Fluorescent Powder Research Articles

Recyclable photoluminescent elastomer incorporating carboxyl‐functionalized fluorescent powder via dynamic covalent cross‐linking

AbstractThe rapid development of photochromic devices has stimulated great enthusiasm for the design and preparation of luminescent materials. Introducing fluorescent powder ZnS:Cu into the cross‐linked polymer matrix is an efficient and simple method to obtain photochromic materials with excellent comprehensive performance. However, the traditional method is to directly introduce fluorescent powder into the polymer matrix by physical mixing. This not only increases the internal defects of the polymer and reduces the mechanical properties, but also hinders the fluorescent powder from absorbing external energy and reduces its luminescence efficiency. In addition, few studies have focused on recyclable photochromic luminescent materials. Inspired by dynamic covalent cross‐linking technology, this paper first modified fluorescent powder with 3‐mercaptopropionic acid and then introduced it into epoxy silicone rubber to prepare recyclable luminescent elastomer. Compared with traditional physical blending, the mechanical properties and luminescence performance of the covalently bonded luminescent elastomer were improved. Excellent mechanical properties and luminescence performance were maintained in multiple recycling processes. This paper provides a feasible and simple scheme for the preparation of recyclable luminescent elastomers, paving the way for the recycling and long‐term utilization of photochromic luminescent materials.

Evidence of aerosol transmission of African swine fever virus between two piggeries under field conditions: a case study.

African swine fever (ASF) is a devastating and economically significant infectious disease that has caused enormous losses in the commercial pig sector in China since 2018. The primary transmission routes of the African swine fever virus (ASFV), the causative agent of ASF, are direct pig-to-pig contact or indirect contact with virus-contaminated objects. While aerosol transmission of ASFV has been previously reported under experimental conditions, no reports have described it under field conditions. In this case study, aerosol-associated samples were collected over a monitoring period of 24 days in an ASFV-positive farm. A complete and clear chain of ASFV transmission through aerosols was observed: pigs in Room A on Day 0-aerosol in Room A on Day 6-dust of air outlets in Room A on Day 9-outdoor aerosols on Day 9-dust of air inlets in Room B on Day 15-aerosols/pigs in Room B on Day 21. Furthermore, a fluorescent powder experiment confirmed the transmission of dust from Room A to Room B. This study represents the first report providing evidence of aerosol transmission of ASFV under field conditions. Further research is needed to study the laws of aerosol transmission in ASFV and develop effective strategies such as air filtration or disinfection to create a low-risk environment with fresh air for pig herds.

Dual-emitting from Bi[formula omitted], Ln[formula omitted] (Ln [formula omitted] Eu, Sm) co-activated Ca[formula omitted]Sb[formula omitted]O[formula omitted] phosphor for optical temperature measurement

In this paper, a series of Ca(2−x−y) Sb2O7: xBi3+, yLn3+ (Ln = Eu, Sm) fluorescent powder samples were successfully obtained, which used the traditional high-temperature solid-phase synthesis method in the preparation process. Samples of Ca2Sb2O7: Bi3+, Ln3+ (Ln = Eu, Sm) fluorescent powder samples were structurally and optically characterized​ using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), photoluminescence excitation spectroscopy and emission spectroscopy, and fluorescence decay measurements. The results show that the prepared Ca(2−x−y) Sb2O7: xBi3+, yLn3+ (Ln = Eu, Sm) samples have an orthogonal spider web structure, which remains unchanged whether Bi3+ is single doped or Bi3+ is co-doped with Ln3+ (Ln = Eu, Sm). Under ultraviolet lamp (λex=340nm) irradiation, Bi3+ doped Ca2Sb2O7 powder shows a wide emission band centered at 435 nm, which is owing to the 3P1→1S0 transition of Bi3+ ion. Therefore, the effect of Bi3+ and Ln3+ (Ln = Eu, Sm) co-doped Ca2Sb2O7 samples on the luminescence intensity of the samples at different concentrations was studied. When the temperature was varied from 293 K to 483 K, the absolute temperature sensitivity (Sa) of doped Bi3+/Eu3+ and Bi3+/Sm3+ phosphors is 0.001K−1 (at 483 K) and 0.02K−1 (at 293 K), respectively, and the relative temperature sensitivity (Sr) is 1.03% K−1 (at 343 K) and 1.19% K−1 (at 293 K), respectively. These results demonstrate that Ca(2−x−y) Sb2O7: xBi3+, yLn3+(Ln = Eu, Sm) phosphors are prospective double emission thermal thermometers.

