Long persistent and optically stimulated luminescence behaviors of calcium aluminates with different trap filling processes

Zhang, Buhao; Xu, Xuhui; Li, Qianyue; Wu, Yumei; Qiu, Jianbei; Yu, Xue

doi:10.1016/j.jssc.2014.06.007

Cited by 27 publications

(12 citation statements)

References 21 publications

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“…, no significant changes in the emission intensity with the prolonged irradiated time was detected in this phosphor. It could be concluded that the introduction of traps has no obvious effect on the PL process, unlike the case of CaAl 2 O 4 :Eu 2+ in our previous report …”

Section: Resultscontrasting

confidence: 59%

Photostimulated and Long Persistent Luminescence Properties from Different Crystallographic Sites of β‐Sr₂SiO₄: Eu²⁺, R³⁺ (R = Tm, Gd)

Zhang

Wang

et al. 2014

J. Am. Ceram. Soc.

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Sintered ceramics of b-Sr 2 SiO 4 : Eu 2+ , R 3+ (R=Tm, Gd) were prepared and their spectroscopic properties were evaluated. A large enhancement of green photostimulated luminescence (PSL) was observed from β-Sr 2 SiO 4 :Eu 2+ codoping with Tm 3+ at a recognizable intensity level, and the most efficient PSL was obtained when the codoping concentration of Tm 3+ was 0.002. It was proved that the introduction of Tm 3+ created a large number of oxygen vacancies which serve as traps for electrons excited by UV irradiation. In addition, a distinguishable difference between the photoluminescence (PL) and PSL spectra of β-Sr 2 SiO 4 : Eu 2+ , Tm 3+ was observed, namely the PSL spectrum exhibits only a symmetric emission band peaked at about 540 nm while both 470 and 540 nm peaks were detected in the PL spectrum. It is safe to say that PSL only derives from one emission center of Eu2 in the crystallographic Sr2 sites, which could be ascribed to the different distribution of trap centers for two crystallographic Sr sites.

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Section: Resultscontrasting

confidence: 59%

Photostimulated and Long Persistent Luminescence Properties from Different Crystallographic Sites of β‐Sr₂SiO₄: Eu²⁺, R³⁺ (R = Tm, Gd)

Zhang

Wang

et al. 2014

J. Am. Ceram. Soc.

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“…As the Cu concentration increased from 0% to 12%, the variation in the a axis (ranging from 3.7619 to 3.7634 Å ), c-axis (ranging from 11.4082 to 11.4119 Å ), and lattice volume, V (ranging from 139.8192 to 139.9754 Å 3 ) remained stable in a narrow range because Zn 21 (0.60 Å , CN 5 4) 28,29 was substituted with Cu 1 (0.60 Å , CN 5 4) 30,31 , which has a similar ionic radius. X-ray photoelectron spectroscopy showed that the CaZnOS was doped with Cu 1 , which also confirmed that the Cu 1 was doped into the Zn 21 site of the CaZnOS crystal structure; it was difficult to Mechanical quenching swaps to mechanoluminescence D Tu et al 2 substitute Cu 1 into the Ca 21 site because of the large radius mismatch of Ca 21 (1.00 Å , CN 5 6) 32 . According to the XRD refinement results, CaZnOS:Cu maintained its original crystal structure, even at a Cu concentration of 12%, and it possessed a noncentrosymmetric layered structure with a space group of P6 3 mc (inset in Figure 2).…”

Section: Resultsmentioning

confidence: 81%

Mechanism of mechanical quenching and mechanoluminescence in phosphorescent CaZnOS:Cu

