Functionalized Mesoporous SBA-15 with CeF<Subscript>3</Subscript>: Eu<Superscript>3+</Superscript> Nanoparticle by Three Different Methods: Synthesis,Characterization, and Photoluminescence

Luminescence functionalization of the ordered mesoporous SBA-15 silica is realized by depositing a CeF₃: Eu³⁺ phosphor layer on its surface (denoted as CeF₃: Eu³⁺/SBA-15/IS, CeF₃: Eu³⁺/SBA-15/SI and CeF₃: Eu³⁺/SBA-15/SS) using three different methods, which are reaction in situ (I-S), solution impregnation (S-I) and solid phase grinding synthesis (S-S), respectively. The structure, morphology, porosity, and optical properties of the materials are well characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, N₂ adsorption, and photoluminescence spectra. These materials all have high surface area, uniformity in the mesostructure and crystallinity. As expected, the pore volume, surface area, and pore size of SBA-15 decrease in sequence after deposition of the CeF₃: Eu³⁺ nanophosphors. Furthermore, the efficient energy transfer in mesoporous material mainly occurs between the Ce³⁺ and the central Eu³⁺ ion. They show the characteristic emission of Ce³⁺ 5d → 4f (200–320 nm) and Eu^{3+ 5}D₀ → ⁷F _J (J = 1–4, with ⁵D₀ → ⁷F₁ orange emission at 588 nm as the strongest one) transitions, respectively. In addition, for comparison, the mesoporous material CeF₃: Eu³⁺/SBA-15/SS exhibits the characteristic emission of Eu³⁺ ion under UV irradiation with higher luminescence intensity than the other materials.     

Photoluminescence properties of Ce3+/Mn2+ doped calcium zirconium silicate phosphors with energy transfer for white LEDs

A series of Ce³⁺ doped and Ce³⁺/Mn²⁺ co-doped calcium zirconium silicate CaZrSi₂O₇ (CZS) phosphors have been synthesized via conventional high temperature solid state reactions. The luminescence properties, energy transfer between Ce³⁺ and Mn²⁺ have been investigated systematically. Under 320 nm excitation, the phosphor CZS: 0.05Ce³⁺ exhibit strong blue emission ranging from 330 nm to 500 nm, attributed to the spin-allowed 5d-4f transitions of Ce³⁺ ions. There are two different emission centers of Ce³⁺ ions, Ce³⁺(I) and Ce³⁺(II). The emission spectra of Ce³⁺, Mn²⁺ co-doped phosphors shows a broad emission around 550 nm corresponding to the ⁴T₁(⁴G)-⁶A₁(⁶S) spin-forbidden transition of Mn²⁺. The energy transfer between Ce³⁺ and Mn²⁺ is detected and the transfer efficiency of Ce³⁺(II) to Mn²⁺ is faster than that of Ce³⁺(I) to Mn²⁺. The resonant type is identified via dipole-dipole mechanism. Additionally, a blue-shift emission of Ce³⁺ and a red-shift emission of Mn²⁺ have been observed following the increase of Mn²⁺ content in relation to the energy transfer. Thermal quenching has been investigated and the emission spectra show a blue-shift with the temperature increases, which have been discussed in details. CZS: 0.05Ce³⁺, yMn²⁺ phosphors can be tuned from blue to white and even to yellow by adjusting the Mn²⁺ content. All the results indicate that CZS: Ce³⁺, Mn²⁺ phosphor have a potential application for near-UV LEDs.     

