  The iron arsenide Sr2CrO3FeAs with the tetragonal Sr2GaO3CuS-type structure
was synthesized and its crystal structure re-determined by neutron powder
diffraction. In contrast to previous X-ray crystallographic studies, a mixed
occupancy of chromium and iron was found within the FeAs4/4 layer (93+/-1% Fe :
7+/-1% Cr). We suggest that the partial Cr-doping at the Fe site is the reason
for the absence of a spin-density wave anomaly and superconductivity in this
compound. Additional experiments via neutron polarization analysis revealed
short-range spin correlations below ~100 K and long-range antiferromagnetic
ordering below T_N = 36 K with a magnetic propagation vector of q = (1/2, 1/2,
0). The Cr3+ ions form a collinear magnetic structure of the C-type in the
magnetic space group C_Pmma' (a' = a-b, b'=a+b, c'=c), where Cr3+-ions occupy
the 4g (0, 1/4, z) Wyckoff position. The magnetic moments are aligned along the
orthorhombic a'-axis. At 3.5 K, an ordered magnetic moment of 2.75+/-0.05 mu_B
for the Cr3+-sublattice was refined.
