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Luminescence property improvement of Ba2LaSbO6:Mn4+ phosphor by using Dy3+ or H3BO3
Physics Letters A 383 (2019) 2102–2105
Contents lists available at ScienceDirect
Physics Letters A www.elsevier.com/locate/pla
Luminescence property improvement of Ba2 LaSbO6 :Mn4+ phosphor by using Dy3+ or H3 BO3 Renping Cao ∗ , Longxiang Xu, Yaqin Ran, Xinyan Lv, Siling Guo, Hui Ao, Ting Chen, Zhiyang Luo ∗ College of Mathematics and Physics, Jinggangshan University, Ji’an 343009, China
a r t i c l e
i n f o
Article history: Received 27 February 2019 Received in revised form 29 March 2019 Accepted 31 March 2019 Available online 4 April 2019 Communicated by M. Wu Keywords: Phosphors Mn4+ ions Luminescence properties Red-emitting
a b s t r a c t Ba2 LaSbO6 :Mn4+ , Ba2 LaSbO6 :Mn4+ , Dy3+ , and Ba2 LaSbO6 :Mn4+ , H3 BO3 phosphors are synthesized in the air by high temperature solid state reaction method. The particle sizes and sintering degree of Ba2 LaSbO6 :Mn4+ phosphor may be changed by doping Dy3+ ion and H3 BO3 . When the small amount of Dy3+ ion and H3 BO3 are codoped, the emission intensity of Ba2 LaSbO6 :Mn4+ phosphor can be enhanced 1.2–1.3 times and the quantum efficiency of Ba2 LaSbO6 :Mn4+ phosphor can be improved. The lifetime of Ba2 LaSbO6 :Mn4+ phosphor may be changed by doping Dy3+ ion and H3 BO3 . The experimental results are valuable in research of luminescence property of Mn4+ -doped luminescence materials. © 2019 Elsevier B.V. All rights reserved.
1. Introduction In resent years, Mn4+ -doped luminescence materials as red phosphors have been widely researched due to the luminescence characteristics of Mn4+ ion [1–3]. Mn4+ ion can usually be stable in host with octahedral coordination, which mainly contains two chemical classes: fluorides and oxides. The Mn4+ -doped fluorides with line red emission peaking at ∼ 630 nm (e.g., Rb2 GeF6 :Mn4+ [4], Na5 Zr2 F13 :Mn4+ [5], BaNbOF5 :Mn4+ [6], (NH4 )3 AlF6 :Mn4+ [7], and LiAl4 O6 F:Mn4+ [8]) are usually unstable at large moisture and high temperature conditions, which affect their practical application. The Mn4+ -doped oxides with red or deep red emission exhibit a good thermal/chemical stability and have different emission band positions in the wavelength region from 640 nm to 750 nm due to the effect of host crystal field, such as Mg2 La2 SnO7 :Mn4+ [9], La2 MgGeO6 :Mn4+ [10], BaLaMgNbO6 :Mn4+ [11], (Ba1−x Srx )2 YSbO6 :Mn4+ [12], and NaMgLaTeO6 :Mn4+ [13]. To further enhance the practical application of Mn4+ -doped oxides, the improvements of luminescence properties of Mn4+ -doped oxides have been widely reported by codoping other cations, such as Lu3−x Yx Al5 O12 :Mn4+ , (Li+ , Na+ , Ca2+ , Mg2+ , Sr2+ , Sc3+ ) [14], La2 LiSbO6 :Mn4+ , Mg2+ [15], Y2 Mg3 Ge3 O12 :Mn4+ , Li+ [16], and Li2 TiO3 :Mn4+ , Zn2+ [17]. Ba2 LaSbO6 :Mn4+ phosphor has been reported and it is chosen as a research subject [18]. Dy3+ and H3 BO3
*
Corresponding authors. E-mail addresses: [email protected] (R. Cao), [email protected] (Z. Luo).
https://doi.org/10.1016/j.physleta.2019.03.044 0375-9601/© 2019 Elsevier B.V. All rights reserved.
