Intense Green Light Research Articles

Varied Growth Media Necessitate Different Light Regimes for Indoor Duckweed Cultivation

Controlled indoor cultivation of duckweed plants can support remediation of wastewaters through generation of plant biomass. Despite numerous advantages, indoor cultivation of duckweeds on agri-food wastewaters remains underexplored. Lighting regimes need to be optimised for duckweed growth and affordability of energy consumption, as it has been shown that the composition of wastewater growth medium can alter light utilisation. In the present study, four duckweed (Lemna minor) clones were grown under four different light regimes on either optimised half-strength Hutner’s medium or wastewater derived from the liquid fractions of anaerobically digested pig slurry. Cultivation of L. minor was assessed for the four light regimes using a commercial hydroponics plant growth medium in a 3.96 m2 multitiered cultivation system. When cultivated on optimised half-strength Hutner’s medium or diluted pig slurry under laboratory conditions, it appeared that photoperiod rather than light intensity was more important for duckweed growth. Yet, under moderate flow conditions within a larger scale multitiered cultivation system, greater light intensity appeared to support duckweed cultivation irrespective of photoperiod. These findings emphasise the need to move beyond small-scale and static assessments of duckweed before embarking on larger, industry-relevant scales.

Improving plant growth, anthocyanin production and oxidative status of red lettuce (Lactuca sativa cv. Lolla Rossa) by optimizing red to blue light ratio with a constant green light fraction in a plant factory

Previous studies have reported contrasting effects of light quality on plant growth and anthocyanin content in lettuce leaves. This study aimed to optimize the red-to-blue light ratio with a constant green light fraction to improve biomass and anthocyanin production in red lettuce (Lactuca sativa cv. ‘Lolla Rossa’) in a plant Factory. Six treatments with varying proportions of red (R, 660 nm) and blue (B, 450 nm), along with a constant fraction of green (G, 540 nm) light, recorded as R125:B25:G50, R120:B30:G50, R112:B37:G50, R100:B50:G50, R75:B75:G50, and R50:B100:G50 were set up in this study. The total photosynthetic photon flux density for all treatments was 200 μmol m−2s−1 with a green light intensity of 50 μmol m−2s−1. The results showed that, compared with treatment R50:B100:G50, the fresh and dry weights, leaf length, leaf area and stem width of lettuce plants under treatment R125:B25:G50 showed an increase of 73.4 %, 47.8 %, 35.5 %, 54.9 %, and 58.3 %, respectively. Additionally, red light was found to promote increased weight of lettuce plant roots. Further, the anthocyanin content, nitrate content, and stomata density under treatment R50:B100:G50 were 6.75, 1.5, and 1.42 times higher than those under treatment R125:B25:G50. Enzymatic activities such as hydrogen peroxide (H2O2), superoxide dismutase (SOD), ascorbic acid (AsA), and anthocyanin concentration per fresh weight of plant were higher under treatment R100:B50:G50, comparing with those under treatment R125:B25:G50. The above results indicate that a higher red-to-blue light ratio enhances plant biomass, photosynthesis, and certain nutrients, while increasing the blue ratio promotes anthocyanin accumulation and antioxidants, protecting cells from oxidative stress. Based on this analysis, treatment R100:B50:G50 can be considered as the suitable light spectrum for optimal growth, anthocyanin accumulation and antioxidant activity of lettuce plants. Further researches are needed to explain these effects and refine lighting methods for optimal lettuce production and nutritional quality.

