Eiichi Iwase

The Luminescence Spectra of Triply-ionized Rare Earths in the Calcination Products of Some Magnesium Compounds

(i) The luminescence spectra of samarium(III), europium(III), terbium(III) and dysprosium(III) ions embedded in the calcination products of Mg(NO3)2·6H2O, MgSO4·7H2O and MgCl2·6H2O have been studied under excitation by cathode-ray bombardment at room temperature. The calcination of these ions was carried out either at about 900°C for 30 min. or by further heating at about 1800°C for 5 min. (ii) The luminescence spectrum of each of the rare earth ions in magnesium oxide matrix was obtained in its pure form in the case of the calcination products derived from Mg(NO3)2·6H2O. A number of distinguishing diffuse luminescence bands were observed arising from the sulfate component remaining in the calcination products derived from MgSO4·7H2O. Calcination products derived from MgCl2·6H2O had a composition very near that of magnesium oxide and contained only a small amount of chlorine. When the triplyionized rare earths here investigated were embedded in these calcination products, several intense and sharp lumines...

Cathodo-luminescence as Applied to the Detection of Rare Earths Contained in Some Natural Calcareous Substances

Specimens of reef corals, stalactite, molluscan fossil and calc-sinters were converted to the form of oxide, in which rare earths, if present in the original specimens, would be concentrated by chemical means. Luminescence spectra given by these samples of calcium oxide were investigated under the cathode-ray bombardment and the presence of minute amounts of rare earths could be confirmed; dysprosium, praseodymium, samarium and terbium in a stalactite from Akiyoshi, dysprosium, praseodymium and presumably samarium in reef corals from Miyako Main Isle, and dysprosium and praseodymium in a molluscan fossil from Hiroshima. Not even slight traces of rare earths were perceived in calc-sinters from several springs, so far as this detecting method was concerned. Two kinds of specimens of reef corals from the same locality gave a remarkable difference in the rare-earth content and this observation may be explained by the different conditions of the surfaces found in these reef corals, during the growth of which t...