SCIENCE PHOTO LIBRARY SCIENCE PHOTO LIBRARY
Rare earth glass beads. From top to bottom, these doped glass beads contain traces of the elements neodymium (Nd), erbium (Er) and praseodymium (Pr). All are lanthanides (rare earth elements) in period 6, and the f-block of the periodic table. In elemental form, they are all soft silvery metals. Here, they are in their +3 oxidation states, giving rise to the colours seen. These beads illustrate one of the uses of the oxides of these elements, to dye and colour glass. They are also used in enamel dyes. Erbium oxide is also used as a photographic filter. Praseodymium oxide is also used in welding goggles, and in carbon arc lamp electrodes.
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