Thermally stable Gd4(P2O7)3: Tb3+ phosphor synthesized via co-precipitation: A study on pH-dependent formation and luminescence

A uniformly doped Gd4(P2O7)3: Tb3+ phosphor was synthesized via the co-precipitation method. The influences of pH and annealing temperature on the formation, phase composition, and morphology of the phosphors were thoroughly investigated. The phase structure, morphology, thermal properties, and luminescence properties of the phosphors were characterized using XRD, SEM, FT-IR, TG-DSC, Raman, and photoluminescence (PL) spectroscopy. The Gd4(P2O7)3: Tb3+ phosphors exhibited optimal crystallinity and phase purity after adjusting the pH to 0.86 and annealing at 850 °C. The excitation-emission spectra demonstrated intense green light emission at 543 nm under 274 nm UV excitation, attributed to the 5D4-7F5 transition of Tb3+. The internal quantum efficiency (IQE) of the Gd4(P2O7)3: 2 % Tb3+ sample is 39.10 %. The luminescent intensity of the Gd₄(P₂O₇)₃: 2 % Tb³⁺ phosphor at 491 K retains 94 % of its intensity at 298 K, demonstrating remarkable luminescent thermal stability. The luminescent lifetime of the sample shows negligible change below 441K, remaining approximately 35.6 ± 0.2 ms. These finding confirm the outstanding luminescent thermal stability of Gd₄(P₂O₇)₃: Tb³⁺ phosphors, positioning them as promising candidates for high power density excitation and high temperature lighting applications.

Preparation of Imidazole Compounds as Latent Curing Agents and Their Application in RGB LED Packaging.

LED packaging miniaturization has raised more requirements for LED materials. As a material contacting the LED chip directly, the reliability of LED non-conductive adhesive has also garnered increasing attention. This study optimized the formula for non-conductive adhesives for an imidazole curing system. The optimized composition of the adhesive is 25%wt for the curing agent and 30%wt for the silica. The prepared non-conductive adhesive has a 7-day pot life and 9-month storage stability. The shear strength reached 87 g and 72 g at 25 °C and 160 °C, respectively. The reliability of the LED modules packaged with the non-conductive adhesive was researched. The green and blue light intensity change was 4.7%, 43.7%, respectively, indicating good anti-aging properties. The blue light decay was mainly due to adhesive aging. The non-conductive adhesive effectively prevented "caterpillar" growth. This provides useful and practical guidelines for industry for applications of adhesive in different packages.

Solid-state reaction synthesis of LuPO4:Yb3+, Tb3+ phosphors and the ultraviolet/near-infrared responsive spectra performances

Yb3+/Tb3+ co-doped LuPO4 phosphors were prepared by solid-state reaction method. The effects of Yb3+/Tb3+ doping concentrations on the downshifting and upconversion spectral performances of the synthesized phosphors were investigated. Upon the ultraviolet light excitation, the phosphors show obvious visible light emission, which can be assigned to the 5D4→7FJ (J=6, 5, 4, and 3) transitions of Tb3+ ions respectively, the green light emission at 543 nm is dominant. Upon 980 nm excitation, the phosphors display intense green and blue light emission, and weak yellow and red light emission, which originates from the cooperative energy transfer process between Yb3+ and Tb3+ ions. The synthesized LuPO4:Yb3+, Tb3+ phosphors show good ultraviolet/near-infrared responsive spectra, color-tunable and thermal-stability performances and may have potential applications in the related fields.

Substitutional effects of the anionic group systems [BO33−], [PO43− ], and [SO42−] on the down-conversion photoluminescence properties of Y2O3:Er3+ nanophosphors

A series of Y2O3, Y2O3: Er3+ (1 %) and Y2O3-AG: Er3+ (1 %) (where AG = BO33−, PO43−, and SO42−) nanophosphors were prepared via a chemical combustion technique. The primary X-ray powder diffraction results showed that the Y2O3:Er3+ phosphor materials crystallized into a cubic standard structure, while the Y2O3-AG: Er3+ phosphor materials transformed to hexagonal and tetragonal structures for the [PO43−] and [BO33−]-based phosphors, respectively. However, no changes were observed for the [SO42−]-based phosphor materials. The scanning electron microscope micrographs revealed that the particles were formed in the nanometre range with different sizes and shapes. The fourier-transformed infrared spectra showed the presence of various structural groups in the pure Y2O3 and Y2O3-AG: Er3+ phosphors. In addition to that, the optical bandgap energy values were obtained using the diffuse reflection spectra (DRS) spectra and Kubelka-Munk function theory. Under UV-379 nm excitation for the Y2O3-AG: Er3+ phosphors, the Y2O3–SO4: Er3+ emitted the most intense green light at 563 nm wavelength. The Commission Internationale de l'Elcairage colour coordinates and correlated color temperature values indicated that the Y2O3:Er3+, Y2O3-PO4:Er3+, and Y2O3–SO4:Er3+ phosphor materials are potential candidates for producing enhanced green color components in white light-emitting diode (w-LED) applications.

