Effect of Al/Sr ratio on the luminescence properties of SrAl2O4:Eu2+, Dy3+ phosphors

Recent studies have brought out many phosphors like Eu²⁺, Dy³⁺-doped alkaline earth aluminates. The trivalent Dy³⁺ ions as co-dopants greatly enhance the duration and intensity of persistent luminescence. These phosphors show excellent properties, such as high quantum efficiency, long persistence of phosphorescence, good stability and suitable color emission.In this work the effect of Al/Sr ratio on the afterglow and phosphorescence decay properties of Eu²⁺ and Dy³⁺ co-activated strontium aluminates synthesized by a solid-state process has been investigated. The luminescence properties of samples were investigated by means of excitation spectra, emission spectra and X-ray diffraction analysis.A variety of strontium aluminates, such as SrAl₂O₄, Sr₄Al₂O₇, Sr₃Al₂O₆, Sr₃Al₂(Eu, Dy, Y)O_7.5, Al₅(Eu, Dy, Y)O₁₂, Sr₄Al₁₄O₂₅, SrAl₁₂O₁₉ and (Eu, Dy, Y)AlO₃ have been identified in the samples prepared from starting precursors with Al/Sr mole ratios ranging from 0.44 to 5. The afterglow decay rate was found to be the fastest for sample with Al/Sr ratio of 4.18, in which SrAl₄O₇ phase was dominant. The afterglow decay rate for phosphor with Al/Sr ratio of 2, in which SrAl₂O₄ phase was dominant, was detected to be slow. Moreover, the emission spectra of the samples shift to yellow-green long wavelength from bluish-green-ultraviolet short wave with the increase of Al/Sr ratios resulting from the change in the composition.     

Characterization of luminescent SrAl2O4 films doped with terbium and europium ions deposited by ultrasonic spray pyrolysis technique

SrAl₂O₄, SrAl₂O₄:Tb³⁺ and SrAl₂O₄:Eu³⁺:Eu²⁺ films were synthesized by means of the ultrasonic spray pyrolysis technique. These samples, characterized by X-Ray Diffraction, showed the monoclinic phase of the strontium aluminate. Images of the surface morphology of these films were obtained by SEM and the chemical composition was measured by EDS and XPS. The photoluminescence and cathodoluminescence characteristics of the films were studied as a function of the terbium and europium concentrations. The optimal PL emission intensities were reached at 8?at% for terbium doped films and 6?at% for europium doped samples. The CL emission spectra for europium doped films showed the typical bands of Eu³⁺ ions and also a broadband centered at 525?nm which is attributed to Eu²⁺ ions. XPS measurements confirm the presence of Eu³⁺ and Eu²⁺ in europium doped SrAl₂O₄ films, without having been subjected to a reducing atmosphere. Chromatic diagrams exhibited green color for SrAl₂O₄:Tb³⁺ films, red and yellow colors for SrAl₂O₄:Eu³⁺:Eu²⁺ films. The PL decay curves were also obtained: the averaged decay time was 2.7?ms for SrAl₂O₄:Tb³⁺ films and 1.9?ms for SrAl₂O₄:Eu³⁺ films. Similar results were obtained by the stretched exponential model.     

Enhanced Light Storage of SrAl2O4 Glass‐Ceramics Controlled by Selective Europium Reduction

A luminescent Eu, Dy: SrAl₂O₄ glass‐ceramics with high transparency in the visible region was successfully synthesized using the frozen sorbet technique with the control of O₂ partial pressure () for the oxidation of Eu²⁺ ions. The glass‐ceramics include Eu²⁺, Eu³⁺, and Dy³⁺ ions, and thus exhibits three characteristic types of emission bands, 4f–5d at around 520 nm (Eu²⁺ ions), 4f–4f at 610 nm (Eu³⁺ ions), and 480 nm (Dy³⁺ ions). The Eu, Dy: SrAl₂O₄ glass‐ceramics provide remarkable long‐persistent luminescence under dark condition. The glass‐ceramics also exhibits color‐changing luminescence in the visible region based on their remarkable light storage properties. The luminescent Eu, Dy: SrAl₂O₄ glass‐ceramics using the frozen sorbet technique with control of are promising materials for application in novel photonic and light storage materials.     

