  We report a combination of X-ray and neutron diffraction studies, Mossbauer
spectroscopy and muon spin relaxation (muSR) measurements to probe the
structure and magnetic properties of the semiconducting beta-Ce2O2FeSe2
oxychalcogenide. We report a new structural description in space group Pna21
which is consistent with diffraction data and second harmonic generation
measurements and reveal an order-disorder transition on one Fe site at TOD ~
330 K. Susceptibility measurements, Mossbauer and muSR reveal antiferromagnetic
ordering below TN = 86 K and more complex short range order above this
temperature. 12 K neutron diffraction data reveal a modulated magnetic
structure with q = 0.444 bN*.
