Sol–gel preparation and luminescent properties of red‐emitting phosphor Sr‐Ba‐Mo‐W‐O‐(Eu3+,Sm3+)

Two series of red‐emitting phosphors Sr‐Ba‐Mo‐W‐O:Eu,Sm and Sr‐Ba‐Mo‐W‐O:Eu have been synthesized by a sol–gel method. The effects of the chemical composition, concentrations of Sm³⁺ and Eu³⁺, the Sr²⁺/Ba²⁺ ratio, and the W⁶⁺/Mo⁶⁺ ratio on the luminescent properties were investigated. The as‐prepared phosphors were characterized by X‐ray diffraction and Raman spectra. Results showed that single phases of the two series were prepared. The compositions of Sr_0.6Ba_0.13Mo_0.8 W_0.2O₄:Eu_0.10Sm_0.08 and Sr_0.75Ba_0.1Mo_0.8 W_0.2O₄:Eu_0.10 had the strongest luminescent intensity. The excitation spectra of Sm³⁺, Eu³⁺ co‐doped phosphors were broader and the strongest peak moved to 404 nm when compared with that of Eu³⁺ single‐doped phosphors. The luminescent intensity of the Sr_0.6Ba_0.13Mo_0.8 W_0.2O₄:Eu_0.10Sm_0.08 at 618 nm were 2.8 times greater than that of Sr_0.75Ba_0.1Mo_0.8 W_0.2O₄:Eu_0.10. The luminescent intensity of Sr_0.6Ba_0.13Mo_0.8 W_0.2O₄:Eu_0.10Sm_0.08 and Sr_0.75Ba_0.1Mo_0.8 W_0.2O₄:Eu_0.10 at 150 °C decreased to 56.8% and 50.3% of the initial value at room temperature, respectively. Copyright © 2015 John Wiley & Sons, Ltd.     

Optical characterization and the energy level scheme for Ce3+‐doped BaY2Si3O10 blue‐emitting phosphor

A series of Ce³⁺‐activated blue‐emitting phosphors BaY₂Si₃O₁₀ (BYSO) was designed and synthesized by a conventional solid‐state method. Upon ultraviolet light (250–370 nm) excitation, the obtained phosphors showed an intense blue emission band centered at 400–427 nm depending on doping concentration, and corresponding to the 5d→4f transition of Ce³⁺. The effects of doping concentration on crystal structure, emitting color, photoluminescence and photoluminescence excitation spectra, as well as the concentration quenching mechanism were studied in detail. The optimal doping concentration of Ce³⁺ in this phosphor was demonstrated to be about 0.75% and the concentration quenching mechanism can be ascribed to electric dipole–dipole interactions with a critical distance of ~38 Å. These fine luminescence properties indicate that BYSO:Ce³⁺ may be a potential blue phosphor for full‐color ultra‐violet (UV) white light emitting diodes (WLEDs).     

Orange light‐emitting Ca3Mg3(PO4)4:Sm3+ phosphors

This work reports the photoluminescence properties of Ca₃Mg₃(PO₄)₄:Sm³⁺ phosphors that were synthesized by the combustion method. The phase formation and morphology of the prepared phosphors were analysed by X‐ray diffraction studies and scanning electron microscopy. Ca₃Mg₃(PO₄)₄:Sm³⁺ phosphors give orange light emission when excited by near‐ultraviolet (NUV) and blue light. The photoluminescence characteristics of the as‐prepared phosphors were investigated and their emission spectra showed three peaks due to ⁴G_5/2 → ⁶H_5/2, ⁴G_5/2 → ⁶H_7/2 and ⁴G_5/2 → ⁶H_9/2 transitions. The mechanism responsible for the concentration quenching of luminescence was found to be an electric dipole–dipole interaction. The CIE chromaticity coordinates suggested that the prepared phosphors are potential candidates for orange light‐emitting diodes (LEDs).     

