Dipole Quadrupole Interaction Research Articles

Luminescence Dynamics of BaAl2O4:Eu2+ Phosphor.

We studied steady-state and time-resolved photoluminescence of Eu doped BaAl2O4 phosphor. The undoped BaAl2O4 sample shows a dominant blue emission band at ~ 428nm and two secondary maxima at ~ 405 and 456nm due to F-centre and aggregate defects such as F2 -centre. The samples after doping of Eu at 1-5% show additional emission bands at ~ 485 and 518 nm due to Eu2+ centre and a red emission band at ~ 657nm is attributed to Eu3+ centre. The sample doped with 2% of Eu shows anomalous emission having the dominant peak at ~ 494nm. The average luminescence lifetime of the emission band at ~ 428nm in the undoped sample was estimated to be (3.29 ± 0.91) ns. The average luminescence lifetime of this emission band after doping of Eu was found to increase by 102 orders of magnitude. The intensity of the 428nm blue emission band was found to quench after doping of Eu beyond 3%. The concentration quenching effect was attributed to dipole-quadrupole interaction. Further, a non-radiative fluorescence energy transfer mechanism from an extrinsic Eu2+ centre to an intrinsic F-centre is proposed to describe the luminescence dynamics of the samples.

Molecular Hydrogen Acts as a Hydrogen Bond Proton Acceptor: From Protonated Betaine Tagging to the Weakest Hydrogen Bond.

In an attempt to gain further insights into the intermolecular interactions implied by Rizzo's group's cautionary tale related to molecular tagging in infrared multiple photon dissociation (IRMPD) spectroscopy with molecular messengers [Masson, A. . J. Chem. Phys. 2015, 143, 104313], in the present study, we provide an in-depth analysis of the noncovalent interaction between the molecular hydrogen and protonated betaine molecule in the gas phase. We aim to shed some new light on the fundamental issues concerning the wide diapason of hydrogen-bonding-type intermolecular interactions, with a wide variety of proton acceptors. We demonstrate that in the course of tagging the protonated betaine with molecular hydrogen from the OH group side, it is the σ bond of molecular hydrogen that plays the role of hydrogen-bonding proton acceptor. The tagging thus induces a small yet significant red shift of the protonated betaine O-H stretching mode. We investigate the performance of a wide range of density functional theory (DFT) functionals for the calculation of anharmonic vibrational frequency shifts of the studied system, which are essential for the correct interpretation of the experimental IRMPD data. For an accurate prediction of the OH stretching frequency shifts, specifically designed functionals such as Handy's group HCTH/407 should be applied. The empirical dispersion correction enhances the systematic overestimation of the anharmonic frequency shift, characteristic of the most widely used DFT functionals. Combining the full-wave function approach with the charge field perturbation and natural bond orbital (NBO) deletion analyses, we demonstrate that the frequency shift in the OH-tagged structure is governed by the σHH → σ*OH intermolecular charge transfer. This interaction stabilizes the OH-tagged dimer as well, in contrast to the dipole-quadrupole electrostatic interaction energy term. Topological analysis of the electron density reveals the presence of an intermolecular bond critical point with a positive value of the density Laplacian very close to the lower limit for hydrogen bonds. NCI analyses demonstrate that the OH···H2 interaction is weaker than the intramolecular CH···O one within the protonated betaine molecule, with the through of reduced density gradient appearing at less negative sign(λ2)·ρ values. Analyzing the O-H stretching vibrational potential with the second-generation absolutely localized molecular orbitals energy decomposition analysis (ALMO-EDA 2) revealed that in the case of betaineH(+) tagged from the OH group side, the permanent electrostatics (ΔEelec), polarization (ΔEpol), and charge-transfer (ΔEct) contributions to the total intermolecular interaction energy contribute favorably to the weak hydrogen bond formation and to the red shift of the fundamental O-H stretching frequency, the ΔEct contribution being the most significant in the last context. The Pauli repulsion term, on the other hand, favors an O-H stretching frequency blue shift as a consequence of the vibrational confinement effects.

