523

Sensors and Materials, Vol. 36, No. 2 (2024) 523–530
MYU Tokyo
S & M 3540

Scintillation Properties of Rb2Cu(Cl,Br)3 Crystals
Keishi Yamabayashi,* Kai Okazaki, Daisuke Nakauchi,
Takumi Kato, Noriaki Kawaguchi, and Takayuki Yanagida
Division of Materials Science, Nara Institute of Science and Technology (NAIST),
8916-5 Takayama-Cho, Ikoma City, Nara 630-0192, Japan(Received October 6, 2023; accepted January 16, 2024)

Keywords: γ-ray detection, phosphor, Hume-Rothery rules, self-trapped excitons, slow cooling method,
one-dimensional structure

Rb2 Cu(Cl,Br) 3 crystals were synthesized by the slow cooling method and theirphotoluminescence (PL) and scintillation properties were evaluated. PL emission peaks at 390
nm due to the recombination of excitons were observed, and the PL quantum yields of Rb2CuCl3,
Rb2Cu(Cl0.5,Br0.5)3, and Rb2CuBr3 were 91.2, 95.3, and 96.3%, respectively. PL decay curves
were approximated using a single exponential function model, and the obtained decay time
constants were 15–66 μs. Under X-ray irradiation, the scintillation emission peaks of the samples
were observed at 390 nm, and the decay times were 11–63 μs. The afterglow levels at 20 ms after
X-ray irradiation were calculated to be 30–450 ppm. Rb2CuCl3 showed the highest scintillation
light yield of 11000 photons/MeV among the samples when calculated from the pulse heightspectra of 137Cs γ-rays (662 keV).

1.

Introduction

Scintillators are luminescent materials for ionizing radiation measurements, and they have afunction to convert a high-energy quantum to numerous low-energy photons.(1–3) They are
generally optically coupled with photomultiplier tubes (PMTs) or photodiodes to convert
scintillation photons to electric signals.(3,4) There is a wide range of applications of scintillators,
for example, medical imaging,(5) security inspection,(6) natural resource exploration,(7) andmaterials analysis.(8) The following characteristics are demanded in scintillators for X- and γ-ray
detection: high scintillation light yield (LY), high density, large effective atomic number, fast
scintillation lifetime, and good transparency. However, no scintillators suitable for all the abovementioned applications have been reported; thus, it is necessary to select scintillators dependingon the required performance of the applications. Owing to their excellent optical properties suchas high transparency, single-crystal scintillators have been widely studied(9–13) and put into
practical applications. For example, Bi4Ge3O12 (BGO),(14–16) CdWO 4 (CWO),(17–19) andTl:CsI(20–22) have been conventionally used for nondestructive inspections, as represented by
X-ray CT and baggage inspections.
*Corresponding author: e-mail: yamabayashi.keishi.yh2@ms.naist.jp

https://doi.org/10.18494/SAM4760

ISSN 0914-4935 © MYU K.K.
https://myukk.org/

524

Sensors and Materials, Vol. 36, No. 2 (2024)

Halide single crystals(23–25) as well as oxides(26–29) have been studied for radiation detection,and many scintillators with high LY and excellent energy resolution (DE) have been discovered.
For example, Tl-doped NaI(30–32) and Eu-doped SrI 2(33,34) show excellent luminescence
properties; however, these crystals have low chemical stability due to hygroscopicity. In contrast,
Cu-based halide compounds are known to have low hygroscopicity.(35,36) In our previous
study,(37) we focused on K 2CuBr3 and Rb2CuBr3 and revealed that a continuous solid solution of(K,Rb)2CuBr3 showed a higher LY than Rb2CuBr3. Besides, Rb2CuCl3 exhibits a high emission
intensity under UV and X-ray irradiations;(36–39) however, their scintillation light yields under
γ-rays have not been clarified. On the basis of Hume-Rothery rules,(40) the continuous solid
solution of Rb2Cu(Cl,Br)3 can be grown. According to previous studies,(41,42) continuous solid
solutions enhanced the scintillation properties owing to changes in bandgap energy or latticedefects. In this study, in addition to Rb2CuCl3 and Rb2CuBr3, Rb2Cu(Cl0.5,Br0.5)3 was developed
to enhance the scintillation properties.

