Neutron diffraction study on the deuterium site occupation and magnetic structure of the Nd2(Fe,Ga)14BDy compounds

Synthesis and chnrarterizntion of Nd2Fe14=xGaxBDy compounds are presented for x=1, 1.8 and y=0 to 4. The influence of the deuteration has been studied both on the structural and magnetic properties. Our present investigation has been performed at both 4 and 300 It by means of high-resolution powder neutron diffraction. A decrease of the maximum quantity of deuterium inserted upon Ga substitution is evidenced. The location of the B atoms within the tetragonal Nd2Fe14B structure for the Nd2Fe13GaBD3.7 and Nd2Fe12.2Ga1.8BD3.2 compounds is presented. The D insertion was revealed to be possible in four tetrahedral D sites. A blocking of the D (16k(2)) site in the Ga-containing samples is demonstrated. The evolution of the occupancies of the different sites is linked with the modification of the distances and of the nature of the nearest neighbors, An increase of the Curie temperature upon D insertion is measured but the magnitude of this enhancement is less pronounced in comparison with the effect of the D insertion in the pure Nd2Fe14B. The evolution of the magnetic moments carried by each atom shows an increase of the mean Fe moment upon D insertion. Finally, the saturation magnetization is found to increase upon D insertion but this rise is not directly related to the quantity Of D inserted. (C) 2001 Elsevier Science B.V. All rights reserved.