Effects of adding B<Subscript>2</Subscript>O<Subscript>3</Subscript> as a flux on phosphorescent properties in synthesis of SrAl<Subscript>2</Subscript>O<Subscript>4</Subscript>: (Eu<Superscript>2+</Superscript>, DY<Superscript>3+</Superscript> phosphor

SrAl₂O₄: (Eu²⁺, Dy³⁺) phosphor was prepared by solid state reaction. B₂O₅ as a flux was added in SrAl₂O₄:(Eu ²⁺, Dy³⁺) in order to accelerate a solid state reaction. In this paper, the effects of B₂O₃ on the crystal structure and the phosphorescent properties of the material have been evaluated. The synthesized phosphor exhibited a broad band emission spectrum peaking at 520 nm, and the spectrum peak showed little effect by the B₂O₃ contents. The maximum afterglow intensity of the SrAl₂O₄: (Eu²⁺, Dy³⁺) phosphor was obtained at the B₂O₃ content of 5%. Adding the B₂O₃ caused uniform distortion to the crystal structure of the phosphor and resulted in reducing the lengths of a and c axes and Β angle of the SrAl₂O₄ crystal. The uniform distortion was accompanied with crystal defects which can trap the holes generated by the excitation of Eu²⁺ ions. The afterglow characteristic of the SrAl₂O₄: (Eu²⁺, Dy³⁺) phosphor was thus enhanced.     

Photoluminescence characteristics and mechanism of SrAl2O4 co-doped with Eu3+ and Cu2+

SrAl₂O₄ co-doped with Cu²⁺ and Eu³⁺ was prepared at high temperature in a weakly oxidizing atmosphere by solid states reaction. X-ray diffraction (XRD) pattern of the sample shows that the doped sample exhibits SrAl₂O₄ crystalline phase. No characteristic peaks of dopant have been observed in XRD pattern of doped sample. The excitation and emission spectra of CuEu:SrAl₂O₄, Eu:SrAl₂O₄, Cu:SrAl₂O₄ samples consist of many sharp peaks. The excitation and emission spectra of the SrAl₂O₄ sample co-doped with Cu²⁺ and Eu³⁺ are significantly different from those of Eu:SrAl₂O₄ and Cu:SrAl₂O₄ samples. The novel photoluminescence (PL) characteristic of the co-doped sample is attributed to the composite luminescence of Cu²⁺ and Eu³⁺ ions in SrAl₂O₄ matrix.     

Eu2+, Dy3+: Sr2B5O9Cl,a new blue-emitting phosphor with long persistence

A new Eu²⁺, Dy³⁺: Sr₂B₅O₉Cl phosphor with long persistence was synthesized in a reducing atmosphere by a solid-state reaction process. The pure-phase phosphor was obtained by calcination at 900 °C. The introduction of Eu²⁺ into the lattice of the matrix resulted in a broad blue emission centered at 423 nm, which was due to the characteristic 4f6⁵d¹ to 4f⁷ energy transfer of Eu²⁺ ions. Both Eu-doped and Dy/Eu-codoped phosphors displayed afterglow behaviors due to the electron traps generated by the incorporation of tri-valanced rare earth cations into the original Sr lattice sites. The afterglow of Eu²⁺: Sr₂B₅O₉Cl and Eu²⁺, Dy³⁺: Sr₂B₅O₉Cl phosphors showed standard double exponential decay behaviors, and the Eu²⁺/Dy³⁺ co-doped sample demonstrated better afterglow properties than Eu²⁺-doped one. A longer lifetime for the electrons was confirmed after the afterglow decay curve simulation. Based on the analysis of thermally stimulated luminescence (TSL), the difference in afterglow was attributed to the different trap concentrations induced by the Dy³⁺ (Eu³⁺) doping in the Sr₂B₅O₉Cl matrix.     

Characterization of strontium aluminate phosphors prepared from milled SrCO3

SrAl₂O₄:Eu²⁺,Dy³⁺ phosphors were prepared by solid-state reaction from milled SrCO₃. The effect of milling treatment of SrCO₃ on the formation and physical properties of SrAl₂O₄ phosphors was investigated by DTA, XRD, BET, SEM and PL. The results indicate that small crystallite size and large specific surface area of the milled SrCO₃ were able to increase the contact points between the reactants and to reduce the average transport distance for materials diffusion. Therefore, the solid-state reaction can be accelerated and the formation of SrAl₂O₄ was facilitated. On the other hand, the number of nucleation sites was also suggested to be increased that leads to a decrease in SrAl₂O₄ crystallite size and an increase in specific surface area. The increased specific surface area was proposed to increase the emission intensity and afterglow decay.     