2.

Materials and Methods

Rb2CuCl3, Rb2Cu(Cl0.5,Br0.5)3, and Rb2CuBr3 were prepared by the slow cooling method.
RbCl [20(1−x)/3 mmol, 99%, Mitsuwa Chemicals], RbBr (20x/3 mmol, 99%, Mitsuwa
Chemicals), CuCl [10(1−x)/3 mmol, 99.9%, High Purity Chemicals], and CuBr (10x/3 mmol,
99.9%, High Purity Chemicals) in the molar ratio of 2−2x:2x:1−x:x (x = 0, 0.5, and 1) weredissolved in a mixed solution of HCl aq [2(1−x) mL, 35–37%, Wako Pure Chemical Industries]
and HBr aq [2(1−x) mL, 47–49%, Wako Pure Chemical]. Subsequently, the solution was stirred
for 2 h at 130 ℃, and then H3PO2 aq (100 µL, 50%, Fujifilm Wako Pure Chemical) was dropped
into the solution to prevent the oxidation of Cu+. Finally, the solution was slowly cooled from 130℃ to room temperature at a rate of 5 ℃/h using a liquid phase synthesizer (Chemi Chemi-300,
Shibata) to synthesize single crystals. The grown crystals were washed with 2-propanol (Fujifilm
Wako Pure Chemical). The measurement of powder X-ray diffraction (XRD) patterns was
performed using a diffractometer (MiniFlex600, Rigaku) to determine crystalline structures.
The PL excitation and emission spectra and PL quantum yields (QY) were obtained using a
Quantaurus-QY (C11347, Hamamatsu Photonics). The PL decay curves were measured using a
Quantaurus-τ (C11367, Hamamatsu Photonics). The X-ray-induced scintillation spectra, decay
curves, afterglow curves, and pulse height spectra of 137Cs γ-rays (662 keV) were determinedusing our original setups.(43,44) A shaping amplifier (CP4479, Clear-Pulse) was used for pulse
height measurement, and the shaping time was set to 10, 50, and 50 μs for Rb2CuCl3,
Rb2Cu(Cl0.5,Br0.5)3, and Rb2CuBr3, respectively.

3.

Results and Discussion

Figure 1 shows photographs and XRD patterns of the synthesized samples. Several crystals
were precipitated after crystal growth. The obtained samples were colorless and transparent, andthe maximum size among the samples was 5–10 mm in length and 1 mm in thickness. The restof the crystal samples were crushed into powders for XRD measurement. All diffraction peaks

Sensors and Materials, Vol. 36, No. 2 (2024)

Fig. 1.

525(Color online) Photographs and XRD patterns of Rb2Cu(Cl,Br)3 crystals.

