Single crystals of Sr5Sb3 in the orthorhombic form (beta-Yb5Sb3 struct
ure type) were obtained as a minor product of a reaction of the elemen
ts and Mn in a welded Nb container. To date only the hexagonal form (M
n5Si3 structure type) of Sr5Sb3 has been reported. The orthorhombic ph
ase of Sr5Sb3 has been synthesized in high yield by the reaction of st
oichiometric amounts of the elements in an alumina crucible, sealed in
a quartz tube.