Atomic layer deposition (ALD) of nanoscale coatings on SrAl2O4-based phosphor powders to prevent aqueous degradation

The aqueous degradation of Eu²⁺-activated and Dy³⁺-codoped strontium aluminate (SrAl₂O₄:Eu²⁺, Dy³⁺, SA2-Green) long afterglow phosphors synthesized from solid-state reaction and coated with nanoscale metal oxide protective layers (≤12 nm) via atomic layer deposition (ALD) is investigated. Uncoated phosphor powders degrade rapidly upon water immersion and lose their green phosphorescence within 48 hours of water exposure. Postmortem investigations reveal hydration and decomposition of the SrAl₂O₄ phase. ALD of ~10 nm Al₂O₃ or ~12 nm TiO₂ is found to significantly improve the powder's resistance to aqueous degradation. All ALD-coated powders show minimal structural and chemical degradation and retain phosphoresence after 48 hours of water immersion. This enhanced durability offers a new pathway for applying long afterglow phosphors to outdoor applications like roadway markings or safety signage and for their incorporation into more eco-friendly waterborne coatings.     

Sunlight‐activated long persistent luminescent polyurethane incorporated with amino‐functionalized SrAl2O4:Eu2+,Dy3+ phosphor

An amino‐terminated long persistent luminescent phosphor (Amino‐SrAl₂O₄:Eu²⁺,Dy³⁺) was prepared based on inorganic SrAl₂O₄:Eu²⁺,Dy³⁺ phosphor, chemically modified with 3‐aminopropyltriethoxysilane (KH550). Fourier transform infrared and X‐ray photoelectron spectral, thermogravimetric and scanning electron microscopic measurements confirmed the successful synthesis of Amino‐SrAl₂O₄:Eu²⁺,Dy³⁺. Then this amino‐functionalized phosphor was introduced into polyurethane (PU) through urea linkages, and the effects of the chemical combination of Amino‐SrAl₂O₄:Eu²⁺,Dy³⁺ and PU on the morphology, structure, storage stability, and mechanical, thermal and luminescent properties of the resultant long persistent luminescent polyurethane (LPLPU) were investigated. Compared with SrAl₂O₄:Eu²⁺,Dy³⁺/PU composites prepared by physical blending, the LPLPU shows better mechanical properties and storage stability due to the good compatibility of Amino‐SrAl₂O₄:Eu²⁺,Dy³⁺ with PU. More residues and higher initial decomposition temperature are observed because the interaction of the amino‐phosphor and PU delays the degradation. Study of the luminescent effect reveals that the LPLPU shows more than 10 h afterglow after cessation of the excitation light, and the brightness of green light in darkness is basically the same as that of LPLPU and SrAl₂O₄:Eu²⁺,Dy³⁺/PU. © 2016 Society of Chemical Industry     

Roles of doping ions in persistent luminescence of SrAl<Subscript>2</Subscript>O<Subscript>4</Subscript>: Eu<Superscript>2+</Superscript>,<Emphasis Type="Italic">RE</Emphasis><Superscript>3+</Superscript> phosphors

The polycrystalline Eu²⁺ and Dy³⁺ codoped strontium aluminates SrAl₂O₄: Eu²⁺,Dy³⁺ were prepared by a solid-state reaction. The UV-excited photoluminescence, persistent luminescence, and thermoluminescence of the SrAl₂O₄: Eu²⁺,Dy³⁺ phosphors with different compositions and ion doping was studied and compared. The results showed that the Eu²⁺ ion doped in SrAl₂O₄: Eu²⁺,Dy³⁺ phosphors is not only the UV-excited luminescent center but also the persistent luminescent center. The Dy³⁺ ion introduced into SrAl₂O₄: Eu²⁺ crystal matrix can hardly yield any luminescence under UV excitation but acts as an electron trap with a suitable depth for persistent luminescence. The Dy³⁺ codoping would effectively enhance the persistent luminescence and thermoluminescence. Different codoping RE ³⁺ ions have a different effect on persistent luminescence. Only the RE ³⁺ ions (for example, Dy³⁺ and Nd³⁺), which have suitable optical electronegativity, can form suitable electron traps and effectively improve the persistent luminescence of SrAl₂O₄: Eu²⁺. Based on the above observations, a persistent luminescence mechanism, electron transfer model, was proposed and illustrated. The text was submitted by the authors in English.     

