Structure and Luminescence Properties of Gd_2(WO_4)_3 and Gd_2(WO_4)_3:Tm~(3+),Yb~(3+) Nanopowders Prepared by Solid-State Sintering and the Pechini Methods

摘要

— Gd_(2)(WO_(4))_(3)and Gd_(2)(WO_(4))_(3):0.5% Tm~(3+), 10% Yb~(3+)nanopowders have been prepared by the Pechini method and solid-state sintering. According to X-ray diffraction results, the materials prepared by the Pechini method are more uniform in phase composition. Optimal synthesis conditions were defined: t = 900°C and τ = 1 h for Gd_(2)(WO_(4))_(3)and t = 950°C and τ = 3 h for Gd_(2)(WO_(4))_(3):0.5% Tm~(3+), 10% Yb~(3+). The surface morphology of the materials has been studied by scanning electron microscopy. The samples prepared by solid-state sintering have been found to be highly agglomerated, and large agglomerates have been shown to persist even after ultrasonic processing. The average size of the doped and undoped nanoparticles prepared by the Pechini method has been determined to be 44.0 and 47.6 nm, respectively. Luminescence spectra of Gd_(2)(WO_(4))_(3):0.5% Tm~(3+), 10% Yb~(3+)were measured and compared the intensities of the Tm~(3+)~(1) G _(4)→~(3) H _(6),~(1) G _(4) →~(3) F _(4),~(3) F _(1,2)→~(3) H _(6), and~(3) H _(4)→~(3) H _(6)radiative transitions in the materials prepared by both methods. The data obtained in this study demonstrate that the Pechini process is a preferable and promising method for the synthesis of Gd_(2)(WO_(4))_(3)and Gd_(2)(WO_(4))_(3):Tm~(3+),Yb~(3+)nanopowders.