Large negative thermal expansion in (Ga0.7Cu0.3)1-xMnxNMn3 (x ≤ 0.4), compensating for the thermal expansion of cryogenic materials

Abstract

As the Mn doping level (x) increases in cubic (Ga0.7Cu0.3)1-xMnxNMn3 (x≤0.4) compounds, the temperature window of negative thermal expansion (NTE) is shifted to lower temperatures and broadened due to the strengthening of ferromagnetism. Large coefficient of linear thermal expansion (α~−22.8ppm/K) is observed for x=0.25 and 0.3 at cryogenic temperatures (<120K). By adding the x=0.3 powders, the thermal expansion of epoxy resin is effectively reduced. Nearly zero thermal expansion (α~1ppm/K) and remarkably improved thermal conductivity are achieved at cryogenic temperatures in the composite with 50vol.% addition of the NTE filler.