Low energy X-ray dosimeter based on LYSO:Ce fluorescent powder.

Cerium-doped lutetium yttrium orthosilicate (LYSO:Ce) powder has been synthesized by the co-precipitation method. The influence of the Ce3+ doping concentration on the lattice structure and luminescence characteristics of LYSO:Ce powder was investigated by X-ray diffraction (XRD) and photoluminescence (PL). The XRD measurement indicates that the lattice structure of LYSO:Ce powder was not changed by doping ions. PL results show that LYSO:Ce powder has better luminescence performance when the Ce doping concentration is 0.3mol%. In addition, the fluorescence lifetime of the samples was measured, and the results show that LYSO:Ce has a short decay time. The radiation dosimeter was prepared by LYSO:Ce powder with a Ce doping concentration of 0.3mol%. Radioluminescence properties of the radiation dosimeter also were studied under X-ray irradiation at doses from 0.03 to 0.76Gy, with dose rate from 0.09 to 2.284Gy/min. The results show that the dosimeter has a certain linear relationship response and stability. The radiation responses of the dosimeter at different energies were obtained under X-ray irradiation with X-ray tube voltages ranging from 20 to 80kV. The results show that the dosimeter has a certain linear relationship response in the low energy range of radiotherapy. These results indicate the potential application of LYSO:Ce powder dosimeters in remote radiotherapy and online radiation monitoring.

MgGa2O4:Mn2+, Mn4+: A dual-emitting phosphors with unique optical temperature sensing

Single-doped manganese with two luminous centers of MgGa2O4 fluorescent powder was generated through a solid-state reaction. It goes into great detail about the optical characteristics and temperature sensitivity of MgGa2O4:Mn2+, Mn4+. The emission spectrum activated by 322 nm UV light showed a sharp green peak for Mn2+ at 502 nm and a red peak for Mn4+ at 694 nm. Additionally, Mn4+ emission reduces as temperature rises, but Mn2+ emission increases initially before declining, demonstrating that Mn2+ and Mn4+ have differing temperature sensitivity in the MgGa2O4 host. The performance of temperature sensor capability at 80–500 K was investigated by the fluorescence intensity ratio (FIR) technology. The sample’s maximal relative sensitivity (Sr) value is calculated as 1.64% K−1 at 260 K, indicating that MgGa2O4:Mn2+, Mn4+ have considerable potential for optical thermometry.

Excitation-wavelength-dependent photochromic Bi3+/Ln3+(Eu3+, Er3+)-codoped phosphors for anticounterfeiting applications

Fluorescent powders exhibiting excitation dependence and luminescent discoloration are profoundly relevant for concealing information and enhancing optical antiforgery protection. In this study, Bi3+/Ln3+ (Eu3+, Er3+)-doped phosphors exhibiting multicolor luminescence and excitation wavelength dependence were synthesized. The Bi3+/Eu3+-codoped phosphors emitted blue, pink, lavender, and red lights under excitation from conventional ultraviolet (UV) sources. In addition to emitting blue light, the Bi3+/Er3+-codoped phosphors also transmitted upconversion-emission light from green to yellow under 980-nm laser excitation. Additionally, the luminous color of the Ca3Y2Ge3O12:0.01Bi3+, 0.2Er3+ phosphor changed from yellow to orange as the temperature increased. Combining the above luminous-color-change phenomena, the word-hiding experiment exhibited excellent realistic information hiding, with complex color transformation in the stamen and petal parts of the flower pattern. Furthermore, rapid multimodal and complex discoloration was achieved using easy-to-obtain light sources, confirming the potential of Bi3+/Ln3+ phosphors for anticounterfeiting applications.

Fabrication, structure, and luminescent properties of Cr-doped CaMgSi2O6 fluorescent ceramics

Chromium-doped CaMgSi2O6 ([Formula: see text]: CMS) fluorescent ceramics with various concentrations were fabricated using solid-state reaction technique. All the samples were sintered at 1250[Formula: see text]C for 3 h. Analysis of microstructure of the Cr[Formula: see text]: CMS ceramics shows homogeneous structure with grain size distributions between 0.86 nm and 2.26 nm. Luminescent spectra of the ceramics show two emission peaks, a strong peak at 872 nm and a weak peak at 960 nm because of [Formula: see text] transition of the Cr[Formula: see text] ions. Intensity of the emission peaks increases with Cr[Formula: see text] concentration, reaches maximum with 0.1 at.% Cr[Formula: see text], then decreases with higher Cr[Formula: see text] concentration. Owing to the differences in crystal field strength, the luminescent properties of the Cr[Formula: see text]: CMS fluorescent ceramics and powder are quite different.

