Luminescence Properties Of Sm3 Research Articles

Structural and photoluminescence properties of SrNb2O6: RE3+ (RE = Sm, Tb) phosphors for solid state lighting

The phosphors for pc-LEDs have high thermal stability requirements due to the high operating temperature of LEDs. In addition, there are many phosphors based on SrNb2O6, but no one has studied Sm3+ or Tb3+ as the luminescent center of SrNb2O6 host. Therefore, two new phosphors based on SrNb2O6 host are proposed in this work. One is an orange phosphor with negative thermal quenching phenomenon using Sm3+ as the luminescent center, and the other is a green phosphor with Tb3+ as the luminescent center. In this work, a series of SrNb2O6:Sm3+ and SrNb2O6:Tb3+ phosphors were prepared by the solid-state reaction method. The structure, morphology, chemical composition, absorption properties and luminescence properties of Sm3+ and Tb3+ doped SrNb2O6 samples were studied. Under 405 nm excitation, the SrNb2O6:Sm3+ samples exhibit the 4f-4f transition of Sm3+ with the strongest emission intensity at 607 nm, the emission intensity of SrNb2O6:0.03Sm3+ phosphor at 150 °C remains at 100.56% of its room temperature value and the chromaticity coordinates are located in the orange region, with a color purity of 88.19%. Under 307 nm excitation, the SrNb2O6:Tb3+ samples exhibit the 4f-4f transition of Tb3+ with the strongest emission intensity at 544 nm, the emission intensity of SrNb2O6:0.09Tb3+ phosphor at 150 °C remains at 7.68% of its room temperature value and the chromaticity coordinates are located in the green region with a color purity of 74.29%. Additionally, Na+ is introduced as a charge compensator in the Sm3+ or Tb3+ doped phosphors, which enhances their luminescence intensity. These results indicate that the two phosphors synthesized in this work have the prospect of application in the field of solid-state lighting.

Influence of barium substitution on the physical, thermal, optical and luminescence properties of Sm3+-doped metaphosphate glasses for reddish orange light applications.

Our present study focuses on examining the thermal, structural and luminescent characteristics of sodium barium metaphosphate glasses doped with Sm3+. Glass samples with molar compositions (100 - y)[(50P2O5)-(50-xNa2O)-(xBaO)]-ySm2O3, where x = 20, 25, 30, 35, 40 and y = 0.3 and 1% were first synthesized by conventional melt quenching and later dehydroxylated under a constant N2 flow to ensure final glasses with a very high degree of chemical and optical homogeneity and free of water. Upon the addition of BaO and Sm2O3, refractive index, molar mass, density, glass transition temperature and dilatometric softening temperature exhibited an increase, whereas the coefficient of thermal expansion showed a decrease. The FTIR spectra analysis reveals a network depolymerization that intensifies with rising BaO concentration, ultimately transitioning from a modifier oxide to a glass-forming element, at higher BaO concentrations. All doped samples exhibited prominent absorption bands in the visible (VIS) and near-infrared (NIR) regions, as revealed by the optical absorption spectra. The Na2O modifier demonstrated greater influence on Sm3+ emission compared to BaO, a phenomenon that can explained by the moderation of the local ligand field strength resulting from this substitution. With an increase in Sm2O3 concentration from 0.3 to 1 mol%, the experimental lifetimes of the 4G5/2 level decrease, primarily attributed to the presence of energy transfer mechanisms. A discussion of Judd-Ofelt parameter analysis and glass radiation properties will be presented.

Energy transfer and tunable-color luminescence properties of a single-phase CaSrNb2O7:Sm3+, Bi3+

