Large negative thermal expansion in (Ga0.7Cu0.3)(1-x)MnxNMn3 (x = 0.4), compensating for the thermal expansion of cryogenic materials

摘要

As the Mn doping level (x) increases in cubic (Ga0.7Cu0.3)(1-x)MnxNMn3 (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 (alpha similar to - 22.8 ppm/K) is observed for x = 0.25 and 0.3 at cryogenic temperatures (<120 K). By adding the x = 0.3 powders, the thermal expansion of epoxy resin is effectively reduced. Nearly zero thermal expansion (alpha similar to 1 ppm/K) and remarkably improved thermal conductivity are achieved at cryogenic temperatures in the composite with 50 vol.% addition of the NTE filler. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.