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Dy 3+ and Eu 3+ co-doped borosilicate glasses have been synthesised via melt quench technique. Amorphous behaviour of the sample has been verified by XRD study. FT-IR analysis confirmed the presence of various bonds in the host lattice. Energy band gap values of the co-doped glasses were estimated from the UV-VIS data via Tauc Plot. Excitation spectra were recorded under 575 nm (Dy 3+ ) and 612 nm (Eu 3+ ) emission wavelengths of co-doped glasses. Emission spectra of the co-doped glasses under 350 nm and 393 nm showed a significant shift towards increasing red emission with increasing Eu 3+ concentrations. Dexter's theory was applied to study the transfer of energy mechanism between Dy 3+ and Eu 3+ ions. Time decay curves were plotted for the co-doped glasses for 350 nm excitation and 576 nm emission wavelength. CIE coordinate diagram shows a shift towards red region with increasing excitation wavelength from 350 nm to 465 nm. The enhancement of red component with increasing Eu 3+ concentrations in the as -prepared borosilicate glasses can be appropriately utilised in various w-LEDs and other optoelectronic devices applications., Competing Interests: Declarations. Competing Interests: The authors declare no competing interests., (© 2025. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

A series of x%Ho 3+ , 5 %Tm 3+ , y%Yb 3+ :Bi 2 WO 6 (x = 0, 0.5, 1, 3, 5; y = 0.5, 1, 3) luminescent materials was prepared using a high-temperature solid-phase method. The microstructure, up-conversion luminescence, and temperature sensing properties of the synthesized powders were analyzed. X-ray diffraction patterns revealed that doping with Ho 3+ , Tm 3+ , and Yb 3+ ions at certain concentrations did not affect the orthorhombic crystal structure of the Bi 2 WO 6 host. Scanning electron microscopy revealed that the morphology of the sample consisted of lumpy particles with a particle size range of 1-5 µm and agglomeration. SEM mapping and energy-dispersive X-ray spectroscopy analyses revealed that each element was relatively uniformly distributed on the particle surface. Under 980 nm excitation (380 mW), the strongest luminescence of the sample was obtained when both Ho 3+ and Yb 3+ doping concentrations were 1 %. Compared with the luminescence of the 5 %Tm 3+ and 1 %Yb 3+ :Bi 2 WO 6 sample, with increasing Ho 3+ concentrations, the luminescence intensity of Tm 3+ was first enhanced and subsequently weakened, whereas the luminescence of Ho 3+ was significantly weakened, which indicates the positive energy transfer from Ho 3+  → Tm 3+ . At 980 nm (80-380 mW), for the 1 %Ho 3+ , 5 %Tm 3+ , and 1 %Yb 3+ :Bi 2 WO 6 sample, the 538 nm, 545 nm, 660 nm, and 804 nm emission peaks originated from the two-photon absorption. FIR 660 nm/804 nm , FIR 545 nm/804 nm , and FIR 538 nm/804 nm were used to characterize the temperature and corresponded to temperature sensitivities S r of 0.0046 K -1 , 0.022 K -1 and 0.024 K -1 at 573 K, respectively. At 498 K, the minimum temperature resolution δT values were 0.03384 K, 0.03203 K and 0.04373 K. When the temperature increased from 298 K to 573 K, the powder sample luminescence gradually shifted from the yellow-green region to the red region. The results of environmental discoloration and thermochromic performance tests indicate that this sample has potential application in optical anti-counterfeiting. FIR 804 nm /660 nm and FIR 804 nm /538 nm were obtained for the 40 NTU turbidity suspension under identical excitation conditions. At 298 K, for the 40 NTU turbidity sample, the maximum S r values were 0.0197 K -1 and 0.0405 K -1 ; at 340 K, the minimum temperature resolutions δT values were 0.54037 K and 0.66237 K. When the temperature decreased from 340 K to 298 K, the luminescence of the 40 NTU suspension samples gradually shifted from the yellow region to the green region., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In the present research work, a solid-state reaction method was employed to synthesize a series of CaGd (0.95-x) SbWO 8 :Sm 0.05 Eu x (x = 1, 1.5, 2, 3 and 4 mol%) phosphors. The phase purity, crystallinity, morphological and compositional studies were analysed via X-ray diffraction (XRD), scanning electron microscopy (SEM) imaging, and energy dispersive spectroscopy (EDS) analysis. The Fourier transform infrared (FT-IR) spectroscopy was utilized to measure OH content in the prepared phosphor material. The diffused reflectance spectroscopy (DRS) analysis was applied to measure the optical energy band gap. The photoluminescence (PL) spectroscopy at excitation wavelengths 275 and 405 nm was carried out to analyze the luminescence properties of the prepared phosphors. The intensity of emission peaks of Sm 3+ ions decreased as the concentration of Eu 3+ ions increased showing the energy transfer mechanism from Sm 3+ to Eu 3+ ions. The dipole-dipole interaction mechanism is responsible for the energy transfer between Sm 3+ to Eu 3+ ions as assessed using the Reisfeld approximation. The CIE coordinates of the prepared samples lie in the warm red region represented by the relatively low (3200 K) value of correlated color temperature. These results show the suitability of the prepared phosphor for white light emitting diode (w-LEDs) and also in indoor plant growth lighting systems., Competing Interests: Declarations. Ethical Approval: The authors declare that no animal or animal data was used in any study or experiment mentioned in this manuscript. We approve all the ethics. Competing Interests: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Barium lead alumino fluoroborate (BaPbAlFB) glasses singly and co-doped with Dy 3+ and Eu 3+ ions were prepared by melt quench method and studied their photoluminescence (PL) properties along with energy migration. Singly doped Dy 3+ /Eu 3+ ions in BaPbAlFB glasses under 365 and 393 nm excitation wavelengths emit the PL bands through Dy: ( 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 ) and Eu: ( 5 D 0 → 7 F 2 ) transitions located at (Dy: 483 and 575 nm) and (Eu: 613 nm) respectively. Further, tunability of PL emissions is achieved by exciting the Dy 3+ /Eu 3+ co-doped BaPbAlFB glasses at various wavelengths. The obtained CIE (0.34, 0.33) and CCT value (5080.4 K) of Dy 3+ /Eu 3+ co-doped BaPbAlFB glass produced white light emission under 365 nm excitation wavelength. The corresponding CCT values of Dy 3+ /Eu 3+ co-doped BaPbAlFB glasses varied from 1580 to 5080 K and their corresponding color emission changes from intense red to white light regime quite suitable for fabrication of epoxy-free w-LED devices., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