Trivalent dysprosium activated LaSr2AlO5 nanophosphors for NUV-excited wLEDs: Insights into structural, optical, Judd-Ofelt parameters and temperature dependent photoluminescence

Gel-combustion (GC) methodology was implemented in the present research to produce a series of single phase Dy3+ doped LaSr2AlO5 nanophosphors for the usage in wLEDs. X-ray powder diffraction patterns verified the phase purity and crystal structure of the produced materials. The XRD inspection supported the successful fabrication of tetragonal structured (I4/mcm space group) phosphors and revealed good accordance with card number 70–2197 on the JCPDS database. We collected diffuse reflectance spectra (DRS) to examine how doping affects the band gap. Furthermore, energy-dispersive X-ray (EDX) spectroscopy and transmission electron microscopy (TEM) have been employed for assessing elemental composition and surface morphology. On 349 nm excitation, LaSr2AlO5:Dy3+ phosphors produce the distinctive yellow PL emissions causedby 4F9/2→6H13/2 transition. Using excitation spectra, the Judd-Ofelt (J-O) characteristic (Ω = 2, 4, 6) have been determined. The Dy3+ transition's features show that the J-O parameters followed the trend which suggested an asymmetric environment around the ligand. The electric dipole transition predominated in the luminescence spectrum, causing the LaSr2AlO5:Dy3+ phosphor to emit a yellowish whitecolor. The fundamental mechanism for the energy transfer and concentration quenching instances among activator ions was discovered to be dipole-quadrupole interactions. Temperature dependent luminescence showed that the synthesized phosphors had thermal stability up to 523 K with activation energy of 0.1312 eV. The future prospects of the synthesized phosphor as an effective choice for near-ultraviolet-activated wLEDs are substantially supported by current comprehensive research.

Effect of ZIF-78 metal-organic framework crystal morphology and defect in resulting polysulfone mixed matrix membranes

BackgroundMixed matrix membranes (MMMs) provide a new possibility for membranes to exceed the tradeoff between permeability and selectivity found in pure polymeric membranes. Factors that enhance gas separation performance in MMMs include filler morphology and aspect ratio. MethodsHigh aspect ratio microporous ZIF-78, a metal-organic framework (MOF) demonstrated in literature to have one of the highest carbon dioxide uptake capacities, was successfully synthesized using a solvothermal method. These particles were incorporated into MMMs in non-defective and systematically defective forms by using two common solvents – chloroform and DMF. Detailed characterization of the various membranes was performed using BET, XRD, SEM, EDS, DSC, TGA, FTIR, and a custom-built gas permeability measurement apparatus. Significant findingsIntroduction of crystals with no apparent defect results in a more tortuous pathway for permeating gas molecules, demonstrated by nitrogen permeation results. Conversely, for carbon dioxide, strong dipole-quadrupole interaction with ZIF-78 creates excellent permeation pathways through the crystal themselves. The defective system possesses more inter-filler free volume which allow all gas components to permeate more easily, in addition to the original mechanism. The gas separation performance of the resulting MMMs in this work displayed a 140 % improvement of CO2 permeability and 129 % improvement of CO2/N2 ideal selectivity over pure polysulfone membranes. This work shows the potential of using deliberately designed fillers to increase performance via special pathways for gas molecules.

Efficient near-infrared emission at 1070 nm in (Eu3+/Nd3+) ions pair activated NAFBT glasses by CET process for improving the silicon solar cell efficiency