New tunable-color luminescent materials are getting a lot of attention. Double-doped activated ions are an important research method. Here, CaSrNb2O7:R3+ (R3+ = Sm3+, Bi3+, and Sm3+/Bi3+) are synthesized by solid state method in the air. Phase purity and successful synthesis of samples are confirmed by X-ray diffractometer (XRD) patterns and energy disperse spectroscopy (EDS) diagram. The luminescence properties of samples are studied. CaSrNb2O7:Sm3+ has an excitation spectrum due to the O2- - Sm3+ charge transfer band (CTB) and the 6H5/2 → 4H9/2, 4D3/2, 4D1/2, 4F7/2, and 4I11/2 transitions of Sm3+ ion. The red-orange emission of CaSrNb2O7:Sm3+ is observed because of the 4G5/2 → 6H5/2, 6H7/2, 6H9/2, and 6H11/2 transitions of Sm3+ ion. PLE spectrum of CaSrNb2O7:Bi3+ comes from the metal-to-metal charge- transfer (MMCT) Bi3+ - Nb5+ and the 1S0 → 1P1 and 3P1 transitions of Bi3+ ion. CaSrNb2O7:Bi3+ shows blue emission due to the 3P1 → 1S0 transition of Bi3+ ion. The excitation spectrum of CaSrNb2O7:Sm3+, Bi3+ contains that of CaSrNb2O7:Bi3+ and CaSrNb2O7:Sm3+. CaSrNb2O7:Sm3+, Bi3+ with excitation at 314, 363, and 406 nm glows orange and red-orange, and red emission, respectively. We observe the energy transfer from Bi3+ to Sm3+ ions and the effect of Bi3+ on luminescence properties of Sm3+ ion by their spectra. The optimal Sm3+ and Bi3+ concentrations are confirmed by the concentration dependent spectra. The energy level diagrams of Sm3+ and Bi3+ are used to analyze the luminous mechanism. The results are conducive to the development of new Sm3+ and Bi3+ co-doped luminescent materials.

Optical, Photo, and X‐Ray Luminescence Properties of Samarium Ions Doped with Borophosphate Glasses

The optical, photo, and X‐ray luminescence properties of Sm3+ ion‐doped Li2O–Al2O3–Gd2O3–B2O3–P2O5 glasses are evaluated. The glasses are fabricated by the melt quenching technique. The absorption spectra exhibit the hypersensitive transitions 6H5/2→6P3/2 and 6H5/2→6F7/2 at the visible and near‐infrared range respectively. The glasses display four major transitions characteristic of Sm3+ ion for photoluminescence and X‐ray luminescence, with the most intense one corresponding to the 4G5/2→6H7/2 transition. The best emitting samarium concentration obtained by X‐ray excitation is compared to BGO crystals. The integral scintillation efficiency of glass is determined by total area under all of peak spectrum. The results indicate the promising application of these glasses in scintillators and for X‐ray sensing devices.

Physical, structural and spectroscopic studies of Al2O3-B2O3-Sm2O3 scintillating glass doped with heavy metal oxides

In the present paper, physical, structural, optical and luminescence properties of Sm3+ activated scintillating glasses with variation in Bi2O3 concentration have been studied. The amorphous nature of the glass samples was ascertained by the presence of a broad hump in XRD spectra. FTIR examinations advocated that Bi2O3 exists primarily as [BiO6] units and BO4 units enhanced with surging bismuth oxide content. The values of density increase continuously with the addition of Bi2O3, whereas Vm first decreases till 25 mol% Bi2O3 content, after that it is found to increase. Optical characterization of samples affirms strong sensitivity towards the absorbance of UV–visible radiation. Among the prepared samples, 35 mol% of Bi2O3 doped glass showed the lowest bandgap, high refractive index and Urbach energy. Also, it contains more localized states that confirm its suitability as a protection material from UV radiation. PL results reveal the strong emission occurs at 562, 598, 644, 704 nm wavelength and Bi15 glass exhibits maximum intensity in both excitation and emission spectrum. The intense emission peak originated from 4G5/2 → 6H7/2 transition centered at 600 nm in XRL which discloses the scintillation properties of the material. The CIE chromaticity diagram demonstrated the emission located in the reddish-orange region, which suggests prepared glasses could be useful for reddish-orange laser and LED. Thus, 15 mol% Bi2O3 doped glass becomes more efficient for the use of scintillators in high-energy physics experiments.

Comprehensive study on optical and luminescence properties of Sm3+ doped magnesium borotellurite glasses

