Hydrothermal synthesis and luminescence behavior of rare-earth-doped NaLa(WO4)2 powders

NaLa(WO4)2 powders doped with Eu3+, Nd3+, and Er3+ have been synthesized by a mild hydrothermal method and a crystal of exclusive scheelite phase could be obtained at low temperature. From the spectrum of Eu3+ it has been concluded that the dopant Eu3+ ion occupies a La3+ site and mainly takes the site with image symmetry. The higher quenching concentration can be observed in the Eu3+-doped NaLa(WO4)2 powders. The Er3+- and Nd3+-doped NaLa(WO4)2 powders exhibit luminescence in the near infrared (Er3+ at 1550 nm, and Nd3+ at 1060 nm). The transition mechanism of the up-conversion luminescence of the Er3+-doped NaLa(WO4)2 powders can be ascribed to two photons absorption process.