Roles of doping ions in persistent luminescence of SrAl<Subscript>2</Subscript>O<Subscript>4</Subscript>: Eu<Superscript>2+</Superscript>,<Emphasis Type="Italic">RE</Emphasis><Superscript>3+</Superscript> phosphors

The polycrystalline Eu²⁺ and Dy³⁺ codoped strontium aluminates SrAl₂O₄: Eu²⁺,Dy³⁺ were prepared by a solid-state reaction. The UV-excited photoluminescence, persistent luminescence, and thermoluminescence of the SrAl₂O₄: Eu²⁺,Dy³⁺ phosphors with different compositions and ion doping was studied and compared. The results showed that the Eu²⁺ ion doped in SrAl₂O₄: Eu²⁺,Dy³⁺ phosphors is not only the UV-excited luminescent center but also the persistent luminescent center. The Dy³⁺ ion introduced into SrAl₂O₄: Eu²⁺ crystal matrix can hardly yield any luminescence under UV excitation but acts as an electron trap with a suitable depth for persistent luminescence. The Dy³⁺ codoping would effectively enhance the persistent luminescence and thermoluminescence. Different codoping RE ³⁺ ions have a different effect on persistent luminescence. Only the RE ³⁺ ions (for example, Dy³⁺ and Nd³⁺), which have suitable optical electronegativity, can form suitable electron traps and effectively improve the persistent luminescence of SrAl₂O₄: Eu²⁺. Based on the above observations, a persistent luminescence mechanism, electron transfer model, was proposed and illustrated. The text was submitted by the authors in English.     

Improvement of Luminescence Properties of Blue‐to‐Red Emitting NaCaBO3: Ce3+, Mn2+ Phosphor Prepared by Sol–Gel Method

Color‐tunable phosphors NaCaBO₃: Ce³⁺, Mn²⁺ were synthesized by sol–gel (SG) and solid state (SS) method. SEM observation indicated that the microstructure of phosphor (SG) consisted of regular fine grains with an average size of about 5 μm. NaCaBO₃: Ce³⁺, Mn²⁺ showed two emission bands: one at 425 nm for Ce³⁺ and another at 610 nm for Mn²⁺. NaCaBO₃: Ce³⁺, Mn²⁺ (SG) exhibit higher energy‐transfer efficiency (90%) and higher Mn²⁺ quantum efficiency (80%) than SS samples, due to smooth surface, narrow size distribution, and improved homogeneity of sensitizer/activator ions. NaCaBO₃: Ce³⁺, Mn²⁺ exhibits blue‐to‐red tunable color by changing Ce³⁺/Mn²⁺ ratio.     

Enhanced Luminescence of Ca14Mg2Si8O28+δN4−δ:Eu2+Phosphors by Codoping Ce3+, Mn2+ for White LEDs and Their Energy‐Transfer Mechanism

The Eu²⁺, M‐codoped(M = Ce³⁺, Mn²⁺) phosphor powders were prepared by a solid‐state reaction. The addition of Ce³⁺ in the Eu²⁺ sites in partially nitridated bredigite‐structure phosphor(CMSN) remarkably enhances the luminescent intensity by ~180% through sensitized luminescence. Dual band emission was observed for Eu, Mn‐codoped CMSN through energy transfer from Eu²⁺ to Mn²⁺. Ce³⁺–Eu²⁺ and Eu²⁺–Mn²⁺ energy‐transfer mechanism was investigated through decay profile analysis using Inokuti–Hirayama model and energy‐transfer parameters are determined. Interaction mechanism was identified as dipole–dipole interaction. In addition, phosphor in glass plates was prepared using the phosphor and its feasibility in white LED application was studied and is presented.     

A Single‐Phased Sr1−y‐3x/2Al2Si2O8: xCe3+, yMn2+ with Efficient Energy Transfer as a Potential Phosphor for White‐Light‐Emitting Diodes

A series of Ce³⁺‐ and Mn²⁺‐(co‐)activated SrAl₂Si₂O₈ phosphors have been prepared at 1350°C under a reducing atmosphere and their photoluminescence properties have been studied as a function of the (co‐)dopant ions concentrations. We have discovered that energy transfer (ET) not only from Ce³⁺ to Mn²⁺ but also from “defects” to Mn²⁺ by the facts that there is existing significant overlap between the emission spectrum of Ce³⁺ (“defects”) and the excitation spectrum of Mn²⁺. The source of the “defects” in the host lattice is originated from the different charge substitution between Ce³⁺ and Sr²⁺. By adopting the principle of ET, the material SrAl₂Si₂O₈: Ce, Mn can act as a phosphor for white‐light ultraviolet light‐emitting diodes (UV‐LEDs) by tuning of the dopants contents.     

