Colloidal Synthesis of Luminescent Rhabdophane LaPO₄:Ln³⁺·xH₂O (Ln = Ce, Tb, Eu; x ≈ 0.7) Nanocrystals

Lanthanide phosphate nanocrystals exhibiting the rhabdophane-type structure and mean particle sizes below 10 nm are synthesized by hydrolysis of an aqueous mixture of sodium tripolyphosphate (Na 5 P 3 O 10 ) and lanthanide salts. 31 P NMR studies show that polyphosphate groups act both as a source of orthophosphate and as complexing agents to, respectively, crystallize and stabilize LnPO 4 · x H 2 O (x ≈ 0.7) nanoparticles. In the ternary system (Ln = La, Ce, and Tb), polyphosphate-capped particles form well-dispersed and highly luminescent aqueous colloids which are promising for applications in light-emitting devices.