Lanthanide Nitride Foams

Lanthanide Nitride Foams


Metal nitrides are ceramic materials that have applications, e.g., in coatings or catalysis. Lanthanide nitrides, however, can be challenging to prepare in high purity and nanostuctured lanthanide nitride foams had not been prepared so far. Bis(tetrazolato)amine (BTA2–, pictured) complexes can act as precursors for metal nanofoams when they undergo a self-propagating combustion reaction.

Thuy-Ai D. Nguyen, Jacqueline M. Veauthier, Los Alamos National Laboratory, NM, USA, and colleagues have synthesized lanthanide bis(tetrazolato)amine complexes of lanthanum, cerium, praseodymium, neodymium, and europium, i.e., NH4[La(BTA)2(H2O)5]·H2O, NH4[Ce(BTA)2(H2O)5]·H2O, NH4[Pr(BTA)2(H2O)5]·H2O, NH4[Nd(BTA)2(H2O)5]·H2O, and [Eu(BTA)(H2O)6][Eu(BTA)2(H2O)4]. The team characterized the complexes using X-ray crystallography and found that La, Ce, Pr, and Nd each coordinate to two BTA2− chelate ligands and five water molecules, while Eu forms the two eight-coordinate ions [Eu(BTA)(H2O)6]+ and [Eu(BTA)2(H2O)4].

Dehydrated forms of the lanthanum and cerium complexes NH4[Ln(BTA)2] (Ln = La, Ce) were then used as precursors for the formation of lanthanum and cerium nitride nanofoams. The dried powders were pressed into pellets and ignited under an inert atmosphere with a laser. The obtained lanthanum nitride and cerium nitride foams are nanoporous and have very high surface areas. According to researchers, it should be possible to synthesize Pr and Nd nitride foams, as well as actinide nitride foams, using the same protocol. The Eu complex contains fewer gas-forming components, which might lead to a denser foam.



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