Fujio

et al. 2015

Light Sci Appl

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This article reports a new phosphorescent material, CaZnOS:Cu, that exhibits two types of mechano-optical conversion: mechanical quenching and mechanoluminescence. An intense mechanical quenching of phosphorescence corresponding to mechanical stimuli can be achieved in CaZnOS:Cu within a short decay time period. Over time, it gradually changes to mechanoluminescence when a mechanical load is applied. We propose that the mechanical quenching and mechanoluminescence arise from the different roles of shallow and deep traps in CaZnOS:Cu. CaZnOS:Cu has promising applications in monitoring mechanical stress in industrial plants, structures, and living bodies. Keywords: mechanical quenching; mechanoluminescence; phosphorescence; traps INTRODUCTIONAdjusting and controlling the optical properties of materials by altering environmental factors are important in the development of various applications in sensing, memory, detection, and display devices [1][2][3][4][5][6] . Mechanical stress is the most common external stimulus, and thus materials that exhibit mechano-optical conversion are promising for practical applications in science and engineering [7][8][9][10][11][12] .Mechanoluminescent (ML) materials emit light when mechanical energy is applied and are effective for mechano-optical conversion 1,9,13,14 . Therefore, ML materials have been used as optical sensors for monitoring changes in mechanical stress. 25 , have been explored. Recently, our group has discovered another type of mechano-optical conversion, which is referred to as mechanical quenching (MQ) 26 . In contrast to ML, MQ is the quenching of phosphorescence intensity by using mechanical stimuli. Previously, we reported that CaZnOS:Cu exhibited MQ under applied mechanical stress. However, to understand the MQ process and mechanism further and use it for practical applications, the crystal structure, phosphorescence properties, and MQ properties of CaZnOS:Cu must be determined.Here, we carry out further study on MQ in a phosphorescent material, CaZnOS:Cu. We examine the change in crystal structure that is caused by changing the Cu concentration, the phosphorescence properties, and the MQ mechanism. We find that CaZnOS:Cu exhibits a variety of mechano-optical conversions depending on the experimental conditions. MATERIALS AND METHODSCaZnOS:Cu was synthesized by a solid-state reaction method. Highpurity CaCO 3 (50 mol% excess) and appropriate amounts of ZnS and Cu 2 O were weighed and ground in an agate mortar with ethanol and then sintered under an air flow at 1100 6 C for 5 h. The excess calcium compounds were removed from the sample by washing with an aqueous solution of acetic acid. After filtration and drying, CaZnOS:Cu was ground again and then pulverized for measurement.The crystalline phase of CaZnOS:Cu was characterized by using X-ray powder diffraction (XRD; RINT-2000, Rigaku Co., Tokyo, Japan) with CuKa radiation (1.5418 Å ; cathode voltage, 40 kV; current, 40 mA) at room temperature. As reported previously, CaZnOS has an unusual structure with the...

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“…), Eu 2 O 3 (99.99%) and other rare earth oxides (Dy 2 O 3 , Tb 4 O 7 , CeO 2 , Gd 2 O 3 , Nd 2 O 3, typically 99.9%). 16 Only for the sample codoped with Dy 3+ ion, the initial LLP brightness is the lowest, and its 65 intensity almost has no change with the increase of the irradiated time. Subsequently, the mixture were fired at 1280 °C for 10 h under a flowing N 2 -H 2 (95:5) reductive atmosphere in a tube furnace and the relative heating rate is 5 °C/min.…”

Section: Methodsmentioning

confidence: 92%

Controlling and revealing the trap distributions of Ca₆BaP₄O₁₇:Eu²⁺,R³⁺ (R = Dy, Tb, Ce, Gd, Nd) by codoping different trivalent lanthanides

