Synthesis and effect of Ce and Mn co‐doping on photoluminescence characteristics of Ca6AlP5O20:Eu novel phosphors

A series of Ca₆AlP₅O₂₀ doped with rare earths (Eu and Ce) and co‐doped (Eu, Ce and Eu,Mn) were prepared by combustion synthesis. Under Hg‐free excitation, Ca₆AlP₅O₂₀:Eu exhibited Eu²⁺ (486 nm) emission in the blue region of the spectrum and under near Hg excitation (245 nm), Ca₆AlP₅O₂₀:Ce phosphor exhibited Ce³⁺ emission (357 nm) in the UV range. Photoluminescence (PL) peak intensity increased in Ca₆AlP₅O₂₀:Eu,Ce and Ca₆AlP₅O₂₀:Eu, Mn phosphors due to co‐activators of Ce³⁺ and Mn²⁺ ions. As a result, these ions played an important role in PL emission in the present matrix. Ca₆AlP₅O₂₀:Eu, Ce and Ca₆AlP₅O₂₀:Eu, Mn phosphors provided energy transfer mechanisms via Ce³⁺ → Eu²⁺ and Eu²⁺ → Mn²⁺, respectively. Eu ions acted as activators and Ce ions acted as sensitizers. Ce emission energy was well matched with Eu excitation energy in the case of Ca₆AlP₅O₂₀:Eu, Ce and Eu ions acted as activators and Mn ions acted as sensitizers in Ca₆AlP₅O₂₀:Eu, Mn. This study included synthesis of new and efficient phosphate phosphors. The impact of doping and co‐doping on photoluminescence properties and energy transfer mechanisms were investigated and we propose a feasible interpretation. Copyright © 2012 John Wiley & Sons, Ltd.     

Luminescence behavior of Li2Sr1‐3x/2EuxSiO4 red phosphors for LED applications

Red‐emitting Li₂Sr_1‐3x/2Eu_xSiO₄ 0≤x≤0.5) phosphors were synthesized at 900°C in air by a solid‐state reaction. The synthesized phosphors were characterized by X‐ray powder diffraction, photoluminescence (PL) excitation (PLE) and PL spectra. The results from the PLE spectra suggest that the strong 394 nm excitation peak associated with the ⁵L₆ state of Eu³⁺ ions is of significance for near ultraviolet pumped white light‐emitting diodes and solid‐state lighting. It is also noted that the position of the charge transfer state of Eu³⁺ ions shifts towards the higher energy side (blue shift) by increasing the content of Eu³⁺ ions. The predominant emissions of Eu³⁺ ions under 394 nm excitation are observed at 580, 593, 614, 656 and 708 nm, which are attributed to the ⁵D₀ → ⁷F_J (J = 0, 1, 2, 3 and 4), respectively. The PL results reveal that the optimal content of the red‐emitting Li₂Sr_1‐3x/2Eu_xSiO₄ phosphors is x = 0.475. Simulation of the white light excited by 394 nm near ultraviolet light has also been carried out for its potential white light‐emitting diode applications. Copyright © 2013 John Wiley & Sons, Ltd.     

Tunable luminescence properties and energy transfer in LaAl11O18:Eu,Tb phosphor

Eu²⁺ and Tb³⁺ singly doped and co‐doped LaAl₁₁O₁₈ phosphors were prepared by a combustion method using urea as a fuel. The phase structure and photoluminescence (PL) properties of the prepared phosphors were characterized by powder X‐ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence excitation and emission spectra. When the content of Eu²⁺ was fixed at 0.01, the emission chromaticity coordinates could be adjusted from blue to green region by tuning the contents of Tb³⁺ ions from 0.01 to 0.03 through an energy transfer (ET) process. The fluorescence data collected from the samples with different contents of Tb³⁺ into LaAl₁₁O₁₈: Eu, show the enhanced green emission at 545 nm associated with ⁵D₄ –⁷F₅ transitions of Tb³⁺. The enhancement was attributed to ET from Eu²⁺ to Tb³⁺, and therefore Eu²⁺ ion acts as a sensitizer (an energy donor) while Tb³⁺ ion as an activator. The ET from Eu²⁺ to Tb³⁺ is performed through dipole–dipole interaction. The ET efficiency and critical distance were also calculated. The present Eu²⁺–Tb³⁺ co‐doped LaAl₁₁O₁₈ phosphor will have potential application for UV convertible white light‐emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd.     

