 250 nm bismuth nanowires was measured to be 6.1 W/mK.•The difference from bulk (8.2 W/m) is due to oxide layer, not quantum confinement.•Pellets are formed from 20 and 250 nm nanowires as well as microparticles.•Thermal conductivity of nanowire pellets (∼1 W/mK) less than individual nanowires.•Porosity, oxide, and thermal interfaces lead to lower pellet conductivities.