Stoichiographic determination of the composition and concentration of phases encapsulated in the bulk of a solid matrix phase

A two-step method of stoichiographic calculations used in the determination of the formulas of phases encapsulated in the bulk of matrices of another composition is proposed. At the first stage of calculations, the stoichiometric composition of the encapsulated phase is determined and, at the second step, the concentrations of this phase and the matrix are found. The use of this method in the analysis of oxide La–Cu catalysts by the method of differential dissolution ensures the detection of the phase La 1 Cu 1 (La 2 Cu 2 O 5 ), incorporated within the matrix La 1 Cu 0.5 (La 2 CuO 4 ) phase.