Eu³⁺-Doped ZnB₂O₄ (B = Al³⁺, Ga³⁺) Nanospinels: An Efficient\nRed Phosphor

Abstract

This paper describes the synthesis\nof Eu­(III)-doped ZnB₂O₄ (B = Al­(III) or Ga­(III))\nnanospinels with Eu­(III) concentrations\nvarying between 1% and 15.6%. The synthesis was achieved through a\nmicrowave (MW) synthetic methodology producing 3 nm particles by the\nthermal decomposition of zinc undecylenate (UND) and a metal 2,4-pentanedionate\n(B­(acac)₃, B = Al³⁺ or Ga³⁺) in oleylamine\n(OAm). The nanospinels were then ligand exchanged with the β-diketonate,\n2-thenoyltrifluoroacetone (tta). Using tta as a ligand on the surface\nof the particles resulted in soluble materials that could be embedded\nin lens mimics, such as poly­(methyl methacrylate) (PMMA). Through\na Dexter energy transfer mechanism, tta efficiently sensitized the\nEu­(III) doped within the nanospinels, resulting in red phosphors with\nintrinsic quantum efficiencies (QEs) and QEs in PMMA as high as 50%\nwhen excited in the UV. Optical measurements on the out of batch and\ntta-passivated nanospinels were done to obtain absorption, emission,\nand lifetime data. The structural properties of the nanospinels were\nevaluated by ICP-MS, pXRD, TEM, FT-IR, EXAFS, and XANES.