of the samples were in good agreement with the reported data of Rb2CuCl3(39,45) and thereference data of Rb2CuBr3 (JCPDS: 98-015-0295(36)). Therefore, the obtained samples had an
orthorhombic crystal system with a space group of Pnma.
Figure 2 shows the PL excitation and emission spectra of all the samples. A broad emission
peak at 350–550 nm was confirmed under excitation at 250–350 nm. The origin of the emissionis the recombination of self-trapped excitons (STEs).(46) When the range of 320–800 nm wasmonitored under the excitation light of 310 nm, the PL QY values of Rb2 CuCl 3,
Rb2Cu(Cl0.5,Br 0.5)3, and Rb2CuBr3 were 91.2, 95.3, and 96.3%, respectively. The QY of
Rb2Cu(Cl0.5,Br0.5)3 slightly increased compared with that of Rb2CuCl3 via the partial anion
substitutions of Cl and Br. In addition, the emission wavelength was shifted to a longer
wavelength by Cl replacement.
The insets of Fig. 2 show the PL decay curves of the obtained samples monitored at 390 nm
under excitation at 315 nm. The observed decay curves were in good agreement with a single
exponential function model. The obtained decay time constants of Rb2CuCl3, Rb2Cu(Cl0.5,Br0.5)3,and Rb2CuBr3 were 15, 31, and 66 μs, respectively, which were comparable to those of previous
studies.(36,39,47) The decay time constants decreased as the Cl proportion decreased.
Figures 3 and 4 show the X-ray-induced scintillation spectra and scintillation decay curves,
respectively. A broad emission peak at 390 nm was observed, and the peak position shifted
toward longer wavelength as the Cl ratio increased. The spectral profile was similar to
scintillation in a previous study;(39) therefore, they were considered to be derived from therecombination of STE. All the scintillation decay curves were approximated by a single
exponential function model except for the instrumental response function (IRF). The obtained
PL and scintillation values were not significantly different and were considered to be within the
typical errors.
Figure 5 shows the afterglow curves of the samples after 2 ms irradiation with X-rays. The
afterglow level (A) was defined as A = (I20 − IBG)/(IMAX − IBG). I20, IMAX, and IBG are the intensity
at 20 ms after X-ray irradiation for 2 ms, the intensity during X-ray irradiation, and the526

Sensors and Materials, Vol. 36, No. 2 (2024)

Fig. 2. (Color online) PL excitation and emission spectra of Rb2Cu(Cl,Br)3. Horizontal and vertical axes indicate
emission and excitation wavelengths, respectively. Insets show PL decay curves measured under excitation at 315
nm and monitored at 390 nm.

Fig. 3.

(Color online) X-ray-induced scintillation spectra of Rb2Cu(Cl,Br)3 crystals.

background intensity before X-ray irradiation, respectively. The obtained A values of Rb2CuCl3,
Rb2Cu(Cl0.5,Br0.5)3, and Rb2CuBr3 were 30, 36, and 450 ppm, respectively. These values
significantly decreased as the Cl ratio increased. In addition, the values of Rb2CuCl3 andRb2Cu(Cl0.5,Br0.5)3 were lower than that of Tl:CsI (300 ppm), which has been one of theconventional halide scintillators,(48) and comparable to that of Bi4Ge3O12 (10 ppm),(48) a
scintillator for X-ray detection under the same measurement condition.
Figure 6 shows the pulse height spectra of 137Cs γ-rays measured using the samples and CWO
as a reference sample, which shows LY of 15800 photons/MeV.(49) All the samples exhibited a
photoabsorption peak. The peak channel was determined by Gaussian approximation, and theSensors and Materials, Vol. 36, No. 2 (2024)

IRF

100
Time [µs]Fig. 4.

200

I = IRF+A1exp(-t/27µs)
IRF

0

100

200
Time [µs]300

Rb2CuBr3

Intensity [arb. unit]

I = IRF+A1exp(-t/11µs)

0

Rb2Cu(Cl0.5Br0.5)3

Intensity [arb. unit]

Intensity [arb. unit]

Rb2CuCl3527

400

I = IRF+A1exp(-t/66µs)
IRF

0

200

400
Time [µs]600(Color online) X-ray-induced scintillation decay curves of Rb2Cu(Cl,Br)3 crystals.

Rb2CuBr3
Rb2Cu(Cl0.5Br0.5)3
Rb2CuCl3
Reference CdWO4105

Counts

104
103
102
101
100

Fig. 5. (Color on l i ne) A f te rglow cu r ves of
Rb2Cu(Cl,Br)3 crystals.

