Composite Phosphor Research Articles

Effect of phosphoric acid composition in the production and characterization of coal activated carbon

Abstract Liquid waste containing heavy metals must be treated before being released into the environment. This study investigated the potential of coal-derived activated carbon as an adsorbent in AMD (Acid Mine Drainage) treatment. Coal was activated with H3PO4 with five weight ratios (10%, 20%, 30%, 40%, and 50%), carbonized for 120 min at 650 °C, and subjected to the proximate analysis of activated carbon. The results showed that the water content, ash content, volatile matter content, and fixed carbon were generally in accordance with Indonesian standards (SNI). The results of FT-IR and SEM on BET surface area and total pore volume of activated carbon were 296.4 m2/g and 0.1562 cc/g, respectively, indicative of sizeable pores, cracks, channels, and active groups. The iodine outnumbered the minimum limit in the SNI, and the activated carbon quantity consistently increased with H3PO4 ratios. The iodine produced with 10%, 20%, 30%, 40%, and 50% H3PO4 was 956.95 mg/g, 967.13 mg/g, 1,221.63 mg/g, 1,206.346 mg/g, and 865.32 mg/g., respectively.

Luminescence Behavior and Structural Characteristics of Novel BaYAl3O7: Tb3+ Nanophosphors.

An innovative green emitting novel BaY1 - xTbxAl3O7 (x = 0.02, 0.03, 0.04, 0.05, and 0.06) was synthesized using urea combustion, which was a low-energy process. Using techniques such as photoluminescence (PL), X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy dispersive x-ray (EDX) spectroscopy, the structure and luminous properties of the phosphor were investigated. Scherrer's equation was utilized in the XRD technique to determine the crystallite size of the suggested materials. When stimulated with the near-ultraviolet photon, PL spectra revealed intense green emission at 541nm (5D4 → 7F5). The composition with the maximum emission intensity is BaY0.96Tb0.04Al3O7. The dipole-dipole mechanism for concentration quenching events was identified with the help of the critical energy transfer distance. The non-radiative relaxation rate (276s- 1), radiative lifetime (0.75754 ms), and quantum efficiency (79%), of the ideal phosphor composition are calculated using Auzel's model. The color coordinates (0.260, 0.496) align with the emission of green light. The remarkable outcomes validated the significance of the targeted nanocrystals as a superior material with prospective applications in solid-state down-converted white light-emitting diodes (WLEDs).

Laser-Controlled Information Releasing and Hiding Based on Perovskite Phosphors.

Laser-active interference with high confidentiality and convenience opens up a cutting-edge path for releasing and hiding key targets; however, its development still faces enormous challenges owing to the difficulty of concealing objects. Herein, a novel conceptual design for laser-controlled information release and hiding (LIRH) is proposed and successfully realized. Cs2NaInCl6:Er3+, Yb3+ (CNIC:Er, Yb) perovskite microcrystal is adopted as a carrier for LIRH implementation, exhibiting excellent up-conversion (UC) emission under NIR (980 and 1530 nm) irradiation due to its ultralow phonon energy. The fluorescence intensity crossover and outstanding photon output capacity are revealed in comparison with Er3+/Yb3+ codoped and Er3+ single-doped CNIC phosphors under different laser sources, and the obvious difference in quantum yields (QY) under 980 and 1530 nm excitation provides theoretical possibility for LIRH. More importantly, the obtained LIRH features high stability at temperatures up to 413 K, showing good adaptability in various potential scenarios. Moreover, CNIC:Er, Yb is further combined with polyacrylonitrile (PAN) polymer to form fluorescent fibers with exceptional crystal stability and composite flexibility, thus making the LIRH code a reality based on perovskite composite phosphors. The laser-active invisibility offers an innovative idea for LIRH, further extending the application of LIRH in the field of information encryption, which has promising prospects in information safety, advanced anticounterfeiting, and smart responsive materials.

Improved ternary composite ceramic phosphors for warm-white laser lighting

Improved ternary composite ceramic phosphors for warm-white laser lighting

PMMA-Au@YAG:Ce phosphor deposited on flexible substrate for white light emitting devices

This paper investigates the possibility to obtain yttrium aluminum garnet doped with cerium ions (YAG:Ce) phosphor, improve the emissive properties by modification with metal nanoparticles, followed by embedding into the polymer matrix, and deposition of nanocomposite on a flexible substrate to produce the white light by excitation with a blue chip. YAG:Ce yellow phosphor was obtained by a modified solid-state process, followed by in-situ anchoring of gold nanoparticles (Au@YAG). To deposit the phosphor on the flexible substrate, the Au@YAG nanocomposite was embedded in a poly(methyl methacrylate) (PMMA) matrix using the ex-situ method. The quality of the phosphor particles and composites was studied using FTIR spectroscopy, X-ray diffraction, and fluorescence spectroscopy. The applicability of the developed materials and the efficiency of methods were confirmed by the photometric studies performed on the composite film to determine the chromaticity coordinates, leading to the parameters of the semiconductor device that generates cold white light.

