A study of hydrogen desorption from alloy by means of ferromagnetic resonance

Abstract

FMR absorption in hydrogen-charged austenitic alloys was measured versus temperature in the range of 4 - 200 K and at 77 K versus duration of hydrogen desorption caused by heatings at 293 - 393 K. Under the influence of hydrogen the FMR signal is shifted towards high magnetic fields, which provides evidence for the increasing role of s electrons in the formation of the magnetic structure of the alloy, and broadened, the latter effect being caused by the effective electron scattering of the hydrogen atoms. The FMR intensity is found to be proportional to the saturation magnetization and obeying the -law at low temperatures , where is Curie temperature). The activation enthalpy and the frequency factor were measured from the dependence of the integral intensity and the line width recorded at 77 K on the duration of desorption at various temperatures. The value of eV is consistent with the data for hydrogen migration in the same alloy obtained by means of the internal-friction technique while the value of the frequency factor reflects the peculiarities of the hydrogen-induced magnetic structure of the alloy. It characterizes the length of the spin correlation of s electrons which determines the distance of hydrogen atom migration needed for a detectable change of the magnetic structure during hydrogen desorption. The results indicate the strong s - d exchange interaction between hydrogen s electrons and the host atoms.