Photoluminescence and energy transfer of efficient and thermally stable white-emitting Ca9La(PO4)7:Ce3+, Tb3+, Mn2+ phosphors

The development of novel single-component white-emitting phosphors with high thermal stability is essential for improving the illumination quality of white light-emitting diodes. In this work, we synthesized a series of Ce³⁺, Tb³⁺, Mn²⁺ single- and multiple-doped Ca₉La(PO₄)₇ (CLPO) phosphors with β-Ca₃(PO₄)₂-type structure by the simple high-temperature solid-state reaction. The crystallization behavior, crystal structure, surface morphology, photoluminescence performance, decay lifetime and thermal stability were systematically investigated. The PL spectra and decay curves have evidenced the efficient energy transfer from Ce³⁺ to Tb³⁺ and from Ce³⁺ to Mn²⁺ in the CLPO host, and corresponding energy transfer efficiency reaches 41.8% and 54.1%, respectively. The energy transfer process of Ce³⁺→Tb³⁺ and Ce³⁺→Mn²⁺ can be deduced to the resonant type via dipole-dipole and dipole-quadrupole interaction mechanism, and corresponding critical distance were determined to be 12.23 and 14.4 Å, respectively. Based on the efficient energy transfer, the white light emission can be successfully achieved in the single-component CLPO:0.15Ce³⁺, 0.10Tb³⁺, 0.04Mn²⁺ phosphor, which owns CIE chromaticity coordinates of (0.3245, 0.3347), CCT of 5878 K, internal and external quantum efficiency of 84.51% and 69.32%. Especially, compared with the emission intensity at 25 °C, it still remains 98.5% at 150 °C and 92.0% at 300 °C. Based on these results, the single-component white light emission phosphor CLPO:0.15Ce³⁺, 0.10Tb³⁺, 0.04Mn²⁺ is a potential candidate for UV-converted white LEDs.     

The luminescence properties,energy transfer mechanism of the color tunable and high quantum efficiency LaAl2.03B4O10.54: Ce3+, Tb3+ phosphors

Tb³⁺ is a typical green emitting luminescence center in inorganic compounds. However, the absorption of Tb³⁺ is very weak in ultraviolet spectral region (from 240 to 400 nm). Ce³⁺ is often used as a sensitizer to transfer energy to Tb³⁺. In this paper, Ce³⁺ and Tb³⁺ were co-doped into a novel aluminates-borates LaAl_2.03B₄O_10.54. Ce³⁺ can absorb UV light (from 240 to 340 nm) and transfer absorbed energy to co-doped Tb³⁺ effectively and bring bright green emission of Tb³⁺. The crystal structure and fluorescence spectra of phosphors, the efficiency of energy transfer between Ce³⁺ and Tb³⁺, decay dynamics, the thermal stability and internal quantum efficiency of luminescence have been investigated in detail. These results indicate that the color tunable LaAl_2.03B₄O_10.54: Ce³⁺, Tb³⁺ phosphor is a potential green-emitting material. Especially, analysis about the relationship of the doping concentration of luminescence centers and thermal stability of luminescence points out a feasible way to enhance the thermal stability of luminescence in the future.     

Controllable modulation of coordination environments of Mn2+ in glasses and glass-ceramics for tunable luminescence

A phase-separated glass is designed to modulate the coordination environments of activators for achieving tunable luminescence in wide wavelength ranges. The luminescent properties and microstructures of Mn²⁺ doped glasses are carefully investigated. It is found that the luminescence center of Mn²⁺ is modulated to 620, 588 and 702 nm via the controllable precipitation of K₂SiF₆, KZnF₃ and ZnF₂ crystals from the glass networks, respectively. The emissions of Mn²⁺-Mn²⁺ dimers centered at 800 nm are also observed when Mn²⁺ ions are confined in the fluoride crystal coordination environments. The phase-separated glass possesses great potential for providing diverse coordination environments for Mn²⁺ and is beneficial for the formation of Mn²⁺-Mn²⁺ dimers. This glass not only provides a highly promising development of optical gain material for tunable fiber lasers, but the modulation strategy based on phase-separated networks also offers excellent opportunities for manufacturing a wide range of photonic materials featuring multiple-wavelength luminescence.     