0

300
200
100
Channeal number [channel]

400

Fig. 6. (Color online) Pulse height spectra of 137Cs
γ-ray (662 keV) measured using Rb2 Cu(Cl,Br) 3
crystals and CWO as a reference.

calculated LY values of Rb2CuCl3, Rb2Cu(Cl0.5,Br0.5)3, and Rb2CuBr3 were 11000, 4900, and1500 photons/MeV, respectively, after corrections of the PMT sensitivity. In addition, the DE
values at 662 keV for Rb2CuCl3, Rb2Cu(Cl0.5,Br0.5)3, and Rb2CuBr3 were 10.4, 10.8, and 12.1%,
respectively. The difference in the estimation of LY was attributed to the different measurement
methods used. In a previous study,(39) the LY of Rb2CuCl3 was estimated from the scintillation
spectrum, whereas the current work used the pulse height spectrum. Rb2CuCl3 showed thehighest LY and the lowest A among the samples. They did not follow the tendency of QY. In
general, scintillation and storage-type luminescence properties such as afterglow show an
inverse relationship.(50,51) The A values of Cl-containing samples were lower than those of
Rb2Cu(Cl0.5,Br0.5)3 and Rb2CuBr3, and the trend was consistent with the relationship.

4.

Conclusions

Continuous solid solutions of Rb2Cu(Cl0.5,Br0.5)3 crystals were successfully synthesized by
the slow cooling method. In the PL and scintillation spectra, a broad emission peak was observed
at 390 nm, and the emission mechanism was attributed to the recombination of STEs. The PL528

Sensors and Materials, Vol. 36, No. 2 (2024)

and scintillation decay curves were approximated using a single exponential function model, andthe obtained decay constants (11–66 µs) decreased as the Cl proportion increased. A was
improved from 450 ppm (Rb2CuBr3) to 36 ppm [Rb2Cu(Cl,Br)3] and 30 ppm (Rb2CuCl3) bychanging the anion part to Cl from Br. The LY values of the samples tended to increase as the Cl
ratio in the composition increased; the maximum LY was 11000 photons/MeV calculated for
Rb2CuCl3. As a comprehensive result, the unsubstituted sample Rb2CuCl3 showed the best
scintillation properties among the samples. The A and LY of Rb2CuCl3 were comparable to thoseof BGO, which is one of the representative commercially available scintillators for security andanticompton spectrometers.(52) Therefore, Rb2CuCl3 can be a promising material for the above
applications.

Acknowledgments
This work was supported by Grants-in-Aid for Scientific Research A (22H00309), Scientific
Research B (21H03733, 21H03736, and 22H03872), and Exploratory Research (22K18997) fromthe Japan Society for the Promotion of Science. JST A-STEP, Foundation from Cooperative
Research Project of the Research Center for Biomedical Engineering, Kazuchika Okura
Memorial Foundation, Asahi Glass Foundation, Nakatani Foundation, and Konica Minolta
Science and Technology Foundation are also acknowledged.