Thermal enhanced upconversion luminescent of Sc2W3O12:Yb3+/Er3+ for optical temperature measurement

In recent years, people have higher requirements for temperature measurement with the development of optical temperature measurement. Meanwhile, the emission intensity of most fluorescent materials is quenched by thermal effects as the temperature rises, making it challenging to meet the specifications of fluorescent materials employed in the field of pyrometry. In this work, the pure phase of Yb3+/Er3+ ions co-doped Sc2W3O12 phosphor was successfully prepared. Sc2W3O12: Yb3+, Er3+ samples showed strong green emission and weak red emission. The optimal doping concentrations of Yb3+ and Er3+ ions are 0.3 and 0.02, respectively. The potential upconversion luminescence (UCL) mechanism was investigated by analyzing the UCL spectra, downshift emission spectra and power dependence spectra of Yb3+/Er3+ ions co-doped Sc2W3O12. The upconversion emission excitation path is mainly through Er3+ ions from 4I11/2 absorption photon excitation to 4F7/2 energy level, then the photons of 4F7/2 relaxes to green and red emission energy levels and returns to ground state for emitting green and red light. In addition, according to the UCL green light intensity increasing with temperature, it serves as an optical temperature sensor. The temperature sensitivity of the sample was explored in the temperature range of 298 K–673 K. This study provides new materials and ideas for non-contact temperature sensing.

A single phased full color emitting pyrochlore type phosphor La2Y0.66Sn0.66Sb0.66O7: Bi3+, Eu3+ for white light emitting diode applications (WLEDs)

The phosphor converted white light emitting diodes (pc-WLEDs) are advancing rapidly in replacing the conventional fluorescent and incandescent light sources. However, the current technology of pc-WLEDs limits their large scale indoor lighting applications due to their high correlated color temperature (CCT) and poor color rendering index (CRI). In this work, a single phased full color emitting phosphor in the pyrochlore oxide system, La2Y0.66Sn0.66Sb0.66O7: Bi3+, Eu3+ has been developed by the high temperature ceramic route. The developed phosphors are characterized by powder X-ray diffraction, luminescence and lifetime measurements. Upon near UV excitation wavelength, the singly doped phosphor, La2Y0.66Sn0.66Sb0.66O7: Bi3+ show intense blue green light in the wavelength region 400–600 nm due to the characteristic transitions (3P1 → 1S0) of Bi3+. The emission spectral analysis suggests that there exist two luminescence centers of Bi3+ due to occupation of different crystallographic sites in the pyrochlore lattice of La2Y0.66Sn0.66Sb0.66O7. The deficit of red component in the emission spectra is overcome by the Eu3+ co-doping in the system, La2Y0.66Sn0.66Sb0.66O7: Bi3+, Eu3+ which results in the full color emission covering the visible spectral range up to 700 nm with broad peaks along with sharp narrow characteristic peaks of Eu3+. The full color emission of the La2Y0.66Sn0.66Sb0.66O7: 0.04Bi3+, yEu3+ phosphors can be tuned by adjusting the suitable Eu3+ dopant concentration and using appropriate energy transfer from Bi3+ to Eu3+. The full color emitting phosphor, La2Y0.66Sn0.66Sb0.66O7:0.04Bi3+, 0.06Eu3+ can be realized with the color coordinates (0.30, 0.36), and correlated color temperature (4383K). All these results demonstrate that La2Y0.66Sn0.66Sb0.66O7:xBi3+, yEu3+ are potential single phased full color emitting phosphors for the development of pc-WLEDs.