Present work reveals the luminescent downconversion (LDC) process in a series of new sodium-aluminumfluoro borotellurite (NAFBT) glasses by co-doping Nd3+ concentrations (0.1, 0.5, 1.5, and 2.0 mol%) with a constant (2.0 mol%) Eu3+ content. The X-ray diffractogram and IR spectral studies have shown the amorphous like structure and functional groups of the fabricated NAFBT glasses. The fabricated glasses’ physical properties like density and molar volume, and their absorption in the 300–780 nm (UV-Visible) and 800–2300 nm (NIR) ranges were studied. The LDC effect via co-operative type energy transfer (CET) in NAFBT:(Eu3+/Nd3+) glasses was tested with the stimulation at 463 nm of Eu3+, showing a prominent 614 nm (visible) photon of Eu3+ and 907, 1070, and 1339 nm photons (NIR) of Nd3+ ions. The variation in percentage (%) of the integrated intensity at 1070 nm (Nd3+) and 614 nm (Eu3+) was studied as a function of Nd3+ concentration at a fixed Eu3+ content. The multipolar interactions between Nd3+ and Eu3+ ions in NAFBT glasses were studied by Reisfeld and Dexter energy transfer (ET) process. The decline of PL decay from 1.91 to 0.38 ms was represented by dipole-quadrupole interaction in NAFBT glasses. Asymmetric ratio and photometric parameters such as correlated color temperatures (∼1020 K), and (x, y) color coordinates nearly (0.65, 0.34) of red emission were also evaluated for NAFBT glasses. The intense NIR (1070 nm) emission matches well with the silicon solar spectrum and an increase of conversion efficiency (ηQE) from 125% to 199% demonstrate the potential application of NAFBT glass materials in crystalline silicon (c-Si) solar cells.

Temperature-responsive insights: Investigating Eu3+ and Dy3+ activated yttrium calcium oxyborate phosphors for structure and luminescence

An investigation into the luminescent behavior of YCOB (Yttrium Calcium Oxyborate) doped with Eu3+ and Dy3+ ions, synthesized via the combustion method, is presented. The study, employing X-ray diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), and Energy-Dispersive X-ray Spectroscopy (EDS) analyses, confirms the structural integrity and purity of the synthesized nanophosphors. An XRD pattern exhibiting distinct crystalline peaks indicates that the dopant ions were successfully integrated into the YCOB lattice. The photoluminescence (PL) response of YCOB with Eu3+ and Dy3+ ions is thoroughly examined, uncovering distinct excitation and emission spectra. In the case of Eu3+ doping, excitation spectra reveal a significant charge transfer (CT) band at 254 nm, indicative of electron transfer between oxygen and europium ions. This CT transition enhances our understanding of the excitation behavior, with the dominant and Laporte-forbidden 5D0 → 7F2 transition. Characteristic peaks at 345 nm in the excitation spectra efficiently stimulate YCOB:Dy3+ when Dy3+ is used as a dopant. The primary emission peak at 585 nm corresponds to the hypersensitive electric dipole transition 4F9/2–6H13/2. Concentration quenching phenomena are observed, with a maximum Eu3+ concentration of 7 wt % attributed to the dipole-quadrupole interaction. Dy3+ doping, with a maximum concentration of 2 wt % primarily shows multipolar interactions, especially dipole-dipole interactions. The study extends to CIE chromaticity analysis, emphasizing Eu3+ doping's suitability for white light-emitting diode (WLED) applications and ensuring color stability. Conversely, varying Dy3+ concentrations do not yield consistent chromaticity coordinates. These findings have significant implications for the development of advanced phosphor materials across diverse applications, offering a roadmap for optimizing their optical performance.

Ab Initio Potential Energy Surface for NaCl-H2 with Correct Long-Range Behavior.

We report a full dimensional ab initio potential energy surface for NaCl-H2 based on precise fitting of a large data set of CCSD(T)/aug-cc-pVTZ energies. A major goal of this fit is to describe the very long-range interaction accurately. This is done in this instance via the dipole-quadrupole interaction. The NaCl dipole and the H2 quadrupole are available through previous works over a large range of internuclear distances. We use these to obtain exact effect charges on each atom. Diffusion Monte Carlo calculations are done for the ground vibrational state using the new potential.