References
1 C. W. E. Van Eijk: Nucl. Instrum. Methods Phys. Res., Sect. A 460 (2001) 1. https://doi.org/10.1016/S01689002(00)01088-3
2 A. Lempicki, A. J. Wojtowicz, and E. Berman: Nucl. Instrum. Methods Phys. Res., Sect. A 333 (1993) 304.
https://doi.org/10.1016/0168-9002(93)91170-R
3 T. Yanagida, T. Kato, D. Nakauchi, and N. Kawaguchi: J. Appl. Phys. 62 (2022) 010508. https://doi.
org/10.35848/1347-4065/ac9026
4 M. Koshimizu: Jpn. J. Appl. Phys. 62 (2022) 010503. https://doi.org/10.35848/1347-4065/ac94fe
5 P. Lecoq: Nucl. Instrum. Methods Phys. Res., Sect. A 809 (2016) 130. https://doi.org/10.1016/j.nima.2015.08.041
6 J. Glodo, Y. Wang, R. Shawgo, C. Brecher, R. H. Hawrami, J. Tower, and K. S. Shah: Phys. Procedia 90 (2017)285. https://doi.org/10.1016/j.phpro.2017.09.012
7 C. L. Melcher: Nucl. Instrum. Methods Phys. Res., Sect. B 40–41 (1989) 1214. https://doi.org/10.1016/0168583X(89)90622-8
8 V. V. Nagarkar, T. K. Gupta, S. R. Miller, Y. Klugerman, M. R. Squillante, and G. Entine: IEEE Trans. Nucl.
Sci. 45 (1998) 492. https://doi.org/10.1109/23.682433
9 P. Kantuptim, D. Nakauchi, T. Kato, N. Kawaguchi, and T. Yanagida: Sens. Mater. 34 (2022) 603. https://doi.
org/10.18494/SAM3690
10 K. Okazaki, D. Onoda, D. Nakauchi, N. Kawano, H. Fukushima, T. Kato, N. Kawaguchi, and T. Yanagida:
Sens. Mater. 34 (2022) 575. https://doi.org/10.18494/SAM3678
11 Y. Fujimoto and K. Asai: Jpn. J. Appl. Phys. 62 (2022) 010605. https://doi.org/10.35848/1347-4065/ac9348
12 D. Nakauchi, T. Kato, N. Kawaguchi, and T. Yanagida: Jpn. J. Appl. Phys. 62 (2022) 010607. https://doi.
org/10.35848/1347-4065/ac9181
13 H. Fukushima, D. Nakauchi, T. Kato, N. Kawaguchi, and T. Yanagida: Jpn. J. Appl. Phys. 62 (2022) 010506.
https://doi.org/10.35848/1347-4065/ac9105
14 K. Okazaki, D. Nakauchi, H. Fukushima, T. Kato, N. Kawaguchi, and T. Yanagida: Sens. Mater. 35 (2023) 459.
https://doi.org/10.18494/SAM4144
15 J. Gironnet, V. B. Mikhailik, H. Kraus, P. de Marcillac, and N. Coron: Nucl. Instrum. Methods Phys. Res., Sect.
A 594 (2008) 358. https://doi.org/10.1016/j.nima.2008.07.008

Sensors and Materials, Vol. 36, No. 2 (2024)

