Background: New insights into materials science provide development of smart
nano/micro structured materials for advanced applications. Rare earth includes a set of chemical
elements (from La to Lu, including Sc and Y) with unique properties, the use of which is evidenced by
luminescence applications. Colloidal processing offers great possibilities to obtain smart materials by
controlling inter-particle forces, as well as their evolution during ceramic processing. The present
article reports a review on colloidal processing with emphasis on rare earth powders. A general view
about rare earths properties, including scientific investigations and applications are also presented.
Methods: General view on rare earth sources, classification, properties, studies, and applications are
reported. Besides, a review on colloidal processing covering particle characteristics, inter- particle
forces, dispersion methods, rheology of suspensions, shaping process, drying-sintering stage, and
microstructure formation is reported.
Results: Yttria is the most used rare earth oxide in phosphors applications (70%). Synthesis routes
imply on powder properties. Particle characteristics as size, shape, density, and surface area are
important parameters for colloidal processing. The control of inter- particle forces by zeta potential
evaluation and using dispersion methods provide conditions to prepare stable suspensions.
Consolidation of colloidal particles into a desired shape depends on both viscosity and rheological
behavior of suspensions. Drying-sintering conditions are effective on microstructure formation and
component characteristics. Bio-prototyping is a low cost method, which provides components with
complex shape and cellular architecture.
Conclusion: Rare earths exhibit remarkable properties, being applied in diverse technological end-use.
Colloidal processing provides opportunities to form smart materials since synthesis of colloids until
development of complex ceramic components by shaping methods and thermal treatment. Even
though colloidal processing is quite mature, investigations on rare earths involving inter- particle
forces, shaping, drying-sintering stage, and microstructure formation are very scarce.