Luminescence properties of Tb3+ -doped sodium phosphate glasses for green laser and X-ray imaging application

Tb3+ doped sodium-gadolinium-aluminum-phosphate glass samples (PGNA) with chemical compositions 30Na2CO3:8Gd2O3:5Al2O3:(57- x)P2O5: x Tb4O7 (where x=0, 0.25, 0.5, 1.0, 2.0, 3.0, 4.0, and 5 mol. %) were manufactured by using adopting the conventional melt quenching technique. The PXRD study of the prepared samples was used to confirm the amorphous structure. FE-SEM, EDS, and FTIR studies were carried out to analyze the elemental and structural characteristics of synthesized glasses. The X-ray induced luminescence spectra were obtained at room temperature and the emission peak at 311 nm corresponding to Gd3+ transition was observed decreasing with the increase of Tb4O7 concentrations, while emission peak intensities corresponding to Tb3+ electronic transitions increased with the concentrations of Tb4O7. The results from the photoluminescence (PL) studies in the UV–Vis–NIR region showed the glasses emitting intense green light with the highest peak at 544 nm under excitations at 220, 272, and 311 nm. The PL emission intensities were found reasonably high under characteristic excitations of both Gd3+ and Tb3+, peaking at 380, 414, 437, 489, 544, 584, and 623 nm, which corresponding to 5D3→7F6,5D3→7F5, 5D3→7F4, 5D4→7F6, 5D4→7F5, 5D4→7F5, 5D4→7F4, 5D4→7F3 transitions, respectively. The decay time of Tb3+ ions has been observed to decrease when the concentration of Tb4O7 increases. The energy transfer from Gd3+ to Tb3+ was found increased with increasing of Tb3+ concentrations. The CIE 1931 chromaticity coordinates of Tb doped PGNA glasses were found to be in the green range, indicating a strong potential for green laser application. The results from X-ray imaging showed that Tb-doped glass scintillators promise of efficient and low-cost solution for X-ray imaging applications.

Visible emission studies by UV light conversion in (Dy3+/Tb3+) ions pair activated zinc-bismuth-barium borotellurite glasses for achieving intense green and white light

Both white light and green emission properties of (Dy3+/Tb3+) ions pair activated zinc-bismuth-barium borotellurite glasses were studied by ultraviolet light (UV:388 and 366 nm) conversion with a focus on down-conversion process. On the dependences of Tb3+ amounts with co-doping of Dy3+, densities of glasses, excitation, emission, area of the integration in percent, decay times, multipolar interactions, and most responsible photometric parameters are investigated in the current work. These co-activated glasses show a broad color production range (450–700 nm) covering of red (∼622 nm), green (∼545 nm), and blue (∼488 nm) colors under the stimulation of UV light wavelengths. The ratio from Yellow to blue emission was analyzed to study the site symmetry of Dy3+ surrounds. With 388 nm of UV radiation, the area of the integrated intensity under the green (Tb3+:545 nm) peak reaches a maximum of 87 %, while it falls under the yellow (Dy3+:575 nm) peak at about 13 %. The decay times of co-activated glasses were found in decreasing order, followed by fitting with a double-exponential function. The Reisfeld and Dexter's energy transfer mechanism confirmed the reduction in Dy3+ emission and its lifetime values through quadrupole-quadrupole interaction (f = 10). Moreover, photometric properties such as relative color temperatures, color coordinates, and color purity were also discussed and compared to discriminate the potentiality of the present fabricated glasses for use in both white light and green-emitting devices.

