Elsevier

Optical Materials

Volume 109, November 2020, 110305
Optical Materials

GAGG:Ce composite scintillator for X-ray imaging

https://doi.org/10.1016/j.optmat.2020.110305Get rights and content

Highlights

  • A composite detector for X-ray imaging based on GAGG:Ce powder embedded into polysiloxane matrix is proposed.

  • A standard GAGG:Ce solid state synthesis procedure provides reduction of production cost.

  • The light output homogeneity over the detector square does not exceed ±6%.

  • The 130 μm spatial resolution of X-ray images is achieved.

Abstract

The paper deals with the development of X-ray imaging composite detectors based on GAGG:Ce powders bound by the organic polysiloxane matrix. The luminescence intensity was improved through optimization of solid state reaction conditions and Ce concentration in GAGG:Ce. The deviation of light output over the detector square does not exceed ±6%. The spatial resolution of 130 μm was achieved with the optimized GAGG:Ce composite detectors.

Introduction

Nowadays gadolinium aluminum gallium garnet Gd3Al5-xGaxO12:Ce (GAGG:Ce) is considered as the most efficient oxide scintillator [[1], [2], [3], [4]]. It possesses a high light yield up to 50000–60000 phot/MeV and a good energy resolution [[5], [6], [7]]. Its other advantages include the high density of 6.63 g/cm3, high Zeff = 54, unhygroscopicity, a relatively short scintillation decay time of around 55 ns, the presence of Gd, which is the element with the highest neutron capture cross section [[8], [9], [10]]. Digital radiography is one of the possible applications of GAGG:Ce since the development of this material [11]. A good performance of GAGG:Ce for X-ray detection was demonstrated [[11], [12], [13], [14], [15], [16], [17], [18]]. A scintillator layer thickness is one of the main features of such detectors. While it should be thin enough to provide a high spatial resolution, the sufficient thickness is necessary for complete X-ray absorption. There are several methods to form the detection layer, including the thin film deposition, and growing and cutting of bulk crystals. For example, 60 μm thick GAGG:Ce single crystalline plates were fabricated from bulk crystals for Synchrotron X-Ray Micro-Imaging [19]. Ceramic samples for X-ray CT detectors were fabricated in Refs. [20,21]. Thin films of Gd3Al5-xGaxO12:Ce were proposed for electron detection in Scanning Electron Microscopy [22]. In Ref. [23], GAGG nanopowders were used as the sensitive element embedded into the organic matrix of the composite scintillator. Meanwhile, nanopowder synthesis is labor consuming and expensive process, especially in case of large-scale production. Organic reagents used for nanoparticle synthesis are the source of undesirable admixtures in finish products. Therefore, nanoparticles substitution with powders prepared by a standard solid-state synthesis would be helpful. Some authors of this work have performance in development of the composition detectors based on powders or ground single crystals of Y2SiO5:Ce, Y3Al5O12:Ce, ZnSe:Te, Lu2-xGdxSiO5:Ce scintillators distributed in the organic binder [[24], [25], [26], [27]]. Apart of a lower production cost, such approach in fact removes the limits on the square and shape of composite scintillation detectors.

This work deals with the solid-state synthesis of GAGG:Ce powders and testing the performance of composite scintillation detectors on their base for X-ray radiography.

Section snippets

GAGG:Ce powder and composite preparation

GAGG:Ce samples with the compositions (Gd1-xCex)3(Al0,48Ga0,52)5O12 (x = 0.0002–0.009) were synthesized by the solid state synthesis. The Gd2O3, Al2O3, Ga2O3, CeO2 initial components were accurately mixed and isostatically pressed, then the pellets were calcined in Ir crucible under Ar atmosphere. The following GAGG:Ce synthesis temperatures were chosen: lower than 2/3 of the melting temperature according to the Tamman criterion [28], and around 90% of the melting temperature. As the GAGG:Ce

Structure of composite detectors

The view of GAGG:Ce synthesized at different temperatures is presented in Fig. 1 (a, b) One can see that the powders synthesized at 1350°С (Fig. 1а) and at 1600°С (Fig. 1b) have the different color. This may be attributed to incomplete solid phase reaction between the components at lower temperature and/or incomplete transfer of cerium from Ce4+ to optically active Ce3+ valence state.

