Analysis of phase changes during synthesis of Sr2Fe1.2Mo0.8O6-δ solid solution by the solid-phase reaction method

Phase transformations during crystallization of the magnetic metal-oxide compound Sr 2 Fe 1.2 Mo 0.8 O 6-δ by the solid-phase reactions method from a mixture of simple reagents 2SrCO 3 + 0.6Fe 2 O 3 + 0.8MoO 3 have been analyzed. By means of differential-thermal and thermogravimetric analyses it was found that the synthesis of strontium ferromolybdate of the Sr 2 Fe 1.2 Mo 0.8 O 6-δ composition proceeds through a series of successive-parallel stages. In this way, when considering the dynamics of phase transformations, it has been found that the main accompanying compounds during the crystallization of the solid solution of double perovskite Sr 2 Fe 1.2 Mo 0.8 O 6-δ are Fe 2 O 3 , SrCO 3 , SrMoO 4 and SrFeO 3 . When analyzing the phase composition of the batch consisting of a mixture of initial reagents of stoichiometric composition: 2SrCO 3 + 0.6Fe 2 O 3 + 0.8MoO 3 , it was noted that with an increase in temperature, complex compounds SrMoO 4 , SrFeO 3 , and then Sr 2 Fe 1.2 Mo 0.8 O 6-δ as well, appear almost simultaneously. This circumstance indicates that the compounds SrMoO 4 and SrFeO 3 are the structure-forming ones for the solid solution of ferromolybdate – strontium. With a subsequent increase in temperature to 1470 K, it was found that the dissolution of SrFeO 3 with the formation of double perovskite Sr 2 Fe 1.2 Mo 0.8 O 6-δ occurs faster than the dissolution of strontium molybdate SrMoO 4 . The results of the analysis indicate the difficult nature of the dynamics of solid-phase reactions during the formation of Sr 2 Fe 1.2 Mo 0.8 O 6-δ .