Luminescence of Eu and Ce in K3Ca2(SO4)3F fluoride material

A new halophosphor K₃Ca₂(SO₄)₃ F activated by Eu or Ce and K₃Ca₂(SO₄)₃ F:Ce,Eu co‐doped halosulfate phosphor has been synthesized by the co‐precipitation method and characterized for its photoluminescence (PL). The PL emission spectra of the K₃Ca₂(SO₄)₃ F :Ce phosphor show emission at 334 nm when excited at 278 nm due to 5d → 4f transition of Ce³⁺ ions. In the K₃Ca₂(SO₄)₃ F:Eu lattice, Eu²⁺ (440 nm) as well as Eu³⁺ (596 nm and 615 nm) emissions have been observed showing ⁵D₀ → ⁷ F₁ and ⁵D₀ → ⁷ F₂ transition of the Eu³⁺ ion, which is in the blue and red region of the visible spectrum respectively. The trivalent europium ion is very useful for studying the nature of metal coordination in various systems owing to its non‐degenerate emitting ⁵D₀ state. K₃Ca₂(SO₄)₃ F:Ce,Eu is suitable for Ce³⁺ → Eu²⁺ → Eu³⁺ energy transfer in which Ce³⁺and Eu²⁺ play the role of sensitizers and Eu²⁺ and Eu³⁺ act as the activators. The observations presented in this paper are relevant for lamp phosphors. Copyright © 2015 John Wiley & Sons, Ltd.     

Luminescence in Li3Al2(PO4)3:Eu2+

A series of efficient Li₃Al₂(PO₄)₃:Eu²⁺ novel phosphors were synthesized by the facile combustion method. The effects of dopant on the luminescence behavior of Li₃Al₂(PO₄)₃ phosphor were also investigated. The phosphors were characterized by X‐ray diffraction, field emission scanning electron microscope and photoluminescence techniques. The result shows that all samples can be excited efficiently by near‐ultraviolet excitation under 310 nm. The emission was observed for Li₃Al₂(PO₄)₃:Eu²⁺ phosphor at 425 nm, which corresponded to the d → f transition. The concentration quenching of Eu²⁺ was observed in Li₃Al₂(PO₄)₃:Eu²⁺ when the Eu concentration was at 0.5 mol%. The prepared powders exhibited intense blue emission at the 425 nm owing to the Eu²⁺ ion by Hg‐free excitation at 310 nm (i.e., solid‐state lighting excitation). Consequently, the availability of such a phosphor will significantly help in the development of blue‐emitting solid‐state lighting applications. Copyright © 2012 John Wiley & Sons, Ltd.     

Characterization and luminescence properties of CaMgSi2O6:Eu2+ blue phosphor

A blue CaMgSi₂O₆:Eu²⁺ phosphor was prepared by the solid‐state reaction method and the phosphor characterized in terms of crystal structure, particle size, photoluminescence (PL), thermoluminescence (TL) and mechanoluminescence (ML) properties using X‐ray diffraction (XRD), transmission electron microscopy (TEM), PL spectroscopy, TLD reader and ML impact technique. The XRD result shows that phosphor is formed in a single phase and has a monoclinic structure with the space group C2/c. Furthermore, the PL excitation spectra of Eu²⁺‐doped CaMgSi₂O₆ phosphor showed a strong band peak at 356 nm and the PL emission spectrum has a peak at 450 nm. The depths and frequency factors of trap centers were calculated using the TL glow curve by deconvolution method in which the trap depths were found to be 0.48 and 0.61 eV. The formation of CaMgSi₂O₆:Eu²⁺ phosphor was confirmed by Fourier transform infrared spectroscopy. The ML intensity increased linearly with the impact velocity of the piston used to deform the phosphor. It was shown that the local piezoelectricity‐induced electron bombardment model is responsible for the ML emission. Finally, the optical properties of CaMgSi₂O₆:Eu²⁺ phosphors are discussed. Copyright © 2015 John Wiley & Sons, Ltd.     

