Dear readers, the intention of this post is to explore why rare earth oxides can be the lotus of ceramics due to one of their interesting intrinsic property. Rare earth based magnets are regularly used in wind turbines, nearly in 14% of them . What if there is another use for rare earths in the same device where in winter freezing water films on blades can lead to a disaster? Well, it turns out that rare earth oxides can save those hefty wind turbine blades because they are intrinsically hydrophobic.
Hydrophobicity is usually achieved by polymeric modifier coatings but they suffer degradation in harsh environments. Water repelling surfaces have a gamut of applications in the field of energy, transportation, medicine, corrosion resistance etc . Conventional ceramics like alumina are highly hydrophilic, so why should rare earth oxides, ceramics themselves be hydrophobic?
Figure: Water repelling REO ceramics 
Everything comes down to electronic configuration. Water‚Äôs oxygen atoms share some of their electrons with electron deficient aluminum atom and the oxygen in the ceramic shares electron with the hydrogen atom  resulting in a hydrophilic hydration structure. But, the unfulfilled 4f electrons of rare earth oxides are shielded from bonding by the full octet of an outer shell. This should make it tough for the water and REOs to form interfacial bonds.
Researchers in MIT have found out that, this property indeed makes the family of rare earth oxides intrinsically hydrophobic . They prepared small discs of these oxides and dropped water on to it. And each one of them indeed repelled the liquid. They characterized the wetting properties of these discs by measuring the contact angle and it was in the range of 100-115, comparable to Teflon when has a contact angle of 119 degree. Interestingly enough, ceria remained hydrophobic even after being subjected to a harsh high temperature environment of 1000 o C. This remarkable property of ceria, if completely harnessed can possibly address the balance problem of lanthanides 
Finally, rare earth oxides are one of the important products in the recycling chain of lanthanides and a larger application requirement for it fuels the recycling research with further impetus. I would like to end this blogpost with a beautiful video of a water droplet bouncing off ceria which can be found in the link below.
- Study of rare earths and their recycling, Oko Institut, 2011 report for the Greens/EFA group in the European parliament.
- Ceramics surprise with durable dryness, Nature news, 20 January 2013
4. Hydrophobicity of rare-earth oxide ceramics, G.Azimi et al., Nature Materials 12, 315‚Äď320 2013
5. Rare-Earth Economics: The Balance Problem, K.Binnemans et al., JOM, Vol. 65, No. 7, 2013