Boron Nitride‐Supported Fluorescein Isothiocyanate for Improving Optical Performance and Stability

AbstractOrganic luminogens play an indispensable role in optoelectronic devices, yet there is a pressing need to address their aggregation‐caused quenching (ACQ) and stability. Here we designed and prepared multilayered boron nitride nanosheets/fluorescein isothiocyanate (MBNNSs/FITC) composite phosphors with tunable photoluminescence by controlling the FITC content and annealing temperature. The research results indicate that MBNNSs/FITC with low or high loading of FITC is not conducive to enhancing the emission intensity of FITC, which can be attributed to the fact that low loading leads to a decrease in the content of fluorescent groups, while high loading promotes intermolecular aggregation of FITC dyes. Interestingly, the emission intensity of FITC in MBNNSs/FITC‐6 composite phosphors can be further enhanced by annealing treatment (200 °C), which can be ascribed to the suppression of the ACQ and effective energy transfer from the MBNNSs to the FITC. Moreover, the resultant composite phosphor displays outstanding thermal stability, remarkable photo stability and exceptional water‐resistance. This work provides a new design space for the development of non‐rare‐earth fluorescent materials using organic fluorescent dyes.

ORAL SUPPLEMENTAL VITAMIN C AND THREE ELECTROLYTES EFFECT ON CARCASS CHARACTERISTICS, CALCIUM AND PHOSPHOROUS COMPOSITION IN MEAT AND BONE OF BROILER CHICKEN

Effect of supplementing broiler diets orally with vitamin C and three electrolytes was assessed using 240 one day Arbor acre broiler chicken strain. In a completely randomized design, birds were randomly allocated to five treatments each in quadruplicates of ten birds per replicate. The formulated experimental diets and water were given to birds ad libitum. In addition, the test electrolytes or vitamin C supplement was administered orally through water to respective birds throughout the duration of the experiment as follows: control without salt or electrolyte (TI), 5g/litre ammonium chloride (T2), 5g/litre sodium bicarbonate (T3), 5g/litre calcium chloride (T4), 3g/litre ascorbic acid (TS). All relative internal offal and carcass weights were similar (P>0.05) except in the eviscerated weight, wing, back and neck which varied significantly (P<0.05). Meat calcium (%) (0.067, 0.043, 0.078, 0.047 and 0.048 from broilers on T1, T2, T3, T4 and T5 respectively) varied significantly due to treatment. However, meat calcium as well as phosphorous compositions of both meat and the bone were not significantly affected (P>0.05) by the treatments. Conclusively, oral supplements of vitamin C and electrolytes neither alter the weights of carcass nor influence the meat and bone compositions appreciably. Further studies would be pertinent to ascertain the economy of ascorbic acid and/or electrolytes to broilers in stress.

Synthesis and luminescence properties of color-tunable BaLaGa3O7: Bi3+,Sm3+ phosphors

We prepared BaLaGa3O7: Bi3+,Sm3+ phosphors via solid state reactions and investigated their crystallinity, lattice occupancy, and photoluminescence performance. The phase and crystal structure, morphology and size, as well as element composition of phosphor were investigated via a series of measurements. The photoluminescence and Bi3+ → Sm3+ energy transfers were investigated in detail. It is proved that Bi3+ → Sm3+ energy transfer occurs in Bi3+/Sm3+ codoped BaLaGa3O7 phosphors and it is induced by dipole–dipole interaction. By calculating the decay lifetime, the efficiency of Bi3+ → Sm3+ energy transfer is evaluated. The CIE coordinates of the prepared show obvious dependence on Sm3+ concentration and temperature.

Phosphor Ceramic Composite for Tunable Warm White Light.