Visible up-conversion luminescence of CaWO<Subscript>4</Subscript>: Er<Superscript>3+</Superscript>,Yb<Superscript>3+</Superscript> and emission enhancement by tri-doping of Li<Superscript>+</Superscript> ions

Er³⁺,Yb³⁺ co-doped CaWO₄ polycrystalline powders were prepared by a solid-state reaction and their up-conversion (UC) luminescence properties were investigated in detail. Under 980 nm laser excitation, CaWO₄: Er³⁺,Yb³⁺ powder exhibited green UC emission peaks at 530 and 550 nm, which were due to the transitions of Er³⁺ (²H_11/2)→Er³⁺ (⁴I_15/2) and Er³⁺ (⁴S_3/2)→Er³⁺ (⁴I_15/2), respectively. Effects of Li+ tri-doping into CaWO₄: Er³⁺,Yb³⁺ were investigated. The introduction of Li⁺ ions reduced the optimum calcinations temperature about 100 °C by a liquid-phase sintering process and the UC emission intensity was remarkably enhanced by Li⁺ ions, which could be attributed to the lowering of the symmetry of the crystal field around Er³⁺ ions.     

The Energy Transfer and Thermal Stability of a Blue‐Green Color Tunable K2CaP2O7:Ce3+,Tb3+ Phosphor

Novel blue‐green emitting Ce³⁺‐ and Tb³⁺‐activated K₂CaP₂O₇ (KCPO) luminescent materials were synthesized via a solid‐state reaction method. X‐ray diffraction, luminescence spectroscopy, decay time, and fluorescent thermal stability tests have been used to characterize the prepared samples. The KCPO:Ce³⁺,Tb³⁺ luminescence spectra show broad band of Ce³⁺ ions and characteristic line of Tb³⁺ ion transition (⁵D₄–⁷F₅). The color variation in the light emitting from blue to green under UV excitation can be obtained by tailoring the Tb³⁺ content in KCPO:Ce³⁺. Besides, Ce³⁺ ions obviously intensify Tb³⁺ ion emission through an effective energy transfer process, which was confirmed from decay curves. The energy transfer efficiency was determined to be 82.51%. A resonant type mechanism via the dipole–quadrupole interaction can be proposed for energy transfer. As a whole, the KCPO:Ce³⁺,Tb³⁺ phosphor exhibits excellent performance in the range from 77 to 673 K, indicating the phosphors are highly potential candidates for solid‐state lighting.     

Spectral properties of Er<Superscript>3+</Superscript> in alkali-zinc-tellurite,barium-tellurite-molybdate,and fluoride glasses

Glasses of three compositions—TeO₂ · ZnO · N₂O (TZN), where N is Li, Na, or K; TeO₂ · MoO₃ · BaO (TMB); and ZrF₄ · BaF₂ · LaF₃ · AlF₃ · NaF (ZBLAN)—activated by Er³⁺ or Yb³⁺ and Er³⁺ ions were synthesized and investigated. For the ZBLAN glass, the brightest luminescence of Er³⁺ ions in the visible range was observed under excitation by the irradiation of a diode laser with the generation wavelength 0.98 μm. The TZN glass is not inferior in the intensity of luminescence with the wavelength 1.55 μm to the TMB glass, having phonons of higher energy than those for the TZN glass (940 and 740 cm⁻¹, respectively). A glass was prepared with a high content of molybdenum oxide. The possibility to increase the up-conversion efficiency in tellurite glasses is considered.     

