Few is known about the magnetism in the negative charge transfer compound Sr2FeO4. Powder neutron diffraction studies report the absense of any magnetic reflections. However, the magnetic susceptibility in the same studies exhibits antiferromagnetic properties of this material. We managed to grow sizeable single crystals of Sr2FeO4. Therefore, the magnetism can be studied much more precisely by means of single crystal neutron scattering now. Next, charge disproportionation has been reproted for other Fe4+ Ruddlesden-Popper-members. Hence, we can also search for signatures of charge disproportionation and ordering within the same measurement. Furthermore, we are also interested in studying the effect of electron doping in Sr2FeO4 with regard to charge stripe instabilities that might also play an important role in the isostructural HTSC cuprates. Due to our phase diagram of the La1-xSr1+xFeO4 system, we expect a break-down of the commensurate magnetism of the type found in LaSrFeO4 somewhere around 40%-80% of doping x. The Sr1.85La0.15FeO4 sample should be clearly above the commensurate ordered regime. Hence, we propose also to search for charge stripe ordering in Sr1.85La0.15FeO4