Novel high-sensitivity optical thermometry based on fluorescence intensity ratio of <inline-formula><tex-math id="Z-20240425115725">\begin{document}${\text{VO}}_4^{3 - } $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240012_Z-20240425115725.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240012_Z-20240425115725.png"/></alternatives></inline-formula> to Pr<sup>3+</sup>

It is noteworthy that since 2010, the number of published and cited scientific papers on optical thermometry has increased exponentially. Optical thermometry technology is about to make a significant process in sensing, therapy, diagnosis, and imaging. The current research mainly focuses on optical thermometry that is developing towards high-sensitivity thermometry. In this work, a new thermometry strategy is proposed based on the different temperature-dependent behaviors between the host ions and the doped ions. Firstly, YVO<sub>4</sub>:<i>x</i>Pr<sup>3+</sup>(<i>x</i> = 0%–1.5%) phosphors are successfully synthesized by the solid-state method. Then, the structure and luminescence properties of the samples are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and fluorescence spectrophotometer. The XRD results show that Pr<sup>3+</sup> ions are successfully incorporated into the YVO<sub>4</sub> host, and the sample has a tetragonal phase crystal structure with space group <i>I</i>41/<i>amd</i>. The SEM results show that the samples are rectangular-shaped micron particles with smooth surfaces, and the average grain size is about 2.1 μm. Under the excitation of 320 nm, the sample mainly exhibits broadband blue emission around 440 nm and red emission at 606 nm, which are attributed to the charge transfer transition of <inline-formula><tex-math id="M2">\begin{document}${\text{VO}}_4^{3 - }$\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240012_M2.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240012_M2.png"/></alternatives></inline-formula> and the <sup>1</sup>D<sub>2</sub>→<sup>3</sup>H<sub>4</sub> transition of Pr<sup>3+</sup>, respectively. The relationship between the luminescence of the sample and the concentration of Pr<sup>3+</sup> is studied. It is found that the optimal doping concentration of Pr<sup>3+</sup> is 0.5%, and a higher doping concentration will cause concentration to be quenched. The reason for quenching concentration is the electric dipole-quadrupole interaction. The luminescence peak position of the temperature-dependent spectrum of YVO<sub>4</sub>:0.5%Pr<sup>3+</sup> is consistent with that at room temperature. As the temperature increases, the total luminescence intensity gradually decreases, which is caused by thermal quenching, and the mechanism of thermal quenching is analyzed. Since the temperature-dependent behaviors of luminescence of <inline-formula><tex-math id="M3">\begin{document}${\text{VO}}_4^{3 - }$\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240012_M3.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240012_M3.png"/></alternatives></inline-formula> and Pr<sup>3+</sup> are significantly different from each other, a new fluorescence intensity ratio thermometry strategy is realized. Temperatures range is 303–353 K, and the maximum absolute sensitivity and relative sensitivity are 0.651 K<sup>–1</sup> and 3.112×10<sup>–2</sup> K<sup>–1</sup> at 353 K, respectively, much higher than the traditional thermally coupled level thermometry strategy. In addition, there is no obvious overlap between the emission peaks of <inline-formula><tex-math id="M4">\begin{document}${\text{VO}}_4^{3 - }$\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240012_M4.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240012_M4.png"/></alternatives></inline-formula> and Pr<sup>3+</sup>, which provides a good discrimination capability for signal detection. The above results show that this work provides a promising path for designing self-reference optical thermometry materials with excellent temperature sensitivity and signal discrimination.

Vinyl-addition polynorbornenes with glycerol and diethylene glycol moieties: Synthesis and structure-property study

A set of new norbornene-type monomers containing linear and branched substituents with three C–O–C fragments was synthesized in good yields from commercially available glycerol and diethylene glycol monomethyl ether. Vinyl-addition polymerization of the synthesized monomers was systematically studied, and highly active Pd-catalysts that made it possible to reach quantitative conversions of the monomers were suggested for their polymerization. As a result, robust thin membranes were successfully prepared directly from the polymerization mixtures in the air. Gas separation performance for a wide range of gases was evaluated for the synthesized polymers, and new valuable structure-property relationships were found. More specifically, these membranes display the facilitated transport of CO2 and solubility-controlled hydrocarbon separation selectivity. The increase in the amount of C–O–C fragments in side chains enhances these effects, but only in the case of the linear structure of the substituents. If the structure of side chains becomes branched, the gas permeability is reduced, the facilitated transport of CO2 is minimized, and the polymer becomes more susceptible to plasticization by butane. The facilitated transport of CO2 is due to the specific dipole-quadrupole interaction between CO2 molecules and polymer matrix. For the studied polymers, the contribution of this specific interaction to the solubility of CO2 achieves 64 %. The significant influence of alkyl tails in side chains on gas transport properties was also observed. To achieve better gas separation performance, it is desirable to incorporate short and rigid alkyl tails. Thus, among substituents containing ether moieties, linear oligoethylene glycols with methyl tails seem to be the most promising side-chain substituents for the macromolecular design of CO2-selective polymeric membrane materials. The results obtained were considered along with NMR, TGA, DSC, DMA, and WAXD data.

