Highly efficient near-infrared solid solution phosphors with excellent thermal stability and tunable spectra for pc-LED light sources toward NIR spectroscopy applications.

Near-infrared (NIR) luminescent materials have attracted wide research interest due to their unique photophysical properties for designing NIR light-emitting diodes (NIR LEDs). Here, a series of Cr3+-activated NIR-emitting solid solution phosphors, Gd1-xLux(Al1-xScx)3(BO3)4:0.01Cr3+ (GLASB:Cr3+) (x = 0 to 0.5), are successfully synthesized via a cosubstitution approach. The GLASB:Cr3+ phosphors reveal extraordinary optical performance with a desirable high IQE of 93.6%, considerable broadened FWHM (from 128 nm to 196 nm) and redshift of 119 nm (747 → 866 nm) as the amount of [Lu3+-Sc3+] ion doping increases. Moreover, their photoluminescent thermal stability is substantially improved, maintaining 105.7% of the initial integral intensity up to 150 °C, namely zero-thermal-quenching. The NIR pc-LED fabricated using the GLASB:Cr3+ phosphor generates an NIR output power of 46 mW and an electro-optical efficiency of 37% at a 120 mA input current. Finally, the characteristic NIR emission of this phosphor can not only be utilized in the fields of night-vision technology and biometric identification, but also exhibits a perfect match with the absorption of the bacteriochlorophyll (BChl) and light-harvesting protein (LHP) of photosynthetic bacteria (PSB), presenting a high application prospect for improving PSB photosynthesis.

Post-doping induced morphology evolution boosts Mn2+ luminescence in the Cs2NaBiCl6:Mn2+ phosphor.

As we know, defects caused in the synthetic process of metal halide perovskite are the most difficult to overcome, and greatly limit their photoelectric performances. Herein, a post-doped strategy was utilized to achieve an interesting morphology evolution from a standard octahedron to a snowflake-like sheet during the Mn2+-doped Cs2NaBiCl6 process, which realizes the obvious photoluminescence quantum efficiency (PLQY) enhancement of the Cs2NaBiCl6:Mn2+ phosphor. This surprising evolution is ascribed to the morphology collapse and reconstruction induced by Mn2+ exchange. The obtained phosphor exhibits enhanced 31.56% PLQY, which is two-fold higher than that synthesized by the traditional co-precipitation method, with broad emission spectrum and good PL color stability at 150 °C. Combined with the Cs2SnCl6 : 1mol%Bi3+ phosphor to fabricate the phosphor-converted light-emitting diode, bright white light emission with Ra = 88, CCT = 4320 K, CIE (0.36, 0.33) and a good application potential in high-resolution PL imaging agents was obtained. This work provides a possible effective strategy to improve the PL performance for impurity-doped lead-free metal halide perovskite.

Highly Stable Orange-Red Long-Persistent Luminescent CsCdCl3 :Mn2+ Perovskite Crystal.

Halide perovskite has been widely studied as a new generation of photoelectronic materials. However, their thermal and humidity-induced emission quenching have greatly limited their utility and reliability. Here, we report a hexagonal Mn2+ -doped CsCdCl3 perovskite crystal that possesses stable photoluminescence (PL) at both high temperature and humidity. The room temperature long-persistent luminescence (LPL) of the single crystals lasts up to 1480 s and can be adjusted by changing the concentration of Mn2+ ion doping. The characteristic emission of d-d transition of Mn2+ is realized, and the photoluminescence quantum yield (PLQY) is up to 91.4 %, it can maintain more than 90 % of the initial PL spectral integral area at 150 °C (423 K). High humid stability PL can be achieved more than 75 % of the initial PL intensity after 55 days of immersion in water. These excellent properties show the application prospect of the LPL material in lighting indication and anti-counterfeiting.

Enhancing Structural Rigidity via a Strategy Involving Protons for Creating Water-Resistant Mn4+-Doped Fluoride Phosphors.

