Abstract
A new perovskite related Sr
0.97
NbO
3
phase has been synthesized. Although both powder X-ray diffraction and selected area electron diffraction studies suggest a primitive cubic perovskite structure with
a
p
4.023 Å, high resolution powder neutron diffraction reveals a subtle lattice distortion from cubic symmetry. The detailed crystal structure has been refined with the orthorhombic space group
P
2
1
2
1
2 with
a
=5.6881 Å,
b
=5.6821 Å and
c
=8.0566 Å. The structure is built up from two types of NbO
6
octahedra, one elongated, the other compressed along
c
. The lattice distortion from cubic symmetry has been found to mainly originate from tilting of NbO
6
octahedra, whereas the √2
a
p
×√2
a
p
×2
a
p
superstructure arises from ordering of alternate elongated and compressed octahedra.