Optimized photoluminescence of red phosphor Na2SnF6:Mn4+ as red phosphor in the application in “warm” white LEDs

The Mn⁴⁺ activated fluostannate Na₂SnF₆ red phosphor was synthesized from starting materials metallic tin shots, NaF, and K₂MnF₆ in HF solution at room temperature by a two‐step method. The formation mechanism responsible for preparing Na₂SnF₆:Mn⁴⁺ (NSF:Mn) has been investigated. The influences of synthetic parameters: such as concentrations of HF and K₂MnF₆ in reaction system, reaction time, and temperature on crystallinity, microstructure, and luminescence intensity of NSF:Mn have been investigated based on detailed experimental results. The actual doping concentration of Mn⁴⁺ in the NSF:Mn host lattice is less than 0.12 mol%. The most of K₂MnF₆ is decomposed in HF solution especially in hydrothermal system at elevated temperatures. The color of the as‐prepared NSF:Mn samples changes from orange to white when the temperature is higher than 120°C, which indicates the lower concentration of luminescence centers in the crystals. A series of “warm” white light‐emitting diodes with color rendering index (CRI) higher than 88 and correlated color temperatures between 3146 and 5172 K were obtained by encapsulating the as‐prepared red phosphors NSF:Mn with yellow one Y₃Al₅O₁₂:Ce³⁺ (YAG:Ce) on 450 nm blue InGaN chips. The advantage of the synthetic strategy to obtain NSF:Mn can be extended to developing Mn⁴⁺‐doped red phosphors from low‐costing metals at room temperature for large‐scale industrial applications.     

A single‐phase,thermally stable and color-tunable white light emitting Na2Ca1-x-yCexMnyP2O7 phosphors for white light emitting diodes via energy transfer

The solid-state reaction method was used to develop a series of Na₂Ca_1-x-yCe_xMn_yP₂O₇ phosphors in an H₂–N₂ environment. The crystal structure of the pyrophosphate host, valence state of dopants (Ce, Mn), emission behavior of dopants, energy transfer mechanism, and thermal quenching behavior were thoroughly examined. Doping with Ce³⁺ and Mn²⁺ ions enhanced the photoluminescence characteristics of Na₂Ca_1-x-yCe_xMn_yP₂O₇ while having negligible effect on the host's phase purity. Under 365 nm UV light irradiation, the addition of Ce³⁺ ion in the Na₂CaP₂O₇ host revealed an asymmetric band with the typical blue emission around 415 nm and a shoulder around 455 nm. To obtain white light, Mn²⁺ ion was supplementarily substituted to the present system. When the Mn²⁺ ions concentration was elevated in the Na₂CaP₂O₇ host, the emission intensity of 560 nm peak corresponding to Mn²⁺ transition enhanced significantly at the cost of Ce³⁺ emission of 415 nm. The systematic decrease of Ce³⁺ emission intensity and corresponding increase in the Mn²⁺ intensity with the increase in Mn²⁺ concentration indicated the possibility of effective energy transfer from Ce³⁺ to Mn²⁺ ions. The obtained results indicated that energy transfer from the Ce³⁺ to Mn²⁺ ions governed by dipole-quadrupole interaction. Because of the efficient energy transfer, the blue emission from Ce³⁺ and the orange red emission of Mn²⁺ provide white light from a single host along with high value of activation energy and low thermal quenching behaviour make the present phosphors to be suitable for high-power LEDs.     