CaWO 4 nanoparticles were obtained by facile mechanochemical synthesis at room temperature, applying two different milling speeds. Additionally, a solid-state reaction was employed to assess the phase composition, structural, and optical characteristics of CaWO 4 . The samples were analyzed by X-ray diffraction (XRD), transition electron microscopy (TEM), and Raman, infrared (IR), ultraviolet-visible (UV-Vis) reflectance, and photoluminescence (PL) spectroscopies. The phase formation of CaWO 4 was achieved after 1 and 5 h of applied milling speeds of 850 and 500 rpm, respectively. CaWO 4 was also obtained after heat treatment at 900 °C for 12 h. TEM and X-ray analyses were used to calculate the average crystallite and grain size. The Raman and infrared spectroscopies revealed the main vibrations of the WO 4 groups and indicated that more distorted structural units were formed when the compound was synthesized by the solid-state method. The calculated value of the optical band gap of CaWO 4 significantly increased from 2.67 eV to 4.53 eV at lower and higher milling speeds, respectively. The determined optical band gap of CaWO 4 , prepared by a solid-state reaction, was 5.36 eV. Blue emission at 425 (422) nm was observed for all samples under an excitation wavelength of 230 nm. CaWO 4 synthesized by the solid-state method had the highest emission intensity. It was established that the intensity of the PL peak depended on two factors: the morphology of the particles and the crystallite sizes. The calculated color coordinates of the CaWO 4 samples were located in the blue region of the CIE diagram. This work demonstrates that materials with optical properties can be obtained simply and affordably using the mechanochemical method.

The present investigation describes the synthesis of luminescent terbium-doped strontium aluminate nanoparticles emitting bright green light, which were synthesized through a solid-state reaction method assisted by microwave radiation. Various samples containing different concentrations of Tb were synthesized, and an analysis of their structural and morphological features was conducted using powder x-ray diffraction, Fourier transform infrared spectroscopy and field emission scanning electron microscopy. The band gaps of the samples were determined utilizing the Kubelka-Munk method. The quenching mechanism observed was identified to be due to dipole-dipole interaction using the Dexter theory. The optimized sample with a terbium concentration of 4 at.% has a luminescence lifetime of 1.05 ms with 20.62% quantum efficiency. The results of this study indicate that the terbium-doped strontium aluminate fluorescent nanoparticles exhibit promising potential for a wide range of applications, including bioimaging, sensing and solid-state lighting., (© 2024 John Wiley & Sons Ltd.)