Experimental evaluation of the luminescence performance of fired clay brick coated with SrAl2O4:Eu/Dy phosphor

This study evaluates the luminescence performance of fired clay bricks coated with SrAl₂O₄:Eu/Dy phosphor. To do so, SrAl₂O₄:Eu/Dy phosphor was first produced using the traditional solid-state reaction synthesis technique. The prepared phosphor was then used for coating fired clay bricks to analyze the luminescence performance via spectral analysis, decay characteristics, and microstructure of the bricks. The results reveal that excitation and emission spectra of the phosphor coated bricks range from 200 to 480 nm and 455 to 650 nm, respectively, suggesting that the phosphor coated bricks have the capacity of absorbing light with a wide range of wavelengths. The peak wavelength projected at 511 nm in the emission spectrum is achieved, which indicates 4f⁶5 d¹-4f⁷ transition of Europium (Eu²⁺). The repeated excitation and deexcitation of Eu²⁺ by using hole traps and trap levels offered by Dysprosium (Dy³⁺), exist between the ground and the excited state of Eu²⁺ leads to luminescent phenomenon. Moreover, the decay characteristics has revealed that phosphor coated bricks can emit light for a considerable amount of time (>8.5 min) upon the removal of the excitation source. The results reveal that phosphor coated bricks has the potential of increasing energy efficiency of residential and commercial buildings.     

Transparent fiber wood composite materials containing long afterglow as lighting equipment

Functional wood composites have been used in the field of optical lighting to alleviate power consumption. In this study, transparent fiber wood (TFW) composite and long afterglow transparent fiber wood (LATFW) composite were prepared by using wood powders with different mesh numbers as raw materials, and then blending with epoxy resin and long afterglow materials (SrAl₂O₄: Eu²⁺, Dy³⁺). By analyzing the material's fluorescence intensity, transmittance, stretch, and other performance, it is revealed that the performance of the materials varies from the number of wood powders mesh number. The comprehensive analysis showed that the TFW prepared by 100–120 mesh wood powders had excellent performance, with transmittance up to 62%, tensile strength 32.06 MPa, and tensile modulus 963.25 MPa. The TFW with wood powders of different mesh number results in materials with different transmittance, thus providing a straightforward way to produce materials with specific light transmittance properties. In addition, LATFW with afterglow time up to 1.5h(3h after irradiation) can be used as lighting equipment such as safety signs.     

Laser synthesis and luminescence properties of SrAl2O4:Eu2+, Dy3+ phosphors

A laser melting method has been developed for the synthesis of highly luminescent, long-lasting SrAl₂O₄:Eu²⁺, Dy³⁺ phosphors. The high temperature achieved in high-power density CO₂ laser irradiation of mixtures of SrCO₃, Al₂O₃, Eu₂O₃, and Dy₂O₃ enabled the one-step, fast synthesis of these phosphors in air at atmospheric pressure. X-ray diffraction, Raman spectroscopy, and scanning electron microscopy characterization studies reveal that the produced materials consist of monoclinic SrAl₂O₄ grains extensively surrounded by rare-earth ion-enriched grain boundaries. The photoluminescence properties of laser-produced SrAl₂O₄:Eu²⁺, Dy³⁺ materials are discussed. The results reported here suggest that this laser melting method is a promising route for the synthesis of ceramic phosphors. It is presented as an alternative to the conventional sol–gel and solid-state methods, which require the use of high-temperature furnaces, flux additives, and reducing atmospheres.     