Downshifting photoluminescence of Erbium doped NaSrZrO3 for solid-state lighting

The synthesis of novel nanophosphors exhibiting unique morphologies with high purity, stability, eco-friendliness, and a high color rendering index is crucial to meet the demands of contemporary solid-state lighting energy devices. In this investigation, we successfully synthesized Na0.2Sr0.9-xZrO3:xEr3+ perovskite nanophosphors. All samples manifested an orthorhombic structure. The crystallite size was observed to increase with rising concentrations of Er3+. The optical band gap exhibited a range of 5.19 eV to 5.36 eV with increments in doping concentration, signifying alterations in the lattice constants attributable to crystalline disorder. The downshifting PL spectra revealed both host emission bands and dopant (Er3+) emission lines. The violet – blue band was attributed to crystalline disorder while the red emission band was assigned to octahedra tilting disorder in the perovskite. The presence of Er3+ ion lines at 523 and 546 nm produced intense green light, as depicted in the CIE chromaticity diagram for all doped samples. The study affirms that the phosphors synthesized in this research possess potential for application in the development of visible green lamps for optical display devices and solid-state lighting.

Influence of Temperature, Light, and H2O2 Concentration on Microbial Spore Inactivation: In‐Situ Raman Spectroscopy Combined with Optical Trapping

To gain insight on chemical sterilization processes, the influence of temperature (up to 70 °C), intense green light, and hydrogen peroxide (H2O2) concentration (up to 30% in aqueous solution) on microbial spore inactivation is evaluated by in‐situ Raman spectroscopy with an optical trap. Bacillus atrophaeus is utilized as a model organism. Individual spores are isolated and their chemical makeup is monitored under dynamically changing conditions (temperature, light, and H2O2 concentration) to mimic industrially relevant process parameters for sterilization in the field of aseptic food processing. While isolated spores in water are highly stable, even at elevated temperatures of 70 °C, exposure to H2O2 leads to a loss of spore integrity characterized by the release of the key spore biomarker dipicolinic acid (DPA) in a concentration‐dependent manner, which indicates damage to the inner membrane of the spore. Intensive light or heat, both of which accelerate the decomposition of H2O2 into reactive oxygen species (ROS), drastically shorten the spore lifetime, suggesting the formation of ROS as a rate‐limiting step during sterilization. It is concluded that Raman spectroscopy can deliver mechanistic insight into the mode of action of H2O2‐based sterilization and reveal the individual contributions of different sterilization methods acting in tandem.

Co-doped NaYF4:Yb/Er/Tm upconversion luminescent coating to enhance the efficiency of photovoltaic cells.

The use of upconversion luminescent materials to broaden the utilization range of the solar spectrum to enhance the efficiency of photovoltaic cells offers a promising and sustainable approach. However, the low luminescence intensity and easy quenching of upconversion luminescent materials bring serious challenges to the practical application. Herein, a novel method using Co2+ ion doping to regulate the luminescence properties of NaYF4:Yb/Er/Tm is proposed. NaYF4:Yb/Er/Tm microcrystals doped with different proportions of Co2+ ions are prepared and used as coatings on the surface of photovoltaic cells. Co2+ ions regulate the crystallinity and size of the NaYF4:Yb/Er/Tm microcrystals and reduce the crystal field symmetry of the activator (Er3+ and Tm3+) ions. The results show that the emission intensity of green and red light is 18.19% and 83.24% times higher than that of undoped Co2+ ion materials, respectively. Besides, the efficiency of photovoltaic cells after coating Co2+ ion doped NaYF4:Yb/Er/Tm is 2.08% higher than that of the uncoated one. This work underscores the importance of Co2+ ion doping to improve and enhance the luminescence properties of NaYF4:Yb/Er/Tm, to further enhance the efficiency of photovoltaic cells.

Anti-thermal quenching of luminescence in Y2W3O12:Yb3+/RE3+ (RE = Er/Ho/Tm) and its temperature sensing application.