Composite phosphor ceramics for warm white LED lighting were fabricated with K2SiF6:Mn4+ (KSF) as both a narrowband red phosphor and a translucent matrix in which yellow-emitting Y3Al5O12:Ce3+ (YAG) particles were dispersed. The emission spectra of these composites under blue LED excitation were studied as a function of YAG loading and thickness. Warm white light with a color temperature of 2716 K, a high CRI of 92.6, and an R9 of 77.6 was achieved. A modest improvement in the thermal conductivity of the KSF ceramic of up to 9% was observed with the addition of YAG particles. In addition, a simple model was developed for predicting the emission spectra based on several parameters of the composite ceramics and validated with the experimental results. The emission spectrum can be tuned by varying the dopant concentrations, thickness, YAG loading, and YAG particle size. This work demonstrates the utility of KSF/YAG composite phosphor ceramics as a means of producing warm white light, which are potentially suitable for higher-drive applications due to their increased thermal conductivity and reduced droop compared with silicone-dispersed phosphor powders.

Fabrication and luminous properties of BaAl2O4-LuAG:Ce composite phosphor ceramics for solid-state laser lighting

Based on the “effective ionic radius match effect” and the “charge balance substitution rule of ions”, mixed Ba2+, Al3+, Lu3+, and Ce3+ ions can be effectively regulated to a BaAl2O4-LuAG:Ce biphasic structure. The contribution of BaAl2O4 like as scattering centers can reduce overall reflection losses and enhance the light extraction efficiency of these composite phosphor ceramics (CPCs). In this work, a series of x wt.% BaAl2O4-LuAG:Ce (x = 0, 3, 5, 10, 15) CPCs were fabricated by vacuum sintering using co-precipitated composite powders. Homogenization at the atomic level of mixed Ba3+, Al3+, Lu3+, and Ce3+ ions in multiphase powders provides uniform distribution of BaAl2O4 and LuAG:Ce constituent phases in composite ceramics. The introduction of BaAl2O4 has an additive effect, which also consists in uniform aggregation of pores near their grains during sintering. It allows to adjust the size and amount of microstructural defects by varying the secondary phase content. Under the excitation of 10.8 W 450 nm LDs in a reflection mode, 3 wt% BaAl2O4-based CPCs show the optimum luminous flux of 2244 lm and a luminous efficiency of 208 lm·W−1. The obtained CPCs show a high application potential in solid-state laser lighting.

MAS:Eu-YAG:Ce composite phosphor converters with excellent thermal performance and enhanced color rendering index for high-power white LDs

Phosphor converters with excellent thermal performance and high color rendering index (CRI) demonstrate vast application prospects in the field of laser diodes (LDs) lighting. Nevertheless, the significant heat accumulation within the converters and the absence of red spectral components pose challenges in achieving both a high saturation threshold and a high CRI for Y3Al5O12:Ce phosphor converters destined for white LDs. In this work, Mg2Al4Si5O18:Eu/Y3Al5O12:Ce (MAS:Eu/YAG:Ce) composite phosphor converters with excellent thermal performance and enhanced CRI were designed and fabricated for reflective laser lighting. Impressively, MAS:Eu/YAG:Ce phosphor-glass-ceramic composites (PGCC) retained a remarkable 97.8 % of the room temperature emission intensity at 150 °C. The reasons for this could be attributed to the strong thermal quenching resistance exhibited by MAS:Eu phosphors, as well as the ultra-thin glass bonding layer of about 150–200 μm. Meanwhile, by integrating the MAS:Eu/YAG:Ce PGCC with a 450 nm laser source, white LD devices operating in a remote excitation mode were fabricated. These white LDs demonstrated an improved CRI of 76 and maintained a low surface temperature of 131.7 °C under an ultra-high laser power density of 47.8 W/mm2 (laser power ∼ 4.70 W). Moreover, the maximum luminous flux and luminous efficiency of the white LDs were 484 lm and 103 lm/W, respectively. Therefore, the design of MAS:Eu/YAG:Ce composite phosphor converters offers a new approach for the development of high-power white LDs.

Fabrication of Al2O3– Ce:(Y, Tb)3 (Al, Mn)5O12 composite ceramic phosphors for high color rendering white LED/LD illumination

Ce: YAG- Al2O3 composite ceramics are regarded as highly promising materials for laser illumination application due to their high luminous efficacy and thermal stability. Nevertheless, the Ce: YAG ceramics exhibit limited color rendering index (CRI) for indoor lighting due to their low red emission component. In this study, we synthesized high-performance Ce, Mn-doped (Y, Tb)3Al5O12–Al2O3 composite ceramic phosphors via a vacuum solid-state sintering method. It was observed that the introduction of Mn2+ ions created a second luminescence center with an emission peak centered at 580 nm. As the Mn2+ concentration increased, the emission peak redshifted from 580 nm to 591 nm, leading to a significant enhancement in the color rendering index of the ceramics. The cross-energy transfer between Tb3+ and Mn2+, Ce3+ ions augmented the absorption and conversion of blue light by the ceramics, thereby reducing the correlated color temperature greatly. Based on these findings, ceramics with a Ce3+ concentration of 3 at% and a Mn2+ concentration of 4 at% exhibited the highest CRI values (81.3 and 75.6) under both laser excitation and LED excitation, establishing them as strong candidates for achieving high color rendering in white LED/LD illumination applications.