Rare-earth free far-red emitting perovskite phosphor NaYBa4W2O12:Mn4+ for indoor plant cultivation lighting

A series of rare-earth free far-red emitting phosphor NaYBa4W2O12: xMn4+ ( ≤ x ≤ 0.75%, NYBW: Mn4+) is successfully synthesized for application in near-ultraviolet (n-UV) light pumped plant cultivation light-emitting diodes (LEDs). The phase purity, crystal structure, electronic structure and luminescent properties of NYBW: Mn4+ are investigated in detail. The results indicate that all NYBW: Mn4+ phosphors are well crystallized with a direct band gap of 3.86 eV. Broad excitation band can be found with dominant wavelengths at 365 and 520 nm, indicating NYBW: Mn4+ can be efficiently excited by commercial n-UV or green LED chip. Upon 360 nm excitation, NYBW: Mn4+ shows intense broad-band far-red emission centered at 696 nm, attributed to the 2Eg→4A2g transition of Mn4+. The optimal doping concentration of Mn4+ is determined to be 0.1% and the concentration quenching mechanism is the dipole-quadrupole interaction. The decay time decreases from 0.58 to 0.081 ms with Mn4+ concentration increasing from 0.025 to 0.75%. The temperature quenching behaviour of Mn4+ in NYBW is investigated, with a thermal activation energy estimated to be about 0.375 eV. Finally, a far-red emitting LED device is fabricated by coating NYBW: Mn4+ phosphor on a 365 nm n-UV LED chip. The above results guarantee that the as-prepared far-red emitting phosphor NYBW: Mn4+ has great potential for application in indoor plant cultivation LEDs.

Synthesis and luminescence properties of oxyapatite-type ZnLa4(SiO4)3O:Eu3+ phosphor for high CRI w-LEDs, latent fingerprints, and security ink

The Eu3+-doped oxyapatite-type ZnLa4(SiO4)3O (ZLSO) phosphors with a strong red emission were successfully synthesized. The pure phase of the phosphors with the hexagonal system was verified through X-ray diffraction. The band gap energy of the ZLSO was calculated using Materials Studio and measured using the diffuse reflection spectra. Attributed to the 7F0→5L6 transition of Eu3+ at 394 nm, the prepared phosphors showed a more intense emission at 614 nm than at 590 nm, due to their asymmetric position. The optimized doping concentration of the ZLSO:xEu3+ sample was 20 mol%, and the relevant mechanism of concentration quenching was dipole-quadrupole interaction. Notably, the ZLSO:Eu3+ phosphors exhibited preferable thermal stability, with an activation energy of 0.289 eV. The fabricated warm white light-emitting diodes (w-LEDs) with ZLSO:Eu3+ phosphors presented a high average colour rendering index (Ra = 95, CCT = 5233 K). Meanwhile, the level 1–3 structures of latent fingerprints (LFPs) were distinctly displayed by ZLSO:Eu3+ samples, and security ink was successfully used to encrypt information. In summary, the highly efficient oxyapatite-type ZLSO:20 mol%Eu3+ phosphors have attractive application potential in multiple application fields, such as w-LEDs, LFPs, and security ink.

