Abstract: | The magnetic properties and the lattice constants of Tm6Mn23 were determined before and after hydrogen absorption. The compound Tm6Mn23 is ferrimagnetic with an ordering temperature Tc = 404 K. After hydrogen absorption the magnetization is strongly reduced and does not point to the occurrence of magnetic ordering. The strongly increasing hyperfine splitting observed by means of 169Tm Mössbauer spectroscopy in the hydride for temperature below 60 K, however, shows that the Tm sublattice becomes magnetically ordered after H2 absorption as well. In uncharged and charged Tm6Mn23 the values of the Tm moments are close to the free ion values. |