Emission Of Sm3 Research Articles

Tailoring high purity orange-red emission in Sm3+ activated SrTi(PO4)2 phosphor for lighting and display devices

An anhydrous double monophosphate, SrTi(PO4)2, was utilized as a host for RE-incorporated phosphor material for the first time. A series of orange-red emitting, Sm3+ doped SrTi(PO4)2 are synthesized by employing high-temperature solid-state reaction method. The structural, optical, luminescent and spectroscopic characteristics are extensively studied using XRD, FTIR, FE-SEM, DRS, PL spectroscopy and JO theory. The sample crystallizes in a monoclinic system with space group C2/m, having a loosely packed bubbly structure in the sub-micrometre range. PL emission spectra reveal the highly pure orange-red emission which can be effectively excited by n-UV radiation. The optimum Sm3+ ion concentration is 0.05 mol and the Dexter theory explains the luminous intensity quenching at higher concentrations as the energy transfer via dipole-dipole interaction. The longer radiative lifetime in the 2 ms range and the excellent color purity make the prepared Sm3+ doped SrTi(PO4)2 an orange-red emitting phosphor for lighting, sensing and display devices.

Investigations on photoluminescence and energy transfer studies of Sm3+ and Eu3+ ions doped Sr9Y2W4O24 red emitting phosphors with high color purity for w-LEDs

Sm3+/Eu3+ co-doped Sr9Y2W4O24 phosphors were prepared using the solid-state reaction process. The structure and micro-morphological analysis of the as-prepared phosphors were explored via x-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. Optical & spectroscopic characteristics were investigated by the mean of diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) techniques. The Sr9Y2W4O24 phosphor is tetragonal in structure and belongs to the I41/a space group. The excitation spectra recorded demonstrates that near-ultraviolet and blue LED chips can effectively excite the titled Sm3+-Eu3+ co-doped phosphors. The emission intensity pertaining to Eu3+ ions increases at the expense of decrease in intensity of Sm3+ ions with increase in the concentration of Eu3+ ion in titled Sm-Eu co-doped Sr9Y2W4O24 phosphors. The Reisfeld's approximation applied to the emission spectra of the titled Sm3+-Eu3+ co-doped Sr9Y2W4O24 phosphor reveal quadrupole-quadrupole as the mechanism responsible for energy transfer (ET) from Sm3+ to Eu3+ ions. The PL decay lifetimes values recorded for 603 nm emission of Sm3+ ions under 407 nm excitation wavelength were found to be decreasing with increase in Eu3+ ions concentration. This clearly reveal the ET from Sm3+ to Eu3+ ions in the titled phosphors. With increase in Eu3+ ion concentration the calculated CIE parameters are gradually shifting towards the deep red region of the visible spectrum under UV excitation. The temperature dependent PL (TD-PL) spectra demonstrate that the Sr9Y2W4O24: Sm3+/Eu3+ phosphor has relatively better thermally stablity with its thermal activation energy at around 0.256 eV. The results obtained in the present investigation allows us to explore the utility of Sm3+/Eu3+ co-doped Sr9Y2W4O24 phosphors as an effective deep red emitter needed to fabricate white LEDs.

High-efficiency energy transfer in the strong orange-red-emitting phosphor CeO2:Sm3+, Eu3.