A novel red phosphor Sr3In2WO9: Eu3+ for WLEDs

A series of Sr3In2WO9: xEu3+ red phosphors were prepared using a solid-state reaction. The strongest excitation peak of Sr3In2WO9: xEu3+ appeared at 394 nm, and the strongest emission peak appeared at 612 nm. The concentration-dependent emission spectra show that the optimal doping concentration of Eu3+ ions is x = 0.30 for all Sr3In2WO9: xEu3+ samples and Eu3+ occupies the non-inverted centrosymmetric site. Analysis of the causes of concentration quenching, the dipole-quadrupole interaction in Sr3In2WO9: xEu3+ was determined to be the main cause. The thermal stability of the Sr3In2WO9: 0.30Eu3+ sample was analyzed, and it was found that the luminescence intensity of the Sr3In2WO9: 0.30Eu3+ was retained by 55.1 % at 423 K. The thermal quenching activation energy ΔE = 0.291 eV was calculated after the thermal quenching analysis. The calculated CIE chromaticity coordinate of Sr3In2WO9: 0.30Eu3+ is (0.6450, 0.3544), which are very close to the standard red light (0.667, 0.333) given by the National Television Standards Committee system. The color purity of all samples is above 95 %, and the associated color temperature is below 2400 K. The chromaticity coordinates of the encapsulated WLED point of (0.329, 0.388) with a lower correlation color temperature of 5841 K and excellent color rendering index of 88, which indicated the near-UV excited SIWO: Eu3+ red phosphor has great potential for application in the field of WLEDs devices.

N-UV triggered green emitting Er3+ doped Zirconia: A bifunctional material for solid-state lighting and optical thermometry

In the current piece of work, we have synthesized the Er3+-activated ZrO2 and illustrated the bifunctional utility of this material for solid-state lighting and non-contact optical thermometry. The synthesized samples were characterized by XRD, XPS, and PL techniques for their structural, surface, and luminescence studies. Under the excitation of 377 nm, characteristic green emission corresponding to intra 4f-4f transitions of Er3+ is obtained. The concentration quenching effect was observed beyond 1.2 mol % concentration of doping. Using Dexter's theory, it was revealed that dipole-quadrupole interactions are predominantly responsible for concentration quenching. The Photometric study was performed using the PL data. For the most intense phosphor, a highly pure green color (color purity ∼ 97.6%) and CCT ∼ 5375 K is observed. Furthermore, the temperature-sensing capability of the most intense sample has also been explored by triggering the synthesized phosphor by n-UV light. The temperature sensing performance is checked by measuring variations in the fluorescence intensity ratio (FIR) of the thermally coupled levels of Er3+ with temperature. The synthesized phosphor gives high relative sensitivity (1.19% K−1 at 303 K)) and absolute sensitivity (11.39 × 10−4 at 603 K)) values. These results suggest that n-UV-triggered Er3+ doped ZrO2 can be a promising bifunctional material for applications in solid-state lighting and non-contact optical thermometry.

Colloidal directional structures at a nematic liquid crystal–air interface

ABSTRACT We present a variety of structures formed by colloidal droplets at a nematic liquid crystal – air interface, where the elastic dipole–dipole, quadrupole–quadrupole and dipole–quadrupole interactions are all essentially involved. The colloidal structures observed not only include chains with kinks or clusters but also comprise directional structures, such as directional chains and branches, whose direction is associated with the tilting director in the liquid crystal layer. The dipole–quadrupole interaction, originating from the polydispersity of the droplets, plays a central role for the formation of these directional structures. Clusters consisting of directional branches and chains are also observed and found to be fractal statistically.

Energy transfer and photoluminescence properties of CaYGaO4:Bi3+,Tb3+ phosphors

Trivalent bismuth and trivalent terbium ions doped CaYGaO4 were prepared. The crystal structure, phase purity, photoluminescence, decay curves, and emission spectra under various temperatures were investigated. The six-coordinate Ca2+ and Y3+ ions are occupied by Bi3+ ions, while Tb3+ ions take up the six-coordinate Y3+ ions in the CaYGaO4:Bi3+,Tb3+ phosphor. The emissions of trivalent bismuth (3P1 → 1S0) and trivalent terbium ions (5D4 → 7F5) excited by 320 nm were observed. The analysis of spectra and decay curves demonstrated that Bi3+ could transfer energy to Tb3+ via electric dipole-quadrupole interaction. By altering the concentration of trivalent terbium ions, the emitting color of phosphor was tuned from blue to green. The temperature sensing property of CaYGaO4:Bi3+,Tb3+ was described, and its relative sensitivity at 303 K achieves a maximum of 0.61% K−1. According to the results, CaYGaO4:Bi3+,Tb3+ is a potential material for color tunable emission and temperature sensing.