Long Afterglow SrAl2O4:Eu2+,Dy3+ Phosphors as Luminescent Down‐Shifting Layer for Crystalline Silicon Solar Cells

SrAl₂O₄:Eu²⁺,Dy³⁺ phosphors can convert near ultraviolet light with lower sensitivity to the solar cell to yellow‐green light at which the solar cell has higher sensitivity and exhibit the excellent luminescent property of long persistence. Therefore, in this study, the authors firstly synthesized the fine SrAl₂O₄:Eu²⁺,Dy³⁺ phosphors and then produced SrAl₂O₄:Eu²⁺,Dy³⁺/SiO₂ composite films as spectral shifters to understand the effects of SrAl₂O₄:Eu²⁺,Dy³⁺ phosphor on photoelectric conversion efficiencies of a crystalline silicon photovoltaic module. Under one sun illumination, the composite film containing an appropriate amount of SrAl₂O₄:Eu²⁺,Dy³⁺ phosphor enhances the photoelectric conversion efficiency of the cell through spectral down‐shifting as compared to the bare glass substrate, and the maximum achieves 11.12%. In contrast, the commercial SrAl₂O₄:Eu²⁺,Dy³⁺ phosphor composite film is not effective for improving the photoelectric conversion efficiency because of the relatively lower visible light transmittance of film caused by the large aggregates. After one sun illumination for 1 min, the light source was turned off, and the cell containing the synthesized SrAl₂O₄:Eu²⁺,Dy³⁺ phosphor still shows an efficiency of 1.16% in the dark due to the irradiation by the long persistent light from SrAl₂O₄:Eu²⁺,Dy³⁺, which provides a possibility to fulfill the operation of solar cells even in the dark.     

Influence of Bi2O3 flux in the structural and photoluminescence properties of SrAl2O4:Eu2+ phosphors

SrAl₂O₄:Eu²⁺ phosphors with various content of Bi₂O₃ flux were synthesized and analyzed. It was observed that the crystallinity and the particle size of the phosphors were increased with the addition of Bi₂O₃ flux. These phenomena are considered to be caused via the melting of the Bi₂O₃ flux particles during the synthesis of the phosphors. The melted Bi₂O₃ flux increased the mobility and homogeneity of solid reactants, thereby enhancing the photoluminescence intensity of the phosphors. SrAl₂O₄:Eu²⁺ phosphors with Bi₂O₃ as the flux exhibited a broad green emission with a peak at 520 nm. The highest photoluminescence emission intensity was observed when 5 mol% Bi₂O₃ flux was added into the phosphors. The emission is due to 4f⁶5d→4f⁷ (⁸S_7/2) transitions of the Eu²⁺ ions. Moreover, Bi₂O₃ flux extended the application of the ultraviolet excited phosphors toward the blue-light excited phosphors. Nevertheless, the influence of Bi₂O₃ on the afterglow and the emission color of SrAl₂O₄:Eu²⁺ phosphors were not significant. This research indicated that Bi₂O₃ flux is effective flux for synthesizing SrAl₂O₄:Eu²⁺ phosphors.     

Luminescent properties of SrAl2O4: Eu,Dy material prepared by the gel method

SrAl₂O₄:Eu,Dy materials were first prepared by the gel method. Compared with samples prepared by solid state reactions, the grain size of the gel method is greatly reduced to nanometer grade. A clear blue shift occurs in the excitation and emission spectra of nano SrAl₂O₄:Eu,Dy, of which the peak of the excitation and emission spectra are at 323 and 500 nm respectively. The brightness of nano SrAl₂O₄:Eu,Dy is greatly reduced. The blue shift and the change of luminescent intensity in nano SrAl₂O₄:Eu,Dy materials can be attributed to the effect of surface energy.     

Preparation and fluorescence properties of Zn2SnO4:Eu3+ orange emitting afterglow phosphor

In this study, an orange emitting afterglow phosphor of Zn₂SnO₄:Eu³⁺ was fabricated using the co-precipitation & hydrothermal method, and then annealed in Ar atmosphere at 1000 °C. X-ray diffraction, Raman spectra, EDX, fluorescence spectrometer, SEM and TEM were performed to characterize the target products. As revealed from the XRD analysis results, the fabricated product was the cubic inverse spinel structure Zn₂SnO₄ (JCPDS 24–1470) exhibiting high crystallinity. As confirmed by Raman and EDX spectra, the target product was Zn₂SnO₄:Eu³⁺. As Zn₂SnO₄:Eu³⁺ was excited at 347 nm, its fluorescence spectra showed the magnetic dipole emission at 589 nm and the electric dipole transition at 610 nm, complying with the transitions of Eu³⁺ ions from ⁵D₀→⁷F₁ and ⁵D₀→⁷F₂. Meantime, Zn₂SnO₄:Eu³⁺ phosphors displayed an orange afterglow, and its attenuating characteristics met the exponential equation. Moreover, the optimal doping amount of Eu³⁺ ions was 15 mol%, and the concentration quenching took place by the cross relaxation. The color coordinate of the product (x = 0.15) was determined as (0.522, 0.4635), and the color purity reached 98.3%.     

