Structural and optical properties of the nanopowder of the Eu3+ doped LiLaP4O12 produced by sol gel route

• Nanoparticles of Eu3+-doped LiLaP4O12 were produced via PVA-assisted sol–gel method.
• Visible, UV and VUV optical characterisations were done.
• Optical band gap, excitation bands due to 4f55d and charge transfer were determined.
• The dependency of the XEOL decay was measured and two processes were identified.

Structural and optical properties of nanopowders of Eu3+-doped LiLaP4O12 (LiLaPO) were studied. The samples were synthetized via polyvinyl alcohol assisted sol gel method. Powder X-ray diffraction (XRD) results showed that the samples have the LiLaPO crystalline phase and scanning electron microscopy (SEM) showed that the particles are in the nanometer scale, mostly as isolated particles with same aggregates. Photoluminescence (PL) properties were evaluated via excitation and emission spectra. The excitation spectra, in the range 2.6–13.8 eV, allowed the identification of the charge transfer band, 4f → 4f5d excitation, exciton formation and the interband excitation of the Eu3+ ions in the matrix. The emission spectra revealed that Eu3+ is located in two different sites in the samples, one of them being at the bulk and the other close to the surface of the nanoparticles, result confirmed by the CT excitation band.