Luminescent Polymer Composites for Optical Fiber Sensors.

Optical fiber sensors incorporating luminescent materials are useful for detecting physical parameters and biochemical species. Fluorescent materials integrated on the tips of optical fibers, for example, provide a means to perform fluorescence thermometry while monitoring the intensity or the spectral variations of the fluorescence signal. Similarly, certain molecules can be tracked by monitoring their characteristic emission in the UV wavelength range. A key element for these sensing approaches is the luminescent composite, which may be obtained upon allocating luminescent nanomaterials in glass or polymer hosts. In this work, we explore the fluorescence features of two composites incorporating lanthanide-doped fluorescent powders using polydimethylsiloxane (PDMS) as a host. The composites are obtained by a simple mixing procedure and can be subsequently deposited onto the end faces of optical fibers via dip coating or molding. Whereas one of the composites has shown to be useful for the fabrication of fiber optic temperature sensors, the other shows promising result for detection of UV radiation. The performance of both composites is first evaluated for the fabrication of membranes by examining features such as fluorescent stability. We further explore the influence of parameters such as particle concentration and density on the fluorescence features of the polymer blends. Finally, we demonstrate the incorporation of these PDMS fluorescent composites onto optical fibers and evaluate their sensing capabilities.

High colour rendering index and adjustable color gamut COB LED light source based on full blue light chips and fluorescent powder zoned coating

High colour rendering index and adjustable color gamut COB LED light source based on full blue light chips and fluorescent powder zoned coating

Evaluating Aseptic Presentation of Different Medical Device Packaging Configurations.

The Medical Device Regulation (MDR) of the European Union (EU) places greater emphasis on the usability of medical devices, with the goal of eliminating or reducing the risk of infection to patients. As this goal also is applicable to sterile packaging, ANSI/AAMI/ISO 11607-1:2019 introduced a usability evaluation requirement for aseptic presentation of terminally sterilized medical devices. In an effort to reduce contamination risks, this requirement focuses specifically on the sterile barrier system (SBS). However, research is limited on evaluating the usability of SBSs and their performance, from an aseptic presentation standpoint, in clinical settings. To address this research gap, we assessed 14 sterile medical devices with five different SBS configurations to elucidate how SBS configuration (type, size, and number of SBS layers) and user satisfaction levels affect usability. A total of 40 experienced clinical nurses participated in 280 individual trials (20 per SBS configuration), which were conducted in a simulated operating room. Ultraviolet fluorescent powder was used to simulate the contamination process and to evaluate the success or failure of the aseptic presentation. Pouch and tray configurations exhibited the best overall performance, while vent bags performed poorly and were considered less acceptable. Double SBS configurations outperformed single SBS configurations. The study highlighted the importance of appropriate SBS symbols to identify SBS layers, which is another patient safety-related requirement of the EU MDR. The current work also includes an analysis of the powder contamination method used in conducting the usability evaluation.

Study on luminescence properties of Bi3+ doped Ba2YAlO5：A wide-band yellow emitting phosphor with excellent thermal stability

The development of phosphors with excellent thermal stability remains a difficult challenge. Here, we synthesized a novel heat-quenching resistant phosphor Ba2YAlO5 doped with Bi3+ by traditional high temperature solid-state method. The crystal structure and luminescence properties of the samples were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflection (DR) spectra, photoluminescence (PL) spectra and so on. Under 324 nm excitation, the phosphor emits a broad-band yellow light with a peak value of 571 nm and a full width at half maximum (FWHM) of 125 nm. It is worth noting that the integrated emission intensity at 560 K is still close to that at room temperature, which can be attributed to the thermal compensation capability of the electron trap energy levels. The matrix may also have high lattice stiffness to reduce thermal quenching. In addition, Ba2YAlO5: Bi3+ exhibits yellowish white light with CIE coordinates of (0.4203, 0.4536) and a color temperature of 3669 K under excitation of a 310 UV chip. The above results indicate that Ba2YAlO5: Bi3+ is a promising yellow fluorescent powder with excellent luminescence performance for high-power devices.