This research reports the optical and luminescence properties of new tellurite glass system with nominal composition of x(Sm2O3)–10MgO–30B2O3−(60−x)TeO2, where x = 0, 0.5, 1.0, 2.0 and 3.0 mol% synthesized via fast cooling melt-quenching method. The physical characteristic, UV–visible, refractive index, and photoluminescence spectroscopy techniques were used to examine the structural changes and optical performance of the glasses. No sharp peak appeared in the diffraction of XRD region proved the amorphous state of the glasses. The bulk density of the prepared glass samples presented an increasing trend from 4.105 to 4.403 g/cm3 meanwhile the molar volume showed opposite pattern with range value of 28.69–29.39 cm3/mol. The highest density governed by glass sample with concentration of samarium ions at 3.0 mol%, which is 4.403 g/cm3. The optical absorption spectra were characterized to determine the energy band gap, Urbach energy, and refractive index of the glasses. The obtained values for refractive index is in between 2.481 and 2.575 meanwhile for Urbach energy is 0.238–0.319 eV. The optical absorption spectra reveal eleven energy transitions bands centered at 4G9/2, 4I11/2, 4F3/2, 4G5/2, 6F11/2, 6F9/2, 6F7/2, 6F5/2, 6F3/2, 6H15/2, 6F1/2 from ground state of 6H5/2. Four strong emission peaks occurred in photoluminescence, with the highest red emission peak at 600 nm. Chromaticity coordinates of the glass samples were determined as well as the dominant wavelength and colour purity, using CIE Chromaticity diagram 1931.

Influence of alkali and alkaline earths on structural and luminescence properties of Sm3+ doped lithium fluoro phosphate glass and different (Na, Mg, K, Ca and Sr) glass ceramics

Transparent glass ceramics comprising of BiPO4 nanocrystals in bismuth phosphate glass ceramics (59.5P2O5+15Bi2O3+10BaF2+10AF+05TeO2+0.5Sm2O3 where AF= alkali and alkaline earth fluorides) doped with Sm3+ ions were synthesized by typical melt quenching route. On the basis of data obtained from differential thermal analysis (DTA), prepared samples were analyzed for their thermal stability. Further powder X-Ray diffraction (PXRD) analysis has been done for all the samples to confirm the crystalline phase of BiPO4 and short-range order i.e., isotropic. Validations of various structural units were done with the help of FTIR. Spectral intensities were obtained using Judd-Ofelt (JO) theory for various absorption bands of Sm3+ ions using least square fit method for all the studied glass and glass ceramics. Various optical parameters of Sm3+ doped lithium phosphate glass and various glass ceramics were obtained from emission and absorption spectra studied in the present work. Theses optical parameters include JO intensity parameters (Ω2, Ω4 andΩ6), radiative transition probabilites (Aed), branching ratios (β), emission cross sections (σe), absorption cross sections (∑),gain bandwidths and optical gains (σe × Δλeff and σe × τR respectively). Influence of alkali and alkaline earths metals on radiation properties of various excited levels of Sm3+ has been investigated. In relation to the other glass networks and ceramics, SrF2 glass ceramics studied in the present work exhibited productive properties and could be useful in development of optical devices for visible laser applications.

Luminescence properties of Sm3+ doped LaP3O9 phosphors

La1−xP3O9:xSm phosphor was synthesized by co-precipitation method. The XRD results revealed the phosphor’s orthorhombic structure where the La3+ ion is present at the bisdisphenoid dodecahedron position but is completely replaced by Sm3+ ions in the host matrix after Sm3+ doping. The FT-IR spectroscopy results show sharp bands in the 400–1400 cm−1 region due to different bonding vibrations in the phosphate groups. Optical transitions and band gaps were estimated for La0.97P3O9:0.03Sm phosphor by using diffuse reflectance spectroscopy. PL excitation and emission spectral studies revealed that La0.97P3O9 phosphor with 0.03 mol of Sm3+ is the optimum composition for reddish-orange emission with relatively better color purity percentage and promising potential application for reddish-orange visible photonic devices.

Luminescence properties of Sm3+ doped Na2B4O7 glasses for lighting application

Sm3+ ions doped sodium-tetra-borate glasses were developed by melt quenching technique and their physical and luminescence properties were studied. The developed glasses absorbs photons in the UV–Vis–NIR regions. Photoluminescence (excitation and emission) characteristics shows that under 402 nm excitation, strong emission in the orange region owing to the 4G5/2 → 6H7/2 transition of Sm3+ ion was observed. Using absorption spectra, Judd–Ofelt (JO) parameters were evaluated. From the JO theory, the radiative properties which includes the radiative transition probabilities, branching ratios and stimulated emission cross section were calculated. Being transparent and a long decay time with an efficient energy transfer from the host matrix to the luminescence center, the developed glasses exhibit promising luminescence properties. The calculated CIE color coordinates and color purity show that the color coordinates of the developed glasses lie in the orange region. The obtained results revealed that the present glasses are promising for the orange light-emitting diodes and solid state laser applications.

