Hydrothermal synthesis of Ba3Sc2F12:Yb3+, Ln3+ (Ln = Er, Ho, Tm) crystals and their up conversion white light emission

Abstract

Ba3Sc2F12:Yb3+, Ln3+ (Ln = Er, Ho, Tm) crystals with various morphologies have been synthesized via a one step hydrothermal route. X-ray diffraction (XRD), scanning electron microscopy (SEM), and up conversion photoluminescence (UCPL) spectra were used to characterize the samples. The influences of surfactants, pH values, and molar ratio of F-/Sc3+ on the crystal phase, size and shape of final products have been studied in detail. The aspect ratio of products increased gradually with the increase of F-/Sc3+ molar ratio. Additionally, the luminescence properties of Ba3Sc2F12:Yb3+, Ln3+ (Ln = Er, Ho, Tm) crystals were systematically studied. The blue emission is attributed to the 1G4 → 3H6 transition of Tm3+; the green emission can be obtained due to the 2H11/2/4S3/2 → 4I15/2 transitions of Er3+ and the 5S2/5F4 → 5I8 transition of Ho3+; the red emission comes from the 4F9/2 → 4I15/2 transition of Er3+ and the 1G4 → 3F4 transition of Tm3+. Based on the generation of red, green, and blue emissions in the different Ln ion-doped Ba3Sc2F12, the white light emission can be obtained by appropriately doping Yb3+, Er3+, and Tm3+ in the present Ba3Sc2F12 crystals due to the color superposition principle. Here, the sample Ba3Sc1.5856F12:0.4Yb3+, 0.01Er3+, 0.0044Tm3+ crystals showed suitable intensity ratio of blue, green and red (RGB) emissions resulting in bright white light with CIE-x = 0.274 and CIE-y = 0.287, which was illustrated by a photograph under excitation of 980 nm. The prepared Ba3Sc2F12:Ln3+ phosphor has potential applications in the fields of three dimensional displays, back lighting and white light sources.