High-efficiency energy transfer (ET) from Sm3+ to Eu3+ leads to dominant red emission in Sm3+, Eu3+ co-doped single-phase cubic CeO2 phosphors. In this work, a series of Sm3+ singly and Sm3+/Eu3+ co-doped CeO2 cubic phosphors was successfully synthesized by solution combustion followed by heat treatment at 800 °C in air. The crystal structure, morphology, chemical element composition, and luminescence properties of the obtained phosphors were investigated using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and photoluminescence analysis. Under 360 nm excitation, the Sm3+ singly doped CeO2 phosphor emitted strong yellow-red light at 573 nm (4G5/2-6H5/2) and 615 nm (4G5/2-6H7/2). Meanwhile, the CeO2:Sm3+, Eu3+ phosphors showed the emission characteristic of both Sm3+ and Eu3+, with the highest emission intensity at 631 nm. The emission intensity of Sm3+ decreased with increasing Eu3+ content, suggesting the ET from Sm3+ to Eu3+ in the CeO2:Sm3+, Eu3+ phosphors. The decay kinetics of the 4G5/2-6H5/2 transition of Sm3+ in the CeO2:Sm3+, Eu3+ phosphors were investigated, confirming the high-efficiency ET from Sm3+ to Eu3+ (reached 84%). The critical distance of energy transfer (RC = 13.7 Å) and the Dexter theory analysis confirmed the ET mechanism corresponding to the quadrupole-quadrupole interaction. These results indicate that the high-efficiency ET from Sm3+ to Eu3+ in CeO2:Sm3+, Eu3+ phosphors is an excellent strategy to improve the emission efficiency of Eu3+.

Effect of Zn2+ co-doping on the luminescence of Sm3+ doped SrMoO4 phosphor

In this paper, we report the result of Zn2+ co-doping on the photoluminescence and structural properties of Sm3+ doped SrMoO4 phosphors which are synthesized by a lucrative auto combustion method. The structural study ascertains the improvement in crystallinity of the Sm3+ doped SrMoO4 phosphor by Zn2+ co-doping. Photoluminescence excitation analysis evinces that the intensity of 404 nm peak (6H5/2 → 4F7/2) is enhanced by 93.5% after 1% Zn2+ co-doping in the 4% Sm3+ doped SrMoO4 phosphor. Emission study manifests that the intensity of Sm3+ doped SrMoO4 phosphors increases up to 4% doping concentration of Sm3+ ion, and its peaks located at 562 nm, 597 nm, 645 nm, and 705 nm are ascribed to 4G5/2 to 6HJ/2 (J = 5, 7, 9, and 11) electronic transitions of Sm3+ ions, respectively. The overall emission of Sm3+ doped SrMoO4 phosphors lies in the reddish-orange region. The emission intensity of 4% Sm3+ doped SrMoO4 is further increased by 87.80% after 1% Zn2+ co-doping. The lifetime of the 4G5/2 level of the Sm3+ ions has also increased on doping 1% Zn2+ ions. The temperature-dependent emission spectra reveal good thermal stability of the phosphor with 0.17eV activation energy. The prepared Zn2+ co-doped SrMoO4:4Sm3+ phosphor has near-UV excitation and reddish-orange emission and thus can be used as a potential red phosphor in lighting devices.

High-reliability all-fiber FIR temperature sensor using LiGd(WO4)2:Er3+/Yb3+ phosphors

Rare earth doped LiGd(WO4)2 phosphors have been prepared by solid sintering technology. The dominant 4G5/2→6H9/2 emission of Sm3+ ions suggests that Sm3+ ions occupy the non-centrosymmetric lattices in LGWO:Sm3+ phosphors. Under the excitation at 980 nm laser, bright green upconversion emissions at 531 nm and 553 nm were detected in LGWO:Er3+/Yb3+ phosphor, which was used to build a high-reliability temperature sensor based on fluorescence intensity ratio (FIR) technology. The calibration curve between FIR and temperature was established at the temperature range of 258–423 K. The highest absolute sensitivity was 0.0137 K−1 at 423 K and the standard deviation of multiple temperature measurements at 313 K was only 0.108%. Experimental data show that this material can be used for the all-fiber temperature sensors.

Role of chemical substitution in the photoluminescence properties of cerium samarium tungstates Ce(2-x)Smx (WO4)3 (0≤x≤0.3)

