The structures of various CaMnO3-x and SrMnO3-x oxygen deficient compounds have been attempted solved from experimental diffraction patterns by Rietveld refinement. All samples used for this purpose have been synthesized with metallic manganese and SrCO3 or CaCO3 as starting materials. Samples of CaMnO3 and SrMnO3 have been produced with the Citric acid sol gel process. These samples have further been reduced by zirconium reduction in closed ampoules in order to obtain reduced phases. The zirconium added controls the oxygen content in the samples. Reoxidation of the totally reduced phases SrMnO2.5 and CaMnO2.5 in TGA furnaces show that the samples reoxidize fully between 400-600¢ªC when heated in air. The sample lose oxygen at temperatures above 800¢ªC
The refinement calculations have been based on various reported structural information in literature. The results show that only a few well defined structures exist with a high degree of certainty. These are CaMnO3, CaMnO2.5, CaMnO2.75, SrMnO3 and Sr2Mn2O5. In the case of CaMnO2.75 it is clear that the structure is not entirely solved. The extra reflections due to the superstructures are not fully understood and a space group has not been found. What has been verified is the unit cell of CaMnO2.75 phase that was proposed in literature. Also, a neutron diffraction pattern of CaMnO2.75 at low temperature revealed extra magnetic reflections. These have been assigned hkl values and a magnetic unit cell. A solution for the magnetic structure of the hexagonal SrMnO3 is presented with ordering of the magnetic momentums.