Structural and spectroscopic properties of Eu3 +-activated nanocrystalline tetraphosphates loaded in silica–hafnia thin film

• LiEuxLa1 − x(PO3)4 nanopowders, where x = 0.01 ÷ 1, were prepared.
• Effective reduction of concentration quenching in LiEuxLa1 − x(PO3)4 was shown.
• Transparent nanocomposite of LiEu0.1La0.9(PO3)4 in SiO2–HfO2 film was fabricated.

Nanoparticles of lithium lanthanum tetraphosphates doped with different concentration of Eu3 + ions were synthesized. The selected tetraphosphate was used to fabricate a transparent composite where nanocrystals were immobilized in a sol–gel-derived silica–hafnia amorphous film. The structural and spectroscopic properties of the systems were investigated by XRD analysis, Raman spectroscopy, and photoluminescence measurements. For all the samples with the Eu3 + ions concentration from 1 to 100 mol% the monoclinic structure with a space group C12/c1 was determined. The mean diameter of nanocrystals determined by Scherrer equation was in the range of 40–55 nm. The luminescence of 10%Eu3 +:LiLa(PO3)4 in silica–hafnia matrix indicated the immobilization of Eu3 + ions into a distorted environment. The dependence of both luminescence intensity and lifetime on the Eu3 + concentration demonstrated effective reduction of concentration quenching in the tetraphosphate nanopowders.