Zero Thermal Expansion Achieved by an Electrolytic Hydriding Method in La(Fe, Si)13 Compounds

The La(Fe, Si) 13-based compounds have been recently developed as promising negative thermal expansion (NTE) materials by elemental substitution, which show large, isotropic and nonhysteretic NTE properties as well as relatively high electrical and thermal conductivities. In this paper, the La(Fe, Si) 13 hydrides are prepared by a novel electrolytic hydriding method. Furthermore, the thermal expansion and magnetic properties of La(Fe, Si) 13 hydrides are investigated by the variable-temperature X-ray diffraction and physical property measurement system. Fascinatingly, it is found that room-temperature NTE properties and zero thermal expansion (ZTE) properties with broad operation-temperature window (20-275 K) have been achieved after electrolytic hydriding. The further magnetic properties combined with theoretical analysis reveal that the improvements of NTE and ZTE properties in the La(Fe, Si) 13 hydrides are ascribed to the variations of magnetic exchange couplings after hydrogenation. The present results highlight the potential applications of La(Fe, Si) 13 hydrides with room-temperature NTE and broad operation-temperature window ZTE properties.