Colloidal synthesis of luminescent rhabdophane LaPO₄:Ln ³⁺·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 (Na₅P₃O₁₀) and lanthanide salts. ³¹P NMR studies show that polyphosphate groups act both as a source of orthophosphate and as complexing agents to, respectively, crystallize and stabilize LnPO₄·xH₂O (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.