The poor water resistance property of a commercial Mn4+-activated narrow-band red-emitting fluoride phosphor restricts its promising applications in high-performance white LEDs and wide-gamut displays. Herein, we develop a structural rigidity-enhancing strategy using a novel KHF2:Mn4+ precursor as a Mn source to construct a proton-containing water-resistant phosphor K2(H)TiF6:Mn4+ (KHTFM). The parasitic [HMnF6]- complexes in the interstitial site from the fall off the KHF2:Mn4+ are also transferred to the K2TiF6 host by ion exchange to form KHTFM with rigid bonding networks, improving the water resistance and thermostability of the sample. The KHTFM sample retains at least 92% of the original emission value after 180 min of water immersion, while the non-water-resistant K2TiF6:Mn4+(KTFM) phosphor maintains only 23%. Therefore, these findings not only illustrate the effect of protons on fluoride but also provide a novel insight into commercial water-resistant fluoride phosphors.

Broadband, Enhanced, and Antithermally Quenched Near-Infrared Phosphors via a Cosubstitution Approach.

Wearable biosensing and food safety inspection devices with high thermal stability, high brightness, and broad near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) could accelerate the next-generation NIR light applications. In this work, NIR La3-xGdxGa5GeO14:Cr3+ (x = 0 to 1.5) phosphors were successfully fabricated by a high-temperature solid-state method. Here, by doping Gd3+ ions into the La3+ sites in the La3Ga5GeO14 matrix, a 7.9-fold increase in the photoluminescence (PL) intensity of the Cr3+ ions, as well as a remarkably broadened full width at half-maximum (FWHM) of the corresponding PL spectra, is achieved. The enhancements in the PL, PLE intensity, and FWHM are attributed to the suppression of the nonradiative transition process of Cr3+ when Gd3+ ions are doped into the host, which can be demonstrated by the decay curves. Moreover, the La1.5Gd1.5Ga5GeO14:Cr3+ phosphor displays an abnormally negative thermal phenomenon that the integral PL intensity reaches 131% of the initial intensity when the ambient temperature increases to 160 °C. Finally, the broadband NIR pc-LED was fabricated based on the as-explored La1.5Gd1.5Ga5GeO14:Cr3+ phosphors combined with a 460 nm chip, and the potential applications for the broadband NIR pc-LEDs were discussed in detail.

Novel Cyan-Green-Emitting Bi3+-Doped BaScO2F, R+ (R = Na, K, Rb) Perovskite Used for Achieving Full-Visible-Spectrum LED Lighting.

Cyan-emitting phosphors are important for near-ultraviolet (NUV) light-emitting diodes (LEDs) to gain high-quality white lighting. In the present work, a Bi3+-doped BaScO2F, R+ (R = Na, K, Rb) perovskite, which emits 506 nm cyan-green light under 360 or 415 nm excitation, is obtained via a high-temperature solid-state method for the first time. The obtained perovskite shows improved photoluminescence and thermal stability due to the charge compensation of Na+, K+, and Rb+ co-doping. Its spectral broadening is attributed to two centers Bi (1) and Bi (2), which are caused by the zone-boundary octahedral tilting due to the substitution of Bi3+ for the larger Ba2+. Employing the blend phosphors of Ba0.998ScO2F:0.001Bi3+,0.001K+ and the commercial BAM:Eu2+, YAG:Ce3+, and CaAlSiN3:Eu2+, a full-spectrum white LED device with Ra = 96 and CCT = 4434 K was fabricated with a 360 nm NUV chip. Interestingly, a novel strategy is proposed: the cyan-green Ba0.998ScO2F:0.001Bi3+,0.001K+ and orange Sr3SiO5:Eu2+ phosphors were packaged with a 415 nm NUV chip to produce the white LED with Ra = 85 and CCT = 4811 K.

Ultraviolet C lasing at 263 nm from Ba2LaF7:Yb3+,Tm3+ upconversion nanocrystal microcavities.