are selected as dopants to improve the luminescence properties of phosphors according to previous reports [19–22]. In this work, Ba2 LaSbO6 :Mn4+ , Ba2 LaSbO6 :Mn4+ , Dy3+ , and Ba2 LaSbO6 :Mn4+ , H3 BO3 phosphors are synthesized in the air by solid-state reaction method. The influence of Dy3+ and H3 BO3 to the emission properties, quantum efficiency, and lifetime of Ba2 LaSbO6 :Mn4+ phosphor is investigated. 2. Experimental The synthesis process is consistent with that used in previous report of Ba2 LaSbO6 :Mn4+ phosphor and the optimal Mn4+ concentration in Ba2 LaSbO6 :Mn4+ phosphor is ∼ 0.2 mol% [18]. In this work, we directly use the chemicals (BaCO3 (99.9%), H3 BO3 (99.9%), La2 O3 (99.99%), Sb2 O5 (99.99%), Dy2 O3 (99.99%), and MnCO3 (99.9%)) as raw materials to synthesize the Ba2 LaSbO6 :0.2%Mn4+ , Ba2 LaSbO6 :0.2%Mn4+ , x%Dy3+ (x = 1 and 2), and Ba2 LaSbO6 : 0.2%Mn4+ , y%H3 BO3 ( y = 1 and 6) phosphors in the air by hightemperature solid state reaction method. These chemicals are purchased from the Aladdin Chemical Reagent Company in Shanghai, China. We use a Philips Model PW1830 X-ray diffractometer with Cu Kα radiation at 40 kV and 40 mA to investigate the phase purity of the samples. The X-ray diffraction (XRD) patterns are collected in the 2θ range of 10–90◦ with a scanning step of 0.02◦ . A fieldemission scanning electron microscopy (FE-SEM) system (MAIA3 TESCAN) equipped with an energy dispersive X-ray (EDX) spectrum at 15 V is used to measure the morphology of the samples.
R. Cao et al. / Physics Letters A 383 (2019) 2102–2105
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Fig. 1. (a) XRD patterns of JCPDS no. 54-958 (Ba2 LaSbO6 ), Ba2 LaSbO6 :0.2%Mn4+ , Ba2 LaSbO6 :0.2%Mn4+ , x%Dy3+ (x = 1 and 2), and Ba2 LaSbO6 :0.2%Mn4+ , 6%H3 BO3 phosphors, (b) The crystal structure diagram of host (Ba2 LaSbO6 ) based on ICSD #153136, and (c) FE-SEM diagrams of Ba2 LaSbO6 :0.2%Mn4+ , Ba2 LaSbO6 :0.2%Mn4+ , 2%Dy3+ , and Ba2 LaSbO6 :0.2%Mn4+ , 6%H3 BO3 phosphors. (For interpretation of the colors in the figure(s), the reader is referred to the web version of this article.)
The luminescence properties, the quantum efficiency (QE), and decay curves are studied by an Edinburgh FLS 980 instrument with a high spectral resolution (signal to noise ratio > 12000:1). 3. Results and discussion As shown in Fig. 1(a), the XRD patterns of the Ba2 LaSbO6 : 0.2%Mn4+ , Ba2 LaSbO6 :0.2%Mn4+ , x%Dy3+ (x = 1 and 2) and Ba2 LaSbO6 :0.2%Mn4+ , 6%H3 BO3 samples are in good relation with those of the Joint Committee Powder Diffraction Standards (JCPDS) no. 54-958 (Ba2 LaSbO6 ) [23] and there are no impurity peaks, indicating that the dopants (Mn4+ , Dy3+ , and H3 BO3 ) do not make significant influence on the host (Ba2 LaSbO6 ) structure. The crystal structure of host (Ba2 LaSbO6 ) based on the data from structure database (ICSD) #153136 [24] is show in Fig. 1(b). The doubleperovskite symmetry Ba2 LaSbO6 is described in the trigonal system with the space group of R3(148) and the cell parameters 3