Photoluminescence properties of a new orange–red‐emitting Sm3+–La3SbO7 phosphor

The antimonate compound La₃SbO₇ has high chemical stability, lattice stiffness and thermal stability. Orange–red‐emitting antimonate‐based phosphors La₃SbO₇:xSm³⁺ (x = 0.02, 0.05, 0.08, 0.10, 0.15, 0.20 and 0.25) were synthesized. The phase structure and photoluminescence properties of these phosphors were investigated. The emission spectrum obtained on excitation at 407 nm contained exclusively the characteristic emissions of Sm³⁺ at 568, 608, 654 and 716 nm, which correspond to the transitions from ⁴G_5/2 to ⁶H_5/2, ⁶H_7/2, ⁶H_9/2 and ⁶H_11/2 of Sm³⁺, respectively. The strongest emission was located at 608 nm due to the ⁴G_5/2→⁶H_7/2 transition of Sm³⁺, generating bright orange–red light. The critical quenching concentration of Sm³⁺ in La₃SbO₇:Sm³⁺ phosphor was determined as 10% and the energy transfer between Sm³⁺ was found to be through an exchange interaction. The International Commission on Illumination chromaticity coordinates of the La₃SbO₇:0.10Sm³⁺ phosphors are located in the orange–red region. The La₃SbO₇:Sm³⁺ phosphors may be potentially used as red phosphors for white light‐emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd.     

Tunable photoluminescence properties of Sr1‐yCayMoO4:Sm3+ phosphors (0 ≤ y < 1)

A series of Sr_1‐x‐yCa_yMoO₄:xSm³⁺ (0 ≤ x ≤ 7 mol% and 0 ≤ y < 1) phosphors was synthesized by a conventional solid‐state reaction method in air, and their structural and spectroscopic properties were investigated. The optimal doping concentration of Sm³⁺ in SrMoO₄:Sm³⁺ phosphor is 5 mol%. Under excitation with 275 nm, in Sr_1‐x‐yCa_yMoO₄:xSm³⁺ (0 ≤ x ≤ 7 mol% and 0 ≤ y < 1) phosphors, the emission band of the host was found to overlap with the excitation bands peaking at ~500 nm of Sm³⁺ ion, and the energy transfer from MoO₄^2? group to Sm³⁺ ion can also be observed. The International Commission on Illumination (CIE) chromaticity coordinates of Sr_0.95‐yCa_yMoO₄:0.05Sm³⁺ phosphors with excitation 275 nm varied systematically from an orange (0.4961, 0.3761) (y = 0) to a white color (0.33, 0.3442) (y = 0.95) with increasing calcium oxide (CaO) concentration. However, Sr_0.95‐yCa_yMoO₄:0.05Sm³⁺ phosphors with excitation at 404 nm only showed red emission and the energy transfer between MoO₄^2? group to Sm³⁺ ion was not observed. The complex mechanisms of luminescence and energy transfer are discussed by energy level diagrams of MoO₄^2? group and Sm³⁺ ion. Copyright © 2015 John Wiley & Sons, Ltd.     

Luminescent properties of MAl(SO4)2Br:Eu3+ (M = Sr or Mg) red phosphors for near‐UV light‐emitting diodes

Eu³⁺‐activated MAl(SO₄)₂Br phosphors (where M = Mg or Sr) are successfully prepared using a wet chemical reaction technique. The samples are characterized by X‐ray diffraction (XRD) and photoluminescence (PL) spectroscopies. The XRD pattern revealed that both the samples are microcrystalline in nature. PL of Eu³⁺‐doped SrAl(SO₄)₂Br and MgAl(SO₄)₂Br phosphors exhibited characteristic red emission coming from the ⁵D₀ → ⁷F₂ (616 nm) electron transition, when excited by 396 nm wavelength of light. The maximum intensity of luminescence was observed at a concentration of 1 mol% Eu³⁺. The intensity of the electric dipole transition at 616 nm is greater than that of the magnetic dipole transition at 594 nm. The results showed that MAl(SO₄)₂Br:Eu³⁺, (M = Mg, Sr) phosphors have potential application in near‐UV light‐emitting diodes as efficient red‐emitting phosphor. Copyright © 2014 John Wiley & Sons, Ltd.     

Multi-color luminescence of Sm3+-doped Na2YMg2V3O12 phosphor potentially applicable in white-LEDs

