Structure and luminescence properties of a Nd³⁺ doped Bi₄Ge₃O₁₂ scintillation crystal: New insights from a comprehensive study

Feiyang CHEN, Meng JU, Gennady L. GUTSEV, Xiao-Yu KUANG, Cheng LU, Yau Yuen YEUNG

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Abstract

The rare-earth Nd³⁺ doped bismuth ortho-germanate Bi₄Ge₃O₁₂ (BGO), serving as an excellent kind of fast scintillator, has been widely used in many scientific and technical areas. However, there are two unsolved problems which hinder its practical applications, namely: (i) there is no detailed information about the microstructure and location sites of Nd³⁺ ions in the BGO lattice; (ii) it is difficult to determine the electric and magnetic dipole transition mechanisms of Nd³⁺ doped BGO. Here, the microstructure and site location of Nd³⁺ ions in BGO have been systematically investigated by means of an unbiased CALYPSO structure search method coupled with first principles calculations. As a result, we have for the first time identified a unique semiconducting phase of the R3 space group where impurity Nd³⁺ ions occupy exactly the host Bi³⁺ ion sites with trigonal symmetry. Based on our developed WEPMD method, new sets of free-ion, crystal field and orthogonal correlation crystal field parameters are obtained, yielding a much better agreement between the calculated and observed values for both optical energy levels and Zeeman splitting g-factors of the ground state. Starting from these new set parameters, the majority of electric dipole and magnetic dipole transition lines, including a large number of absorption and emission lines, in the region of visible and near-infrared spectra of Nd³⁺ ions in BGO are predicted and discussed. It is shown that the main emission channel of Nd³⁺ doped BGO occurs at the inter-Stark laser transitions of ⁴F₃̷₂ → ⁴I₁₁̷₂ corresponding to an emission wavelength of approximately 1064 nm. Copyright © 2017 The Royal Society of Chemistry.
Original languageEnglish
Pages (from-to)3079-3087
JournalJournal of Materials Chemistry C
Volume5
Issue number12
Early online dateFeb 2017
DOIs
Publication statusPublished - 2017

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Scintillation
Luminescence
Ions
Crystals
Bismuth
Microstructure
Phosphors
Electron energy levels
Ground state
Rare earths
Impurities
Infrared radiation
Wavelength
Lasers

Bibliographical note

Chen, F., Ju, M., Gutsev, G. L., Kuang, X., Lu, C., & Yeung, Y. (2017). Structure and luminescence properties of a Nd³⁺ doped Bi₄Ge₃O₁₂ scintillation crystal: New insights from a comprehensive study. Journal of Materials Chemistry C, 5(12), 3079-3087.