Rare Earth Elements

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Rare earth elements

The rare earth elements or REEs consist of the 15 lanthanides plus scandium and yttrium. The last two are also considered REEs because they are found in the same ore deposits and they have similar properties. They are divided into 2 groups: the light rare earth elements (LREEs), with lanthanum, cerium, praseodymium, neodymium, promethium and samarium, and the heavy rare earth elements (HREEs), with yttrium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Although Yttrium normally would fall under the LREEs, it is a HREE because of the similar properties with the other HREEs. All REEs can be seen on the periodic table in Figure 1. Figure 1 The heavy and light rare earth elements [1]. …show more content…

It was also discovered by Carl Gustaf Mosander, but now in 1839 and from cerium salt. It is one the most reactive lanthanides and Mosander discovered its existence by accident. The name comes from the Greek word ‘lanthanein’, which means ‘to lie hidden’.
Lanthanum is never used as a pure metal but always as an alloy. Of course it is used as lamp phosphor. It is used in the ‘mischmetal’ alloy (20%) for the purpose of flints in lighters. It is also used to raise the refractive index of glass while limiting the dispersion of light and raises its alkali resistance. For this application is it used in lenses for cameras and telescopes. Furthermore it used for dating very old rocks with the La-Ba technique. Lastly it is used as a catalyst in the refining industry.
Cerium

Based on [19]
The last element found in the LAP lamp phosphor is cerium. Cerium is the 58th element in the periodic table. It is discovered by Jöns Jacob Berzelius and Wilhelm Hisinger in 1803. As there are minerals that are almost completely cerium salt, it is discovered independently from the other lanthanides. Cerium is named after the Roman God of agriculture:

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