Effect of sintering and boron content on rare earth dopant distribution in long afterglow strontium aluminate

B has been proposed to extend persistent luminescence from minutes to > 10 h in Eu, Dy, and B co-doped Sr₄Al₁₄O₂₅ (S4A7EDB) by facilitating the incorporation of Eu²⁺ and Dy³⁺ into adjacent Sr sub-lattice sites and enabling energy transfer between them. To evaluate additional influences of B on the kinetics of microstructural evolution and dopant distribution that support afterglow in S4A7EDB, the effect of heating rates to 1300 °C is compared for spark-plasma sintering and conventional sintering, with and without the addition of B₂O₃. Analysis of the microstructure and elemental distribution, by a combination of imaging, WDS, and CL in the SEM, XRD, dilatometry, and STEM-EELS, reveals that when the diffusivity of Eu and Dy is increased, Eu and Dy segregate to the intergranular phase. The partitioning of Eu and Dy concentrations to below their solubility limit in the grains appears to be essential to material structure enabling longer afterglow.     

Origin of long afterglow in strontium aluminate phosphors: Atomic scale imaging of rare earth dopant clustering

Ceramic pigments emitting long afterglow have enormous potential for emerging lighting applications that consume zero energy from the power grid. One of the most efficient compounds is strontium aluminate, when co-doped with 2 rare-earth elements — an optically active emitter, such as Eu²⁺, and an auxiliary ion, such as Dy³⁺— and B. To date, spectrophotometric methods are commonly used to determine the material structure supporting long afterglow, yielding indirect evidence of energy transfer between the rare-earth co-dopants. Here, atomic resolution HAADF-STEM imaging is used to resolve columns of Sr sub-lattice sites in the (012)-projection of a Sr₄Al₁₄O₂₅:Eu,Dy single crystal. Through quantitative STEM image simulations, heavy rare earth dopants are shown to incorporate substitutionally into Sr sites, causing an enhancement in image contrast over that of neighboring atomic columns by 125%. DFT structural simulations demonstrate that Eu²⁺ and Dy³⁺ would incorporate into adjacent Sr lattice sites along the [012], enabling energy transfer between them that we see as afterglow. With the help of atomic resolution HAADF-STEM imaging, we also provide direct experimental evidence of clustering of ionic point defects induced by B doping, leading to extremely long (>14 h) afterglow in strontium aluminate phosphors.     

Red-shift and improved afterglow of Sr3Al2-xBxO5Cl2:Eu2+, Dy3+ phosphors via a cation substitution strategy

Sr₃Al_2-xB_xO₅Cl₂:Eu²⁺, Dy³⁺ (x = 0, 0.2, 0.4) long persistent phosphors were prepared via solid-state process. The pristine Sr₃Al₂O₅Cl₂:Eu²⁺, Dy³⁺ phosphor exhibits orange/red broad band emission around 609 nm, which can be attributed to the electric radiation transitions 4f⁶5 d¹→4f⁷ of Eu²⁺. Upon the same excitation, the B³⁺-doped Sr₃Al_2-xB_xO₅Cl₂:Eu²⁺, Dy³⁺ phosphors display red-shift from 609 nm to 625 nm with increasing B³⁺ concentrations. The XRD patterns show that Al³⁺ can be replaced by B³⁺ in the host lattice at the tetrahedral site, which causes lattice contraction and crystal field enhancement, and thereafter achieves the red-shift on the emission spectrum. The XPS investigation provides direct evidence of the dominant 2-valent europium in the phosphor, which can be ascribed for the broad band emission of the prepared phosphors. The afterglow of all phosphors show standard double exponential decay behavior, and the afterglow of Sr₃Al₂O₅Cl₂:Eu²⁺, Dy³⁺is rather weak, while the sample co-doped with B³⁺shows longer and stronger afterglow, as confirmed after the curve simulation. The analysis of thermally stimulated luminescence showed that, when B³⁺ is introduced, a much deeper trap is created, and the density of the electron trap is also significantly increased. As a result, B³⁺ ions caused redshift and enhanced afterglow for the Sr₃Al_2-xB_xO₅Cl₂:Eu²⁺, Dy³⁺ phosphor.