Controllable Thermal Expansion and Magnetic Structure in Er2(Fe,Co)14B Intermetallic Compounds

The control of thermal expansion is attractive but remains challenging for the studies of negative thermal expansion materials. Here, we report a continuously controllable thermal expansion from negative to positive by means of adjusting magnetic moment of Fe in the Er2(Fe,Co)14B intermetallic compounds. Interesting, a zero thermal expansion (ZTE) has been achieved in a wide temperature range (ΔT = 355 K), which is larger than most existing ZTE alloys. The spontaneous magnetostriction (ωS) reveals a negative contribution arising from magneto-volume effect to the controllable thermal expansion. The present study could be suitable to the design of controllable thermal expansion of other alloys related to the magneto-volume effect.