Luminescence and spectroscopic studies of halosulfate phosphors: a review

This review discusses the photoluminescence (PL) characteristics of halosulfate phosphors developed by us. Halosulfate phosphors KCaSO₄Cl:X,Y (X = Eu or Ce; Y = Dy or Mn) and Na₆(SO₄)₂FCl (doped with Dy, Ce or Eu) were prepared using a solid‐state diffusion method. The mechanism of energy transfer from Eu²⁺→Dy³⁺, Ce³⁺→Dy³⁺ and Ce³⁺→Mn²⁺ has also been studied. Dy³⁺ emission in the host at 475 and 570 nm is observed due to ⁴F_9/2→⁶H_15/2 and ⁴F_9/2→⁶H_13/2 transition, whereas the PL emission spectra of Na₆(SO₄)₂FCl:Ce phosphor shows Ce³⁺ emission at 322 nm due to 5d→4f transition of the Ce³⁺ ion. The main property of KCaSO₄Cl is its very high sensitivity, particularly when doped by Dy, Mn or Pb activators. This review also discusses the PL characteristics of some new phosphors such as LiMgSO₄F, Na₆Pb₄(SO₄)₆Cl₂, Na₂₁Mg(SO₄)₁₀Cl₃ and Na₁₅(SO₄)₅F₄Cl. Copyright © 2014 John Wiley & Sons, Ltd.     

A novel reddish‐orange phosphor,NaLi2PO4:Eu3+

A series of Eu³⁺‐activated NaLi₂PO₄ novel phosphors was synthesized by the solid‐state reaction method. The X‐ray diffraction (XRD) and photoluminescence (PL) properties of these phosphors were investigated at room temperature. The excitation spectra indicate that these phosphors can be effectively excited by near‐UV (370–410 nm) light. The emission spectra exhibit strong reddish‐orange performance, which is due to the ⁵D₀ → ⁷F_J transitions of Eu³⁺ ions. The orange emission from transition ⁵D₀ → ⁷F₁ is dominant over that of ⁵D₀ → ⁷F_2. The concentration quenching of Eu³⁺ was observed in NaLi₂PO₄:Eu³⁺ when the Eu concentration was at 1 mol%. The impact of doping Eu³⁺ and photoluminescence properties were investigated and we propose a feasible interpretation. Copyright © 2012 John Wiley & Sons, Ltd.     

Optical properties of CaAl(SO4)2Br:RE (RE = Dy,Eu, Ce) novel phosphors

A new phosphor CaAl(SO₄)₂Br doped with Dy, Ce and Eu is reported. Rare earth (Dy, Eu and Ce)‐doped polycrystalline CaAl(SO₄)₂Br phosphors were prepared using a wet chemical reaction method and studied for X‐ray diffraction and photoluminescence (PL) characteristics. Dy³⁺ emission in the CaAl(SO₄)₂Br lattice was observed at 484 and 574 nm in the blue and yellow regions of the spectrum, which are assigned to ⁴ F_9/2 → ⁶H_15/2 and ⁴ F_9/2 → ⁶H_13/2 transitions of the Dy³⁺ ion, respectively. While the PL emission spectra of CaAl(SO₄)₂Br:Ce phosphor showed Ce³⁺ emission at 347 nm due to 5d → 4f transition of the Ce³⁺ ion. In a CaAl(SO₄)₂Br:Eu lattice, Eu³⁺ emissions were observed at 593 and 617 nm, coming from the ⁵D₀ → ⁷ F₁ and ⁵D₀ → ⁷ F₂ electron transitions, respectively. The PL study showed that the intensity of electric dipole transition at 617 nm dominates over that of magnetic dipole transition at 590 nm. The maximum PL intensity was obtained for a 1 mol% concentration of Eu³⁺ in CaAl(SO₄)₂Br host lattice. The results showed that the material may be a promising candidate as a blue‐, yellow‐ and red‐emitting phosphor. Copyright © 2013 John Wiley & Sons, Ltd.     

Persistent luminescence of CaMgSi2O6:Eu2+,Dy3+ and CaMgSi2O6:Eu2+,Ce3+ phosphors prepared using the solid‐state reaction method

CaMgSi₂O₆:Eu²⁺,Dy³⁺ and CaMgSi₂O₆:Eu²⁺,Ce³⁺ phosphors were synthesized using the solid‐state reaction method. X‐Ray diffraction (XRD) and photoluminescence (PL) analyses were used to characterize the phosphors. The XRD results revealed that the synthesized CaMgSi₂O₆:Eu²⁺,Dy³⁺ and CaMgSi₂O₆:Eu²⁺,Ce³⁺ phosphors were crystalline and are assigned to the monoclinic structure with a space group C2/c. The calculated crystal sizes of CaMgSi₂O₆:Eu²⁺,Dy³⁺ and CaMgSi₂O₆:Eu²⁺,Ce³⁺ phosphors with a main (221) diffraction peak were 44.87 and 53.51 nm, respectively. Energy‐dispersive X‐ray spectroscopy (EDX) confirmed the proper preparation of the sample. The PL emission spectra of CaMgSi₂O₆:Eu²⁺,Dy³⁺ and CaMgSi₂O₆:Eu²⁺,Ce³⁺ phosphors have a broad band peak at 444.5 and 466 nm, respectively, which is due to electronic transition from 4f⁶5d¹ to 4f⁷. The afterglow results indicate that the CaMgSi₂O₆:Eu²⁺,Dy³⁺ phosphor has better persistence luminescence than the CaMgSi₂O₆:Eu²⁺,Ce³⁺ phosphor. Copyright © 2015 John Wiley & Sons, Ltd.     

