Silicate Phosphors Research Articles

Correlation among photoluminescence and the electronic and atomic structures of Sr2SiO4:xEu3+ phosphors: X-ray absorption and emission studies

A series of Eu3+-activated strontium silicate phosphors, Sr2SiO4:xEu3+ (SSO:xEu3+, x = 1.0, 2.0 and 5.0%), were synthesized by a sol–gel method, and their crystalline structures, photoluminescence (PL) behaviors, electronic/atomic structures and bandgap properties were studied. The correlation among these characteristics was further established. X-ray powder diffraction analysis revealed the formation of mixed orthorhombic α'-SSO and monoclinic β-SSO phases of the SSO:xEu3+ phosphors. When SSO:xEu3+ phosphors are excited under ultraviolet (UV) light (λ = 250 nm, ~ 4.96 eV), they emit yellow (~ 590 nm), orange (~ 613 nm) and red (~ 652 and 703 nm) PL bands. These PL emissions typically correspond to 4f–4f electronic transitions that involve the multiple excited 5D0 → 7FJ levels (J = 1, 2, 3 and 4) of Eu3+ activators in the host matrix. This mechanism of PL in the SSO:xEu3+ phosphors is strongly related to the local electronic/atomic structures of the Eu3+–O2− associations and the bandgap of the host lattice, as verified by Sr K-edge and Eu L3-edge X-ray absorption near-edge structure (XANES)/extended X-ray absorption fine structure, O K-edge XANES and Kα X-ray emission spectroscopy. In the synthesis of SSO:xEu3+ phosphors, interstitial Eu2O3-like structures are observed in the host matrix that act as donors, providing electrons that are nonradiatively transferred from the Eu 5d and/or O 2p–Eu 4f/5d states (mostly the O 2p–Eu 5d states) to the 5D0 levels, facilitating the recombination of electrons that have transitioned from the 5D0 level to the 7FJ level in the bandgap. This mechanism is primarily responsible for the enhancement of PL emissions in the SSO:xEu3+ phosphors. This PL-related behavior indicates that SSO:xEu3+ phosphors are good light-conversion phosphor candidates for use in near-UV chips and can be very effective in UV-based light-emitting diodes.

Photoluminescence and comparative thermoluminescence studies of UV/γ-irradiated Dy3+ doped bismuth silicate phosphor

A series of Bi4Si3O12:Dy3+ phosphor have been synthesized via conventional solid-state reaction method and its luminescence properties were investigated as near cool white light emitting and long afterglow phosphor. Crystal structure and phase structure characterization is determined using X-ray diffraction (XRD), SEM and EDS. Rietveld structural refinement and XRD confirms that prepared sample exhibit pure cubic structure [space group I-43d]. Photoluminescence spectra of both doped and undoped Bi4Si3O12 phosphor were efficiently excited in the range of 200-450 nm, and prepared phosphor under 272 nm excitation exhibit three emission peaks located at 463 nm(blue), 482 nm(blue) and 576 nm (yellow) corresponding to 3P1 → 1S0, 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions. Characteristic emission peaks of Dy3+ centered at 482 nm and 576 nm were assigned for white light emission. The calculated Commission Internationale de I’Eclairage (CIE) chromaticity confirms that with Dy3+ doping, the luminescence co-ordinates of Bi4Si3O12 phosphor shift to near white(x = 0.316, y = 0.358) region which is close to commercial pc-LED (Blue LED + YAG:Ce3+) (x = 0.320, y = 0.320) co-ordinates. Computation of correlated color temperature 6184 K endorses that prepared phosphor is cool in nature and can be served as white light emitting phosphor. Comparative thermoluminescence study of UV and γ-irradiated Bi4Si3O12:Dy3+ phosphor is performed for the dosimetry application. TL intensity is recorded maximum at 30 min under UV irradiation (256 nm), and for γ irradiation, it was recorded at 10 kGy dose rate. γ-irradiated Bi4Si3O12:Dy3+ phosphor TL study is reported for the first time at different dose rate and concentration for high dosimetry application. The defect characteristic is examined, Trap depths and other kinetic parameters are also evaluated by Chen’s peak shape method. Decay and fading measurement under UV/γ irradiation are performed to examine the long after glow properties of prepared samples. TL emission spectrum studies are also performed.