(a = b = c = 6.0825(1) Å, V = 160.17(1) Å , and Z = 1) [24]. As shown in Fig. 1(b), the La3+ and Sb5+ ions are coordinated by six oxygen atoms and form [LaO6 ] and [SbO6 ] octahedra, respectively, and Ba2+ ion coordinated by three oxygen atoms are in the interspace between [LaO6 ] and [SbO6 ] octahedra. Here, the ionic radii of the cations are (CN = 6, La3+ : ∼ 1.032 Å, Sb5+ : ∼ 0.62 Å, Dy3+ : ∼ 0.912 Å, and Mn4+ : ∼ 0.53 Å), B3+ : ∼ 0.27 Å, and Ba2+ : ∼ 1.35 Å [25]. According to ionic radii relation and charge similarity, it can be inferred that Dy3+ ion will occupy the La3+ sites, and Mn4+ ions will substitute the Sb5+ sites in host (Ba2 LaSbO6 ) lattice. B3+ ions are not introduced into the host lattice because H3 BO3 plays a flux role and there is a big ion radius difference between B3+ ion and the cations (Ba2+ , La3+ , and Sb5+ ). Because of the different valence states of Mn4+ and Sb5+ ions, the electron hole (v − ) in host lattice may occur for the charge balance (Mn4+ → Sb5+ + v − ). As seen the FE-SEM patterns in Fig. 1(c), Ba2 LaSbO6 :0.2%Mn4+ , Ba2 LaSbO6 :0.2%Mn4+ , 2%Dy3+ , and Ba2 LaSbO6 :0.2%Mn4+ , 6%H3 BO3 phosphors contain irregular particles, and the Dy3+ ion and H3 BO3 have some effects on the particle size and sintering degree of Ba2 LaSbO6 :Mn4+ phosphor.
Fig. 2. PL spectra of (a) Ba2 LaSbO6 :0.2%Mn4+ , x%Dy3+ (x = 1 and 2), (b) Ba2 LaSbO6 :0.2%Mn4+ , y%H3 BO3 ( y = 1 and 6) phosphors at room temperature (λex = 380 nm).
The luminescence properties of Ba2 LaSbO6 :Mn4+ phosphors were reported in detail in Ref. [18], and we do not re-describe them here. The photoluminescence (PL) spectra of Ba2 LaSbO6 : 0.2%Mn4+ , x%Dy3+ (x = 1 and 2) and Ba2 LaSbO6 :0.2%Mn4+ , y%H3 BO3 ( y = 1 and 6) phosphors excited at 380 nm at room temperature are presented in Fig. 2. The QEs values are measured directly by an Edinburgh FLS 980 instrument with an integrat-
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R. Cao et al. / Physics Letters A 383 (2019) 2102–2105
Table 1 The QEs of Ba2 LaSbO6 :0.2%Mn4+ , Ba2 LaSbO6 :0.2%Mn4+ , x%Dy3+ (x = 1 and 2), and Ba2 LaSbO6 :0.2%Mn4+ , y%H3 BO3 ( y = 1 and 6) phosphors.
(mol%) QE
Mn4+
0.2%Mn4+ , x%Dy3+
0.2%Mn4+ , y%H3 BO3
0.2% 33.5%
1% 34.6%
1% 36.4%
2% 34.2%
Ba2 LaSbO6 :Mn4+ phosphor. The experimental results are beneficial to research the luminescence property improvement of Mn4+ -doped luminescence materials. Acknowledgements
6% 31.3%
This work is financially supported by the National Natural Science Foundation of China (No. 51862015) and Foundation of Jiang’xi Educational Committee (No. GJJ180564). References
Fig. 3. Decay curves of Ba2 LaSbO6 :0.2%Mn4+ , Ba2 LaSbO6 :0.2%Mn4+ , x%Dy3+ (x = 1 and 2), and Ba2 LaSbO6 :0.2%Mn4+ , y%H3 BO3 ( y = 1 and 6) phosphors at room temperature (λex = 380 nm; λem = 678 nm).
