Holmium was analyzed indirectly by diluting it with yttrium oxide.After the solutions of holmium sample and high purity yttrium were mixed (Ho: Y=1: 100, by weight), oxalic acid solution was added to the mixture to precipitate the oxalate.The precipitate was filtered, dried and fired at 1000°C for 1.5 hours. The oxide powder thus prepared was irradiated by X-rays, and emission lines of Dy (572 mμ), Gd (315 mμ) and Eu (611 mμ) were measured. The detection limits of thes elements in holmium were 5, 50 and 30 ppm, respectively.
The intensities of X-ray-excited optical fluorescence of rare earth elements in zirconium oxide were found to be strongly enhanced by addition of several per cent of thorium oxide to it.Zirconium and thorium were coprecipitated from the solution of them by ammonium hydroxide (Zr: Th=10: 1, by weight).The precipitate was filtered, dried and fired at 1000°C for 1.5 hours. Fluorescences of Pr, Eu, Er, Ho and Sm were all detectable in a mixed matrix, while only Dy, Gd and Tb showed positive responses in pure zirconium oxide.Detection limits of these elements and quenching effects due to residual impurities were also investigated.
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