A comparative photoluminescence and Judd–Ofelt study on alumino silicate phosphors

In this article, un-doped and (0.01) Eu3+-activated series of M2Al2SiO7 (M = Ca, Sr, Ba) phosphors have been prepared via traditional high temperature solid-state reaction method. Phase purity and structural characterization of prepared phosphors were done by XRD. Estimated particle size of un-doped and Eu3+ activated M2Al2SiO7 (M = Ca, Sr, Ba) phosphors are 23.77, 19.76, 14.19 nm, 27.38, 18.21 and 16.84 nm, respectively, using Scherrer formula. To confirm the elemental composition and presence of hydrated phase EDX and FTIR analysis were performed. Photoluminescence studies and Judd–Ofelt (J–O) analysis were done. Photoluminescence studies show that all the doped phosphors show intense red emission centered at 618 nm, 619 nm and 613 nm, when excited at 394 nm due to 5D0-7FJ(J = 0,1,2,3) transition of Eu3+. Calculated CIE co-ordinates of all the phosphors are very close to commercial phosphor Y2O3:Eu3+. Calculated Judd–Ofelt (J–O) parameter reveals that Ω2 is greater than Ω4 and in all the three cases it is much greater for Ba2Al2SiO7. Thus, these phosphors can act as potential candidate for novel red-light-emitting phosphor.

Data-Driven Photoluminescence Tuning in Eu2+-Doped Phosphors.

Discovery of rare earth phosphors has generally relied on the chemical intuition and time-intensive trial-and-error synthesis; therefore, finding new materials assisted by data-driven computations is urgent. Herein, we utilize a regression model to predict the emission wavelengths of Eu2+-doped phosphors by revealing the relationships between the crystal structure and luminescence property. The emission wavelengths of [Rb(1-x)K(x)]3LuSi2O7:Eu2+ (0 ≤ x ≤ 1) phosphors, as examples for the data-driven photoluminescence tuning, are successfully predicted on the basis of the existing data of only eight systems, also consistent with the experimental results. These phosphors can be excited by blue light and exhibit broad-band red and near-infrared emission ranging from 619 to 737 nm. These findings in Eu2+-doped silicate phosphors indicate that data-driven computations through the regression mode would have bright application in discovering novel phosphors with a target emission wavelengths.

Synthesis of orange emitting Sm3+ doped sodium calcium silicate phosphor by sol-gel method for photonic device applications

Samarium (Sm3+) doped sodium calcium silicate (Na2CaSiO4: NCS) phosphors have been synthesized by employing a sol-gel technique. The structural, morphological, excitation and emission spectral studies have been carried out for the as-prepared phosphors. The phase purity in synthesized NCS phosphor with cubic structure has been confirmed by X-ray diffraction (XRD) pattern. The scanning electron microscopic images depict the irregular morphology and non-uniform microcrystalline particles in synthesized phosphor. The excitation spectra of NCS: Sm3+ phosphors disclose strong absorption in UV (ultraviolet), n-UV (near UV) and blue spectral regions. The emission spectra recorded under 402 nm excitation exhibit peaks at 565, 602 and 649 nm attributed to characteristic 4f-4f transitions of Sm3+ ions. The Sm3+ concentration optimized for NCS host as 1.0 mol%, and concentration quenching phenomenon has been discussed in detail. The chromaticity coordinates (0.579, 0.419) for optimized NCS: Sm3+ phosphor lie in the pure orange region. The temperature-dependent photoluminescence studies demonstrate that luminescence intensity even at 423 and 463 K persists up to 85.4 and 79.6% of the intensity at room temperature, respectively. Above mentioned results substantiate the potentiality of NCS: Sm3+ phosphor to use as a thermally stable orange emitting component in photonic devices.

Promising green Sr5B3O9F: Ce3+/ Tb3+/Na+ phosphors for NUV-executable LED applications

Abstract Green phosphors such as Sr5-3(x+y)/2CexTbyB3O9F (x = 0.1, y = 0.4) and Sr5-x-y-zCexTbyNazB3O9F (x = 0.1, y = 0.4, z = 0.1, 0.4, 0.5) were prepared via solid-state reactions. The X-ray diffraction patterns of the obtained phosphors were examined to properly index their peak positions. Enhanced photoluminescence (PL) excitation and emission spectra were observed when Na+ and Ce3+ were co-doped into the Sr5B3O9F:Tb3+ phosphors. An intense green light due to the prepared phosphors was observed in the emission spectra upon near-ultraviolet (NUV) excitation. Scanning electron microscopy (SEM) images of the luminescent particles were obtained and the green emission light of a Sr4Ce0.1Tb0.4Na0.5B3O9F phosphor was compared to that of commercially available green phosphate and silicate phosphors. The thermal quenching of such phosphor occurred at 298–448 K. In addition, the internal quantum efficiency, color rendering index, correlated color temperature, and Commission Internationale de l’Eclairage coordinates were characterized for the Sr4Ce0.1Tb0.4Na0.5B3O9F phosphor using a 365 nm LED chip.