In the general framework of the development of materials with tunable photoluminescence, a series of cerium samarium tungstates Ce(2-x)Smx(WO4)3 with x≤0.3 was synthesized by a coprecipitation method followed by thermal treatment at 1000 °C. The polycrystalline compounds were characterized by X-ray diffraction, scanning electron microscopy and photoluminescence experiments. In the present work, the objective would be to determine the role of PL emitting centers in the variations of PL intensities. Firstly, Rietveld analysis showed a decrease of cell parameters and confirmed that a solid solution was obtained. Diffraction profile analyses showed that structural distortions increasing with composition x were observed: they were ascribed to difference in cation sizes of Ce3+ and Sm3+, and to defects generated during crystal growth. The photoluminescence (PL) spectra were obtained under X-Ray (45 kV-35 mA) and UV (364.5 nm) excitations. Two PL emissions of Ce3+ were observed only under UV excitation. Four PL emissions of Sm3+ were observed under UV and X-ray excitations, and their intensities decreased with increasing composition x. Two additional transitions were observed under UV and X-ray excitations: they were attributed to oxygen vacancy defects. In the range 800 to 1000 nm, an increasing IR emission is observed: it was ascribed to emissions due to other oxygen vacancies. The main results are reported in Table 1. The chromaticity diagram (see Figure 1) showed that the colors associated with PL responses vary with Sm composition and excitation energies. This offers the opportunity to develop materials with tunable PL. To better understand this complex behavior, now, we plan to study the solid solution in the composition range x>0.3.

Luminescent properties of Sm3+ doped metal fluoro phosphate glasses

Trivalent Samarium doped multi-component Cadmium Lead Sodium Fluoro-Phosphate glass was prepared and characterized through optical absorption, emission and excitation measurements. With the support of Judd-Ofelt theory, the intensity parameters and other radiative parameters were determined using optical absorption spectra from visible region to NIR region and reasonable less deviation obtained between the experimental and calculated oscillator strengths. The emission and excitation spectra of Sm3+ have been recorded under the excitation wavelength λex =399 nm and the emission wavelength λem =596 nm. The emission of Sm3+ in this phosphate host is assigned to the transition from 4G5/2 to 6H5/2, 6H7/2, 6H9/2 and 6H11/2 levels and relative parameters like branching ratio, emission cross section were calculated. In addition to that 1 mol% of MgO also added to the host and compared with the obtained results. GSm5 glass emits high intense red emission for 4G5/2 → 6H7/2 transition suggests the suitability of these glasses for red light emission or laser applications in visible region.

Near-ultraviolet light induced red emission in Sm3+-activated NaSrLa(MoO4)O3 phosphors for solid-state illumination

The Sm3+-activated NaSrLa(MoO4)O3 phosphors were synthesized by the solid-state reaction technique. Upon 403 nm excitation, bright reddish-orange emissions arising from the 4G5/2 → (6H5/2, 6H7/2, 6H9/2 and 6H11/2) transitions were gained in these resultant compounds. The optimal luminescence intensity was obtained at the dopant concentration of 4 mol% and the dipole-dipole interaction mechanism was contributed to the concentration quenching process in the NaSrLa(MoO4)O3:Sm3+ phosphors. The temperature dependent luminescent properties were discussed in detail and the crossover process was responsible for the involved thermal quenching behavior. At a forward bias current of 100 mA, the fabricated LED lamp emitted reddish-orange light with the color coordinate of (0.602, 0.316). These properties demonstrated that the Sm3+-activated NaSrLa(MoO4)O3 phosphors were promising red-emitting materials for solid-state illumination.

Synthesis and multicolor luminescence of Tb3+ and Sm3+ co-doped LiGd(MoO4)2 phosphor

Herein, Tb3+ and Sm3+ single doped and co-doped LiGd(MoO4)2 phosphors were prepared via a sol–gel method. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) fluorescence spectroscopy were utilized to investigate the structure, morphology and luminescent properties of the samples, respectively. XRD and FESEM analyses show that the samples are tetragonal phase crystals with an average size of 3 μm. In the photoluminescence excitation spectra, the MoO42− group plays a dominant role in absorbing near ultraviolet light and transferring energy to Tb3+ and Sm3+. Under the excitation of 287 nm ultraviolet light, both the green emission of Tb3+ and the orange–red emission of Sm3+ could be observed from the emission spectra of LiGd(MoO4)2: 0.01 Tb3+, xSm3+ phosphors. Accordingly, LiGd(MoO4)2: 0.01 Tb3+, 0.01Sm3+ phosphor shows an emission color that can be modulated from yellow to red, and then to yellow–green light when excited by 287, 365, 377, 405, 417, 465, 483, and 488 nm, respectively. As a result, the tunable emission color of the phosphors can be provided by changing the doping concentration of Sm3+ and the excitation wavelength.

