V. Paulboncour et al., DEUTERIDE ABSORPTION AND DESORPTION EFFECTS ON MAGNETIC-PROPERTIES OFYFE2DX, Journal of applied physics, 79(8), 1996, pp. 4253-4259
Magnetic properties of YFe2 and its deuterides YFe2Dx have been invest
igated in the temperature range 300 < T < 800 K. Both the lattice stru
cture and the Curie temperature T-c show strong dependence on the deut
erium composition x. The deuterides have a C15 cubic structure up to x
= 2.7 and T-c rises from 560 K for x = 0, up to 715 K for x = 2.2 and
2.7. Amorphous YFe2D2.3 was also synthetized and surprisingly display
s a lower T-c = 330 K. For larger deuterium concentrations, the deuter
ides show a rhombohedral distortion and the Curie temperature is reduc
ed. Rhombohedral deuteride YFe2D3.6 has T-c = 345 K. Heating this deut
eride above 410 K leads to partial desorption of the deuterium and tra
nsformation of the material into a cubic phase. This is evidenced by t
he fact that a spontaneous magnetization at these high temperatures is
restored, characteristic of cubic deuterides with x less than or equa
l to 2.7. On the other hand, additional desorption upon heating above
700 K induces a transition to the amorphous state, as a result of the
weakening of the Y-Fe bond. The time dependence of the magnetization a
t a given temperature shows that the desorption at high temperature is
due to the diffusion of deuterium through the surface. (C) 1996 Ameri
can Institute of Physics.