A novel multi-color emitting Na₂YMg₂V₃O₁₂:Sm³⁺ phosphor was synthesized using a solid-state reaction, and its crystal structure, luminescence properties, and thermal stability were studied. Charge transfer within the (VO₄)³⁻ groups in the Na₂YMg₂V₃O₁₂ host led to a broad emission band between 400 and 700 nm, with a maximum at 530 nm. The Na₂Y_1−xMg₂V₃O₁₂:xSm³⁺ phosphors exhibited a multi-color emission band under 365 nm near-ultraviolet (near-UV) light, consisting of the green emission of the (VO₄)³⁻ groups and sharp emission peaks at 570 nm (yellow), 618 nm (orange), 657 nm (red), and 714 nm (deep red) of Sm³⁺ ions. The optimal doping concentration of Sm³⁺ ions was found to be 0.05 mol%, and the dipole–dipole (d–d) interaction was primarily responsible for the concentration quenching phenomenon. Using the acquired Na₂YMg₂V₃O₁₂:Sm³⁺ phosphors, commercial BaMgAl₁₀O₁₇:Eu²⁺ blue phosphor, and a near-UV light-emitting diode (LED) chip, a white-LED lamp was designed and packaged. It produced bright neutral white light, manifesting a CIE coordinate of (0.314, 0.373), a color rendering index (CRI) of 84.9, and a correlated color temperature (CCT) of 6377 K. These findings indicate the potential of Na₂YMg₂V₃O₁₂:Sm³⁺ phosphor to be used as a multi-color component for solid-state illumination.     

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.     

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.     

Dy3+‐activated NaM4 (VO4)3 (M = Ca,Ba, Sr) phosphor for near‐UV solid‐state lighting

We report the photoluminescence characterization of Dy³⁺‐activated NaM₄(VO₄)₃ (M = Ca, Ba, Sr) phosphors prepared by a solid‐state method. The synthesis was confirmed by X‐ray diffraction (XRD) characterization and photoluminescence (PL) emission results showed sharp blue and yellow bands for NaM₄(VO₄)₃ (M = Ca, Ba, Sr):Dy³⁺ phosphors at the excitation wavelength of 323 nm, which is near‐UV excitation. Thus, these phosphors could be applicable for near‐UV excited solid‐state lighting devices. Copyright © 2011 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.     

Photoluminescence properties and energy transfer in Ce3+/Dy3+ co‐doped Sr3MgSi2O8 phosphors for potential application in ultraviolet white light‐emitting diodes

Sr₃MgSi₂O₈:Ce³⁺, Dy³⁺ phosphors were prepared by a solid‐state reaction technique and the photoluminescence properties were investigated. The emission spectra show not only a band due to Ce³⁺ ions (403 nm) but also as a band due to Dy³⁺ ions (480, 575 nm) (UV light excitation). The photoluminescence properties reveal that effective energy transfer occurs in Ce³⁺/Dy³⁺ co‐doped Sr₃MgSi₂O₈ phosphors, and the co‐doping of Ce³⁺ could enhance the emission intensity of Dy³⁺ to a certain extent by transferring its energy to Dy³⁺. The Ce³⁺/Dy³⁺ energy transfer was investigated by emission/excitation spectra, and photoluminescence decay behaviors. In Sr_2.94MgSi₂O₈:0.01Ce³⁺, 0.05Dy³⁺ phosphors, the fluorescence lifetime of Dy³⁺ (from 3.35 to 27.59 ns) is increased whereas that of Ce³⁺ is greatly decreased (from 43.59 to 13.55 ns), and this provides indirect evidence of the Ce³⁺ to Dy³⁺ energy transfer. The varied emitted color of Sr₃MgSi₂O₈:Ce³⁺, Dy³⁺ phosphors from blue to white were achieved by altering the concentration ratio of Ce³⁺ and Dy³⁺. These results indicate Sr₃MgSi₂O₈:Ce³⁺, Dy³⁺ may be as a candidate phosphor for white light‐emitting diodes. Copyright © 2012 John Wiley & Sons, Ltd.     

Impact of ligand environment on optical,luminescence and thermometric behavior of A3(PO4)2:Sm3+ (A = Ca,Sr) phosphors