Herein, a series of Y2W3O12:10%Yb3+/x%RE3+ (RE = Er/Ho/Tm) phosphors is prepared via a solid-state reaction. The upconversion and downshift luminescence properties of the phosphors were investigated under an excitation of 980 nm. The bright blue light emission from Tm3+ ion and the green and red light emissions from Ho3+(Er3+) ions were observed. The near-infrared light intensity of NIR-I (Tm3+, ∼850 nm), NIR-II (Er3+: ∼1550 nm; Tm3+: ∼1783 nm) and NIR-III (Ho3+: ∼2050 nm) were analyzed. In particular, the dramatic thermal enhancement phenomenon in visible and NIR regions was exhibited by the Y2W3O12:10%Yb3+/x%RE3+ (RE = Er/Ho/Tm) phosphors. Among them, the green light intensity of Er3+ ions increased 26.77 times, from 303 to 573 K. The NIR-II emission band (∼1783 nm) intensity of Tm3+ ions at 533 K increased 168.7 times compared to that at 313 K. The possible thermal enhancement mechanism is illustrated by the negative thermal expansion (NTE) and Frenkel defect of the Y2W3O12 host. Finally, the optical temperature sensing performances of Y2W3O12:10%Yb3+/x%RE3+ (RE = Er/Ho/Tm) samples are investigated according to the luminescence intensity dependence relationship on temperature. The maximum value of SR reached 4.24% K-1 at 353 K for Y2W3O12:10%Yb3+/0.6%Ho3+ phosphor. The results indicate that the Y2W3O12:10%Yb3+/x%RE3+ (RE = Er/Ho/Tm) phosphors possess anti-thermal quenching properties and are suitable for developing optical temperature sensors.

Codoping of Yttria (Y2O3): Ho–Yb Nanoparticles with Li Increase Emitted Green Light Intensity for Security Ink and Bioimaging

Codoping of Yttria (Y₂O₃): Ho–Yb Nanoparticles with Li Increase Emitted Green Light Intensity for Security Ink and Bioimaging

Engineering a novel role for Yb3+ to overcome thermal quenching and improve photothermal conversion efficiency as well as temperature sensing performance

In this paper, two types of phosphors, Cs3GdGe3O9:Er3+ and Cs3GdGe3O9:Yb3+/Er3+, were synthesized using the high-temperature solid-state method, and a new role for Yb3+ was successfully achieved. The presence of low phonon energy in the matrix and the low energy level mismatch between the 2F5/2 and the 4I11/2 enables the construction of a phonon-assisted channel between Yb3+ and Er3+ through doping with Yb3+ ions. This channel overcomes thermal quenching and achieves thermal enhancement at high temperatures. Additionally, Yb3+ increases the chance of non-radiative transition within the matrix, effectively converting the 980 nm laser into heat energy. This leads to a significant change in the surface temperature of the sample, greatly improving the photothermal conversion efficiency. Moreover, Yb3+ greatly enhances the emission intensity of green light, resulting in a maximum relative sensitivity of 1.11 % K−1 for temperature measurements in the Er3+ single-doped system and 1.28 % K−1 in the Yb3+/Er3+ co-doped system, based on the Er3+ thermally coupled energy level. These results demonstrate that this paper provides a new idea for materials to overcome thermal quenching and improve the efficiency of photothermal conversion and temperature sensing performance.

Visible Light Responsive Soft Actuator Based on PVA‐DR1

AbstractThere is a growing interest in creating biomimetic actuators that can perform human‐like actions in response to external stimuli. Despite the significant advancements in soft actuators, using high‐energy UV light in photoresponsive actuators remains a great challenge. Herein, we develop a film composed of polyvinyl alcohol and photo responsive Disperse Red 1 (PVA/DR1) that actuate in response to visible light. The photoresponsive film starts to actuate in the presence of green light due to trans→cis isomerization of photoresponsive dye. The actuation response of the films was investigated by varying concentrations of DR1 dye and the intensity of green light. Based on these features, we demonstrated a four‐arm soft‐gripper that can mimic human‐hand‐like motions in response to green light. This kind of actuator may find potential applications in soft robotics and biomimetic microgrippers.