Crystal chemistry and optical analysis of a novel perovskite type SrLa2Al2O7:Sm3+ nanophosphor for white LEDs

Abstract Perovskite orange-red SrLa2(1-x)Al2O7:2xSm3+ (x = 0.01–0.07) nanocrystalline phosphor series were successfully synthesized by means of solution combustion route for the first time. X-ray diffraction (XRD) measurements were performed to analyze the structural framework and it was concluded that the resulted nanophosphors were well-crystallized in tetragonal lattice with the space group I4/mmm (139). The lattice constants and refinement factors for SrLa2Al2O7 and SrLa1.92Sm0.08Al2O7 compositions were obtained by performing Rietveld refinement technique. From transmission electron micrographs, the spherical or semi-spherical nature of highly agglomerated particles (20–30 nm range) was noticed. Further, the diffuse reflectance (DR) studies yielded the band-gaps for SrLa2Al2O7 (5.03 eV) and SrLa1.92Sm0.08Al2O7 (4.88 eV) powder samples. The photoluminescence investigation of nanophosphors revealed the strong orange-red luminescence at 600 nm (most prominent) attributed to 4G5/2 → 6H7/2 emission of Sm3+ ions under near-ultraviolet (NUV) excitation (λex = 407 nm). The optimum composition of Sm3+ in SrLa2Al2O7 lattice was found to be 4 mol%. However, the double exponential decay behaviour confirmed the simultaneous occupancy of two crystallographic sites by activator ions in the host matrix. In addition, the critical distance for non-radiative energy migration amid adjacent activator centres was calculated to be 15.07 A, using Blasse's relation. A detailed analysis of non-radiative relaxation rates (131.9531 s−1), radiative life time (1.79 ms) and quantum efficiencies (81%) was carried out using Auzel's modal. Finally, the results highlight the importance of SrLa2Al2O7:Sm3+ orange-red nanophosphors in white LEDs under NUV excitation.

Investigation of spectroscopic properties of Sm3+-doped oxyfluorophosphate glasses for laser and display applications

In this manuscript, samarium (Sm3+)-doped titania-oxyfluorophosphate (PCfBfTiS) glasses have been fabricated using regular melt-quenching procedure. These glass samples were investigated through optical absorption, photoluminescence excitation, emission and decay characterization techniques. An intense emission was professed at the wavelength of 598 nm owing to the 4G5/2 → 6H7/2 transition of Sm3+ ions under 401 nm excitation. In addition, the reddish-orange emission was also perceived at around 645 nm. Stimulated emission cross-section of 2.0 mol% Sm3+-doped PCfBfTiS20 glass was found to be 0.47 × 10−22 cm2, which was described to be efficient among other reported glasses. Photoluminescence (PL) decay profiles were demonstrated that the lifetime was increased up to 0.5 mol% Sm3+-doped PCfBfTiS05 glass then it was decreased for high Sm3+ ions concentration. Moreover, CIE color coordinates proven that the emission of Sm3+ ions was appeared in the reddish - orange region.

Electronic structure, photoluminescence and phosphorescence properties in Sr2ScGaO5:Sm3+

Novel reddish long lasting phosphorescence material Sr2ScGaO5:Sm3+ was designed and prepared by a solid state reaction. The results of morphology showed that the irregular microparticles were formed by the agglomeration of uniform submicron particles with the size of about 0.5–1 μm. The electronic structure with an indirect bandgap was evaluated in detail by the density functional theory calculations and the diffuse reflectance spectrum for the first time. By the two different methods, the bandgap energy of Sr2ScGaO5 was determined to be about 4.24 and 4.75 eV, respectively. The emission of Sm3+ ion at 604 nm is strongest in the photoluminescence process, while in the phosphorescence process the emission at 619 nm is dominant. According to the analysis on the optical properties, the interesting phenomenon about the difference between the photoluminescence and phosphorescence was revealed and explained by the fact that the conduction band played an important role in the phosphorescence process. Additionally, the result showed that the material can be stimulated effectively in very short time and would have great potential in the applications such as AC-light emitting diodes.

