Studies on the Co-ordination State of Atoms in the MgO⋅Al₂O₃-MgO⋅nAl₂O₃ Spinel by Means of Characteristic X-ray Emission Spectrum

Abstract

It is well known that the energy distribution, the spectrum profile of emission and absorption spectrum are affected by the electron orbit according to the binding state of atoms, and the analysis of those spectra in order to investigate the binding state of constituent atoms became widely applied.
The present study was performed in order to confirm how those spectra would be observed according to the co-ordination state of atoms in solid solution phases of synthetic MgO⋅Al₂O₃-MgO⋅nAl₂O₃ system by means of electron microprobe spectroscopy.
The X-ray emission spectrum energies were obtained from the mean value of 3/4 peak height position and analyses were carried out from a standpoint of the half width and the asymmetry index for the spectrum profile.
In this experiment, the AlK_{α, β}, MgK_α and their satellite line profile remained unchanged, even though n was varied from 1 to 1.8. The OK_α spectra, however, showed shift toward high energy side, and the half width and their asymmetry indices were increased.
From these experimental results it was assumed that the distribution of Mg²⁺ and Al³⁺ ions did not change while n was varied from 1 to 1.8 for MgO⋅nAl₂O₃.
Though the character change of OK_α spectra is not so easily determined, it may be attributed to the existence of anisotropic O^2- ions caused by cation vacancy formation.