ing sphere and the results are shown in Table 1. It can be found that small amount of dopants (Dy3+ and H3 BO3 ) can be used to improve the emission properties and QE of Ba2 LaSbO6 :Mn4+ phosphor because of the ET from Dy3+ to Mn4+ and the flux role of H3 BO3 after co-doping Dy3+ and H3 BO3 [19–22]. In addition, after the Dy3+ ions occupy the La3+ sites in host, the unit of La3+ − O2− − Mn4+ in Ba2 LaSbO6 :Mn4+ is changed to the unit of Dy3+ − O2− − Mn4+ . Because the ionic radius of Dy3+ ion is less than that of La3+ ion (CN = 6, La3+ : ∼ 1.032 Å and Dy3+ : ∼ 0.912 Å), the electron cloud of O2− ion is far away from Mn4+ ion, resulting in the improvement of luminescence property of Mn4+ ion, which is consistent with the results in Fig. 2. If H3 BO3 content is increased, it can affect the host crystal field, leading to the decrease of emission. The decay curves of Ba2 LaSbO6 :0.2%Mn4+ , Ba2 LaSbO6 : 0.2%Mn4+ , x%Dy3+ (x = 1 and 2), and Ba2 LaSbO6 :0.2%Mn4+ , y%H3 BO3 ( y = 1 and 6) phosphors at room temperature are shown in Fig. 3. The excitation wavelength is 380 nm with monitoring at 678 nm. The decay curves can be well fitted via the first order exponential decay function [26]:
I (t ) = I (0) exp(−t /τ )
(1)
where I (t ) is the luminescence intensity at time t, I (0) is the initial luminescence intensity, t is the time, and τ is the decay time for the exponential component. The lifetimes may be changed by the dopants (Dy3+ and H3 BO3 ) and are 277.1 μs (Ba2 LaSbO6 :0.2%Mn4+ ), 253.2 μs (Ba2 LaSbO6 :0.2%Mn4+ , 1%Dy3+ ), 254.8 μs (Ba2 LaSbO6 :0.2%Mn4+ , 2%Dy3+ ), 261.2 μs (Ba2 LaSbO6 : 0.2%Mn4+ , 1%H3 BO3 ), and 286.4 μs (Ba2 LaSbO6 :0.2%Mn4+ , 6%H3 BO3 ). The possible reason for the change in lifetimes is that the dopants (Dy3+ and B3+ ) change the non-radiative or radiative transition time of free electrons of Mn4+ ion. 4. Conclusions In conclusion, Ba2 LaSbO6 :Mn4+ , Ba2 LaSbO6 :Mn4+ , Dy3+ , and Ba2 LaSbO6 :Mn4+ , H3 BO3 phosphors are synthesized in the air by solid-state reaction method. The Dy3+ ion and H3 BO3 can affect the particle size and sintering degree of Ba2 LaSbO6 :Mn4+ phosphor. The small amount of Dy3+ ion and H3 BO3 can be used to change the emission properties, QE, and lifetime of
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Contents lists available at ScienceDirect
Physics Letters A www.elsevier.com/locate/pla
Luminescence property improvement of Ba2 LaSbO6 :Mn4+ phosphor by using Dy3+ or H3 BO3 Renping Cao ∗ , Longxiang Xu, Yaqin Ran, Xinyan Lv, Siling Guo, Hui Ao, Ting Chen, Zhiyang Luo ∗ College of Mathematics and Physics, Jinggangshan University, Ji’an 343009, China
a r t i c l e
i n f o
Article history: Received 27 February 2019 Received in revised form 29 March 2019 Accepted 31 March 2019 Available online 4 April 2019 Communicated by M. Wu Keywords: Phosphors Mn4+ ions Luminescence properties Red-emitting
a b s t r a c t Ba2 LaSbO6 :Mn4+ , Ba2 LaSbO6 :Mn4+ , Dy3+ , and Ba2 LaSbO6 :Mn4+ , H3 BO3 phosphors are synthesized in the air by high temperature solid state reaction method. The particle sizes and sintering degree of Ba2 LaSbO6 :Mn4+ phosphor may be changed by doping Dy3+ ion and H3 BO3 . When the small amount of Dy3+ ion and H3 BO3 are codoped, the emission intensity of Ba2 LaSbO6 :Mn4+ phosphor can be enhanced 1.2–1.3 times and the quantum efficiency of Ba2 LaSbO6 :Mn4+ phosphor can be improved. The lifetime of Ba2 LaSbO6 :Mn4+ phosphor may be changed by doping Dy3+ ion and H3 BO3 . The experimental results are valuable in research of luminescence property of Mn4+ -doped luminescence materials. © 2019 Elsevier B.V. All rights reserved.