Investigation of a thermally robust orange-red MgO-YMASG: Ce composite phosphor ceramic for white light LED/LD illumination

With its distinctive ability to emit red light with a wavelength surpassing 600 nm, Mg2+-Si4+ co-doped Y3Al5O12: Ce (YMASG: Ce) ceramics emerge as superior candidates for achieving high color rendering and high power white light illumination compared to YAG ceramics. However, due to its higher Stokes energy loss, the orange-red phosphor ceramic YMASG: Ce encounters more pronounced thermal accumulation issues when excited by high-power blue light LEDs/LDs. In response to this challenge, we employed vacuum solid-state sintering technology to fabricate MgO-YMASG: Ce composite phosphor ceramics. As the MgO content increased from 0 to 30 wt%, the thermal conductivity of the samples rose from 5.13 W/(m∙K) to 8.96 W/(m∙K). Additionally, the lower refractive index of MgO effectively enhanced the light extraction efficiency of the ceramics. Consequently, even at a 30 wt% MgO content, the luminescent efficiency of the sample remained comparable to that of YMASG: Ce phosphor ceramics. This suggests that MgO-YMASG: Ce composite phosphor ceramics can serve as high thermal robust orange-red phosphor materials for white light LED/LD illumination.

Effect of Ce<sup>3+</sup> Concentration and YAG Crystal Particles Size on Photoluminescence

Purpose of research. Determine the effect on the photoluminescence of phosphors from yttrium-aluminum garnet activated by cerium ions Ce3+, the size of its particles and the concentration of cerium ions in them.Methods. Structural electron and confocal microscopic, fluorescent, microspectral studies using a laser lex = 473 nm as an excitation source, energy dispersive, X-ray diffraction studies, as well as goniophotometric measurements on the radial distribution of light intensity excited by the LED matrix were carried out.Results. A detailed granulometric analysis of the particle sizes of phosphors was carried out for two samples from different manufacturers, cumulative distributions M(d) were constructed and their quantiles were established. Based on the results of measuring photoluminescence from individual particles in the compositions of phosphors based on YAG:Ce3+, a Stokes shift was detected in these samples: short-wavelength – for particles with sizes less than 10 μm and with low concentration and long-wavelength – with sizes greater than 10 μm with an increased concentration of over ~0.2% . The obtained microspectral size-emission dependences lem(d) and energy Imax(d) were consistent with the description based on the proposed physical mechanism of their formation by the 5d → 2F5/2 and 5d → 2F7/2 transitions.Conclusion. A short-wavelength shift of photoluminescence intensity maxima for particles smaller than 10 μm was discovered, due to a significant increase in the influence of surface stresses due to a reduction in the number of atoms. For larger particle sizes, the characteristic photoluminescence intensity maxima cease to depend on the wavelength. The radial distribution of luminous intensity determined by the goniophotometric method made it possible to calculate the value of the luminous flux equal to 1350 lm and 1140 lm, respectively, for LED matrices containing 8 LEDs with the studied phosphors.

Crystal structure of strontium aluminates phosphors containing bismuth oxides

The composite phosphors SrAl2O4/Sr3Al2O6:Bi2O3/Bi2O4 synthesized by a solid-phase approach have been studied by means of X-ray diffraction, Raman spectroscopy, and optical spectroscopy methods. A redistribution of Bi3+ ions between two phases was observed by changes in crystal parameters, bond length, and vibrational frequencies on Raman spectra. A relationship between the structure of the host matrix and the optical characteristics of phosphors has been established.

Confinement reaction synthesis of CsPbBr3 quantum dots within long afterglow mesoporous materials as lighting equipment

Long afterglow materials are fluorescent materials with unique optical properties and excellent light-converting materials. However, long afterglow materials have the problem of emitting relatively single colors that are difficult to change, thus limiting their further application. Here, we propose a composite method of fully inorganic cesium lead perovskite quantum dots (QDs) with long afterglow materials, which uses the confinement reaction of CsPbBr3 in the pores of mesoporous CaAl2O4:Eu2+, Nd3+ (M-CAO) during high-temperature melting to form M-CAO-CsPbBr3. M-CAO-CsPbBr3 has better thermal and photostability than the common composite materials. Meanwhile, CsPbBr3 QDs can generate green afterglow emissions by absorbing the afterglow energy of M-CAO. In addition, the polydimethylsiloxane (PDMS) film formed by mixing the composite material phosphor M-CAO-CsPbBr3 with PDMS by heating and curing showed bright green fluorescence under 365 nm UV illumination, and it could still exhibit a weak green afterglow under dark conditions after stopping the irradiation. This article is an essential reference for long afterglow materials and anti-counterfeit labels.