In the present investigation cyanostilbene based molecular probes, PCS and PCO, bearing N,N-dimethylthiocarbamate and N,N-dimethylcarbamoyal groups, respectively, have been synthesised. These probes exhibit AIEE activity in their aggregated state in the mixed solvent system of THF: H 2 O by way of turning on their emission, which has also been observed in powder, neat thin films and hybrid polymer films. While the probe PCO is silent to ClO - , PCS exhibits a significant response towards ClO - rationalised on the basis of HOCl specific oxidation of thiocarbamate, which is also extended to detect ClO - in water samples. Additionally, applicability of the test strips of PCS for rapid on-site detection of ClO - has been demonstrated. The experimental results are supplemented by the theoretical calculations wherever possible., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Different concentrations of Sm 2 O 3 -doped lead borosilicate glass were synthesized using a melt-quenching method and their characteristics were analyzed using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy absorption, emission, and decay curves. From the XRD patterns, the noncrystalline nature of titled glass was confirmed. The structural groups that existed in the host glass were observed from FTIR spectra. The Judd-Ofelt (JO) intensity parameters and oscillator strengths were derived from the absorption spectra and compared with various reported systems. The excitation luminescence levels of the Sm 3+ ion radiative properties were further computed using the JO intensity parameters. Effective bandwidth, emission cross-sections (σ e ), and several lasing properties were assessed from emission spectra and compared with other reported glass systems. The decay curves of the 4 G 5/2 level of Sm 3+ ion were also been measured and examined. Additionally, the colour coordinates of the Commission International de I'Éclairage chromaticity were assessed. The titled glass were suitable for visible reddish orange luminescence devices based on all obtained parameters., (© 2023 John Wiley & Sons Ltd.)

In the present investigation, we have designed and synthesised Zn 2+ sensitive Julolidine-hydrazone (JSB) based chemosensor, which crystallised in a monoclinic crystal system with P21/c space group. The bare JSB was nonemissive, but in the presence of Zn 2+ ions in solution it showed emission, ascribed to the chelation enhanced emission process, which is also utilised to detect Zn 2+ in water samples. Comparing the chromaticity coordinates deduced from the emission colors of the JSB-Zn 2+ in solution, powder and hybrid polymer thin film, using CIE (Commission Internationale de I'Eclairage 1931) chromaticity diagram, it was found that compared to the emission of the solution, the emission of the powder was red shifted, while that of the thin film was blue shifted. Further, the sensing of Zn 2+ showed reversibility in the presence of pyrophosphate (PPi), which allowed quantification of PPi. Interestingly, in addition to the detection of PPi using the in-situ formed JSB-Zn 2+ complex, the process was selective and discriminated PPi from ADP and ATP. The detection of PPi was rationalized via a decomplexation reaction, and translated in the construction of INHIBIT logic gate. Additionally, the possible use of the JSB coated sensor paper for the on-site detection of Zn 2+ and subsequent JSB-Zn 2+ complex for PPi ions has been demonstrated. The experimental results showed good correlation with the theoretical calculations wherever possible., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

A new red-emitting Eu 3+ (1-17 mol%)-doped Na 3 Mg 4 LiSi 12 O 30 (NMLS) phosphor was prepared using a conventional solid-state reaction method at low temperature. The prepared samples belong to a hexagonal structure with a good match to JCPDS card no. 73-0934. The photoluminescence (PL) emission spectrum showed an intense peak at 612 nm when excited at 393 nm. The variation of electric dipole transition ( 5 D 0 - 7 F 2 ) emission intensity with increasing Eu 3+ ion concentration was investigated. The concentration quenching at 11 mol% is due to the dipole-dipole interaction mechanism in the NMLS host. The optimized NMLS:Eu 3+ phosphor shows 2.18 times higher luminescence intensity than the (Y,Gd)BO 3 (YGB) commercial phosphor. The NMLS:Eu 3+ showed an intense red emission, having Commission Internationale de l'éclairage (CIE) coordinates (0.6280, 0.3691) and colour purity of 99.2%. The resulting phosphor exhibits good thermal stability of 80% at 423 K. The magnified images of fingerprint showed various minute features such as bridges, sweat pores, ridge end, bifurcation, island and core with better visualization under 393 nm excitation. Furthermore, the optimized NMLS:Eu 3+ was used for pc-LED, latent fingerprints, and anticounterfeit applications as a promising red phosphor., (© 2022 John Wiley & Sons Ltd.)

