Hydrothermal synthesis of BaLu2F8:Ln3+ crystals: phase/morphology evolution, energy transfer and tunable multicolor luminescence. Issue 29 (7th July 2020)

• Record Type: Journal Article
• Authors: Xiong, Jie; Wang, Wei; Mao, Yini; Liu, Qingyuan; Yang, Jun; Tang, Jianfeng; Hu, Shanshan
• Is Part Of: CrystEngComm. Volume 22:Issue 29(2020)
• Page Start: 4862
• Page End: 4874
• Publication Date: 2020-07-07
• Subjects: Crystals -- Periodicals; Crystal growth -- Periodicals; Crystallography -- Periodicals; Cristaux -- Périodiques; Cristaux -- Croissance -- Périodiques; Cristallographie -- Périodiques; 548
• DOI: 10.1039/d0ce00818d
• Languages: English
• ISSNs: 1466-8033

Abstract

Abstract : BaLu2− x F8 : x Ln 3+ crystals have been synthesized via a one-step hydrothermal route without any surfactants. Abstract : BaLu2− x F8 : x Ln 3+ crystals have been synthesized via a one-step hydrothermal route without any surfactants. X-ray diffraction (XRD), scanning electron microscopy (SEM), and down-shift/up-conversion photoluminescence spectroscopy were used to characterize the samples. Pure monoclinic BaLu2 F8 crystals were obtained at pH = 7 with NaBF4 as a fluoride source. Doping 0.06 mmol Ln 3+ ions from Ho 3+ to La 3+ and doping Yb 3+ ions from 0.1 to 0.4 mmol both have caused dramatic changes to the product's morphology from prismatic microrods of about 10 μm to particles of about 3 μm aggregated by flakes. The differences in the phase, size and shape of the final products were greatly related to the fluoride source and pH values, which have been studied in detail. In addition, surfactants also affected the phase and morphology of the BaLu2 F8 crystals. Multicolor down-shift emission was achieved in the BaLu1.94 F8 :0.06Ln 3+ (Ln = Sm, Eu, Tb, Dy, Er and Tm) crystals under UV lamp excitation at 365 nm, and multicolor UC luminescence has been achieved in BaLu2 F8 :Yb 3+, Ln 3+ (Ln = Er, Tm, Ho) systems. When the Yb 3+ –Er 3+ ions are co-doped into the host, the mechanism for the red emission ( 4 F9/2 → 4 I15/2 ) retains the tri-photon process like the single-doped Er 3+ ion, but the mechanism for the green emission ( 2 H11/2 / 4 S3/2 → 4 I15/2 ) is a two-photon process. Furthermore, the UC luminescence mechanism for the co-doped Yb 3+ –Ho 3+ pairs is also a tri-photon process in the BaLu2 F8 matrix. The as-prepared BaLu2 F8 :Ln 3+ phosphors have potential applications in the fields of light emitting devices, three-dimensional displays and backlights.