529

16 K. Takagi, T. Oi, T. Fukazawa, M. Ishii, and S. Akiyama: J. Cryst. Growth 52 (1981) 584. https://doi.
org/10.1016/0022-0248(81)90345-6
17 S. P. Burachas, F. A. Danevich, A. S. Georgadze, H. V. Klapdor-Kleingrothaus, V. V. Kobychev, B. N.
Kropivyansky, V. N. Kuts, A. Muller, V. V. Muzalevsky, A. S. Nikolaiko, O. A. Ponkratenko, V. D. Ryzhikov,
A. S. Sai, I. M. Solsky, V. I. Tretyak, and Y. G. Zdesenko: Nucl. Instrum. Methods Phys. Res., Sect. A 369(1996) 164. https://doi.org/10.1016/0168-9002(95)00675-3
18 A. Phunpueok, V. Thongpool, and S. Jaiyen: J. Phys. Conf. Ser. 1380 (2019) 012128. https://doi.
org/10.1088/1742-6596/1380/1/012128
19 D. V. Poda, A. S. Barabash, P. Belli, R. Bernabei, R. S. Boiko, V. B. Brudanin, F. Cappella, V. Caracciolo, S.
Castellano, R. Cerulli, D. M. Chernyak, F. A. Danevich, S. D’Angelo, V. Y. Degoda, M. L. Di Vacri, A. E.
Dossovitskiy, E. N. Galashov, A. Incicchitti, V. V. Kobychev, S. I. Konovalov, G. P. Kovtun, M. Laubenstein,
A. L. Mikhlin, V. M. Mokina, A. S. Nikolaiko, S. Nisi, R. B. Podviyanuk, O. G. Polischuk, A. P. Shcherban, V.
N. Shlegel, D. A. Solopikhin, V. I. Tretyak, V. I. Umatov, Y. V. Vasiliev, and V. D. Virich: Radiat. Meas. 56(2013) 66. https://doi.org/10.1016/j.radmeas.2013.02.017
20 M. R. Farukhi: IEEE Trans. Nucl. Sci. 29 (1982) 1237. https://doi.org/10.1109/TNS.1982.4336345
21 W. Mengesha: IEEE Trans. Nucl. Sci. 45 (1998) 456. https://doi.org/10.1109/23.682426
22 D. W. Aitken, B. L. Beron, G. Yenicay, and H. R. Zulliger: IEEE Trans. Nucl. Sci. 14 (1967) 468. https://doi.
org/10.1109/TNS.1967.4324457
23 Y. Fujimoto, D. Nakauchi, T. Yanagida, M. Koshimizu, and K. Asai: Sens. Mater. 34 (2022) 629. https://doi.
org/10.18494/SAM3693
24 D. Nakauchi, Y. Fujimoto, T. Kato, N. Kawaguchi, and T. Yanagida: Crystals 12 (2022) 517. https://doi.
org/10.3390/cryst12040517
25 D. Onoda, M. Akatsuka, N. Kawano, T. Kato, D. Nakauchi, N. Kawaguchi, and T. Yanagida: Sens. Mater. 34(2022) 585. https://doi.org/10.18494/SAM3679
26 H. Fukushima, D. Nakauchi, T. Kato, N. Kawaguchi, and T. Yanagida: Sens. Mater. 35 (2023) 429. https://doi.
org/10.18494/SAM4139
27 P. Kantuptim, T. Kato, D. Nakauchi, N. Kawaguchi, K. Watanabe, and T. Yanagida: Sens. Mater. 35 (2023) 451.
https://doi.org/10.18494/SAM4141
28 T. Yanagida, T. Kato, D. Nakauchi, and N. Kawaguchi: Sens. Mater. 34 (2022) 595. https://doi.org/10.18494/
SAM3684
29 D. Nakauchi, H. Fukushima, T. Kato, N. Kawaguchi, and T. Yanagida: Sens. Mater. 34 (2022) 611. https://doi.
org/10.18494/SAM3696
30 R. Hawrami, E. Ariesanti, A. Farsoni, D. Szydel, and H. Sabet: Crystals 12 (2022) 1517. https://doi.org/10.3390/
cryst12111517
31 M. Gascón, S. Lam, S. Wang, S. Curtarolo, and R. S. Feigelson: Radiat. Meas. 56 (2013) 70. https://doi.
org/10.1016/j.radmeas.2013.04.017
32 J. Brechtl, X. Xie, R. Feng, G. Wang, C. Melcher, M. Zhuravleva, and P. K. Liaw: J. Mater. Sci. Technol. 153(2023) 120. https://doi.org/10.1016/j.jmst.2022.12.047
33 A. Smerechuk, E. Galenin, V. Nesterkina, O. Sidletskiy, and C. Dujardin: J. Cryst. Growth 521 (2019) 41.
https://doi.org/10.1016/j.jcrysgro.2019.05.031
34 E. V. Van Loef, C. M. Wilson, N. J. Cherepy, G. Hull, S. A. Payne, W. S. Choong, W. W. Moses, and K. S. Shah:IEEE Trans. Nucl. Sci. 56 (2009) 869. https://doi.org/10.1109/TNS.2009.2013947
35 T. D. Creason, T. M. McWhorter, Z. Bell, M. H. Du, and B. Saparov: Chem. Mater. 32 (2020) 6197. https://doi.
org/10.1021/acs.chemmater.0c02098
36 B. Yang, L. Yin, G. Niu, J. H. Yuan, K. H. Xue, Z. Tan, X. S. Miao, M. Niu, X. Du, H. Song, E. Lifshitz, and J.
Tang: Adv. Mater. 31 (2019) 1904711. https://doi.org/10.1002/adma.201904711
37 K. Yamabayashi, K. Okazaki, D. Nakauchi, T. Kato, N. Kawaguchi, and T. Yanagida: Radiat. Phys. Chem. 214(2024) 111292. https://doi.org/10.1016/j.radphyschem.2023.111292
38 W. Naewthong, W. Juntapo, R. Amarit, K. Duangkanya, S. Sumriddetchkajorn, T. Rungseesumran, N.
Kamwang, Y. Tariwong, J. Kaewkhao, A. Kopwitthaya, and A. Kopwitthaya: Opt. Mater. Express 12 (2022)
308. https://doi.org/10.1364/OME.444631
39 X. Zhao, G. Niu, J. Zhu, B. Yang, J. H. Yuan, S. Li, W. Gao, Q. Hu, L. Yin, K. H. Xue, E. Lifshitz, X. Miao, and
J. Tang: J. Phys. Chem. 11 (2020) 1873. https://doi.org/10.1021/acs.jpclett.0c00161
40 W. Hume-Rothery, P. W. Reynolds, and G. V. Raynor: Nature 146 (1940) 528. https://doi.org/10.1038/146528a0
41 M. Arai, Y. Fujimoto, M. Koshimizu, H. Kimura, T. Yanagida, and K. Asai: Mater. Res. Bull. 120 (2019)110589. https://doi.org/10.1016/j.materresbull.2019.110589