Structure and tunable luminescence in Sm3+/Er3+ doped host-sensitized LaNbO4 phosphor by energy transfer

The pure Sm3+/Er3+ doped host-sensitized LaNbO4 phosphors were synthesized and characterized. By virtue of the Rietveld Method, crystal structure of LaNbO4:Sm3+/Er3+ were refined, with the occupation of dopants determined. The luminescence properties of Sm3+/Er3+ doped LaNbO4 phosphors were carefully measured and analyzed by diffuse reflectance spectra, ultraviolet and cathodoluminescence (CL). The energy transfer was recognized between host and doped Sm3+/Er3+ ions based on the luminescence spectra and decay lifetimes, which is dominated by electric multipolar interaction. Further, the calculated critical distance is 23.71 and 23.08 Å for Sm3+ and Er3+ doped, respectively. Moreover, the temperature sensitivity of Sm3+/Er3+ doped LaNbO4 was evaluated at the temperature ranging from 23 K to 298 K. By adjusting the concentration of Sm3+/Er3+ ions, the emission colors of LaNbO4:Sm3+ and LaNbO4:Er3+ are varied from blue to pink and from blue to cyan. These results indicate that LaNbO4:Sm3+/Er3+ phosphors can be applied in the plasma display panels (PDP) and general lighting.

Comparative study of optical and luminescence properties of Sm3+-ions doped Li2O–Gd2O3–PbO–SiO2 and Li2O-GdF3-PbO–SiO2 glasses for orange emission solid state device application

25Li2O–05Gd2O3– 15PbO – (55-x) SiO2:x Sm2O3 (LPOSm) and 25Li2O–05GdF3- 15PbO – (55-x) SiO2:x Sm2O3 (LPFSm)glasses were prepared by melt quenching method. Optical, luminescence JO-parameters and radiative properties were studied using various techniques. While comparing Ω2 parameter values between LPOSm05 and LPFSm05, the LPFSm05 glass has more asymmetric environment around Sm3+-ions and more covalency between Sm3+-O bonding then LPOSm05 glass. Moreover, LPFSm05 has higher value of branching ratio than LPOSm05 showing its suitability for laser active medium. The current investigation reveals that value of IR/O-ratio for LPFSm05 is more than LPOSm05 showing its more asymmetric nature and more local disorder for Sm3+-ions than LPOSm05 glass. From evaluated results the CIE-color-coordinates for LPOSm and LPFSm glasses fall in orange region. The calculated value of prepared LPOSm and LPFSm glass are less than warm CCT (<4000 K). The lifetime of 4G5/2state atλext = 402 nm and λemi = 600 nm for LPOSm glasses is longer than LPFSm glasses. The dominant interaction responsible for non-exponential behavior for higher concentration in present glasses were found to be dipole-dipole type of interaction for energy transfer between donor (Sm3+) and acceptor (Sm3+) ions. From the present investigation it is suggested that presents glasses are suitable for orange light emitting devices (LEDs and laser).

Synthesis and luminescence properties of Sm3+ doped molybdate glass ceramic

Sm3+ doped precursor glass (PG) was obtained successfully via melt-quenching method and glass ceramic (GC) was precipitated via subsequent heat treatment. Combining the X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses, the optimum heat treatment condition is determined is 635 °C/3 h. The FTIR spectra of the precursor glass and glass ceramic indicate that the enhancement of the luminescent intensity of glass ceramics is related to the MoO42− group appearance. From the transmittance curve of the glass ceramic presents its transmittance can reach 78% in the visible region. The emission spectra indicate the optimum doped concentration of Sm2O3 is 0.3 mol%. Concentration quenching caused by dipole-dipole interaction will occur when Sm2O3 is greater than 0.3 mol%. The calculation results of chromaticity coordinates (CIE) indicates that Sm3+ doped glass ceramic containing SrMoO4 crystallite may be promising as reddish orange emitting materials.