1. Introduction In resent years, Mn4+ -doped luminescence materials as red phosphors have been widely researched due to the luminescence characteristics of Mn4+ ion [1–3]. Mn4+ ion can usually be stable in host with octahedral coordination, which mainly contains two chemical classes: fluorides and oxides. The Mn4+ -doped fluorides with line red emission peaking at ∼ 630 nm (e.g., Rb2 GeF6 :Mn4+ [4], Na5 Zr2 F13 :Mn4+ [5], BaNbOF5 :Mn4+ [6], (NH4 )3 AlF6 :Mn4+ [7], and LiAl4 O6 F:Mn4+ [8]) are usually unstable at large moisture and high temperature conditions, which affect their practical application. The Mn4+ -doped oxides with red or deep red emission exhibit a good thermal/chemical stability and have different emission band positions in the wavelength region from 640 nm to 750 nm due to the effect of host crystal field, such as Mg2 La2 SnO7 :Mn4+ [9], La2 MgGeO6 :Mn4+ [10], BaLaMgNbO6 :Mn4+ [11], (Ba1−x Srx )2 YSbO6 :Mn4+ [12], and NaMgLaTeO6 :Mn4+ [13]. To further enhance the practical application of Mn4+ -doped oxides, the improvements of luminescence properties of Mn4+ -doped oxides have been widely reported by codoping other cations, such as Lu3−x Yx Al5 O12 :Mn4+ , (Li+ , Na+ , Ca2+ , Mg2+ , Sr2+ , Sc3+ ) [14], La2 LiSbO6 :Mn4+ , Mg2+ [15], Y2 Mg3 Ge3 O12 :Mn4+ , Li+ [16], and Li2 TiO3 :Mn4+ , Zn2+ [17]. Ba2 LaSbO6 :Mn4+ phosphor has been reported and it is chosen as a research subject [18]. Dy3+ and H3 BO3
*
Corresponding authors. E-mail addresses: [email protected] (R. Cao), [email protected] (Z. Luo).
https://doi.org/10.1016/j.physleta.2019.03.044 0375-9601/© 2019 Elsevier B.V. All rights reserved.
are selected as dopants to improve the luminescence properties of phosphors according to previous reports [19–22]. In this work, Ba2 LaSbO6 :Mn4+ , Ba2 LaSbO6 :Mn4+ , Dy3+ , and Ba2 LaSbO6 :Mn4+ , H3 BO3 phosphors are synthesized in the air by solid-state reaction method. The influence of Dy3+ and H3 BO3 to the emission properties, quantum efficiency, and lifetime of Ba2 LaSbO6 :Mn4+ phosphor is investigated. 2. Experimental The synthesis process is consistent with that used in previous report of Ba2 LaSbO6 :Mn4+ phosphor and the optimal Mn4+ concentration in Ba2 LaSbO6 :Mn4+ phosphor is ∼ 0.2 mol% [18]. In this work, we directly use the chemicals (BaCO3 (99.9%), H3 BO3 (99.9%), La2 O3 (99.99%), Sb2 O5 (99.99%), Dy2 O3 (99.99%), and MnCO3 (99.9%)) as raw materials to synthesize the Ba2 LaSbO6 :0.2%Mn4+ , Ba2 LaSbO6 :0.2%Mn4+ , x%Dy3+ (x = 1 and 2), and Ba2 LaSbO6 : 0.2%Mn4+ , y%H3 BO3 ( y = 1 and 6) phosphors in the air by hightemperature solid state reaction method. These chemicals are purchased from the Aladdin Chemical Reagent Company in Shanghai, China. We use a Philips Model PW1830 X-ray diffractometer with Cu Kα radiation at 40 kV and 40 mA to investigate the phase purity of the samples. The X-ray diffraction (XRD) patterns are collected in the 2θ range of 10–90◦ with a scanning step of 0.02◦ . A fieldemission scanning electron microscopy (FE-SEM) system (MAIA3 TESCAN) equipped with an energy dispersive X-ray (EDX) spectrum at 15 V is used to measure the morphology of the samples.
R. Cao et al. / Physics Letters A 383 (2019) 2102–2105
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Fig. 1. (a) XRD patterns of JCPDS no. 54-958 (Ba2 LaSbO6 ), Ba2 LaSbO6 :0.2%Mn4+ , Ba2 LaSbO6 :0.2%Mn4+ , x%Dy3+ (x = 1 and 2), and Ba2 LaSbO6 :0.2%Mn4+ , 6%H3 BO3 phosphors, (b) The crystal structure diagram of host (Ba2 LaSbO6 ) based on ICSD #153136, and (c) FE-SEM diagrams of Ba2 LaSbO6 :0.2%Mn4+ , Ba2 LaSbO6 :0.2%Mn4+ , 2%Dy3+ , and Ba2 LaSbO6 :0.2%Mn4+ , 6%H3 BO3 phosphors. (For interpretation of the colors in the figure(s), the reader is referred to the web version of this article.)