It is a daunting challenge to realize ultraviolet C (UVC) lasing (i.e., has a wavelength range from 200 to 275 nm) from upconversion nanocrystals due to their low upconversion efficiency. Here, we fabricate Ba2LaF7:Yb3+(90mol%), Tm3+(5mol%) upconversion nanocrystals from amorphous borosilicate glass to support emission at ∼263nm under 980 nm ns laser excitation. The excitation threshold can be further reduced from ∼130 to ∼26.5mJ/cm2 by using a cylindrical microcavity. We also found that the growth of defect-free Ba2LaF7 nanocrystals with a high concentration of codoping Yb3+ and Tm3+ ions inside high optical damage threshold borosilicate glass is the key to achieving room-temperature UVC upconversion lasing under high-intensity excitation.

Phase Transformation of a K2GeF6 Polymorph for Phosphors Driven by a Simple Precipitation-Dissolution Equilibrium and Ion Exchange.

Tuning crystal phase transformations is very important for obtaining polymorphs for phosphors with the ideal optical properties and stability. Mn4+-doped K2GeF6 (KGF) is a typical polymorphic phosphor, but the thermodynamic and kinetic mechanism of its phase transformation is still unclear. Herein, the phase transformation of polymorphs varying from P63mc KGF and trigonal KGF to P63mc Si4+-doped KGF is realized by introducing the synergistic action of an HF solution and Si4+ ions. The full structural refinements of KGF polymorphs at room temperature and the electronic band structure calculations were performed. The results show that the Si4+-doped hexagonal KGF polymorph with good photoluminescence properties is the most stable phase according to the calculated total energy landscape and relative formation energy. The morphologic changes were monitored in situ to clearly understand the rapid phase transformation mechanism, which proves that the phase transformation is driven by a simple precipitation-dissolution equilibrium and ionic exchange.

Diverse belowground resource strategies underlie plant species coexistence and spatial distribution in three grasslands along a precipitation gradient.

Functional traits and their variation mediate plant species coexistence and spatial distribution. Yet, how patterns of variation in belowground traits influence resource acquisition across species and plant communities remains obscure. To characterize diverse belowground strategies in relation to species coexistence and abundance, we assessed four key belowground traits - root diameter, root branching intensity, first-order root length and mycorrhizal colonization - in 27 coexisting species from three grassland communities along a precipitation gradient. Species with thinner roots had higher root branching intensity, but shorter first-order root length and consistently low mycorrhizal colonization, whereas species with thicker roots enhanced their capacity for resource acquisition by producing longer first-order roots and maintaining high mycorrhizal colonization. Plant species observed across multiple sites consistently decreased root branching and/or mycorrhizal colonization, but increased lateral root length with decreasing precipitation. Additionally, the degree of intraspecific trait variation was positively correlated with species abundance across the gradient, indicating that high intraspecific trait variation belowground may facilitate greater fitness and chances of survival across multiple habitats. These results suggest that a small set of critical belowground traits can effectively define diverse resource acquisition strategies in different environments and may forecast species survival and range shifts under climate change.

Complementarity in nutrient foraging strategies of absorptive fine roots and arbuscular mycorrhizal fungi across 14 coexisting subtropical tree species.

In most cases, both roots and mycorrhizal fungi are needed for plant nutrient foraging. Frequently, the colonization of roots by arbuscular mycorrhizal (AM) fungi seems to be greater in species with thick and sparsely branched roots than in species with thin and densely branched roots. Yet, whether a complementarity exists between roots and mycorrhizal fungi across these two types of root system remains unclear. We measured traits related to nutrient foraging (root morphology, architecture and proliferation, AM colonization and extramatrical hyphal length) across 14 coexisting AM subtropical tree species following root pruning and nutrient addition treatments. After root pruning, species with thinner roots showed more root growth, but lower mycorrhizal colonization, than species with thicker roots. Under multi-nutrient (NPK) addition, root growth increased, but mycorrhizal colonization decreased significantly, whereas no significant changes were found under nitrogen or phosphate additions. Moreover, root length proliferation was mainly achieved by altering root architecture, but not root morphology. Thin-root species seem to forage nutrients mainly via roots, whereas thick-root species rely more on mycorrhizal fungi. In addition, the reliance on mycorrhizal fungi was reduced by nutrient additions across all species. These findings highlight complementary strategies for nutrient foraging across coexisting species with contrasting root traits.