Halogen-content-dependent photoluminescence of Mn2+-doped CsPbCl3 nanocrystals

The thermodynamically viable halogen vacancy defects in CsPbCl₃ perovskite nanocrystals (NCs) are considered the main factor in weakening their optical quality. However, their separate impact on the dopant emission in Mn²⁺-doped CsPbCl₃ perovskite NCs is still under exploration owing to the absence of comparable samples. Herein, a series of Mn²⁺-doped CsPbCl₃ samples were synthesized with different oleylamine-Cl (OAm-Cl) contents based on a halogen-hot-injection strategy. It is found that the Mn²⁺ concentration of as-prepared samples fixed at 0.65%, and the Mn²⁺ photoluminescence (PL) also exhibited an OAm-Cl content-independent lifetime of ∼ 1.78 ms, implying the efficient and identical luminescence of isolated Mn²⁺ ion in all samples. In contrast, the excitonic and Mn²⁺ PL intensities of the NCs are strong related to the amount of OAm-Cl, which are attributed to the coordination effect of the suppressed excitonic nonradiative recombination owing to the passivation of chloride vacancies and the enhanced energy transfer from the host exciton to Mn²⁺ ions in the samples with sufficient OAm-Cl contents. The temperature-dependent of Mn²⁺ PL disclosed an initial increase and was followed by a decrease with increasing temperature for the samples with relatively higher OAm-Cl contents, while it monotonously decreases for the sample with lower OAm-Cl content of 0.4 mL. The different PL intensity change trend results from the effective passivation of chloride vacancies by extra OAm-Cl. Above results present here will help clarify the underlying influence mechanism of halogen vacancy on the PL properties of Mn²⁺-doped perovskite NCs, which is essential for targeted modulation of their optical properties.     

Orderly‐Layered Tetravalent Manganese‐Doped Strontium Aluminate Sr4Al14O25:Mn4+: An Efficient Red Phosphor for Warm White Light Emitting Diodes

Searching for an efficient non rare earth‐based oxide red phosphor, particularly excitable by light in the wavelength from 380 to 480 nm and unexcitable by green light, is essential for the development of warm white light emitting diodes (WLEDs). Here, we report a promising and orderly‐layered candidate: Sr₄Al₁₄O₂₅:Mn⁴⁺ with CIE color coordinates (0.722, 0.278). It has higher luminescence efficiency particularly upon blue excitation and is much cheaper than the commercial red phosphor 3.5MgO·0.5MgF₂·GeO₂:Mn⁴⁺ (MMG:Mn⁴⁺). In sharp contrast to Eu²⁺‐doped (oxy)nitrides, the phosphor can be synthesized by a standard solid‐state reaction at 1200°C in air. The effects of flux boron content, environment, and preparation temperature, sintering dwelling time as well as Mn concentration have been systematically investigated for establishing the optimal synthesis conditions. The low temperature emission spectra reveal that there are at least three types of Mn⁴⁺ ions in Sr₄Al₁₄O₂₅:Mn⁴⁺ due to the substitution for the distorted octahedral Al³⁺ sites. The AlO₆ layers where Mn⁴⁺ prefers to reside are well separated from one another by AlO₄ tetrahedra in one dimension parallel to axis a. This scenario can efficiently isolate Mn⁴⁺ ions from local perturbations, thereby enabling the high efficiency of luminescence. The energy transfer rates and mechanism are discussed.     

Ce/Mn/Cr: Y3Al5O12 phosphor ceramics for white LED and LD lighting with a high color rendering index

Ce/Mn/Cr: Y₃Al₅O₁₂ transparent ceramics with a pure garnet structure and a high color rendering index were prepared by a solid-state reaction method. Mn²⁺ and Cr³⁺ enhance the emission between 500 and 700 nm and expand the conventional Ce: YAG phosphors spectrum. The Ce³⁺ can work both, as activators and sensitizers, and the intense energy transfer from Ce³⁺ to Mn²⁺/Cr³⁺ is realized through the non-radiative and radiative processes. In the sample with the optimized doping concentration the high color rendering index (CRI) value of 75.3 can be achieved under a 450 nm laser diode excitation. The chromaticity coordinates can be tuned from (0.3125, 0.3232) to (0.2917,0.2851) by varying the doping concentration. With the increasing Mn²⁺/Cr³⁺ doping concentration, the lifetime of Ce³⁺, quantum efficiency and luminous efficiency are all gradually decreased. This work effectively offers a scheme for realizing the high color rendering performance of phosphor-converted transparent ceramics in white LEDs/LDs.     