et al. 2015

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Thermoluminescence (TL) glow curves of Ca 6 BaP 4 O 17 :Eu 2+ ,R 3+ (R=Dy, Tb, Ce, Gd, Nd) samples were measured above room temperature in order to compare the trap distributions in the band gap. The observed phenomenon indicates that R 3+ ions (R=Dy, Tb, Ce, Gd, Nd) have different effects on trap properties of Ca 6 BaP 4 O 17 :Eu 2+ phosphor. The most shallow trap (0.620 eV) for Tb 3+ ion and the deepest trap (0.762 eV) for Dy 3+ ion eventually led to shorter duration (4.3 h and 1.2 h respectively), while 10 appropriate trap depth (0.716 eV) for Nd 3+ ion makes Ca 6 BaP 4 O 17 :Eu 2+ ,Nd 3+ sample show the longest afterglow duration (37.9 h). Codoping with Tb 3+ ion slightly increases the instinct traps of Ca 6 BaP 4 O 17 :Eu 2+ sample and creates a new low-temperature TL peak corresponding to relatively shallow trap leading to the strongest initial afterglow brightness (0.887 cd/m 2 ), while, codoping with other R 3+ ions (R=Dy, Ce, Gd, Nd) creates new appropriate or inappropriate traps. By performing a series of long-15 lasting phosphorescence (LLP) spectra with various irradiated time and TL experiments with varying delay time after ceasing the UV irradiation, the trap distribution of the depth and shape was evaluated. The result provides a better understanding of the role of these trapping centers played in the persistent luminescent mechanism. Journal Name, [year], [vol], 00-00 | 3 Fig. 2 LLP spectra of Ca6BaP4O17:Eu 2+ and Ca6BaP4O17:Eu 2+ ,R 3+ (R=Dy, Tb, Ce, Gd, Nd) measured with varying the UV irradiation duration. 3.3. Afterglow decay curves of Ca 6 BaP 4 O 17 :Eu 2+ and Ca 6 BaP 4 O 17 :Eu 2+ ,R 3+ (R=Dy, Tb, Ce, Gd, Nd). 5The afterglow decay curves of Ca 6 BaP 4 O 17 :Eu 2+ ,R 3+ (R=Dy, Tb, Ce, Gd, Nd) were also plotted as a function of reciprocal persistent luminescence intensity (I -1 ) versus time (t), as shown in 30

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Long persistent and optically stimulated luminescence behaviors of calcium aluminates with different trap filling processes

Cited by 27 publications

References 21 publications

Photostimulated and Long Persistent Luminescence Properties from Different Crystallographic Sites of β‐Sr₂SiO₄: Eu²⁺, R³⁺ (R = Tm, Gd)

Photostimulated and Long Persistent Luminescence Properties from Different Crystallographic Sites of β‐Sr₂SiO₄: Eu²⁺, R³⁺ (R = Tm, Gd)

Mechanism of mechanical quenching and mechanoluminescence in phosphorescent CaZnOS:Cu

Controlling and revealing the trap distributions of Ca₆BaP₄O₁₇:Eu²⁺,R³⁺ (R = Dy, Tb, Ce, Gd, Nd) by codoping different trivalent lanthanides

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Long persistent and optically stimulated luminescence behaviors of calcium aluminates with different trap filling processes

Cited by 27 publications

References 21 publications

Photostimulated and Long Persistent Luminescence Properties from Different Crystallographic Sites of β‐Sr2SiO4: Eu2+, R3+ (R = Tm, Gd)

Photostimulated and Long Persistent Luminescence Properties from Different Crystallographic Sites of β‐Sr2SiO4: Eu2+, R3+ (R = Tm, Gd)

Mechanism of mechanical quenching and mechanoluminescence in phosphorescent CaZnOS:Cu

Controlling and revealing the trap distributions of Ca6BaP4O17:Eu2+,R3+ (R = Dy, Tb, Ce, Gd, Nd) by codoping different trivalent lanthanides

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Photostimulated and Long Persistent Luminescence Properties from Different Crystallographic Sites of β‐Sr₂SiO₄: Eu²⁺, R³⁺ (R = Tm, Gd)

Photostimulated and Long Persistent Luminescence Properties from Different Crystallographic Sites of β‐Sr₂SiO₄: Eu²⁺, R³⁺ (R = Tm, Gd)

Controlling and revealing the trap distributions of Ca₆BaP₄O₁₇:Eu²⁺,R³⁺ (R = Dy, Tb, Ce, Gd, Nd) by codoping different trivalent lanthanides