Neutron-diffraction measurements were performed on Er5Si3 in the tempe
rature range between 1.8 and 120 K. The compound crystallizes in the h
exagonal Mn5Si3-type structure. The temperature variation of the 010 i
ntensity shows a Neel temperature equal to 20 K. The erbium magnetic m
oments are 8.3 mu(B) for site 4d and 5.2 mu(B) for site 6g. The magnet
ic moments of both sites lie on the (b, c) plane forming an angle of 3
0 degrees with the c-axis.