what is the exact definition for Rare Earth Metal and Rare Earth Elements?
The Rare Earth Elements (REE), also simply called Rare Earths (RE) or Rare
Earth Metals (REM), are a group of 17 elements—according to the International Union of Pure and Applied Chemistry (IUPAC) .The 17 REE therefore
consist of the elements scandium (Sc), yttrium (Y) and the 15 so called lanthanoids
(Ln) which are the elements lanthanum (La), cerium (Ce), praseodymium (Pr),
neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium
(Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Th),
ytterbium (Yb) and lutetium (Lu) .
The answer is not that simple.
The IUPAC has defined REE as a group of 17 chemical elements appearing in the periodic table, comprising of the 15 lanthanides plus yttrium (Y) and scandium (Sc). But these are NOT to be called Rare Earth Metals (REM).
Rare earth elements are also referred to as rare earth oxides (REO). These terms are often used interchangeably, but they are also not the same. Rare earth oxides (REO) are rare earth elements which are separated, purified and sold in their oxide form. Thus, it is customary to render rare earth deposit data in terms of REO equivalents.
Rare earth metals (REM) are following the oxidation step (REO) and are found in a form that meets specific downstream technology applications.
Therefore, you may see all three terms (REE, REO, REM) being used for the description of rare earth elements but there is a difference between them. In addition to that, you shall find different prices for REE, REO and REM.
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