The present study investigates the impact of the ligand environment on the luminescence and thermometric behavior of Sm³⁺ doped A₃(PO₄)₂ (A = Sr, Ca) phosphors prepared by combustion synthesis. The structural and luminescent properties of Sm³⁺ ions in the phosphate lattices were investigated using powder X-ray diffraction (PXRD) and photoluminescence (PL) techniques. PXRD results of the synthesized phosphors exhibit the expected phases that are in agreement with their respective standards. Fourier-transform infrared (FTIR) spectroscopy confirms the presence of PO₄ vibrational bands. Upon excitation with near ultraviolet light, the PL studies indicated that Sr₃(PO₄)₂:Sm³⁺ phosphors exhibit a yellow light emission, whereas Ca₃(PO₄)₂:Sm³⁺ phosphors exhibit an emission of orange light. The PL emission results are in accordance with the CIE coordinates, with the Sr₃(PO₄)₂:Sm³⁺ phosphors showing coordinates of (0.56, 0.44), and the Ca₃(PO₄)₂:Sm³⁺ phosphors displaying coordinates of (0.60, 0.40). Thermal analysis shows improved stability of Ca₃(PO₄)₂:Sm³⁺ based on lower weight reduction in thermogravimetric analysis. The effect of temperature on the luminescence properties of the phosphor has been examined upon a 405 nm excitation. By using the fluorescence intensity ratio (FIR) method, the temperature responses of the emission ratios from the Sm³⁺: the ⁴F_3/2 → ⁶H_5/2 transition to the ⁴G_5/2 → ⁶H_7/2 and ⁴F_3/2 → ⁶H_5/2 transition to the ⁴G_5/2 → ⁶H_9/2 emissions are characterized. The Ca₃(PO₄)₂:Sm³⁺ phosphors are more sensitive as compared with the Sr₃(PO₄)₂:Sm³⁺ phosphors. The earlier research findings strongly indicate that these phosphors hold great promise as ideal candidates for applications in non-invasive optical thermometry and solid-state lighting devices.     

Thermally stable Sm3+-doped alkali zinc alumino borosilicate (AZABS) glass for warm white light generation and w-LED applications

Samarium ion (Sm³⁺)-doped alkali zinc alumino borosilicate (AZABS) glass was synthesized via quick melt quench technique. Various spectroscopic studies like optical absorption, photoluminescence (PL) emission, PL excitation, temperature-dependent PL and PL decay kinetics were performed on the as prepared glass system. Under 402 nm excitation, three sharp bands at wavelengths 563, 599 and 645 nm corresponding to transitions ⁴G_5/2 → ⁶H_5/2, ⁶H_7/2 and ⁶H_9/2, respectively, can be seen in the PL emission spectra. The 0.25 mol% Sm³⁺ glass has the highest intensity for these emissions. The lanthanide interaction in the glass matrix is dipole–dipole in nature as was proven from Dexter's analysis. The direct bandgap of 0.25 mol% Sm³⁺-doped AZABS glass was calculated to be 2.88 eV. The lifetimes of the as prepared glass range from 1.93 ms for the lowest concentration of Sm³⁺ to 0.75 ms for the highest. From temperature dependent PL studies, the activation energy for 0.25 mol% Sm³⁺-doped AZABS glass was found to be 0.19 eV which shows high thermal stability of this glass. We propose to utilize these Sm³⁺-doped AZABS glasses for white-light emitting diodes (w-LEDs) and solid-state lighting (SSL) applications.     

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.     

Sr2ZnWO6:Eu3+,Bi3+,Li+: a potential white‐emitting phosphor for near‐ultraviolet white light‐emitting diodes

A series of Sr₂ZnWO₆ phosphors co‐doped with Eu³⁺, Bi³⁺ and Li⁺ were prepared using the Pechini method. The samples were tested using X‐ray diffraction and luminescence spectroscopy. The results show that the samples can be effectively excited by near‐ultraviolet (UV) and UV light. The introduction of Bi³⁺ and Li⁺ significantly enhances the fluorescence emission of Sr₂ZnWO₆:Eu³⁺ and changes the light emitted by the phosphors from bluish‐green to white. When excited at 371 nm, Sr_2–x–zZn_1–yWO₆:xEu³⁺,yBi³⁺,zLi⁺ (x = 0.05, y = 0.05, z = 0.05, 0.1 and 0.15) samples emit high‐performance white light. Intense red–orange emission is also observed when excited by UV light. The obtained phosphor is a potential white‐emitting phosphor that could meet the needs of excitation sources with near‐UV chips. In addition, this phosphor might have promising application as a red–orange emitting phosphor for white light‐emitting diodes based on UV light‐emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd.     

Novel red colour emitting Ca0.995Mg2(SO4)3:0.5Eu2+ phosphor under ultraviolet,blue, and green excitation for plant growth LEDs

