This study was concerned with the characterization on the α-alumina-manganese solid solution, so-called manganese pink or tohshikoh. A mixture of aluminium hydroxide and manganese phosphate was calcined in air at 1250°C for 1h. The products were washed with (3:1) HCl to leach out all uncombined manganese compounds. Specimens were examined by X-ray diffraction technique for phase analysis and lattice parameter calculation, measurement of spectral reflectance, chemical analysis of manganese, and chemical state analysis of manganese by high resolution fluorescent X-ray analysis. In high resolution fluorescent X-ray analysis, chemical effects on MnK
β1.3 and MnK
α1 spectra were investigated. The width of MnK
α1 and the energy shift of MnK
β1.3 were found to be dependent on the chemical state, especially on the oxidation number of manganese. The changes in the MnK
α1 width and in the energy shift of MnK
β1.3 were large enough for the identification of the oxidation state of manganese in various compounds.
The results were summarized as follows.
1. X-ray diffraction patterns showed that the specimens consisted of only one phase, α-alumina. According to the chemical analysis, manganese content of these specimens ranged from 1 to 5%, and slight lattice expansion was observed.
2. Large difference in MnK
α1 width and the energy shift of MnK
β1.3 of products between before and after acid washing was observed. These values after washing corresponded to Mn
3+. On the other hand, these values before washing showed the existence of Mn
2+. From these observation, it was thought that crude specimens contained Mn
2+ and small amount of Mn
3+, and by acid washing, Mn
2+ was eliminated and refined specimens contained only Mn
3+. The color of specimens (manganese pink) could, therefore, be due to the incorporation of Mn
3+ into corundum lattice.
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