Rare Earth is a group of 17 elements including 15 lanthanides (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) located in the bottom of the Periodic Table from atomic number 57 to 71, and Sc numbered 21 and Y numbered 39. Scandium and yttrium are considered rare earth elements because they tend to occur in the same ore deposits as the lanthanides and exhibit similar chemical properties.Abbreviated Words in the Rare Earth Industry
- RE: Rare Earth
- REM: Rare Earth metals
- REE: Rare Earth elements
- REO: Rare Earth oxides
- REY: Rare Earth elements and yttrium
- LREE: Light Rare Earth elements (Sc, La, Ce, Pr, Nd)
- MREE: Medium Rare Earth elements (Sm, Eu, Gd, Y, Tb, Dy)
- HREE: Heavy Rare Earth elements (Ho, Er, Tm, Yb, and Lu)
- TREO: Total Rare Earth Oxide
- TREM: Total Rare Earth Metal
- L. O. I.: Loss on ignition
Purity on Rare Earth Oxide Basis
In the rare earth industry, chemical purities of rare earth oxides and compounds are often presented on rare earth oxide basis (REO basis), i.e., the content of a specific rare earth oxide in comparison to total rare earth oxides (TREO) present: REO/TREO. The statement of "CeO2 > 99%", often means CeO2/TREO > 99%. To obtain the absolute purity of a specific oxide, you can use the formula: REO/TREO X Percentage of TREO in the material.
Purity on Rare Earth Metal Basis
In the rare earth industry, chemical purities of rare earth metals are often presented on rare earth metal basis (REM basis)), i.e., the content of a specific rare earth metal in comparison to total rare earth metals (TREM) present: REM/TREM. The statement of "Ce > 99%" often means Ce/TREM > 99%. To obtain the absolute purity of a specific metal, you can use the formula: REM/TREM X Percentage of TREM in the material.