Abstract:
Metal oxides, in general, are known to exhibit significant wettability towards water molecules because
of the high feasibility of synergetic hydrogen-bonding interactions possible at the solid-water interface.
Here we show that the nano sized phosphates of rare earth materials (Rare Earth Phosphates, REPs),
LaPO4 in particular, exhibit without any chemical modification, unique combination of intrinsic
properties including remarkable hydrophobicity that could be retained even after exposure to extreme
temperatures and harsh hydrothermal conditions. Transparent nanocoatings of LaPO4 as well as
mixture of other REPs on glass surfaces are shown to display notable hydrophobicity with water
contact angle (WCA) value of 120° while sintered and polished monoliths manifested WCA greater than
105°. Significantly, these materials in the form of coatings and monoliths also exhibit complete nonwettability
and inertness towards molten metals like Ag, Zn, and Al well above their melting points. These properties, coupled with their excellent chemical and thermal stability, ease of processing, machinability and their versatile photo-physical and emission properties, render LaPO4 and other REP ceramics utility in diverse applications.