Tunable white light emission from single‐phased Li2SrSiO4:Dy3+ phosphors by co‐doping with Eu3+

A series of single‐phase full‐color emitting Li₂Sr_1−x−ySiO₄:xDy³⁺,yEu³⁺ phosphors were synthesized by solid‐state reaction and characterized by X‐ray diffraction and photoluminescence analyses. The samples showed emission peaks at 488 nm (blue), 572 nm (yellow), 592 nm (orange) and 617 nm (red) under 393 nm excitation. The photoluminescence excitation spectra, comprising the Eu–O charge transfer band and 4f–4f transition bands of Dy³⁺ and Eu³⁺, range from 200 to 500 nm. The Commission Internationale de I'Eclairage chromaticity coordinates for Li₂Sr_0.98−xSiO₄:0.02Dy³⁺,xEu³⁺ phosphors were simulated. By manipulating Eu³⁺ and Dy³⁺ concentrations, the color points of Li₂Sr_1−x−ySiO₄:xDy³⁺,yEu³⁺ were tuned from the greenish‐white region to white light and eventually to reddish‐white region, demonstrating that a tunable white light can be obtained by Li₂Sr_1−x−ySiO₄:xDy³⁺,yEu³⁺ phosphors. Li₂Sr_0.98−xSiO₄:0.02Dy³⁺, xEu³⁺ can serve as a white‐light‐emitting phosphor for phosphor‐converted light‐emitting diode. Copyright © 2014 John Wiley & Sons, Ltd.     

Effect of Dy3+ or Eu2+ co‐activator on a BaCa(SO4)2:Ce3+ mixed alkaline earth sulfate phosphor

The individual emission and energy transfer between Ce³⁺ and Eu²⁺ or Dy³⁺ in BaCa(SO₄)₂ mixed alkaline earth sulfate phosphor prepared using a co‐precipitation method is described. The phosphor was characterized by X‐ray diffraction (XRD) and photoluminescence (PL) studies and doped by Ce;Eu and Dy rare earths. All phosphors showed excellent blue–orange emission on excitation with UV light. PL measurements reveal that the emission intensity of Eu²⁺ or Dy³⁺ dopants is greater than when they are co‐doped with Ce³⁺. An efficient Ce³⁺ → Eu²⁺ [²T_2g(4f⁶5d) → ⁸S_7/2(4f₇)] and Ce³⁺ → Dy³⁺ (⁴ F_9/2 → ⁶H_15/2 and ⁴ F_9/2 → ⁶H_13/2) energy transfer takes place in the BaCa(SO₄)₂ host. A strong blue emission peak was observed at 462 nm for Eu²⁺ ions and an orange emission peak at 574 nm for Dy³⁺ ions. Hence, this phosphor may be used as a lamp phosphor. Copyright © 2015 John Wiley & Sons, Ltd.     

Enhanced luminescence and white light emission from Eu3+‐co‐doped K3Ca2(SO4)3Cl:Dy3+ phosphor with near visible ultraviolet excitation for white LEDs

The luminescent properties of europium (Eu)‐ and dysprosium (Dy)‐co‐doped K₃Ca₂(SO₄)₃Cl halosulfate phosphors were analyzed. This paper reports the photoluminescence (PL) properties of K₃Ca₂(SO₄)₃Cl microphosphor doped with Eu and Dy and synthesized using a cost‐effective wet chemical method. The phosphors were characterized by X‐ray diffraction and scanning electron microscopy. The CIE coordinates were calculated to display the color of the phosphor. PL emission of the prepared samples show peaks at 484 nm (blue), 575 nm (yellow), 594 nm (orange) and 617 nm (red). The emission color of the Eu,Dy‐co‐doped K₃Ca₂(SO₄)₃Cl halophosphor depends on the doping concentration and excitation wavelength. The addition of Eu in K₃Ca₂(SO₄)₃Cl:Dy greatly enhances the intensity of the blue and yellow peaks, which corresponds to the ⁴ F_9/2 → ⁶H_15/2 and ⁴ F_9/2 → ⁶H_13/2 transitions of Dy³⁺ ions (under 351 nm excitation). The Eu³⁺/Dy³⁺ co‐doping also produces white light emission for 1 mol% of Eu³⁺, 1 mol% of Dy³⁺ in the K₃Ca₂(SO₄)₃Cl lattice under 396 nm excitation, for which the calculated chromaticity coordinates are (0.35, 0.31). Thus, K₃Ca₂(SO₄)₃Cl co‐doped with Eu/Dy is a suitable candidate for NUV based white light‐emitting phosphors technology. Copyright © 2014 John Wiley & Sons, Ltd.     