A novel orange-red emitting phosphor Sr3Lu(PO4)3:Sm3+ for near UV-pumped white light-emitting diodes

A series of Sr3Lu1 − x (PO4)3:xSm3+phosphors were synthesized via a conventional solid-state reaction method. The prepared phosphors were investigated using X-ray diffraction and Scanning electron microscopy. The excitation and emission spectra, concentration quenching mechanism, and fluorescence decays of the phosphors were also measured and discussed. Under 403 nm excitation, the 4G5/2 → 6HJ (J = 5/2, 7/2, 9/2, and 11/2) emissions of Sm3+ were obviously observed with peaks located at 564, 599, 646 and 705 nm, respectively. The optimum dopant concentration of Sm3+ ions in Sr3Lu(PO4)3 is 3 mol% and the corresponding Commission Internationale deL’Eclairage chromaticity coordinate of the Sr3Lu0.97(PO4)3:0.03Sm3+ phosphor was located in the orange reddish region. In addition, the temperature dependent luminescence and the absolute quantum efficiency of the typical sample was also investigated. The results confirmed that the as-synthesized Sr3Lu(PO4)3:Sm3+ phosphors can act as a suitable candidate of the warm components of near-ultraviolet white light-emitting diodes.

Synthesis, Luminescence Properties and Energy Transfer of CaZrO3:Sm3+, Bi3+ Phosphor

Novel CaZrO3:Sm3+, Bi3+ phosphor is synthesized by a solid-state reaction method in air and the crystal structures and luminescence properties are investigated. The emission spectrum with excitation 308 nm contains emission of Sm3+ and Bi3+ ions at the same time; however, it only has an emission of Sm3+ ion with excitation 408 nm. Emission intensity of CaZrO3:Sm3+ phosphor can be enhanced about four times owing to energy transfer from the Bi3+ ion to the Sm3+ ion and with the fluxing agent role of Bi3+ ion when Bi3+ ion is co-doped. The possible luminous mechanism is analyzed by energy level diagrams of Bi3+ and Sm3+ ions and the energy transfer process in CaZrO3:Sm3+, Bi3+ phosphor. The experimental results indicate that, hopefully, CaZrO3:Sm3+, Bi3+ phosphor can be used as a reddish orange phosphor candidate for white light-emitting diodes based on near an ultraviolet (~408 nm) chip.

Spontaneous and stimulated emission in Sm3+-doped YAl3(BO3)4 single crystal

Single crystals of YAl3(BO3)4 doped with trivalent samarium were grown by the top-seeded high temperature solution method and their absorption and emission spectra were investigated. Optical pumping into prominent absorption band around 405nm feeds the 4G5/2 metastable level giving rise to intense visible luminescence distributed in several spectral lines with the most intense line around 600nm characterized by a branching ratio of 0.42 and peak emission cross section of 0.25×10−20cm2. Optical amplification at 600nm with a gain coefficient of 2.9cm−1 was achieved during a pump-and-probe experiment.

Preparation and luminescence properties of orange–red Ba3Y(PO4)3:Sm3+ phosphors

Ba3Y(PO4)3:Sm3+ phosphors were prepared by a high temperature solid-state reaction in air. X-ray diffraction (XRD), photoluminescence spectra and temperature-dependent emission spectra were utilized to characterize the structure and luminescence properties of the as-prepared phosphor. The results show that the phosphor can be efficiently excited by ultraviolet light and emit a satisfactory orange–red performance, nicely, fitting in well with the widely used UV LED chip. Under 403nm excitation, the 4G5/2→6HJ (J=5/2, 7/2, 9/2, and 11/2) emissions of Sm3+ are obviously observed. The optimum doping concentration is 5mol% and corresponding quenching behavior is ascribed to be electric dipole–dipole interaction according to Dexter’s theory. The temperature dependent luminescence of Ba3Y(PO4)3:Sm3+ phosphor is also discussed, and the activation energy for thermal quenching is calculated as 0.34eV. Furthermore, the chromaticity coordinates of Ba3Y(PO4)3:Sm3+ phosphor are calculated to be (0.5558, 0.4380) and the lifetime values of Ba3Y0.995(PO4)3:0.005Sm3+ was 2.45ms.