SrAlOCl:Bi<sup>3+</sup>@SiO<sub>2</sub> phosphor with broad emission band and its effects on LED optical power and correlated color temperature

Sr3Al2O5Cl2:Bi3+ (SAlOCl:Bi3+)phosphor for broadband emission was made using a solid-state method. From the extensive spectroscopic analysis and theoretical computation, significant conclusions about the origin of the Bi3+ emission were drawn. For the Sr 3 and Sr 1 sites, respectively, the dipole-quadrupole and quadrupole-quadrupole interactions were responsible for the concentration quenching in SAlOCl:Bi3+. The resulting luminescence mechanism demonstrated that the crystallization of Bi3+ at the two sites is what causes the emission from each site. The warm white light emitting diodes (LED) models were built with a 380-nm ultraviolet (UV) chip, SAlOCl:Bi3+, and two other phosphors. Then, the color rendering indeces (CRI) and the correlated color temperature (CCT) were calculated. Particularly, the CRI values ranged from 84.3 to 86.2 under operating currents of 20–50 mA, respectively. The increasing SAlOCl:Bi3+ dosage also heightened particle density, resulting in higher scattering coefficients. High scattering results in improved color coordination (lower color variance). The CRI and luminous flux are reduced as the phosphor SAlOCl:Bi3+ concentration increases more than owing to color loss and energy loss by backscattering and re-absorption. Thus, it is advisable to consider SAlOCl:Bi3+ carefully before applying in production.

SrAlOCl:Bi<sup>3+</sup>@SiO<sub>2</sub> phosphor with broad emission band and its effects on LED optical power and correlated color temperature

Sr3Al2O5Cl2:Bi3+ (SAlOCl:Bi3+)phosphor for broadband emission was made using a solid-state method. From the extensive spectroscopic analysis and theoretical computation, significant conclusions about the origin of the Bi3+ emission were drawn. For the Sr 3 and Sr 1 sites, respectively, the dipole-quadrupole and quadrupole-quadrupole interactions were responsible for the concentration quenching in SAlOCl:Bi3+. The resulting luminescence mechanism demonstrated that the crystallization of Bi3+ at the two sites is what causes the emission from each site. The warm white light emitting diodes (LED) models were built with a 380-nm ultraviolet (UV) chip, SAlOCl:Bi3+, and two other phosphors. Then, the color rendering indeces (CRI) and the correlated color temperature (CCT) were calculated. Particularly, the CRI values ranged from 84.3 to 86.2 under operating currents of 20–50 mA, respectively. The increasing SAlOCl:Bi3+ dosage also heightened particle density, resulting in higher scattering coefficients. High scattering results in improved color coordination (lower color variance). The CRI and luminous flux are reduced as the phosphor SAlOCl:Bi3+ concentration increases more than owing to color loss and energy loss by backscattering and re-absorption. Thus, it is advisable to consider SAlOCl:Bi3+ carefully before applying in production.

A New Efficient Deep-Red-Emission Phosphor Y3Al4.9Sb0.1O12: Ce3+, Cr3+ with Application Potential in Plant Growth

