First Observation of the Scintillation Cascade in Tb³⁺‐Doped Quaternary Garnet Ceramics

Abstract

A mechanism of firefly high‐scintillation light yield (LY) of Tb‐doped quaternary (Gd, Y)3Al2Ga3O12 garnet ceramics is reported. Through measurements with the synchrotron source, the high efficiency of the luminescence excitation, providing a quantum yield Q > 1 below the photon multiplication energy range, is defined. The excitation efficiency reaches two at the excitation energy slightly above 2Eg. The cascade of photons is explained by combining three factors: first, the high quantum yield Q ≈ 1 of the luminescence at excitation in lower mixed states 4f75d1 with high spin (HS) and low spin (LS); second, the cross‐relaxation 4f7(6P)5d1(HS) → 4f7(8S)5d1(HS) provides the excitation of 4f8(7F0) →4f8(5D1,4) transition of the 4f8 configuration of the same or neighboring Tb ion, which is followed by the luminescence from 5D1,4; and finally, the relaxation of 4f7(8S)5d1‐5(HS) configuration into the excited 4f8 configuration occurs with future emission from 4f8(5D1,4) states. This cascade forms the final stage of the scintillation in the compound being studied and provides a LY twice as high compared with the material when doped with Ce.

Effect of a Phosphorus Additive on Luminescent and Scintillation Properties of Ceramics GYAGG:Ce

“…Starting powder was fabricated by co-precipitation method [5][6][7][11][12][13]33]. High purity commercially available chemical reagents such as Gd 2 O 3 (99.995%), Y 2 O 3 (99.995%), AlOOH (99.998%), Ga (99.999%) and Ce(NO 3 ) 3 (99.95%) were used as raw materials to prepare nitrate solutions.…”

“…Garnet structure oxides doped with lanthanides are a group of widely used luminescence, laser, and scintillation materials [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Y 3 Al 5 O 12 :Ce (YAG:Ce) and Lu 3 Al 5 O 12 :Ce (LuAG:Ce) are well-established scintillators, which are widely used in radiation detection applications in science and industry.…”

“…Nevertheless, recently, along with binary compositions, such as YAG:Ce and LuAG:Ce, multicationic garnets have been actively studied [1][2][3][5][6][7][8][9]. The garnet matrix has been developed to become more complex; yttrium is partially or completely replaced by gadolinium or a Gd/Lu mixture in different ratios; and aluminum is partially replaced by gallium [8][9][10][11]. In addition, garnets doped with other lanthanides, or their combination are being actively studied [1,[5][6][7]12].…”

Compositionally Disordered Ceramic (Gd,Y,Tb,Ce)3Al2Ga3O12 Phosphor for an Effective Conversion of Isotopes’ Ionizing Radiation to Light

“…In this work, we set the goal of creating a scintillator with a high yield and radiation resistance not only for detection purposes but also for obtaining maximum optical photon fluxes when converting the energy of absorbed charged particles in the visible spectral range. The activator providing high excitation efficiency in the compositionally disordered garnet compound (Gd,Y) 3 Al 2 Ga 3 O 12 is the Tb 3+ ion [20], which isovalently substitutes for the Gd and Y ions in the matrix. Tb 3+ ions possess slowly decaying luminescence but with a high luminosity [21][22][23] and cathodoluminescence yield [24].…”

On the Quenching Mechanism of Ce, Tb Luminescence and Scintillation in Compositionally Disordered (Gd, Y, Yb)3Al2Ga3O12 Garnet Ceramics

“…Finally, Gd ions can compete with Yb ions to catch electrons and to resist complete quenching of luminescence and scintillation in the material in the visible range. In this context, combining terbium ions with a high excitation efficiency [38] and ytterbium ions in the same material promises obvious advantages both in terms of enriching the luminescence spectrum and the efficient use of the mechanisms of luminescence photon multiplication.…”