In-situ neutron investigation of hydrogen absorption kinetics in La(FexSi1−x)13 magnetocaloric alloys for room-temperature refrigeration application

•The deuterium absorption and desorption in La(Fe,Si)13 alloys are observed « in-situ » with neutron diffraction.•The interstitial kinetics is successfully modeled with JMA law.•Carbon addition effectively slows down deuterium interstitial kinetics and enhances stability of deuterium in host alloy.•The changes in kinetics with carbon addition is attributed to changes in Fe–Fe bond lengths in the structure.

Promising magnetocaloric material La(Fe,Si)13 with a first-order magnetic transition has been widely investigated. The observed instability of hydrogen in the material is detrimental for its industrial upscale and a better control of the hydrogen absorption/desorption is necessary to optimize its application potential. In this article, the hydrogen absorption kinetics is studied through an in-situ neutron diffraction experiment. The results allow us to have an inside look at the structure “breathing” to accommodate the interstitial atoms and compare the effect of hydrides with carbohydrides.