530

Sensors and Materials, Vol. 36, No. 2 (2024)

42 T. Hayashi, K. Ichiba, D. Nakauchi, K. Watanabe, T. Kato, N. Kawaguchi, and T. Yanagida: J. Lumin. 255(2023) 119614. https://doi.org/10.1016/j.jlumin.2022.119614
43 T. Yanagida, K. Kamada, Y. Fujimoto, H. Yagi, and T. Yanagitani: Opt. Mater. 35 (2013) 2480. https://doi.
org/10.1016/j.optmat.2013.07.002
44 T. Yanagida, Y. Fujimoto, T. Ito, K. Uchiyama, and K. Mori: Appl. Phys. Express 7 (2014) 062401. https://doi.
org/10.7567/APEX.7.062401
45 K. X. Xu, Z. Zhou, and J. Zhang: J. Phys. Chem. Lett. 14 (2023) 32. https://doi.org/https://doi.org/10.1021/acs.
jpclett.2c03514
46 T. D. Creason, A. Yangui, R. Roccanova, A. Strom, M. H. Du, and B. Saparov: Adv. Opt. Mater. 8 (2020)
1901338. https://doi.org/10.1002/adom.201901338
47 S. Zhao, Z. Jia, Y. Huang, Q. Qian, Q. Lin, Z. Zang, S. Zhao, Y. Huang, Q. Qian, Z. Zang, Z. Jia, and Q. Lin:
Adv. Funct. Mater. (2023) 2305858. https://doi.org/10.1002/adfm.202305858
48 D. Nakauchi, T. Kato, N. Kawaguchi, and T. Yanagida: Appl. Phys. Express 13 (2020) 122001. https://doi.
org/10.35848/1882-0786/abc574
49 W. Klamra, T. Szczesniak, M. Moszynski, J. Iwanowska, L. Swiderski, A. Syntfeld-Kazuch, V. N. Shlegel, Y.
V. Vasiliev, and E. N. Galashov: J. Instrum. 7 (2012) P03011. https://doi.org/10.1088/1748-0221/7/03/P03011
50 T. Yanagida: J. Lumin. 169 (2016) 544. https://doi.org/10.1016/j.jlumin.2015.01.006
51 T. Yanagida: Proc. Jpn. Acad. Ser. B 94 (2018) 75. https://doi.org/10.2183/pjab.94.007
52 I. Holl, E. Lorenz, and G. Mageras: IEEE Trans. Nucl. Sci. 35 (1988) 105. https://doi.org/10.1109/23.12684