The luminescence properties, the quantum efficiency (QE), and decay curves are studied by an Edinburgh FLS 980 instrument with a high spectral resolution (signal to noise ratio > 12000:1). 3. Results and discussion As shown in Fig. 1(a), the XRD patterns of the Ba2 LaSbO6 : 0.2%Mn4+ , Ba2 LaSbO6 :0.2%Mn4+ , x%Dy3+ (x = 1 and 2) and Ba2 LaSbO6 :0.2%Mn4+ , 6%H3 BO3 samples are in good relation with those of the Joint Committee Powder Diffraction Standards (JCPDS) no. 54-958 (Ba2 LaSbO6 ) [23] and there are no impurity peaks, indicating that the dopants (Mn4+ , Dy3+ , and H3 BO3 ) do not make significant influence on the host (Ba2 LaSbO6 ) structure. The crystal structure of host (Ba2 LaSbO6 ) based on the data from structure database (ICSD) #153136 [24] is show in Fig. 1(b). The doubleperovskite symmetry Ba2 LaSbO6 is described in the trigonal system with the space group of R3(148) and the cell parameters 3
(a = b = c = 6.0825(1) Å, V = 160.17(1) Å , and Z = 1) [24]. As shown in Fig. 1(b), the La3+ and Sb5+ ions are coordinated by six oxygen atoms and form [LaO6 ] and [SbO6 ] octahedra, respectively, and Ba2+ ion coordinated by three oxygen atoms are in the interspace between [LaO6 ] and [SbO6 ] octahedra. Here, the ionic radii of the cations are (CN = 6, La3+ : ∼ 1.032 Å, Sb5+ : ∼ 0.62 Å, Dy3+ : ∼ 0.912 Å, and Mn4+ : ∼ 0.53 Å), B3+ : ∼ 0.27 Å, and Ba2+ : ∼ 1.35 Å [25]. According to ionic radii relation and charge similarity, it can be inferred that Dy3+ ion will occupy the La3+ sites, and Mn4+ ions will substitute the Sb5+ sites in host (Ba2 LaSbO6 ) lattice. B3+ ions are not introduced into the host lattice because H3 BO3 plays a flux role and there is a big ion radius difference between B3+ ion and the cations (Ba2+ , La3+ , and Sb5+ ). Because of the different valence states of Mn4+ and Sb5+ ions, the electron hole (v − ) in host lattice may occur for the charge balance (Mn4+ → Sb5+ + v − ). As seen the FE-SEM patterns in Fig. 1(c), Ba2 LaSbO6 :0.2%Mn4+ , Ba2 LaSbO6 :0.2%Mn4+ , 2%Dy3+ , and Ba2 LaSbO6 :0.2%Mn4+ , 6%H3 BO3 phosphors contain irregular particles, and the Dy3+ ion and H3 BO3 have some effects on the particle size and sintering degree of Ba2 LaSbO6 :Mn4+ phosphor.
Fig. 2. PL spectra of (a) Ba2 LaSbO6 :0.2%Mn4+ , x%Dy3+ (x = 1 and 2), (b) Ba2 LaSbO6 :0.2%Mn4+ , y%H3 BO3 ( y = 1 and 6) phosphors at room temperature (λex = 380 nm).
The luminescence properties of Ba2 LaSbO6 :Mn4+ phosphors were reported in detail in Ref. [18], and we do not re-describe them here. The photoluminescence (PL) spectra of Ba2 LaSbO6 : 0.2%Mn4+ , x%Dy3+ (x = 1 and 2) and Ba2 LaSbO6 :0.2%Mn4+ , y%H3 BO3 ( y = 1 and 6) phosphors excited at 380 nm at room temperature are presented in Fig. 2. The QEs values are measured directly by an Edinburgh FLS 980 instrument with an integrat-
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Table 1 The QEs of Ba2 LaSbO6 :0.2%Mn4+ , Ba2 LaSbO6 :0.2%Mn4+ , x%Dy3+ (x = 1 and 2), and Ba2 LaSbO6 :0.2%Mn4+ , y%H3 BO3 ( y = 1 and 6) phosphors.