Photoluminescence and thermoluminescence characteristics of Sr3B2O6:Eu2+ yellow phosphor

Sr₃B₂O₆:Eu²⁺ yellow phosphor was prepared by the combustion method. The crystalline structure, photoluminescence and thermoluminescence properties of Sr₃B₂O₆:Eu²⁺ were investigated extensively. The X‐ray diffraction result indicates that the Sr₃B₂O₆:Eu²⁺ phosphor exhibited a rhombohedral crystal structure. The emission spectra under a 435 nm excited wavelength showed an intense broad band peaking at 574 nm, which corresponds to the 4f⁶5d¹ → 4f⁷ transition of Eu²⁺ ion. There were two different sites of Sr replaced by Eu in host lattice. The concentration quenching process between Eu²⁺ ions is determined and the corresponding concentration quenching mechanism was verified as dipole‐quadrupole interaction. The glow curve under 3 Gy β‐ ray irradiation had the glow peak at 160°C and the average activation energy was defined as about 0.98 eV. Copyright © 2015 John Wiley & Sons, Ltd.     

Insights into the discrepant luminescence for BaSiO3:Eu2+ phosphors prepared by solid‐state reaction and precipitation reaction methods

Two synthesis routes, solid‐state reaction and precipitation reaction, were employed to prepare BaSiO₃:Eu²⁺ phosphors in this study. Discrepancies in the luminescence green emission at 505 nm for the solid‐state reaction method sample and in the yellow emission at 570 nm for the sample prepared by the precipitation reaction method, were observed respectively. A detail investigation about the discrepant luminescence of BaSiO₃:Eu²⁺ phosphors was performed by evaluation of X‐ray diffraction (XRD), photoluminescence (PL)/photoluminescence excitation (PLE), decay time and thermal quenching properties. The results showed that the yellow emission was generated from the BaSiO₃:Eu²⁺ phosphor, while the green emission was ascribed to a small amount of Ba₂SiO₄:Eu²⁺ compound that was present in the solid‐state reaction sample. This work clarifies the luminescence properties of Eu²⁺ ions in BaSiO₃ and Ba₂SiO₄ hosts.     

Microwave‐assisted sintering synthesis of greenish‐yellow emitting Sr2SiO4:Eu2+ phosphors

Europium ion (Eu²⁺) doped Sr₂SiO₄ phosphors with greenish‐yellow emission were synthesized using microwave‐assisted sintering. The phase structure and photoluminescence (PL) properties of the obtained phosphor samples were investigated. The PL excitation spectra of the Sr₂SiO₄:Eu²⁺ phosphors exhibited a broad band in the range of 260 nm to 485 nm with a maximum at 361 nm attributed to the 5f‐4d allowed transition of the Eu²⁺ ions. Under an excitation at 361 nm, the Sr₂SiO₄:Eu²⁺ phosphor exhibited a greenish‐yellow emission peak at 541 nm with an International‐Commission‐on‐Illumination (CIE) chromaticity of (0.3064, 0.4772). The results suggest that the microwave‐assisted sintering method is promising for the synthesis of phosphors owing to the decreased sintering time without the use of additional reductive agents.     

Energy transfer in M5(PO4)3 F:Eu2+,Ce3+ (M = Ca and Ba) phosphors

M₅(PO₄)₃ F:Eu²⁺ (M = Ca and Ba) co‐doped with Ce³⁺ phosphors were successfully prepared by the combustion synthesis method. The introduction of co‐dopant (Ce³⁺) into the host enhanced the luminescent intensity of the M₅(PO₄)₃ F:Eu²⁺ (M = Ca and Ba) efficiently. Previously, we have reported the synthesis and photoluminescence properties of same phosphors. The aim of this article is to report energy transfer mechanism between Ce³⁺?Eu²⁺ ions in M₅(PO₄)₃ F:Eu²⁺ (M = Ca and Ba) phosphors, where Ce³⁺ ions act as sensitizers and Eu²⁺ ions act as activators. The M₅(PO₄)₃ F:Eu²⁺ (M = Ca and Ba) co‐doped with Ce³⁺ phosphor exhibits great potential for use in white ultraviolet (UV) light‐emitting diode applications to serve as a single‐phased phosphor that can be pumped with near‐UV or UV light‐emitting diodes. Copyright © 2013 John Wiley & Sons, Ltd.     