Tb 3+ -doped Na 4 Ca 4 Si 6 O 18 (NCMS:Tb 3+ ) phosphors were synthesized using a solid-state reaction route with increasing dopant concentration. The phase identification studies for NCMS:Tb 3+ phosphors were carried out using an X-ray diffraction (XRD) technique. The XRD patterns for the as-synthesized phosphors showed satisfactory agreement with the standard pattern (JCPDS card no. 75-1687) for the pure phase of the Na 4 Ca 4 Si 6 O 18 compound. The morphology and size of particles were illustrated from scanning electron microscope (SEM) micrographs. The photoluminescence excitation (PLE) spectrum of Tb 3+ -doped Na 4 Ca 4 Si 6 O 18 phosphor depicts the strong excitation peak obtained in the UV spectral region. The trivalent terbium-activated NCMS phosphors excited in the UV region (232 nm wavelength) exhibited intense emission in the blue (350-470) and green (470-650) spectral regions. When increasing the concentration of Tb 3+ ions in the host matrix, the emission colour shifted from the blue to the green region due to cross-relaxation energy transfer (CRET) mechanisms and showed the tunable behaviour of the Tb 3+ -activated as-synthesized NCMS phosphor. These results demonstrated that the Tb 3+ -activated sodium calcium metasilicate phosphor has immense potential to contribute as a green- and blue-green-emitting component in lighting and display device applications., (© 2022 John Wiley & Sons Ltd.)

In this paper, we present new aspects of Sm 3+ -doped pure Li 2 CaSiO 4 as a suitable candidate for white light emitting diode (WLED) applications. The samples were mainly prepared using a conventional modified solid-state synthesis technique. The structural studies were done using X-ray diffraction and Rietveld refinement. Instruments such as a scanning electron microscope (SEM) were used to obtain information about the morphology of the as-prepared samples. Photoluminescence (PL) analysis of phosphor samples for variable concentrations of doping ions with variable excitations were presented. When doped with Sm 3+ in host Li 2 CaSiO 4 it emitted intense blue, green and red emissions and a more intense red emission peak (605 nm) under 408 nm excitation (near-UV-blue). Our study shows that the as-prepared phosphor may be useful for optical devices and mainly for WLEDs. The corresponding transitions of doping ions and concentration quenching effect were studied in detail. The 1931 Commission Internationale de l'Eclairage (x, y) chromaticity coordinates showed the distribution of spectral regions calculated from PL emission spectra and this was found (0.63, 0.36) in the red region, so the phosphor may be useful for near-UV-blue excited WLED applications., (© 2022 John Wiley & Sons Ltd.)

Ce 3+ /Dy 3+ and Ce 3+ /Sm 3+ co-doped alumino-borophosphate glasses (CDABP/ CSABP) were prepared and characterized for luminescence and SHG efficiency properties. FT-IR and FT-Raman spectra have been utilized to identify different functional groups of Phosphate networks. Various optical properties such as, optical absorption, optical band gap energy (E g ), Urbach energy (ΔE) and linear refractive index (n) of the glasses were determined using UV-Vis spectrometer in the spectral range 200-1200 nm. Scanning Electron Microscopy/Energy Dispersive spectrometry (SEM/EDS) reveals information about the elemental compositional homogeneity as well as the surface morphology of the prepared glasses. Influences of a luminescence co-activator of Ce 3+ /Dy 3+ and Ce 3+ /Sm 3+ ions in alumina-borophosphate glasses were interpreted under the excitation wavelength of 300 nm. Two emission peaks detected at 426 nm (blue) and 574 nm (Yellow) in CDABP glass corresponding to the Dy 3+ , whereas three emission peaks traced at 558 nm (green), 598 nm (orange) and 652 nm, (red) in CSABP glass corresponding to the Sm 3+ . The Influence of internal and external quantum efficiency (QE) on the glass's photoluminescence spectrum was measured. The CIE chromaticity obtained from the luminescence spectra, confirming that the CSABP glass emits white light. The colour purity (P c ) and excitation purity (P e ) of the glasses were investigated in order to quantify the quality of light emitted by them. The second harmonic generation (SHG) efficiency of the synthesized glasses was determined without the need of a thermal polling mechanism, and the magnitude was compared to that of Urea and KDP crystal reference samples., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Cyclometalated Ir(III) complexes are widely used as phosphorescent materials in organic light-emitting diodes. In this work, the vibrationally resolved phosphorescence spectra of an experimental reported and four novel designed Ir(III) complexes with 2-(2,5,2',3',4',5',6'-heptafluoro-biphenyl-4-yl)-pyridine (HFYP) as primary ligand are investigated by theoretical calculations. The ancillary ligands are 3-(pentafluorophenyl)-pyridin-2-yl-1,2,4-triazolate (exp3), 3-(trifluoromethyl)-pyridin-2-yl-1,2,4-triazolate (5), 5-methylsulfonyl-2-oxyphenyl-2-oxazole (6), 5-trifluoromethyl-2-oxyphenyl-2-oxazole (7), 2-(3-(trifluoromethyl)-1H-1,2-diazol-5-yl)pyridine (8), respectively. Phosphorescence spectra show that there are mainly two strong peaks, which can be ascribed as low-frequency vibrational modes such as the rotation of ligand plane, and benzene ring/pyridine ring in ligand HFYP1 skeleton vibration coupled with CH in pyridine ring in plane bending vibration. The phosphorescence quantum yields were quantitatively determined by evaluating radiative decay rate constant k r , intersystem crossing rate constatant k ISC and temperature-dependent nonradiative decay rate constant k nr (T). It shows that the quantum yields of compounds exp3, 5 and 8 are relative higher, while those of compounds 6 and 7 are much smaller. This is mainly caused by larger k nr (T) of compounds 6 and 7. It is anticipated that in Ir(III) complex with HFYP primary ligand, pyridin-2-yl-1,2,4-triazolate, 1,2-diazol-5-yl-pyridine are good ancillary ligand, while 2'-oxyphenyl-2-oxazoline is not appropriate to be ancillary ligand., (Copyright © 2019. Published by Elsevier B.V.)