Differences in photoluminescence properties and thermal degradation between nanoparticle and bulk particle BaMgAl10O17:Eu2+ phosphors under UV?VUV irradiation.

BaMgAl10O17:Eu2+ (BAM) phosphors used for plasma display panels and three-band fluorescence lamps are exposed to an oxidizing environment at about 500 degrees C, which is currently unavoidable in actual applications. We investigated the mechanism of the luminance degradation of BAM caused by annealing at 500 degrees C based on the difference in luminance degradation of bulk particle and nanoparticle samples under various excitation source irradiations. When the samples were excited by the different light sources, more than 30% degradation of luminance occurred under 147 nm while less than 10% degradation occurred under 254 nm both for nanoparticle and bulk particle samples. In addition, the luminescence degradation of nanophosphors shows a different tendency compared to the bulk phosphors. With a model based on the particle size and excitation light penetration depth, we demonstrate that the degradation is still mainly ascribed to the oxidized of divalent Eu. The differences in luminescence properties between nanophosphors and bulk phosphors are also illustrated by this model. As a result, the potential industrial applications of nanophosphors are evaluated.

The luminous and magnetic properties of Tb3+-doped four angle star-like NaGd(WO4)2.

Four angle star-like double tungstates NaGd(WO4)2 have been prepared hydrothermally with cetyl trimethyl ammonium bromide (CTAB) as the chelating agent and ethanol as the mixing solvent. Monodisperse micron-sized four angle star-like NaGd(WO4)2 were fabricated for the first time. The samples were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and vibrating sample magnetrometer (VSM) techniques. This work emphasizes the luminescence properties of Tb(3+)-doped NaGd(WO4)2 under ultraviolet (UV) and vacuum ultraviolet (VUV) excitation and the magnetic properties. The results demonstrate the phosphors are expected to have potential applications in weak lighting systems and magnetic resonance imaging.

A super water-resistant MXene sponge flexible sensor for bifunctional sensing of physical and chemical stimuli.

Flexible wearable sensors with multifunctional features have attracted great interest in various applications such as disease diagnosis, environmental detection and healthcare monitoring. However, it is still a challenge to achieve a multifunctional sensor with super water resistance without compromising the overall performance of the sensing material. Here, we developed a 3D bifunctional flexible sensor based on an MXene melamine sponge (MS) through a simple and effective ultrasonic mixing process and a further vacuum annealing process. The sensor is able to show excellent response to different stimuli, including pressure and humidity. The thermal annealing treatment allows MXene to adhere more firmly to the internal skeleton of the sponge, which does not easily fall off and improves the water resistance, thus achieving wearability and high sensitivity over a wide area. The T-MXene@MS sensor has a sensitivity of 9.97 kPa-1 in the 5-15 kPa range, a fast response time (180 ms), and good stability at 4000 cycles, enabling accurate monitoring of human movement. The sensor has a rich porous structure while maintaining its inherent flexibility, which allows for long term testing of human respiration as well as the ability to respond quickly to dynamic changes in humidity, demonstrating excellent long-term stability for 40 days of humidity detection.

High-Quality Cs3Cu2I5@PMMA Scintillator Films Assisted by Multiprocessing for X-ray Imaging.

In recent years, novel metal halide scintillators have shown great application potential due to their tunable emission wavelength, high X-ray absorption, and high luminescence efficiency. However, poor stability and complex device packaging remain key issues for metal halide scintillators, making it difficult to achieve high-resolution and flexible X-ray imaging applications. To address the above issues, a multiprocessing strategy was introduced to prepare Cs3Cu2I5@PMMA scintillator films for long-term stable application, mainly undergo different annealing treatments to make Cs3Cu2I5 crystals to accurately nucleate and then grow in-situ in the PMMA matrix. Then, a series of characterization results illustrate that the prepared Cs3Cu2I5@PMMA scintillator films have high crystallinity, uniform size, excellent flexibility, high stable photoluminescence (PL) and radioluminescence (RL) performance, and high-resolution X-ray imaging capability. Most importantly, Cs3Cu2I5@PMMA scintillator films can not only provide clear and accurate imaging recognition of objects with different complex structures but also maintain stable X-ray imaging quality within 60 days and can achieve flexible X-ray imaging. Therefore, we have provided an effective strategy for producing high-quality scintillator films to meet the multidimensional needs of a new generation of scintillators.