Prospective directions for the development of means and methods for detection and fixation of handprints

Identification by fingerprints remains one of the most common ways of proving the involvement of persons in the commission of a criminal offense in law enforcement practice around the world. Over the past hundred years, the methodology of detecting and collecting fingerprints at the scene has evolved from the first attempts to use carbon black and metal powders (at the end of the 19th century) to the use of modern fluorescent powders and molecularly selective chemical compounds.
 The type of surface and its condition affect the choice of one or another means of finding and developing a papillary pattern. According to empirical data, difficulties arise when working with heterogeneous surfaces, leather products, granular and porous materials. Until recently, the search for prints at the scene has been negated by contamination of surfaces, as well as the presence of moisture or organic liquids. It was practically impossible to develop outdated traces, as well as to determine the approximate time of leaving the trace. The analysis of the latest foreign publications has shown significant achievements that help to effectively solve the above problems, significantly expanding the arsenal of forensic tools and methods of working with traces at the scene.
 Physical methods of detecting traces have received significant development. Among them, it can be singled out the use of luminescent dactyloscopic powders, which better visualize papillary patterns under UV and IR special lighting. Silicon nanoparticles with the addition of dyes, depending on the color of the surface, have shown a better result compared to the cyanoacrylate method.
 The scientists have managed to improve the results regarding the detection of outdated traces by combining homogeneous chemical compounds. The main ones among them are ninhydrin, which works well with dirty and wet surfaces, as well as silver nitrate and DFO solution, which reacts with organic secretions of human skin well. A vacuum deposition method (VMD) has proven to be effective, making visible prints on the surfaces of four-year-old organic plastic. The direction of immunological research of the sebaceous trace of a finger for taking samples for a DNA profile remains relevant. The presented review of foreign and domestic experience has indicated the continuation of active searches for improving methods and means of working with traces.

Study of thermoluminescence, photoluminescence and dosimetry for the YAGG:Ce (Y2.96Al3.4Ga1.6O12:0.04Ce) phosphor

The comprehensive effect of ionizing radiation should be considered in the use and or analysis of certain electronic equipment. Fluorescent powders are widely used in electronic equipment, so they are attempted to be used as thermoluminescence (TL) dosimeter directly. Green YAGG:Ce phosphors were prepared by a high-temperature solid-state reaction method. The TL glow curves, TL dose response, TL three-dimensional (3D) spectra (80 K–800 K) and photoluminescence spectra for the phosphors were measured. The measurement results show that the luminescence peak temperature for the sample occurs at approximately 458 K and the luminescence peak temperatures in the TL 3D spectra are located at 130 K, 240 K and 458 K; there are four kinds of activation energies of traps in the material; the TL response of each component for the YAGG:Ce phosphor shows good linearity and the detection sensitivity of the phosphor is estimated to be less than 2 mGy. TL 3D spectra and PL spectra show that the luminescence from the phosphors arises from the 2D3/2 → 2F5/2,7/2 transition of Ce ions, and the TL 3D spectra at 130 K, 240 K and 458 K are almost the same, which proves that the temperature can hardly change the relative probability of the 2D3/2 → 2F5/2,7/2 transitions. The results show that YAGG:Ce could be used as dosimeter material.

One-step large-scale fabricating aggregation-induced emission carbon dots with strong solid-state fluorescence emission

Carbon dots (CDs) possessing favorable stability and optical properties have attracted extensive attention for their potential application in solid-state light-emitting devices. However, due to the stacking of π–π conjugated systems, solid-state CDs often suffer aggregation-caused quenching effect, resulting in fluorescence quenching. There are few reports on solid-state fluorescent CDs fabricated without using other solid matrices. In this work, we report a facile approach for one-step synthesis of yellow-green solid-state CDs without using matrix. The synthesized CDs show an independent excitation and emission in various organic solvents. Importantly, the prepared CDs show solvatochromism and aggregation-induced emission redshift effect. By simply drying the colloidal solution of CDs, yellow-green solid-state fluorescent CD powders with a photoluminescence quantum yield of 25.5% can be obtained. High-performance white light-emitting diodes with Commission Internationale de L'Eclairage coordinates at (0.35, 0.37) are prepared by employing the yellow-green solid-state CD powders. The corresponding color temperature and color rendering index are 4691 K and 91.5 under ultraviolet excitation of 365 nm, respectively. The facile synthesis method of solid-state fluorescent CDs with unique optical features offers promising future for CDs-based optoelectronic devices.