Luminescent characterization of CaMgSiO4:Dy3+phosphor for white light emitting diodes

Different concentration of Dy3+ doped calcium magnesium silicate (CMS) phosphors are synthesized via solid state synthesis (SSS) method at high temperature. The structural properties are analyzed by X-ray diffraction (XRD). The surface microstructures are confirmed by scanning electron microscopy (SEM)and energy dispersive X-ray (EDX) spectra. The vibrational properties of the synthesized phosphor are carried out using fourier transform infrared (FT-IR) spectra. The luminescence properties are explained in terms of photoluminescence (PL) and thermoluminescence (TL) characteristics. The PL spectra showed maximum emission intensity peaking at 484 and 578 nm, which are attributed to the 4F9/2 → 6H15/2 and4F9/2 → 6H13/2 transitions of Dy3+ ion respectively. The PL properties of the prepared phosphors are carried out at room temperature. The maximum PL intensity occurs at 0.5 mol% of doping concentrationof Dy3+ ions due to concentration quenching. The glow peak and TL parameters of the prepared phosphors are computed by means of peak shape method. The CIE color co-ordinates are originated (x= 0.3263, y= 0.3451) and correlated color temperature (CCT) are determined to be 5769 K. The results indicate that the prepared phosphor produces cool light in the white region.

Synthesis and luminescence properties of novel red-emitting Eu3+ ions doped silicate phosphors for photonic applications

In the present work, we report on luminescence properties of Eu3+ ions doped KBaScSi3O9 silicate phosphors (KBSS) synthesized by high temperature solid state reaction method and the prepared phosphor samples were characterized through XRD, FE-SEM, photoluminescence and decay spectral measurements. The XRD pattern confirmed that the KBSS host lattice exhibited a monoclinic crystal structure. Room temperature photoluminescence (PL) spectroscopic results reveal that, on Eu3+ ion doping in the KBSS host matrix, the magnetic dipole transition (5D0 → 7F1) at 593 nm responsible for orange light, dominates the red emission with respect to the electric dipole transition (5D0 → 7F2) at 611 nm. The Judd-Ofelt (JO) intensity parameters Ωλ (λ = 2 and 4) have been calculated from the emission spectra to understand the nature of ligand environment around the Eu3+ ions. The radiative parameters, such as transition probability (A), stimulated emission cross-section (σPE), radiative lifetime (τR) and branching ratios (βR) corresponding to the 5D0→7F0, 5D0→7F1, 5D0→7F2, 5D0→7F3 and 5D0→7F4 emission transitions have been determined by using JO parameters and the refractive indices respectively. The concentration quenching effect for Eu3+ was found at the optimum doping concentration of 7 mol %. The CIE chromaticity coordinates were calculated from the luminescence spectra to explore the dominant emission colour of the title phosphors. The experimental lifetime values of 5D0 level of the Eu3+ doped silicate phosphors have been calculated and the obtained results were discussed in detail.

The effect of Dy3+ doping on the thermoluminescence properties of Ba2SiO4

AbstractThe thermoluminescence (TL) properties of barium silicate phosphor, Ba2SiO4:%3Dy3+ synthesized by using hydrothermal method were investigated and presented in detail. The crystallographic structure of Ba2SiO4:%3Dy3+ was determined by conventional x‐ray diffraction technique and the results showed that the sample was grown in orthorhombic phase with Pmcn (62) space group (PDF: 01‐077‐0150). The excitation spectra of Ba2SiO4:Dy3+ were measured in the wavelength range of 220‐400 nm and the spectra showed that there were several excitation bands in the sample. The CIE chromaticity coordinates were also calculated from emission spectra for Dy3+‐doped Ba2SiO4. In order to calculate the kinetic parameters of the sample the additive dose, peak shape and computerized glow curve deconvolution methods were used. It was found that Ba2SiO4:Dy3+ was composed of five general order TL glow peaks. The fading characteristics of the sample were also studied over a period time. At the end of the planned storage times, the normalized TL peak area of Ba2SiO4:Dy3+ reduced 60% of its original value.