Tunable luminescence Y3Al5O12:0.06Ce³âº, xMn²âº phosphors with different charge compensators for warm white light emitting diodes.

Y3Al5O12:0.06Ce³âº, xMn²âº (YAG:0.06Ce,xMn) phosphors have been synthesized and the effect of different charge compensators on the color adjustment has been investigated for the first time. The luminescence properties of Mn2+ singly doped and co-doped with Ce3+ into YAG host have been discussed. It is observed that in singly doped sample, Mn2+ ions not only occupy two kinds of Al3+ sites to generate a yellow and a deep red emission bands, but also occupy Y3+ sites to obtain a green emission band in YAG host. Considering Mn2+ substitution for Al3+, quadrivalence ions including Zr4+, Ge4+ and Si4+ ions are introduced to balance the charge difference. The results show that Si4+ as charge compensator exhibits the best tunable effect on controlling the Mn2+ emissions in YAG:0.06Ce, xMn. In Si4+-Mn2+ co-doped samples, the emission color can be tuned from greenish-yellow to red with increasing the content of Mn2+. The Commission International de L'Eclairage (CIE) chromaticity coordinates are also investigated.

Gender and single nucleotide polymorphisms in MTHFR, BHMT, SPTLC1, CRBP2, CETP, and SCARB1 are significant predictors of plasma homocysteine normalized by RBC folate in healthy adults.

Using linear regression models, we studied the main and 2-way interaction effects of the predictor variables gender, age, BMI, and 64 folate/vitamin B-12/homocysteine (Hcy)/lipid/cholesterol-related single nucleotide polymorphisms (SNP) on log-transformed plasma Hcy normalized by RBC folate measurements (nHcy) in 373 healthy Caucasian adults (50% women). Variable selection was conducted by stepwise Akaike information criterion or least angle regression and both methods led to the same final model. Significant predictors (where P values were adjusted for false discovery rate) included type of blood sample [whole blood (WB) vs. plasma-depleted WB; P < 0.001] used for folate analysis, gender (P < 0.001), and SNP in genes SPTLC1 (rs11790991; P = 0.040), CRBP2 (rs2118981; P < 0.001), BHMT (rs3733890; P = 0.019), and CETP (rs5882; P = 0.017). Significant 2-way interaction effects included gender × MTHFR (rs1801131; P = 0.012), gender × CRBP2 (rs2118981; P = 0.011), and gender × SCARB1 (rs83882; P = 0.003). The relation of nHcy concentrations with the significant SNP (SPTLC1, BHMT, CETP, CRBP2, MTHFR, and SCARB1) is of interest, especially because we surveyed the main and interaction effects in healthy adults, but it is an important area for future study. As discussed, understanding Hcy and genetic regulation is important, because Hcy may be related to inflammation, obesity, cardiovascular disease, and diabetes mellitus. We conclude that gender and SNP significantly affect nHcy.

A Wearable Respiration Sensor for Real-Time Monitoring of Chronic Kidney Disease.