In the recent few years, Eu²⁺- and Mn⁴⁺-activated phosphors are widely used as potential colour converters for indoor plant cultivation lighting application due to their marvellous luminescence characteristics as well as low cost. In this investigation, we synthesized novel red colour-emitting Ca_(2−x)Mg₂(SO₄)₃:xmol% Eu²⁺ (x = 0–1.0 mol%) phosphors via a solid-state reaction method in a reducing atmosphere. The photoluminescence (PL) excitation spectra of synthesized phosphors exhibited a broad excitation band with three excitation bands peaking at 349 nm, 494 nm, and 554 nm. Under these excitations, emission spectra exhibited a broad band in the red colour region at ~634 nm. The PL emission intensity was measured for different concentrations of Eu²⁺. The maximum Eu²⁺ doping concentration in the Ca₂Mg₂(SO₄)₃ host was observed for 0.5 mol%. According to Dexter theory, it was determined that dipole–dipole interaction was responsible for the concentration quenching. The luminous red colour emission of the sample was confirmed using Commission international de l'eclairage colour coordinates. The results of PL excitation and emission spectra of the prepared phosphors were well matched with excitation and emission wavelengths of phytochrome P_R. Therefore, from the entire investigation and obtained results it was concluded that the synthesized Ca_0.995Mg₂(SO₄)₃:0.5mol%Eu²⁺ phosphor has huge potential for plant cultivation application.     

Spectral investigations on Eu3+,Sm3+‐doped and Sm3+/Eu3+ co‐doped potassium‐fluoro‐phosphate glass emitting intense orange‐red for lighting applications

Potassium fluoro‐phosphate (KFP) glass singly doped with different concentrations of europium (Eu³⁺) or samarium (Sm³⁺) or co‐doped (Sm³⁺/Eu³⁺) was prepared, and their luminescence spectra were investigated. The phase composition of the product was verified by X‐ray diffraction analysis. Optical transition properties of Eu³⁺ in the studied potassium phosphate glass were evaluated in the framework of the Judd–Ofelt theory. The radiative transition rates (A_R), fluorescence branching ratios (β), stimulated emission cross‐sections (σ_e) and lifetimes (τ_exp) for certain transitions or levels were evaluated. Red emission of Eu³⁺ was exhibited mainly by the ⁵D₀→⁷F₂ transition located at 612 nm. Concentration quenching and energy transfer were observed from fluorescence spectra and decay curves, respectively. It was found that the lifetimes of the ⁵D₀ level increased with increase in concentration and then decreased. By co‐doping with Sm³⁺, energy transfer from Sm³⁺ to Eu³⁺ occurred and contributed to the enhancement in emission intensity. Intense orange‐red light emission was obtained upon sensitizing with Sm³⁺ in KFP glass. This approach shows significant promise for use in reddish‐orange lighting applications. The optimized properties of the Sm³⁺/Eu³⁺ co‐doped potassium phosphate glass might be promising for optical materials.     

Investigation of UV‐emitting Gd3+‐doped LiCaBO3 phosphor

Incorporating the Gd³⁺ rare earth ion in the LiCaBO₃ host lattice resulted in narrow‐band UV‐B emission peaking at 315 nm, with excitation at 274 nm. The LiCaBO₃:Gd³⁺ phosphor was synthesized via the solid‐state diffusion method. The structural, morphological and luminescence properties of this phosphor were characterized by X‐ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and photoluminescence (PL) spectroscopy. Electron paramagnetic resonance (EPR) characterization of the as‐prepared phosphors is also reported here. XRD studies confirmed the crystal formation and phase purity of the prepared phosphors. A series of different dopant concentrations was synthesized and the concentration‐quenching effect was studied. Critical energy transfer distance between activator ions was determined and the mechanism governing the concentration quenching is also reported in this paper. Copyright © 2015 John Wiley & Sons, Ltd.     

Study of trivalent samarium ion embedded lithium‐based borate glass for high‐density optical memory devices

Sm³⁺ ions doped strontium lithium lead borate glasses (SLLB:Sm) were prepared using a conventional melt‐quenching technique. The glasses were analyzed using X‐ray diffractometry and Fourier transform infrared spectroscopy, optical absorption, fluorescence spectral analysis, and fluorescence lifetime decay. The Judd–Ofelt (J–O) parameters and radiative parameters of the SLLB:Sm10 glass (1.0 mol% Sm³⁺ ion‐doped glass) were calculated using J–O theory. From the emission spectra, among all the synthesized glass, SLLB:Sm10 glass had the highest emission intensity for ⁴G_5/2→⁶H_11/2 transition (610 nm). Emission parameters, such as stimulated emission cross‐section and optical gain bandwidth, were calculated. For all concentrations of Sm³⁺ ions, the decay profile showed an exponential nature and decreased when the Sm³⁺ ion concentration was increased due to a concentration quenching effect. This result suggests that the synthesized SLLB:Sm10 glass could be used for application in high‐density optical memory devices.