The Luminescence Properties of Sm3+ or Tb3+ —doped Lu3Ga2Al3O12 Phosphors for X-ray Imaging

Sm3+ or Tb3+ -doped Lu3Ga2Al3O12 phosphors were synthesized by using a solid-state reaction method with Lutetium oxide, gallium oxide and aluminum oxide as host materials, samarium oxide and terbium oxide as doping materials. The mixed powders were sintered at 1500 °C for 5 hours by using a horizontal furnace. In this study, the structures of Sm3+ or Tb3+ -doped Lu3Ga2Al3O12 phosphors were observed using an XRD (X-ray diffraction). The emission spectrum of Sm3+ -doped Lu3Ga2Al3O12 phosphor shows 550–650 nm in wavelength due to 4Gj to 6Hj. The measurement of emission spectrum of Tb3+ -doped Lu3Ga2Al3O12 phosphor was confirmed to 450 to 650 nm wavelength due to 5Dj to 7Fj. These phosphors have a sharp emission spectrum due to their physical properties of f-f transition. The Lu3Ga2Al3O12 has a high effective Z-number (Zeff = 57) which is sensitive to X-ray or γ-ray. Therefore Sm3+ or Tb3+ -doped Lu3Ga2Al3O12 phosphors can be applied for diagnostic X-ray imaging in the medical field.

Luminescence properties of Sm3+ and Dy3+ co-doped BaY2ZnO5 phosphor for white LED

Single-phased warm-white-emitting BaY2ZnO5:Dy3+,Sm3+ phosphors were synthesized by a high-temperature solid state reaction method. The crystal structure, luminescence properties, decay lifetimes, thermal stability and internal quantum efficiency (IQE) were investigated. Under 354 nm excitation, the emission spectrum exhibits the characteristic transitions of Sm3+ and Dy3+. Concentration quenching of Sm3+ and energy transfer mechanism are determined to be the dipole-dipole interactions. Due to the energy transfer from Dy3+ to Sm3+, the color tones and correlated color temperature (CCT) can be changed from near cool-white to warm-white when adjusting Sm3+ concentrations. The optimal BaY2ZnO5: 0.14Dy3+, 0.04Sm3+ emits warm-white light with CIE coordinates of (0.404, 0.367), low CCT of 3337 K, activation energy of 0.2389 eV and IQE of 61.5%, making it as a promising candidate white-emitting phosphor for LEDs application.

Synthesis and luminescence properties of Sm3+ doped NaKLaMO5 (M = Nb, Ta) red-emitting phosphors

A series of Sm3+ doped NaKLaMO5 (M = Nb, Ta) phosphors were successfully synthesized via high temperature solid-state reaction. The X-ray diffraction results indicated that the as-prepared phosphors crystallized in pure phases with tetragonal structure. The obtained photoluminescence spectra revealed that these phosphors can be excited by near-UV (406 nm) and they emit red light due to the predominant 4G5/2→6H9/2 transition (664 nm) of Sm3+. The optimal doping concentration of Sm3+ was found to be 0.03 (3 mol%), based on which the critical energy transfer distance of Sm3+ ions in NaKLaMO5 (M = Nb, Ta) phosphors was calculated, and the concentration quenching mechanism was determined. The measured decay curves indicated that these phosphors had short decay lifetime (<1 ms), which decreased with the increase of Sm3+ concentration. As to NaKLa0.97Sm0.03Ta1-xNbxO5 series, with the Nb5+-contents (x) increase, the emission intensity gradually increased up to the complete replacement of Ta5+ by Nb5+. So, among all as-prepared phosphors, the phosphor NaKLa0.97Sm0.03NbO5 has the optimal luminescence performance, and its internal quantum efficiency, CIE coordinates, and temperature-dependent luminescence properties were investigated in detail. The research in this work provides a reference for choosing appropriate red phosphor for white light-emitting diodes.

Luminescence properties of Sm3+ doped alkali/earth alkali orthoborates of the type XZBO3 with X = Li, Na, Cs and Z = Ca, Sr, Ba

Two series of Sm3+ doped alkali/alkaline earth borates of the stoichiometric composition XZBO3 were produced by solid state reaction: one series with constant Z = Ca and varied X = Li, Na, Cs, and one with constant X = Na and varied Z = Ca, Sr, Ba. The compounds have very different crystal structures. Nonetheless the emission spectra show a systematic increase in the ratios of the emission peaks at around 645 and 600 nm for compositions with ligands of larger ionic radii such as e.g. Ba2+ or Cs+ resulting in a red shift of the emitted light. The highest red emission was found for Sm3+:NaBaBO3. Here the Sm3+ emission peak at 645 nm is atypically the most intense. The intensity increase of the red emission peak at around 645 nm is discussed in detail with respect to the specific crystal structures and potential crystallographic positions of the Sm3+ ions. The excitation spectra show that the red emission can be excited at around 400 nm or in a relatively broad range between 460 and 500 nm in the blue spectral region.

