Formation of nanocrystalline particles on the basis of La$_2$(Ni,Mn,Fe)$_2$O$_6$ variable composition phases having a structure of double perovskite under conditions of solution combustion

Nanocrystalline particles on the basis of La$_{2}$(Ni,Mn,Fe)$_{2}$O$_{6}$ variable composition phases of a double perovskite structure have been produced by glycine-nitrate combustion. The size of crystallites grows from 5 to 45 nm with an increase in iron content of synthesized particles. It is demonstrated that iron unevenly builds into octahedral sites of nickel and manganese ions substituting mainly manganese ions. At the same time, the dependence of double perovskite unit cell volume on the iron ions concentration is well described by Retgers' law.