Luminescence of (La,Dy)F3: Effect of solvent ratio (water/ethylene glycol) and Ce3+ co-doping

Luminescent LaF₃:Dy³⁺ and LaF₃:Dy³⁺ co-doped with Ce³⁺ have been successfully synthesized separately via co-precipitation method. Different ratios of ethylene glycol(EG)/water have been used for the synthesis of LaF₃:Dy³⁺ whereas LaF₃:Dy³⁺ co-doped with Ce³⁺ have been prepared only in ethylene glycol(EG) medium. The synthesized products have been characterized using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infra‐red (FT-IR) and photoluminescence spectroscopy. XRD results show all the samples prepared to be well crystallized in a pure hexagonal structure with no impurity phases. Photoluminescence, lifetime decay and energy transfer efficiency studies indicate the existence of an energy transfer between the Ce³⁺ and Dy³⁺ ions, which increases with increase of Dy³⁺ ions concentration. LaF₃:Dy³⁺ nanophosphor prepared in EG:water mixture(1:1) showed the highest luminescence intensity when compared with those prepared in EG or water alone. This enhancement in luminescence (when using EG-water mixture) might be related to the increase in crystallinity/particle size as well as to the decrease in agglomeration of particles in the corresponding solvent mixture medium.     

Morphology Tunable Self‐Assembled Sr2P2O7:Ce3+, Mn2+ Phosphor and Luminescence Properties

Uniform orange‐to‐red spherical phosphors of Sr₂P₂O₇:Ce³⁺, Mn²⁺ have been synthesized by the co‐precipitation method and characterized by X‐ray powder diffraction, scanning electron microscopy, and photoluminescence spectroscopy. The results indicate that the morphology, size, and photoluminescence properties of Sr₂P₂O₇:Ce³⁺, Mn²⁺ phosphors can be effectively controlled by the reaction and the sintering temperatures. Energy transfer from Ce³⁺ to Mn²⁺ in Sr₂P₂O₇ phosphor was observed from photoluminescence spectra of Sr₂P₂O₇:Ce³⁺, Sr₂P₂O₇:Mn²⁺, and Sr₂P₂O₇:Ce³⁺, Mn²⁺. Moreover, based on a self‐assembly process, a possible formation mechanism for the spherical phosphors is proposed. The uniform phosphor spheres obtained in this work exhibit great potential for high‐resolution display devices such as light emitting diodes.     

Er<Superscript>3+</Superscript>- and Tm<Superscript>3+</Superscript>-Containing Ultra-Transparent Oxyfluoride-Based Glass Ceramics for Wavelength Division Multiplexing Optical Amplifiers

Ultratransparent glass ceramics activated with thulium and erbium ions were fabricated. The precursor oxyfluoride glass was 32SiO₂ · 9AlO_1.5 · 31.5CdF₂ · 18.5PbF₂ · 5.5ZnF₂ · 3.5ReO_1.5 with Re = Tm or Er. Upon heat treatment, Er³⁺ and Tm³⁺ nucleate the growth of nanocrystalline β-PbF₂, which acts as a host for rare-earth ions. The spectroscopic properties of the thulium and erbium ions, studied via UV-VIS-NIR absorption and luminescence spectroscopy, show that most of the active ions are embedded in the crystalline phase. From the absorption measurement, we extracted the cross sections of Tm³⁺ ions embedded in the crystalline and glassy phases. The comparison between the experimental lifetimes before and after thermal treatment gave as a result that the ceramming process increases the quantum efficiency of the Tm³⁺ electronic transitions. In the case of Er³⁺-activated glass ceramics, the ⁴ I _13/2 ⇄ ⁴ I _15/2 telecom transition broadens and flattens.Original English Text Copyright © 2005 by Fizika i Khimiya Stekla, Tosello, Montagna, Mattarelli, Ferrari, Chaussedent, Monteil, Tikhomirov, Seddon.This article was submitted by the authors in English.