(mol%) QE
Mn4+
0.2%Mn4+ , x%Dy3+
0.2%Mn4+ , y%H3 BO3
0.2% 33.5%
1% 34.6%
1% 36.4%
2% 34.2%
Ba2 LaSbO6 :Mn4+ phosphor. The experimental results are beneficial to research the luminescence property improvement of Mn4+ -doped luminescence materials. Acknowledgements
6% 31.3%
This work is financially supported by the National Natural Science Foundation of China (No. 51862015) and Foundation of Jiang’xi Educational Committee (No. GJJ180564). References
Fig. 3. Decay curves of Ba2 LaSbO6 :0.2%Mn4+ , Ba2 LaSbO6 :0.2%Mn4+ , x%Dy3+ (x = 1 and 2), and Ba2 LaSbO6 :0.2%Mn4+ , y%H3 BO3 ( y = 1 and 6) phosphors at room temperature (λex = 380 nm; λem = 678 nm).
ing sphere and the results are shown in Table 1. It can be found that small amount of dopants (Dy3+ and H3 BO3 ) can be used to improve the emission properties and QE of Ba2 LaSbO6 :Mn4+ phosphor because of the ET from Dy3+ to Mn4+ and the flux role of H3 BO3 after co-doping Dy3+ and H3 BO3 [19–22]. In addition, after the Dy3+ ions occupy the La3+ sites in host, the unit of La3+ − O2− − Mn4+ in Ba2 LaSbO6 :Mn4+ is changed to the unit of Dy3+ − O2− − Mn4+ . Because the ionic radius of Dy3+ ion is less than that of La3+ ion (CN = 6, La3+ : ∼ 1.032 Å and Dy3+ : ∼ 0.912 Å), the electron cloud of O2− ion is far away from Mn4+ ion, resulting in the improvement of luminescence property of Mn4+ ion, which is consistent with the results in Fig. 2. If H3 BO3 content is increased, it can affect the host crystal field, leading to the decrease of emission. The decay curves of Ba2 LaSbO6 :0.2%Mn4+ , Ba2 LaSbO6 : 0.2%Mn4+ , x%Dy3+ (x = 1 and 2), and Ba2 LaSbO6 :0.2%Mn4+ , y%H3 BO3 ( y = 1 and 6) phosphors at room temperature are shown in Fig. 3. The excitation wavelength is 380 nm with monitoring at 678 nm. The decay curves can be well fitted via the first order exponential decay function [26]:
I (t ) = I (0) exp(−t /τ )
(1)
where I (t ) is the luminescence intensity at time t, I (0) is the initial luminescence intensity, t is the time, and τ is the decay time for the exponential component. The lifetimes may be changed by the dopants (Dy3+ and H3 BO3 ) and are 277.1 μs (Ba2 LaSbO6 :0.2%Mn4+ ), 253.2 μs (Ba2 LaSbO6 :0.2%Mn4+ , 1%Dy3+ ), 254.8 μs (Ba2 LaSbO6 :0.2%Mn4+ , 2%Dy3+ ), 261.2 μs (Ba2 LaSbO6 : 0.2%Mn4+ , 1%H3 BO3 ), and 286.4 μs (Ba2 LaSbO6 :0.2%Mn4+ , 6%H3 BO3 ). The possible reason for the change in lifetimes is that the dopants (Dy3+ and B3+ ) change the non-radiative or radiative transition time of free electrons of Mn4+ ion. 4. Conclusions In conclusion, Ba2 LaSbO6 :Mn4+ , Ba2 LaSbO6 :Mn4+ , Dy3+ , and Ba2 LaSbO6 :Mn4+ , H3 BO3 phosphors are synthesized in the air by solid-state reaction method. The Dy3+ ion and H3 BO3 can affect the particle size and sintering degree of Ba2 LaSbO6 :Mn4+ phosphor. The small amount of Dy3+ ion and H3 BO3 can be used to change the emission properties, QE, and lifetime of
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