Judd–Ofelt analysis of Sm3+-doped lanthanum-aluminosilicate glasses

In this paper we report on the Judd–Ofelt analysis of Sm3+-doped lanthanum aluminosilicate glasses. The Judd–Ofelt calculations were done using two different least-squares fitting procedures (absolute and normalized) and two different cavity models (virtual and empty cavity model). It is shown that the absolute least-squares fitting procedure for the reported glasses yields physically more reliable results for the radiative lifetimes and branching ratios of the 4G(4)5/2 emission of Sm3+ than the normalized fitting method. The Ω2 parameters decrease with increasing lanthanum concentration of the glasses indicating an effect of the glass structure (network connectivity) on hypersensitive transitions in Sm3+. For the Ω4 and Ω6 parameters a clear correlation to the glass composition was not found.

Crystal Growth and Photoluminescence Properties of Sm<SUP>3+</SUP> Doped CeO<SUB>2</SUB> Nanophosphors by Solvothermal Method

The phosphor of CeO2 activated with the trivalent rare-earth Sm3+ ions were synthesized by using a solvothermal method. The CeO2:Sm3+ powders were finally obtained through calcination process sintered in the air at 800-1200 degrees C. The synthesized phosphors were characterized systematically by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), photoluminescence (PL) and photoluminescence excitation spectra (PLE). The XRD and FE-SEM results reveal that the phosphor exhibit agglomerated spherical shape and with the increase of sintering temperature peaks become sharper and narrower and the crystal sizes also increase, respectively. The room temperature photoluminescence spectra of Sm3+ doped CeO2 powders were recorded on a PTI (Photon Technology International) flurimeter using a Xe-arc lamp with a power of 60 W. The emitted radiation was dominated by the orange light with the characteristic emission of Sm3+ from the transitions of 4G5/2 --> 6H5/2,7/2. The sharp emission properties show that the CeO2 has the potential to serve as a host material for rare-earth doped laser crystal and phosphor material.

Luminescent properties and energy transfer mechanism of CaWO4：Sm3+ phosphors

The scheelite-structured CaWO4 phosphors doped with different concentrations of Sm3+ were prepared by precipitation method. Photoluminescence properties of Sm3+-doped CaWO4 samples were studied. Results indicate that red light emission of Sm3+ with higher color purity in the samples can be excited by 404 nm blue light. There are 4f-4f intrinsic emission of Sm3+ and a strong self-excitation emission of CaWO4 when excited by 240 nm short-wave ultraviolet, and the white light emission can be obtained. Experiments show that the best Sm3+ doping concentration is 2%. The energy transfer type between Sm3+ ions was determined to be the electric dipole-electric dipole interaction and the critical energy transfer distance (Dc) was calculated to be 2.0 nm.

Absolute Luminous Flux and Quantum Yield of Sm<sup>3+</sup>-Doped Cadmium-Aluminum-Silicate Glasses under the Pumping of Blue Light Emitting Diode

Absolute luminous flux and quantum yield for multichannel transition emissions have been determined in samarium ion (Sm3+)-doped cadmium-aluminum-silicate (CAS) glasses under the pumping of blue light emitting diode (LED) using an integrating sphere of 30 cm diameter, which connected to a CCD detector with a 400 μm-core optical fiber. The radiant flux and luminous flux for the visible transition emissions (550–750 nm) of Sm3+under the blue LED excitation were solved to be 123 μW and 32 mlm, respectively, which occupied 1.51% and 7.16% of the whole. The total quantum yield of the visible fluorescence of Sm3+has been calculated to be 2.52%. Investigation on optical radiation parameters for multichannel visible transition emissions of Sm3+in CAS glasses provides a reference in developing luminescence and display materials.