Gadolinium (Gd(3+)) doped CaMoO4:Eu nanoparticles were prepared via facile auto-combustion route and annealed at 900 °C for ∼4 h. X-ray diffraction study confirms the tetragonal scheelite type of CaMoO4 phase. Low voltage cathodoluminescent (CL) measurement were performed for Gd(3+) (0 and 10 at.%) co-doped CaMoO4:Eu as a function of accelerating voltage and filament current. CL studies confirm that Gd(3+) co-doped CaMoO4:Eu has a visible emission peak centered at ∼615 nm and a broad host emission band in the range 380-550 nm. Commission Internationale de L'Eclairage chromaticity diagram co-ordinates of Gd(3+) co-doped CaMoO4:Eu are found to be in reddish orange region as was observed through photoluminescence and CL spectra., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Eu(3+) co-doped ZnO/Zn2SiO4:Mn(2+) composites were synthesized via conventional solid state reaction route and were characterized by X-ray diffraction (XRD) scanning electron microscopy (SEM) and Fourier transform infra-red (FTIR) techniques. XRD studies reveal the presence of both ZnO and Zn2SiO4 phases. Photoluminescence properties of the samples were studied using 266 Nd-YAG laser excitations. Emission bands observed at ~400 nm are ascribed to ZnO phosphor. The green emission bands at 530 nm is associated with the presence of Mn(2+) ion, while orange (~583) and red (615 nm) bands are supposed to be due to the presence of Eu(3+) doped Zn2SiO4 phosphor. Energy transfer from power dependence of the sample for electric dipole transition (615 nm) was studied under 532 nm excitation by varying the power from 0.1 to 4.5 W. The estimated colour correlated temperature (CCT) values are found to be ~4875 and 4458 K under 266 nm and 532 nm laser (0.5 W) excitations. These values are close to those of tubular fluorescent or cool white/daylight compact fluorescent (CFL) (~5000 K) lamps. The present composite phosphor may have potential application in display devices., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Upon 980 nm diode laser excitation visible upconversion emission from the Tb(3+) ions has been observed in combustion synthesized Tb(3+)-Yb(3+) codoped Y2O3 phosphor. The intensity of upconversion as well as downconversion emission bands has been increased by codoping of Li(+) ions into Tb(3+)-Yb(3+):Y2O3 phosphor and the reason behind this increment is discussed. The pump power dependence of upconversion emission bands has shown two-photon absorption process. The cooperative energy transfer from Yb(3+) to Tb(3+) ions is supposed to be responsible for the upconversion emission from the Tb(3+) ions on near infrared excitation. The calculated colour coordinates indicate the purity of intense green emission from present phosphor which is suitable for various photonic applications., (Copyright © 2013 Elsevier B.V. All rights reserved.)