Luminescent properties of CaSc2O4:Ce3+ green phosphor for white LED and its optical simulation

Green-emissive Ce3+-doped CaSc2O4 phosphors were synthesized by solid-state method. The water washing process of the as-prepared samples was several times conducted because of severe hydration of unreacted CaO and CaF2 flux residual. The washed CaSc2O4:Ce3+ phosphors showed a single phase with a crystallite size of 1–3 μm, and its photoluminescence intensity was 10% improved compared with the as-prepared. It shows the broad 450 nm excitation peak and the green emission peak at 520 nm with a half width of 105 nm. Its temperature dependence showed the similar thermal stability with a commercial silicate phosphor. The optical simulation and the real fabrication of white LEDs with a combination of our green phosphor and one of possible orange-red phosphors demonstrated that the white LED with Sr3SiO5:Eu2+ orange phosphor gives the best luminous efficacy and the appropriate color rendering index of 70 under the daylight color temperature of 6400 K.

Highly efficient and thermally stable Cr3+-activated silicate phosphors for broadband near-infrared LED applications

A novel broadband near-infrared (NIR) phosphor LiInSi2O6:Cr3+ (LIS:Cr3+) is successfully synthesized via solid-state reaction. Its crystal structure, photoluminescence properties as well as the application in NIR phosphor-converted LEDs (pc-LEDs) are explored. The LIS:Cr3+ phosphor has two absorptions bands centered at ~460 and 670 nm, respectively. Under 460 nm excitation, it shows the broadband NIR emission peaking at ~840 nm with a full width at half maximum (FWHM) of ~143 nm. The optimum Cr3+ concentration is found to be ~6 mol%, whereas the intensity decrease at further increased Cr3+ content is attributed to the radiative energy transfer process. The LIS:0.06Cr3+ phosphor has a quantum yield of ~75% and can retain ~77% of the initial intensity at 150 °C. Highly efficient, thermally stable and broad NIR emissions of LIS:Cr3+ phosphors are caused by the Cr3+ preferential occupancy in [InO6] octahedron with weak crystal field but relatively strong rigidity. The NIR pc-LED is fabricated by combining the LIS:Cr3+ phosphor with the blue LED chip, which has the NIR output power of ~51.6 mW and the photoelectric efficiency of ~17.8% at 100 mA drive current. The results suggest that LIS:Cr3+ phosphors have great potential for applications in broadband NIR pc-LEDs.

Structural and Photoluminescent Studies of Eu3+-Doped Sr2SiO4 Phosphor

Here, we report the synthesis of Sr2−xEuxSiO4 (Sr2SiO4:Eu3+) [x = 0.01, 0.015, 0.02, 0.025, 0.03] silicate phosphors via high-temperature solid-state reaction method. The prepared phosphors were X-ray diffraction (XRD) characterized, and the analysis of XRD data conveyed that all the samples are crystalline, single-phased and have crystallized to orthorhombic structure (Pmnb). The structure, space group (Pmnb) and other structure concerned parameters were further verified using Rietveld refinement for x = 0.01 phosphor. The XRD pattern for all the synthesized phosphors was identical in appearance, and there is no evidence of the new peak with increased doping of Eu3+ ion. This behavior may be attributed to the uniform distribution of rare earth Eu3+ ion at Sr2+ site due to comparative ionic size of the host and guest ion. The formation of Sr2SiO4:Eu3+ phosphors is verified further by FTIR spectroscopic technique. To investigate optical band gap of prepared phosphors, UV–Vis diffuse reflectance spectroscopic studies have been carried out. Photoluminescence property of Sr2SiO4:Eu3+ phosphors was studied. The emission spectrum displayed characteristic emission peaks corresponding to Eu3+ around 587, 612 and 702 nm. The Commission International de I’Eclairage color coordinates were found lying in orange-red region.