General view of the composite scintillators based on GAGG:Ce powder and typical GAGG:Ce granules sizes are

Conclusions

Composite scintillation detectors for X-ray imaging based on GAGG:Ce grains synthesized by the solid state reaction were developed. The highest X-ray luminescence intensity was achieved at 1600 °С powder calcination temperature and the Ce concentration of 0.12 at. % in GAGG:Ce. The deviation of light output over the detector square does not exceed ±6%. The spatial resolution of 4 lp/mm was achieved on X-ray images obtained by the developed composite scintillator with the 0.1 mm thickness. This

Authorship contribution statement

Ia Gerasymov: Methodology, Development or design of methodology, creation of models. Writing - review & editing, Preparation, creation and/or presentation of the published work by those from the original research group, specifically critical review, commentary or revision – including pre-or postpublication stages. T. Nepokupnaya: Methodology, Development or design of methodology; creation of models. A. Boyarintsev: Ideas; formulation or evolution of overarching research goals and aims. O.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This work was supported by the project No.0117U000988 «Composite» of National Academy of Science of Ukraine. We greatly acknowledge to Dr. S. Minenko for performing the absorption spectra measurements, and Dr. V. Tarasov and Dr. A. Lebedynskiy for helpful comments regarding the results interpretation.

References (37)

  • K. Kamada et al.

    2 inch diameter single crystal growth and scintillation properties of Ce:Gd3Al2Ga3O12

    J. Cryst. Growth

    (2012)
  • K. Kamada et al.

    2-inch size single crystal growth and scintillation properties of new Scintillator; Ce:Gd3Al2Ga3O12, 2011

    IEEE Nucl. Sci. Symp. Conf. Rec.

    (2011)
  • K. Kamada et al.

    Crystal growth and scintillation properties of Ce doped Gd3Al2Ga3O12 single crystals

    IEEE Trans. Nucl. Sci.

    (2012)
  • K. Kamada et al.

    Composition Engineering in cerium-doped (Lu,Gd)3(Ga,Al)5O12 single-crystal scintillators

    Cryst. Growth Des.

    (2011)
  • M. Korzhik et al.

    Compact and effective detector of the fast neutrons on a base of Ce doped Gd3Al2Ga3O12 scintillation crystal

    IEEE Trans. Nucl. Sci.

    (2019)
  • T. Kanai et al.

    Characteristics of a nonstoichiometric Gd31d(Al,Ga)5O12:Ce garnet scintillator

    J. Am. Ceram. Soc.

    (2008)
  • S.L. David et al.

    X-ray luminescence efficiency of GAGG:Ce single crystal scintillators for use in tomographic medical imaging systems

    J. Phys. Conf.

    (2015)
  • I.E. Seferis et al.

    Light Emission Efficiency of Gd3Al2Ga3O12:Ce (GAGG:Ce) Single Crystal Under X-ray Radiographic Conditions, XIII Mediterranean Conference on Medical and Biological Engineering and Computing 2013

    IFMBE Proceedings

    (2014)
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      The cerium ion doped gadolinium gallium aluminate garnet crystal Gd3(Ga,Al)5O12:Ce (GAGG:Ce) belongs to the cubic crystal system of garnet structure, body-centered cubic lattice, with high light yield about 60 000 ph/MeV [4] and excellent energy resolution. Other advantages of GAGG:Ce include relatively fast decay time, high density (6.63 g/cm3) [5–7], high effective atomic number of 54.4 and non-hygroscopicity [4]. It has become a research hotspot in the field of scintillators.

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