The Effect of Zinc Oxide Nanoparticles on Properties and Burn Wound Healing Activity of Thixotropic Xymedone Gels

Zinc oxide nanoparticles (ZnO NPs) modified by oxopyrymidine alcohol, also known as xymedone (Xym), were obtained and studied using FTIR, UV-vis, and fluorescent spectroscopy, and SEM, BET, powder XRD, and DLS analysis. A formulation of thixotropic hydrophilic gels containing Carbopol-based Xym and ZnO NPs was developed. A vertical Franz cell with a cellulose acetate membrane was used as a model to investigate the passive diffusion of the gel components by AAS. The gel components—Xym and ZnO NPs—were shown to penetrate through acetyl cellulose membrane within 5–7 h depending on an initial amount, and its values were in the range of 56–77%. The penetration of modified ZnO NPs by Xym was more effective in contrast to ZnO NPs without modification. The burn wound healing activity of ZnO NPs–Xym gel was demonstrated on a thermal burn wound model on rats. SOD and GR activity was increased by 30–35% during ZnO NPs–Xym gel treatment, the burn area on 10 postburn day decreased by 10% in contrast to a positive control, Methyluracyl®® ointment.

Valorization of spent fluorescent lamp waste glass powder as an activator for eco-efficient binder materials

• Use of spent fluorescent lamp waste glass was investigated. • Alternative activators were successfully synthesized using this waste glass. • These activators had similar effects to the commercial activator in producing AAM. • A recycling route for hazardous e-waste was preliminary demonstrated. Spent fluorescent lamp waste glass is considered hazardous and requires an appropriate management and recycling route. Due to its highly alkali-siliceous nature, the feasibility of using the powdered form of the fluorescent lamp waste glass (FGP) to synthesize an activator for activating the GGBS/FA blend was studied. Additionally, the solubility and reactivity of FGP were compared with waste beverage bottle glass powder (BGP). Results showed that FGP had a higher solubility and reactivity than BGP due to the presence of the higher network modifiers. A significant enhancement in solubility (about 19 %), total heat release (57 – 62 %), and compressive strength (85 – 89 %) was observed in FGP-based mixtures, implying its suitability for activator design. The mechanical and microstructural properties of the alkali-activated pastes (AAP) prepared with the FGP activators were similar to those prepared with the commercially sourced reference activator. Before activator preparation, washing FGP with water or acid enhanced the availability of soluble silicates. The activators prepared with those washed FGP accelerated the alkali-activation process and helped achieve better strengths for the corresponding AAP. Their 28-day compressive strength values were in the range of 36 – 40 MPa and comparable to the control (FGP-C). In addition, the microstructural analysis showed that the reaction products in these mixtures were of C-(N)-A S H gels type with high Si/Al and low Ca/Si ratios. Thus, a recycling route for spent fluorescent lamp waste glass was preliminary demonstrated in this study.

The fear diet: Risk, refuge, and biological control by omnivorous weed seed predators

Weed seed biocontrol by omnivorous mice and insects can limit weed seedbanks, but this ecosystem service can be difficult to predict given the broad diet breadth of seed predators and their potential for intraguild predation. Seed foraging behavior is further modified by fluctuating cues of predation risk from higher trophic levels and the availability of refuge habitat. Uncertainty about whether co-occurring insects and mice additively contribute to weed biocontrol or interfere with each other via intraguild predation limits our ability to recommend habitat management strategies that reliably promote seed destruction. Using seed removal assays, fluorescent powder tracking, and stable isotope analyses, we assessed effects of a predation risk cue (moonlight) on mouse foraging patterns in a patchwork of vegetated and exposed plots in a cultivated field. Mouse foraging activity decreased on exposed ground during the full moon, compared to dark nights, yet foraging movements were unaffected by moon cycle within refuge patches. Weed seed consumption was more than three times higher in cover than exposed soil, and 78% of that difference was attributable to invertebrate granivores. Mice and invertebrate granivores both exhibited higher foraging activity in cover, indicating co-occurrence of intraguild predators and prey. However, stable isotope analyses of fecal samples revealed that mice captured in refuge habitats fed at slightly lower trophic levels than those in exposed habitats (suggesting minimal intraguild predation in refuge habitat), and mouse diet was unaffected by moonlight. Despite increased availability of invertebrate prey in cover patches, mice do not appear to preferentially exploit prey when avoiding their own predators or interfere with weed seed predation. Therefore, functional redundancy of mice and invertebrate seed predators in cover crops and other refuge habitats may strengthen and stabilize weed seed biocontrol.