Novel cyan‐emitting KBaScSi2O7:Eu2+ phosphors with ultrahigh quantum efficiency and excellent thermal stability for WLEDs

AbstractOwing to the conventional phosphor‐converted white LEDs (pc‐WLEDs) generally suffer from blue‐green cavity, thus, developing an appropriate phosphors covering both the blue and green regions in their emission spectra are very urgent. Herein, a novel Sc silicate phosphor, KBaScSi2O7:Eu2+ (KBSS:Eu2+), has been successfully designed and prepared via a solid‐state reaction. The crystal structure, luminescent properties, thermal quenching, quantum efficiency as well as its application in UV‐pumped WLEDs have been investigated systematically. The KBSS:Eu2+ phosphor exhibits a strong and broad excitation band ranging from 290 to 450 nm, and gives a sufficient cyan emission of 488 nm with a full‐width half‐maximum (FWHM) of 70 nm, which filled the blue‐green cavity. Importantly, the optimized KBSS:Eu2+ phosphor possesses an ultrahigh quantum efficiency (QE) up to 91.3% and an excellent thermal stability retaining 90% at 423 K with respect to that measured at room temperature. Finally, the as‐fabricated UV‐based WLEDs device, with only coupled the mixture of KBSS:Eu2+ cyan phosphor and CaAlSiN3:Eu2+ red ones to a commercial 365nm UV chip, exhibits a satisfactory color‐rendering index (Ra = 88.6), correlated color temperature (CCT = 3770K), and luminous efficiency (LE = 21 lm/W).

Synthesis and Optical Properties of BaSiO3:RE3+ (RE = Sm, Eu) Phosphors

BaSiO3:RE3+ (RE = Sm or Eu) phosphor powders with different concentrations of activator ions are synthesized using the solid-state reaction method. The effects of the concentration of activator ions on the structural, photoluminescent, and morphological properties of the barium silicate phosphors are investigated. X-ray diffraction data reveals that the crystal structure of all the phosphors, regardless of the type and the concentration of the activator ions, is an orthorhombic system with a main (111) diffraction peak. The grain particles agglomerate together to form larger clusters with increasing concentrations of activator ions. The emission spectra of the Sm3+-doped BaSiO3 phosphors under excitation at 406 nm consist of an intense orange band at 604 nm and three weak bands centered at 567, 651, and 711 nm, respectively. As the concentration of Sm3+ increases from 1 to 5 mol%, the intensities of all the emission bands gradually increase, reach maxima at 5 mol% of Sm3+ ions, and then decrease significantly with further increases in the Sm3+ concentration due to the concentration quenching phenomenon. For the Eu3+-doped BaSiO3 phosphors, a strong red emission band at 621 nm and several weak bands are observed. The optimal orange and red light emissions of the BaSiO3 phosphors are obtained when the concentrations of Sm3+ and Eu3+ ions are 5 mol% and 15 mol%, respectively.

Optical and photoluminensce properties of Eu2+-activated strontium magnesium silicate phosphors using different rare earth co-activators

Nanostructured powders of Sr1.96MgSi2O7:Eu 0.01 2+ , R 0.01 3+ (R3+ = Er3+, Tm3+ and Tb3+) have been fabricated via urea combustion technique. XRD results implied that tetragonal Sr2MgSi2O7 was the major phase whereas monoclinic Sr2SiO4 and SrSiO3 were the minor phases. Meanwhile, field emission SEM textures showed the hollow spherical network-like shape structures filled with fused interconnections for the Sr1.96MgSi2O7:Eu 0.01 2+ sample. It has been recognized that the replacement of Sr2+ with co-dopant R3+ ions e.g. Er3+, Tm3+ and Tb3+ considerably help obtaining homogeneous structure as well. The values of band gap energy and calculated refractive index were ultimately dependant on the ionic radius of R3+ co-doping ion. It has been suggested that the divalent activator ion (Eu2+) was responsible for the number of PL emission spectra, while the trivalent co-activator ions (R3+) were the key reasons for variations in the broadening and intensity of PL emission spectra.

Polyhedron Transformation toward Stable Narrow‐Band Green Phosphors for Wide‐Color‐Gamut Liquid Crystal Display

AbstractA robust and stable narrow‐band green emitter is recognized as a key enabler for wide‐color‐gamut liquid crystal display (LCD) backlights. Herein, an emerging rare earth silicate phosphor, RbNa(Li3SiO4)2:Eu2+ (RN:Eu2+) with exceptional optical properties and excellent thermal stability, is reported. The resulting RN:Eu2+ phosphor presents a narrow green emission band centered at 523 nm with a full width at half maximum of 41 nm and excellent thermal stability (102%@425 K of the integrated emission intensity at 300 K). RN:Eu2+ also shows a high quantum efficiency, an improved chemical stability, and a reduced Stokes shift owing to the modified local environment, in which [NaO8] cubes replace [LiO4] squares in RbLi(Li3SiO4)2:Eu2+ via polyhedron transformation. White light‐emitting diode (wLED) devices with a wide color gamut (113% National Television System Committee (NTSC)) and high luminous efficacy (111.08 lm W−1) are obtained by combining RN:Eu2+ as the green emitter, K2SiF6:Mn4+ as the red emitter, and blue‐emitting InGaN chips. Using these wLEDs as backlights, a prototype 20.5 in. LCD screen is fabricated, demonstrating the bright future of stable RN:Eu2+ for wide‐color‐gamut LCD backlight application.

