Growth and Scintillation Properties of Zn Ions Doped γ-CuI Crystals

doi:10.16553/j.cnki.issn1000-985x.2025.0048

Abstract

Abstract: In this paper， high purity γ-CuI raw materials were purified using recrystallization and zone melting methods， and γ-CuI single crystals doped with different Zn ion concentrations were grown by Bridgman method. The crystal structure， photoluminescence， X-ray excited optical luminescence， and fluorescence lifetime of the samples were thoroughly investigated. X-ray diffraction and scanning electron microscopy analyses confirm the high purity of the synthesized γ-CuI samples and the successful incorporation of Zn ions into the γ-CuI lattice. The photoluminescence and X-ray excited emission spectra indicate that Zn ion doping enhanced the emissions of free excitons and Cu⁺ vacancies while suppressing deep-level emissions. At a Zn ion doping concentration of 5%， the Cu_0.95I:Zn_0.05 crystal demonstrats a fluorescence lifetime of 0.36 ns， which is significantly better than that of γ-CuI （0.62 ns）.

Key words: γ-CuI crystal; Zn ion doping; recrystallization purification; zone melting method; Bridgman method; ultrafast decay time

CLC Number:

CHEN Can, HU Yizhe, ZHANG Zhijing, PAN Jianguo, PAN Shangke. Growth and Scintillation Properties of Zn Ions Doped γ-CuI Crystals[J]. Journal of Synthetic Crystals, 2025, 54(9): 1558-1565.

Figures/Tables 11

Fig.1 γ-CuI crystals grown by Bridgman method. （a） CuI， Cu0.975I:Zn0.025， Cu0.95I:Zn0.05， Cu0.9I:Zn0.1， Cu0.8I:Zn0.2 crystals；（b） Cu0.95I:Zn0.05 wafer

Fig.2 γ-CuI crystal. （a） γ-CuI crystals grown by recrystallization with different solvents；（b） purified γ-CuI crystal by zone melting

Table 1 Element content of γ -CuI after purification by different solvents

Sample	Content of Cu/%	Content of I/%	Content of K/%	Ratio of Cu and I
NaI	48.90	52.10	0	0.94
KI	47.61	52.33	0.06	0.91
NH₄I	45.92	54.08	0	0.85

Table 2 Element content of γ -CuI after horizontal zone melting

Sample	Content of Cu/%	Content of I/%	Content of Na/%	Ratio of Cu and I
Left end	51.46	48.54	0	1.06
Middle	50.26	49.73	0	1.01
Right end	49.19	49.88	0.93	0.98

Fig.3 XRD patterns of γ-CuI doped with different concentrations of Zn ions. （a） 10°~80°；（b） 20°~30°

Fig.4 PL spectra of CuI doped with different concentrations of Zn ions

Table 3 Peak areas and ratios at different positions of γ -CuI doped with different concentrations of Zn ions

Sample	Peak position/nm	Peak area	Peak area ratio
CuI	410	61 548	5.35
	425	184 712	16.06
	700	903 372	78.58
Cu_0.975I:Zn_0.025	410	120 528	10.67
	425	406 157	35.98
	720	602 038	53.33
Cu_0.95I:Zn_0.05	410	156 672	19.80
	425	520 714	65.81
	720	113 762	14.37
Cu_0.9I:Zn_0.1	410	153 103	18.83
	425	506 566	62.31
	720	153 243	18.85
Cu_0.8I:Zn_0.2	410	16 321	2.59
	425	71 844	11.45
	720	539 683	85.96

Fig.5 UV-Vis transmission curve of Cu0.95I:Zn0.05 crystal. （a） Optical transmission curve；（b） optical band gap curve

Fig.6 Fluorescence lifetime curve. （a） γ-CuI crystal；（b） Cu0.95I:Zn0.05 crystal

Table 4 High density， fast delay scintillation crystals and their properties compared with γ -CuI:Zn crystals

Crystal	Ultrafast emission wavelength/nm	Decay time/ps	Density/（g·cm^-3）	Bandgap/eV
γ-CuI:Zn	420	360	5.71	2.92
BaF₂^［29］	225	600	4.83	0.5
Cs₂LiYCl₆:Ce^［30］	315	1 000	3.31	5.52
PbI₂^［31］	490	150	6.61	2.55

Fig.7 X-ray excited optical luminescence of γ-CuI and Cu0.95I:Zn0.05 crystal

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