Aiming at a system of more efficient plant growth, cationic substitutions for garnet-structure host crystal activated by Ce3+ and Cr3+ are investigated. A series of Y3Al5O12: Ce3+-Cr3+, red-emitting materials excited by near-ultraviolet and blue light with a peak emission near 693 nm, are synthesized using a solid-state method. The substitution of Sb3+ for Y3Al5O12: Ce3+, Cr3+ is found to increase the emission intensity of deep red about +80% because it improves the energy transfer from Ce3+ to Cr3+, where yellow emission of Ce3+ is depressed and deep red of Cr3+ increased. It also enhances the intensity-ratio of zero phonon line (ZPL) vs phonon assisted side band. It is induced that the substitution of Sb3+ having strong covalent property influences symmetric Ce3+O2– 6 octahedron, significantly increasing the intensity of 2E→4A2 ZPL of Cr3+ under the resonance energy transfer of Ce3+ to Cr3+. From the ratio of Ce3+ emission intensity in the absence and presence of Cr3+, the energy transfer has a mechanism of dipole-quadrupole interaction. By using Sb3+ substitution and flux AlF3, the original emission intensity of Y3Al5O12: Ce3+, Cr3+ is increased about +183%. The new phosphor has application potential for plant growth in both methods of using LED and converting Sunlight.

UV excitable GdSr2AlO5:Eu3+ red emitting nanophosphors: Structure refinement, photoluminescence, Judd-Ofelt analysis and thermal stability for w-LEDs

Combustion derived Gd1−xSr2AlO5:x mol% Eu3+(x = 1–5 mol%) nanophosphors have tetragonal structure with space-symmetry of I4/mcm (space group no. 140), which was supported by X-ray diffraction patterns. Rietveld refinement pattern revealed that the doping of Eu3+ ions expanded the lattice constants/volume and shifted the diffraction peaks to a lower angle side. Investigations using SEM and TEM confirm the excellent morphology with almost spherical particles in nanoscale. The production of material with the proper stoichiometry was confirmed by EDX analysis. Optical band-gap value (5.21 eV) of optimum Gd0.97Sr2AlO5:3 mol% Eu3+ which was determined by Kubelka-Munk model, showed the good optical quality of the samples. At 268 nm excitation wavelengths, PL spectra characteristics show a strong red emission at 612 nm that corresponds to the doped Eu3+ ions hypersensitive 5D0→7F2 transition with good asymmetric ratio. The optimal doping concentration of Eu3+ ions in GdSr2AlO5 is determined to be about 3 mol% and the concentration quenching phenomenon arise from the electric dipole-quadrupole interaction. Additionally, the Judd-Ofelt investigation of GdSr2AlO5:Eu3+ phosphors were intended to determine the coordinated Eu3+ environment inside the host matrix. The experimental life time analysis of the excited state 5D0 was determined to be in the millisecond range and the quantum efficiency for optimum sample was found to be 67.62 % yielding a good white light emission. The temperature dependent luminescence behavior of Gd0.97Sr2AlO5:3 mol% Eu3+ phosphor exhibits its good thermal stability and the activation energy for thermal quenching characteristics is calculated to be 0.216 eV. The potential applicability of GdSr2AlO5:Eu3+ nanophosphor in the production of wLEDs was further improved by the color coordinates.

One-Step Synthesis of Structurally Stable CO2-Philic Membranes with Ultra-High PEO Loading for Enhanced Carbon Capture

Membrane technology has been considered a promising strategy for carbon capture to mitigate the effects of increasing atmospheric CO 2 levels because CO 2 -philic membranes have demonstrated significant application potential, especially, for CO 2 /light gas separation. In this regard, poly(ethylene oxide) (PEO), which is a representative CO 2 -philic material, has attracted extensive research attention owing to its specific dipole–quadrupole interaction with CO 2 . Herein, we report a facile one-step synthesis protocol via the in situ polymerization of highly flexible polyethylene glycol to overcome the limitations of PEO, including high crystallinity and poor mechanical strength. The robust structure derived from intricate entanglements between short PEO chains and the polymer matrix enables an extremely high loading of linear polyethylene glycol (up to 90 wt%). Consequently, the separation performance easily surpasses the upper-bound limit. Moreover, the high structural stability allows for the concurrent increase of CO 2 permeability and CO 2 /light gas selectivity at high feed pressure (up to 20 bar). This study provides a promising strategy to simultaneously improve the toughness and gas separation properties of all-polymeric membranes, demonstrating significant potential for industrial carbon capture and gas purification.