Development of Eu2+ and Mn2+ co-activated silicate phosphor for plant cultivation light source

Various light sources for plant production have been developed to establish a completely controlled factory. We propose a pulse light source using Xe discharge. For the rapid growth of the plant, an intense light covering the absorption spectral region of chlorophyll is demanded, and periodic irradiation is also required because the photosynthetic reaction has a certain period. In this study, Sr3MgSi2O8:Eu,Mn phosphor powders with various Eu and Mn content, which show two emission peaks in the absorption region of photosynthetic pigment and phytochrome, were synthesized, and were analyzed using X-ray diffraction, photoluminescence and electron spin resonance spectroscopy. It was found that the exchange-coupled Mn-Mn and Eu-Mn pairs lead the rapid decay of Mn emission and efficient energy transfer from Eu and Mn ions, respectively. A plasma tube array panel using the phosphor was also fabricated and the similar emission spectrum of Sr3MgSi2O8:Eu,Mn is obtained under vacuum-UV excitation in comparison to the UV excitation.

Detection of Cell Viability via Fluorescence Labeling of Silicate Phosphor with a Low-Temperature Superlong Persistent Luminescence

Cell viability detection is usually accompanied by large errors and toxicity. For the accuracy and safety of detection, it is urgent to develop a practical approach to realize the real-time monitoring of cell viability. Here, a low-temperature persistent phosphor was employed to facilitate the detection of cell viability. Stable low-temperature persistent luminescence originating from Ba4Si6O16:Eu2+, Pr3+ (BSEP) was developed, which could be quantified to describe the viability of baby Syrian hamster kidney (BHK-21) cells. The defect state structure guarantees the excellent persistent luminescence at 193 K of more than 200 h of the as-prepared BSEP phosphor, which ensures the long-term biological application. The structural thermal stability and water tolerance of BSEP suggest the feasibility of the practical application. Our results provide the underlying insights of the low-temperature persistent phosphors for real-time biological detection.

Effect of Eu doping on room temperature phase and phase transition of Sr2SiO4:Eu2+ phosphor synthesized by polymerized complex method

Eu2+ activated silicate phosphor, Sr2SiO4:Eu2+ were synthesized by polymerized complex method to investigate the effect of Eu doping on room temperature phases. Firstly, synthesis condition for β phase was optimized and found that β-Sr2SiO4:Eu2+ phosphors can be obtained at reduction temperature of 1150 °C using HCl, which provide SrCl2 flux during synthesis process. The characterization for various Eu concentration of Sr2SiO4:Eu2+ phosphors show that pure β-Sr2SiO4:Eu2+ phosphors were obtained at 1%, 3% and the samples which are almost in β phase can be achieved until 5%. Temperature dependence of crystal structure and PL properties of Sr2SiO4:Eu2+ (3%) phosphors were also characterized to investigate the phase transition and thermal hysteresis between β and α′ phase. Phase transition between β ↔ α′ phase was observed from XRD around 60 °C–100 °C and change in PL spectra owing to phase transition was observed around same temperature range. The further analysis show that the thermal hysteresis between β → α′ and α’→ β directions of Sr2SiO4:Eu2+ (3%) phosphors were about 40 K, which was much larger than the reported thermal hysteresis of undoped Sr2SiO4.

Structural and optical properties of Dy3+ doped Sr2SiO4 phosphors

Abstract Dysprosium doped strontium silicate phosphor namely (Sr2SiO4:Dy3+) was prepared by low-temperature solution combustion method using urea (CO(NH2)2) as a fuel. The material was characterized by powder X-ray diffraction (XRD), FT-IR, SEM and EDX. The average crystallite sizes was calculated by Scherer formula. Thermoluminescence study was carried out for the phosphor which showed single glow curve. The kinetic parameter were calculated by using Chen’s glow curve method. Photoluminescence spectra revealed strong transition at 473 nm (blue), 571 nm (yellow) and weak transition at 645 nm (red). These peaks were assigned to transition 4F9/2 →6H15/2, 13/2, 11/2. CIE graph of Sr2SiO4:Dy3+ phosphor is suitable for the generation of white light emission.