Controlled Growth of Perovskite Nanocrystals on Nanotubes via a Nanoseeding Intermediate Stage: Toward Novel Optoelectronic Applications.

CsPbBr3 perovskite nanocrystals (CNCs) were densely anchored on multiwalled carbon nanotubes (MWNTs) via a nanoseeding intermediate stage, in which lead-based nuclei are formed on the nanotube surface. After the formation of the intermediate, a cesium precursor was added to promote the growth of CNCs from the surface nuclei and to thereby obtain CNC-decorated MWNT nanohybrids (CMNHs). The morphology and properties of the CMNHs were determined by the reaction temperature employed during their synthesis. Importantly, the use of MWNTs promoted the formation of larger CNCs that emitted intense green light and modified the electronic structure and bandgap energy of the CNCs. Consequently, the CMNHs could function as optoelectronic transducers and exhibit a "turn-on" photocurrent response when exposed to UV light of narrow specific-range wavelengths. In a novel approach for preventing counterfeit products, the CMNHs were used as a light-emitting black ink to create quick-response codes with fake pixels.

Intense green light emission and thermoluminescence glow curve analysis of Tb3+ -activated CaY2 O4 phosphor.

Here, the synthesis and luminescence analysis of the Tb3+ -activated phosphor were reported. The CaY2 O4 phosphors were synthesized using a modified solid-state reaction method with a variable doping concentration of Tb3+ ion (0.1-2.5mol%). As synthesized, the phosphor was characterized using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction analysis techniques for the optimized concentration of doping ions. The prepared phosphor showed a cubic structure, and FTIR analysis confirmed functional group analysis. It was discovered that the intensity of 1.5mol% was higher than at other concentrations after the photoluminescence (PL) excitation and emission spectra were recorded for different concentrations of doping ions. The excitation was monitored at 542 nm, and the emission was monitored at 237 nm. At 237 nm excitation, the emission peaks were found at 620 nm (5 D4 →7 F3 ), 582 nm (5 D4 →7 F4 ), 542 nm (5 D4 →7 F5 ), and 484 nm (5 D4 →7 F6 ). The 1931 CIE (x, y) chromaticity coordinates showed the distribution of the spectral region calculated from the PL emission spectra. The values of (x = 0.34 and y = 0.60) were very close to dark green emission. Therefore, the produced phosphor would be very useful for light-emitting diode (green component) applications. Thermoluminescence glow curve analysis for various concentrations of doping ions and various ultraviolet (UV) exposure times was carried out, and a single broad peak was found at 252°C. The computerized glow curve deconvolution method was used to obtain the related kinetic parameters. The prepared phosphor exhibited an excellent response to UV dose and could be useful for UV ray dosimetry.

Reproducible, self-healable polyurethane composite networks with high toughness, florescence and water-insensitivity

For self-healing polymers, the poor elastic properties and low self-healing efficiency have limited their applications, smart polymer systems adaptable to complex environment have became a hot topic. To address this issue, in this study, a series of polyurethane composite networks were developed, using poly(ɛ-caprolactone) (PCL) and polytetramethylene ether glycol (PTMG) as the soft segment, isophorone diisocyanate (IPDI) as the hard segment, with the incorporation of florescent SrAl2O4: Eu2+, Dy3+ phosphors. The chemically crosslinked networks were investigated by differential scanning calorimetry (DSC), X-ray scattering (XRD), and dynamic mechanical analysis (DMA) on their crystalline properties. Atomic force microscopy (AFM) confirmed the micro-phase separation structures, where soft segments facilitated self-healing and the hard segments enhanced rigidity. Scanning electron microscopy (SEM) and optical microscopy presented highly efficient and rapid healing could be achieved. The materials emitted an intense green light in UV without significant fluorescent intensity reduction in water emersion. Additionally, the synergistic effect of transesterification provided the composite networks reproducibility for recycling use.