Dy<sup>3+</sup>对Tb<sup>3+</sup>激活硅酸盐氟氧闪烁玻璃发光性能的影响

doi:10.3964/j.issn.1000-0593(2019)05-1412-08

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Abstract Dy³⁺, Tb³⁺ doped and Dy³⁺/Tb³⁺ co-doped silicate oxyfluoride scintillating glass were prepared by high temperature melting method. The Fourier transform infrared spectra, transmission spectra, photoluminescence excitation and emission spectra, X-ray excited luminescence spectra and luminescence decay curves were analyzed. The influence of the energy transfer between Dy³⁺ and Tb³⁺ions and Dy³⁺doping onluminescence properties of Tb³⁺ activated silicate oxyfluoride scintillating glass was studied. The results indicated that Dy³⁺/Tb³⁺ co-doped silicate oxyfluoride scintillating glass has relatively high density and good transmittance in visible region. The networkstructure of glass isconstituted of tetrahedral [SiO₄] and [AlO₄]. Under the irradiation of ultraviolet light, the luminescence of Dy³⁺-doped glass originates from ⁴F_9/2→⁶H_15/2 (483 nm) and ⁶H_13/2 (576 nm) transition emission of Dy³⁺ ions, while the luminescence of Tb³⁺-doped glass originates from ⁵D₄→⁷F₆ (489 nm), ⁷F₅ (544 nm), ⁷F₄ (586 nm) and ⁷F₆ (623 nm) transition emission of Tb³⁺ ions. As for Dy³⁺/Tb³⁺ co-doped silicate oxyfluoride scintillating glasses, the emission spectra aremainly due to fluorescence emission of Tb³⁺ ions. The emission spectra under ultraviolet excitation with different wavelengths revealed that Dy³⁺/Tb³⁺ co-doped scintillating glass includes manifold energy transfers. When Tb³⁺-doped glass is excited by the characteristic excitation wavelength (452 nm) of Dy³⁺ ions, the luminous intensity of Tb³⁺-doped glass is very weak. With the introduction of Dy³⁺ ions, Tb³⁺ ions emission are sensitized and enhanced by the energy transfer of ⁴F_9/2 (Dy³⁺)→⁵D₄ (Tb³⁺). The luminous intensity ofDy³⁺/Tb³⁺ co-doped glassesis improved with the increase of Dy₂O₃. The luminous intensity ofDy³⁺/Tb³⁺ co-doped glasses reaches the maximum when the content of Dy₂O₃ is 1mol%. However, when the content of Dy₂O₃ is further increased, the concentration of Dy³⁺ ions is quenched, which results in the decrease of the energy transfer to Tb³⁺ions and the reduction of the luminous intensity. When the excitation wavelength is decreased to 350 nm, Dy³⁺ and Tb³⁺ ions are excited to higher energy levels of ⁶P_7/2 (Dy³⁺) and ⁵L₉ (Tb³⁺). At this point, the energy transfer of both ⁴F_9/2 (Dy³⁺)→⁵D₄ (Tb³⁺) and ⁵D₄(Tb³⁺)→⁴F_9/2 (Dy³⁺) occurs. When the doping concentration of Dy³⁺ ions is relatively low, the energy transfer of Dy³⁺→Tb³⁺ is stronger than that of Tb³⁺→Dy³⁺, which enhancesthe luminescence of Tb³⁺ ions by sensitization. With the increase of Dy₂O₃ content, the energy transfer of Tb³⁺→Dy³⁺ is enhanced. When the content of Dy₂O₃ is above 0.4 mol%, the energy transfer of Tb³⁺→Dy³⁺ is strongerthan that of Dy³⁺→Tb³⁺, which reduces the transition luminescence of Tb³⁺ ions and thus decreases theluminous intensity of Dy³⁺/Tb³⁺ co-doped glass. Due to the efficient energy transfer from Gd³⁺ to Dy³⁺ or Tb³⁺, the competition of energy transferfrom Gd³⁺ to Dy³⁺ and Tb³⁺ion soccurs under characteristic excitation wavelength of Gd³⁺ ion at 274 nm. With the increase of content of Dy₂O₃, the captured energy of Tb³⁺ions decreases constantly. At the same time, the energy backtransfer of Tb³⁺→Dy³⁺ and the nonradiative cross relaxation between Dy³⁺ ions appear, which leads to the reduction of theluminous intensity of Dy³⁺/Tb³⁺ co-doped glass. The ⁵D₄→⁷F₅ luminescence decay curves of Tb³⁺ions for Dy³⁺/Tb³⁺co-doped scintillating glass showed that with the increase of Dy₂O₃ content, the lifetime of ⁵D₄ (Tb³⁺) reduces from 2.24 to 1.15 ms and the curve changes from single-exponential to double-exponential form, indicating the possibility of the energy back transfer of ⁵D₄ (Tb³⁺)→⁴F_9/2 (Dy³⁺) in the glass. The X-ray excited luminescence emission spectra showed that the introduction of Dy³⁺ ions has a negative effect on the luminescence of Tb³⁺ activated scintillating glass. Becausethat negative effect is not enough to make up for the Dy³⁺→Tb³⁺ energy transfer, the radiation luminescence intensity of Dy³⁺/Tb³⁺ co-doped glass decreases with the increase of the Dy₂O₃ content. Therefore, Dy³⁺ ions should not be used as sensitizers to enhance the luminescence intensity of Tb³⁺ ions in Tb³⁺ activated silicate oxyfluoride scintillating glass.

Key words：Scintillating glass；Dy³⁺/Tb³⁺ co-doped；X-ray excitation；Energy transfer

Received: 2018-02-01 Accepted: 2018-06-22

ZTFLH:

O482.31

Corresponding Authors: YANG Li-li E-mail: llyang1980@126.com

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https://www.gpxygpfx.com/EN/10.3964/j.issn.1000-0593(2019)05-1412-08 OR https://www.gpxygpfx.com/EN/Y2019/V39/I05/1412