Comparative study of composite single crystal and polycrystalline YAG:Ce phosphors for laser-based lighting applications

YAG:Ce, a widely employed phosphor for LED wavelength conversion applications, comes in different forms, including polycrystal (powder), single crystal, and composite single crystal varieties. We investigated Epoch NeoTM, a composite single crystal incorporating Al2O3 as a heat distribution and optical guiding material embedded within its luminescent core. The properties of Epoch Neo were analyzed and compared with those of its polycrystal counterparts in this paper. Multiple characterization techniques like chromaticity points, color temperature, phosphor temperature, and speckle pattern were employed to study the effect of variable laser input power on both polycrystal powder and composite single crystal of YAG:Ce. It was found that under the influence of pumping blue laser high input optical power the composite single crystal phosphor’s performance was significantly better compared to that of the polycrystal.

Performance of Ce:YAG-MgO composite ceramics as high-power LED phosphor densified by non-reactive sintering

A novel white light converter has been successfully synthesized using a non-reactive sintering process to afford a fully densified Ce:YAG-MgO composite ceramic phosphor with high wavelength conversion efficiency under excitation at 450 nm. The composite obtained by HIP (hot isostatic pressing) treatment at 1080 ºC has no residual pores and the XRD (X-ray diffraction) analysis shows that there are no secondary phases other than Ce:YAG and MgO, moreover, the EDS (Energy-dispersive X-ray spectroscopy) analysis indicates no interdiffusion at the Ce:YAG-MgO contact interface. The thermal conductivity of 5–7.5 wt% Ce:YAG-added MgO composites is over 40 W/mK, nearly reaching the theoretical value. Due to the synergetic effect of “the difference in refractive index between MgO and Ce:YAG” and “MgO matrix with strong birefringence”, the excitation light (450 nm) is multiply scattered inside the composite medium, which provides efficient excitation even in a thin medium, resulting in the photoluminescence intensity that is 2.6 times higher than that of transparent Ce:YAG ceramics. This innovative white light converter combines a highly thermal conductive MgO matrix and Ce:YAG phosphor with high emission intensity.

Advancements of Lanthanide-doped Phosphors in Solid-state Lighting Applications

Abstract: The challenge of energy conversion and enhancement has been a problem in the world of lighting technologies as the population and global industrialization grow rapidly. Solid-state lighting (SSL) has proven to be a better alternative in the illumination industry because of its environmentally friendly and high energy efficiency. Lanthanide-doped phosphors have gained global attention in SSL because they have versatile applications with enhanced overall performance and luminescence. This review delves into the advancement in lanthanide-doped phosphors for Solid-state lighting (SSL) applications. It discusses the in-depth analysis of how to tailor the crystal lattice design, optimize the host material for emission efficiency, and minimize the non-radiative pathways. This paper further discusses the lanthanide-doped phosphor composition, strategies to obtain desired emission spectra, and enhanced color rendering index with the Energy transfer mechanism and the synthesis techniques. This review also addresses 3 processes for expanding the light spectrum, current challenges, future directions, and emerging trends present in the lanthanide-doped phosphor in Solid-state lighting (SSL) applications.

Bright white light emission from lanthanide oxide LaGdO3 for LED lighting by Bi3+ to Eu3+ energy transfer.

Phosphors with intrinsic white light emission are of great potential in constructing high-quality white LEDs (WLEDs). In this work, we propose the use of energy transfer from Bi3+ to Eu3+ ions for white light emission. A unique Bi3+-activated phosphor LaGdO3 (LGO):Bi3+ was generated using the conventional high-temperature solid-state process. An energy transfer was established by introducing Eu3+ into the phosphor composition. The emission colour of LGO:Bi3+,Eu3+ phosphors changes from cyan to white to orange-red depending on the Bi3+/Eu3+ doping proportion. The energy transfer between the Bi3+ and Eu3+ ions results from the dipole-dipole interaction. The LGO:Bi3+,Eu3+ phosphors were combined with a near-ultraviolet chip to successfully create a single-component WLED device with a colour-rendering index of 92.4. Our work demonstrates the energy transfer as a route for single-component white light emission and makes LGO:Bi3+,Eu3+ phosphors one of the candidate materials for near-ultraviolet lighting.