A Method of Accompanying Signal for Determination of the Chemical Composition of Multicomponent Phases

Abstract

A general method for determination of the chemical composition of multicomponent phase in equilibrium solid-phase mixtures without their isolation is developed. The method is based on the dependence of any of intensive or extensive characteristics of the system (accompanying signal: reflection intensities, lines of Raman and IR spectra, thermal effects, etc.) on the composition of test samples of the system under study. For example, to determine the unknown phase X (A_xB_yC_z, wherein 0 ≤ x ≤ y, z, x + y + z ≤ 1, and z = 1- x - y) of a ternary (three-component) system, it suffices to prepare three equilibrium samples P - A_pB_fC_1-p-f, Q - A_qB_gC_1-q-g, and R - A_rB_hC_1-r-h . The intensity of the signal accompanying the reaction in sample P: p^A +f^B +⁽1 -p -f)C → a⁽A_xB_yC_1-x-y + I_p) +⁽p - ax)A + (f- ay^)B is I_p = aI. Expressions for I_q and I_r follow from the reaction equations in samples Q and R. Solution of the system of the equations thus obtained provides determination of the unknown values x, y, and z. Thus, for n-component systems it is necessary to prepare n samples, measure the intensity of accompanying signal for each sample and carry out similar calculations.