Phase evolution, structure, and up‐/down‐conversion luminescence of Li6CaLa2Nb2O12:Yb3+/RE3+ phosphors (RE = Ho, Er, Tm). Issue 4 (6th January 2020)

• Record Type: Journal Article
• Authors: Du, Panpan; Ma, Jing; Zhu, Qi; Li, Ji‐Guang
• Is Part Of: Journal of the American Ceramic Society. Volume 103:Issue 4(2020)
• Page Start: 2674
• Page End: 2685
• Publication Date: 2020-01-06
• Subjects: down‐conversion -- energy process -- Li‐garnet -- phosphor -- up‐conversion; Ceramics -- Periodicals; 620.1405
• DOI: 10.1111/jace.16977
• Languages: English
• ISSNs: 0002-7820

Abstract

Abstract: Garnet‐type Li6 Ca(La0.97 Yb0.02 RE0.01 )2 Nb2 O12 (RE = Ho, Er, Tm) new phosphors were successfully synthesized via solid reaction at 900°C for 5 hours, whose course of phase evolution, macroscopic/local crystal structure and up‐/down‐conversion (UC/DC) photoluminescence were clarified. Mechanistic study and materials characterization were attained via XRD, Rietveld refinement, DTA/TG, electron microscopy (FE‐SEM/TEM), and Raman/reflectance/fluorescence spectroscopies. The phosphors were shown to exhibit UC luminescence dominated by a ~ 553 nm green band ( 5 F4 / 5 S2 → 5 I8 transition) for Ho 3+, a ~ 568 nm green band ( 4 S3/2 → 4 I15/2 transition) for Er 3+ and a ~ 806 nm near‐infrared band ( 3 H4 → 3 H6 transition) for Tm 3+ under 978 nm laser excitation, with CIE chromaticity coordinates of around (0.31, 0.68), (0.38, 0.60) and (0.17, 0.24), respectively. Analysis of the pump‐power dependence of UC intensity indicated that all the emissions involve a two‐photon mechanism except for the ~ 486 nm blue emission of Tm 3+ ( 1 G4 → 3 H6 ), which requires a three‐photon process. The DC luminescence of these phosphors is featured by dominant bands at ~ 553 nm for Ho 3+ (green, 5 F4 / 5 S2 → 5 I8 transition), ~568 nm for Er 3+ (green, 4 S3/2 → 4 I15/2 transition) and ~ 464 nm for Tm 3+ (blue, 1 D2 → 3 F4 transition). The UC and DC properties were also comparatively discussed. Abstract : A series of garnet‐type Li6 Ca(La0.97 Yb0.02 RE0.01 )2 Nb2 O12 (RE = Ho, Er, Tm) new phosphors were successfully synthesized via solid reaction at 900°C, whose course of phase evolution, macroscopic/local crystal structure and up‐/down‐conversion photoluminescence were elucidated.