Degradation of polymer banknotes through handling, and effect on fingermark visualisation

The surface structure of mint (as-issued) and handled polymer five pounds sterling banknotes was studied by atomic force microscopy and laser scanning confocal microscopy. A total of 1856 fingermarks on mint and handled banknotes from four different issuing banks (Bank of England, Bank of Scotland, Royal Bank of Scotland and Clydesdale Bank) were visualised with Vacuum Metal Deposition (VMD), Cyanoacrylate Fuming (CAF) and, on Clydesdale Bank notes, magnetic fluorescent powder. VMD was significantly more effective in developing fingermarks on handled banknotes, across all the banks studied, although effectiveness varied with issuing bank. For example, on handled Bank of England notes 45% of marks showed ridge detail with VMD development and 28% with CAF; for Bank of Scotland handled notes success rates were 17% with VMD and 1% with CAF. Microscopy of degraded banknotes showed the loss of intaglio printing and the formation of a cracked surface structure in the handled notes. These features can lead to the trapping of powder, or contaminants, increasing quantity of development agent in fingermark background between the ridges, decreasing contrast and decreasing performance of powder-based fingermark development techniques. These same features can restrict the migration of components of the fingermark, preventing fingermarks degrading through spread of material and thus reducing potential formation of empty prints, so that VMD development is not adversely affected.

SLAP@g-C3N4 Fluorescent Photocatalytic Composite Powders Enhance the Anti-Bacteria Adhesion Performance and Mechanism of Polydimethylsiloxane Coatings.

Fluorescent antifouling and photocatalytic antifouling technologies have shown potential in the field of marine antifouling. SLAP@g-C3N4/PDMS (SLAP@CN/PDMS) composite antifouling coatings were designed and prepared using g-C3N4, sky-blue long afterglow phosphor (SLAP), and polydimethylsiloxane (PDMS). The fluorescence emitted by SLAP under dark conditions was used to excite g-C3N4 for fluorescent photocatalysis and to prolong the photocatalytic activity of g-C3N4. Key data were collected by testing and characterization and are presented in this work. The results showed that g-C3N4 was successfully coated on the SLAP surface and formed a heterogeneous structure. After the composite powder was added to the PDMS coating, the coating maintained low surface energy but enhanced the surface roughness of the coating. The experimental results of degraded Rhodamine B (RhB) showed that SLAP prolonged the g-C3N4 photocatalytic activity time. The anti-marine bacterial adhesion performance of the coating was investigated by bacterial adhesion experiments. The results showed that SLAP@CN could effectively improve the anti-bacterial adhesion performance of PDMS coating, in which the anti-bacterial adhesion performance of SLAP@CN-2.5/PDMS was improved by nearly 19 times. This antifouling coating introduces fluorescent antifouling, photocatalytic antifouling, and fluorescence-driven photocatalytic antifouling based on the low surface energy antifouling of silicones and achieves “all-weather” fluorescent photocatalytic antifouling.

Opportunities in Critical Rare Earth Metal Recycling Value Chains for Economic Growth with Sustainable Technological Innovations

Rare earth elements (REEs) are often referred to as the industrial vitamins and the key drivers of the industry 4.0 revolution. The current global supply chain of REEs for green and high-tech applications with more than 220 metric kilotons per year involves a huge environmental impact (backpack) as well as the piling up of radioactive by-products to about 1.5 times the amount of REEs produced. E-wastes and municipal solid waste streams are attractive secondary resources. The current opinion paper discusses the recycling of rare earth metals along the value chain with the opportunities and challenges associated with it. The way to mitigate the economic constraints has been pointed out in terms of competitive quality and recovery of the REEs when compared with the mineral exploration options in the market. It is also emphasised that the technical complexity, capital expenditures and operating expenses need to fit the economic boundary conditions to make the recycling viable. In future, the appropriate REE-rich feedstocks such as fluorescent lamp e-waste powders and magnets can be potential secondary sources of the critical raw materials necessary for the green transition. The success of the viable recycling approaches and technologies will largely depend on the public–private partnerships based on hybrid financing models and local know-how generation to compete with quasi-monopoly in the REE supply chains. However, to break the monopolies, it will not be sufficient to only recycle the REEs; it will also be relevant to diversify the industries that produce REE-containing goods from recycled waste streams.