Investigation of precipitated alumina structures by secondary-ion mass spectrometry and electron paramagnetic resonance spectrometry. Part 1.—Prediction of electron paramagnetic resonance conditions for tracer ions in alumina structures

Abstract

The potential of a tracer electron paramagnetic resonance (e.p.r.) method for distinguishing crystalline regions in a de-solvated alumina gel is assessed in principle. A conventional matrix-diagonalisation procedure is used in order to establish the variation of principal-axis chromium(3+) and iron(3+) e.p.r. conditions as functions of their local structure (represented by the spin-matrix parameters D and E/D) and the external magnetic field. Simplified equations, assuming a crystal field of point electrical charges, provide a basis for estimating λ=E/D from crystallographic data.