Photoluminescence properties of LiBaPO4:M3+ phosphor for near‐UV light‐emitting diode (M = Eu and Dy)

A novel phosphor LiBaPO₄ doped with rare earths Eu and Dy prepared by high temperature solid‐state reaction method is reported. The phosphors were characterized by X‐ray powder diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL). The emission and excitation spectra of these materials were measured at room temperature with a spectrofluorophotometer. The excitation spectra of LiBaPO₄:Eu³⁺ phosphor can be efficiently excited by 394 nm, which is matched well with the emission wavelength of near‐UV light‐emitting diode (LED) chip. PL properties of Eu³⁺‐doped LiBaPO₄ exhibited the characteristic red emission coming from ⁵D₀ → ⁷ F₁ (593 nm) and ⁵D₀ → ⁷ F₂ (617 nm) electronic transitions with color co‐ordinations of (0.680, 0.315). The results demonstrated that LiBaPO₄:Eu³⁺ is a potential red‐emitting phosphor for near‐UV LEDs. Emission spectra of LiBaPO₄:Dy³⁺ phosphors showed efficient blue (481 nm) and yellow (574 nm) bands, which originated from ⁴ F_9/2 → ⁶H_15/2 and ⁴ F_9/2 → ⁶H_13/2 transitions of the Dy³⁺ ion, respectively. The 574 nm line is more intense than the 481 nm lines, which indicates that the site Dy³⁺ is located with low symmetry. This article summarizes fundamentals and possible applications of optically useful inorganic phosphates with visible photoluminescence of Eu³⁺ and Dy³⁺ ions. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis and luminescent properties of novel BaGd2O4:Eu3+ scintillating phosphor

BaGd_2‐xO₄:xEu³⁺ and Ba_1‐yGd_1.79‐2yEu_0.21Na_3yO₄ phosphors were synthesized at 1300°C in air by conventional solid‐state reaction method. Phosphors were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence excitation (PLE) spectra, photoluminescence (PL) spectra and thermoluminescence (TL) spectra. Optimal PL intensity for BaGd_2‐xO₄:xEu³⁺ and Ba_1‐yGd_1.79‐2yEu_0.21Na_3yO₄ phosphors at 276 nm excitation were found to be x = 0.24 and y = 0.125, respectively. The PL intensity of Eu³⁺ emission could only be enhanced by 1.3 times with incorporation of Na⁺ into the BaGd₂O₄ host. Enhanced luminescence was attributed to the flux effect of Na⁺ ions. However, when BaGd₂O₄:Eu³⁺ phosphors were codoped with Na⁺ ions, the induced defects confirmed by TL spectra impaired the emission intensity of Eu³⁺ ions. Copyright © 2012 John Wiley & Sons, Ltd.     

Photo and thermoluminescence of KMgSO4F: Ce and :Mn phosphors

KMgSO₄F:Ce and KMgSO₄F:Mn phosphors were prepared by a wet chemical method and studied for their photoluminescence (PL) and thermoluminescence (TL) characteristics. PL emission of KMgSO₄F:Ce peaked at around 440 nm for the excitation at 377 nm due to 5d → 4f transition, while KMgSO₄F:Mn had a peak at 540 nm for an excitation at 363 nm and 247 nm due to ⁴T_1g → ⁶A_1g transition. The phosphors also showed good thermoluminescence characteristics when they were exposed to γ‐rays at a 5 Gy dose at the rate of 0.36 kGyh^?1. KMgSO₄F:Ce exhibited a single thermoluminescence (TL) peak at around 167 °C and KMgSO₄F:Mn also exhibited a single TL peak at around 177 °C. Possible trapping parameters such as order of kinetics (b), the geometrical factor (μ_g), the frequency factor (s) and the activation energy were also evaluated by Chen's half width method. This article discusses fundamental PL and TL characteristics in inorganic fluoride material activated by Ce³⁺ and Mn²⁺ ions and prepared by a wet chemical method. Copyright © 2014 John Wiley & Sons, Ltd.