The effect of glass composition on the luminescence properties of Sm3+ doped alumino silicate glasses

A large variety of more than sixty Sm3+ doped alumino silicate glass compositions were investigated for their luminescence properties in dependence of their chemical composition. To do so, mainly metaluminous and peralkaline alumino silicate glasses with the network modifiers lithium, sodium, potassium, magnesium, calcium, strontium, barium, yttrium, lanthanum, zinc, and lead were prepared. For some compositions also the effect of fluoride addition, the Al2O3/SiO2 ratio and the substitution of Al2O3 for B2O3 was investigated. A constant Sm3+ doping concentration of 1 × 1020 Sm3+/cm3 was used, which corresponds to about 0.22 mol% Sm2O3.Due to the large quantity of samples, a systematic compositional effect on the Sm3+ emission spectra could be observed: The intensity ratio of the emission peaks at 600 nm and 645 nm is decreased for network modifying ions of larger ionic radii, lower electric field strengths and for higher network modifier concentrations in the glass composition. For exceptionally low network modifier field strengths and concentrations, the emission peak at 645 nm is even stronger than the peak at 600 nm resulting in a more reddish Sm3+ emission in these glasses. The Sm3+ luminescence lifetimes generally decrease with increasing atomic weight, density and refractive index of the glasses. However, peralkaline sodium, potassium, strontium and barium alumino silicate glasses show notably higher luminescence lifetimes than other glass compositions of similar atomic weight. The lifetimes of these glasses are up to 80% higher than their respective metaluminous compositions.

Retraction Note to: “Crystallization and Luminescence Properties of Sm3+-Doped SrO–Al2O3–SiO2 Glass-Ceramics”

This article [1] has been retracted at the request of the Editor in Chief because it has been previously published in Journal of Wuhan University of Technology. Materials Science Edition [2]. This article is therefore redundant. All authors agree to this retraction. 1. Li, H., Liu, L., Tang, X. et al. Glass Phys. Chem. (2017) 43: 548. https://doi.org/10.1134/S1087659617060049 2. Li, H., Liu, L., Tang, X. et al. J. Wuhan Univ. Technol.-Mat. Sci. Edit. (2017) 32: 1025. https://doi.org/10.1007/s11595-017-1706-7

Structural and luminescence properties of Sm3+ -doped bismuth phosphate glass for orange-red photonic applications.

In the present study, the effect of bismuth oxide (Bi2 O3 ) content on the structural and optical properties of 0.5Sm3+ -doped phosphate glass and the effect of concentration on structural and optical properties of Sm3+ -doped bismuth phosphate (BiP) glass were studied. Structural characterization was accomplished using X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy and 31 P nuclear magnetic resonance (NMR) spectroscopy. Optical properties were studied using absorption, photoluminescence and decay measurements. Using optical absorption spectra, Judd-Ofelt parameters were derived to determine the local structure and bonding in the vicinity of Sm3+ ions. The emission spectra of Sm3+ -doped BiP glass showed two intense emission bands, 4 G5/2 →6 H7/2 (orange) and 4 G5/2 →6 H9/2 (red) for which the stimulated emission cross-sections (σe ) and branching ratios (β) were found to be higher. The quantum efficiencies were also calculated from decay measurements recorded for the 4 G5/2 level of Sm3+ ions. The suitable combination of Bi2 O3 (10mol%) and Sm3+ (0.5mol%) ions in these glasses acted as an efficient lasing material and might be suitable for the development of visible orange-red photonic materials.

Structural and luminescence properties of Sm3+-doped Ca2SiO4 phosphors from agricultural waste

Trivalent samarium (Sm3+) ions-doped calcium silicate Ca2SiO4 phosphor powders were successfully prepared by conventional solid-state reaction method using SiO2 and CaO which were obtained from rice husk and egg shells, respectively. The structure of these phosphor powders were studied by X-ray diffraction. Luminescence properties of Sm3+:Ca2SiO4 phosphors were derived using the excitation, emission and decay curve analyses. The luminescence spectra of these phosphors exhibit intense orange-reddish luminescence at 600 nm due to the 4G5/2→6H7/2 transition. The luminescent decay curves for 4G5/2 level of Sm3+ ions measured under 404 nm excitation exhibit non-exponential behaviors at higher Sm3+ concentrations. The non-exponentiality of the decay curves with shortening of lifetimes were explored by Inokuti-Hirayama model and found that the interaction between Sm3+ ions is of dipole-dipole type.