Human respiration is accompanied with abundant physiological and pathological information, such as the change in ammonia (NH3) content, which is related to chronic kidney disease (CKD); hence, monitoring the breathing behavior helps in health assessment and illness prediction. In this work, a wearable respiration sensor based on CeO2@polyaniline (CeO2@PANI) nanocomposites that underwent a hydrogen plasma treatment is developed. The results unambiguously show that the response of the corresponding nanocomposites is significantly enhanced from 165 to 670% to 100 ppm NH3 compared to the counterpart that did not undergo hydrogen plasma treatment and even reaches 24% to 50 ppb NH3, suggesting its fascinating capability of detecting the trace level of NH3 in human breathing. The superior response for NH3 is ascribed to the stable oxygen vacancies produced by the hydrogen plasma treatment. Furthermore, the clinical tests for patients with uremia suggest that the as-designed sensor has potential applications in clinical monitoring for CKD. Herein, this work offers a new strategy to obtain respiration sensors with high performance and provides a feasible approach for health evaluation and disease monitoring of patients with CKD.

Controllable morphology and high photoluminescence of (Y, Gd)(V, P) O4:Eu3+ nanophosphors synthesized by two-step reactions.

Multi-ion doped YVO(4):Eu(3+) nanophosphors with high photoluminescence intensity were successfully prepared by a two-step reaction process for the first time, including YVO(4):Eu(3+) seeds synthesized by hydrothermal reaction and co-doping P(5+) and Gd(3+) in a sol-gel process. X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and photoluminescence spectroscopy were adopted to detect the structure, grain size, morphology and optical properties of the nanophosphors, respectively. Owning to the template-induced effect of the seeds, the morphology and size of the nanophosphors could be controlled by adjusting the molar ratios between the seeds and doping ions. The size of these nanophosphors increased as P(5+) and Gd(3+) co-doped. However, most of the samples kept approximately spherical morphology and narrow size distribution. The composition-optimized (Y, Gd)(V, P)O(4):Eu(3+) nanophosphors with spherical morphology in the 80-100 nm range exhibit better red emission and superior color saturation under vacuum ultraviolet excitation compared with that of the commercial phosphor (Y, Gd)BO(3):Eu(3+).

The Response of Plants and Mycorrhizal Fungi to Nutritionally-Heterogeneous Environments Are Regulated by Nutrient Types and Plant Functional Groups.

Nutrient type and plant functional group are both important in influencing proliferation of roots or hyphae and their benefit to plant growth in nutritionally heterogeneous environments. However, the studies quantifying relative importance of roots vs. hyphae affecting the plant response to nutrient heterogeneity are lacking. Here, we used meta-analysis based on 879 observations from 66 published studies to evaluate response patterns of seven variables related to growth and morphological traits of plants and mycorrhizal fungi in nutritionally heterogeneous environments. We found that phosphorus [P] and organic fertilizer [OF] supply significantly increased shoot (+18.1 and +25.9%, respectively) and root biomass (+31.1 and +23.0%, respectively) and root foraging precision (+11.8 and +20.4%, respectively). However, there was no significant difference among functional groups of herbs (grasses, forbs, and legumes), between herbs and woody species, and between arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) tree species in the shoot, root and mycorrhizal fungi responses to nutrient heterogeneity, except for root biomass and root foraging precision among grasses, forbs, and legumes, and mycorrhizal hyphal foraging precision between AM and ECM tree species. Root diameter was uncorrelated with neither root foraging precision nor mycorrhizal hyphal foraging precision, regardless of mycorrhizal type or nutrient type. These results suggest that plant growth and foraging strategies are mainly influenced by nutrient type, among other factors including plant functional type and mycorrhizal type.

Thermal stability and photoluminescence of S-doped BaMgAl10O17:Eu2+ phosphors for plasma display panels.

Sulfur-doped BaMgAl(10)O(17):Eu(2+) phosphors were synthesized by an environmentally benign synthesis reaction. The photoluminescence spectrum, the energy dispersion spectrum, powder x-ray diffraction, and decay curves were used. The photoluminescence and thermal stability were discussed. It was revealed that sulfur doping leads to an increase in luminance intensity and thermal stability. This could be due to the decrease of defects and lower electronegativity of sulfur while sulfur occupied the unstable O (1) sites. The change of trap concentration was evaluated by the decay curves. The result shows sulfur doping is expected to be potentially applicable to the industrial production of BaMgAl(10)O(17):Eu(2+) phosphors.