Highly Efficient Far-Red Emitting Mg21Ca4Na4(PO4)18: Ce3+, Eu3+ Luminescent Glasses: A Novel Approach Towards Plant Cultivation Technologies.

One of the exciting developments in contemporary luminescence research is the development of rare earth triggered luminescent glasses, which are a type of lanthanide activated luminous material. For the first time, Ce3+, Eu3+ activated/co-activated Mg21Ca4Na4(PO4)18 orthophosphate glasses have been synthesized using the proposed work's melt quenching technique. The proposed glass sample's XRD pattern has an amorphous character, although its most prominent peak matches data from the Mg21Ca4Na4(PO4)18 standard ICSD database. FT-IR analysis was used to analyze the proposed glass sample's vibrational characteristics. Co-activated Mg21Ca4Na4(PO4)18 glass exhibits large emission peaks under UV excitations that cover the far red area during a photoluminescence examination. These outcomes demonstrate the proposed sample's value in applications such as WLEDs and plant cultivation.

Photoluminescence properties of Pb5(PO4)3Br:RE (RE = Dy3+, Eu3+ and Tb3+) phosphor synthesised using solid-state method.

This study describes the luminous properties of Pb5(PO4)3Br doped with RE3+ (RE = Dy3+, Eu3+ and Tb3+) synthesised using the solid-state method. The synthesised phosphor was characterised using Fourier-transform infrared, X-ray diffraction, scanning electron microscopy and photoluminescence measurements. Dy3+-doped Pb5(PO4)3Br phosphor exhibited blue and yellow emissions at 480 and 573 nm, respectively, on excitation at 388 nm. Eu3+-doped Pb5(PO4)3Br phosphor exhibited orange and red emissions at 591 and 614 nm, respectively, on excitation at λex = 396 nm. Pb5(PO4)3Br:Tb3+ phosphor exhibited the strongest green emission at 547 nm on excitation at λex = 380 nm. Additionally, the effect of the concentration of rare-earth ions on the emission intensity of Pb5(PO4)3Br:RE3+ (RE3+ = Dy3+, Eu3+ and Tb3+) phosphors was investigated.

Luminescence Thermometry Based on the Upconversion Luminescence from the Stark Sublevels of BaY2F8:Yb3+, Tm3+ Phosphor.

Visible and near-infrared (NIR) upconversion luminescence (UCL) emissions originating from the BaY2F8: Yb3+, Tm3+ systems were investigated under a laser excitation at 980 nm. The BaY2F8:20 mol% Yb3+, x mol% Tm3+ and BaY2F8: y mol% Yb3+, 0.5 mol% Tm3+ phosphors showed prominent UCL at 800 and 810 nm. The optimized doping concentrations of Yb3+ and Tm3+ in the BaY2F8 host matrix were evaluated, their spectroscopic properties were determined, and studies on their temperature-dependent behaviour were carried out. The temperature-sensing properties were studied by generating the fluorescence intensity ratio (FIR) of the UCL peaks originating from the thermally-coupled energy levels of the Tm3+ ions. The Stark sublevels of 1G4 level of Tm3+ ions were utilized to estimate the temperature-sensing abilities of the phosphor.

Persistent phosphors for luminous paints: A review.

The article briefly reports the fundamental scientific principles and landmarks in the field of luminescence and further enlightens the importance of persistent phosphor that is now widely used in luminous paints. Its main focus is on phosphorescence that makes use of lanthanides that have gained paramount importance in various cross-sections of luminescent applications. Both inorganic and organic afterglow materials, synthesis and characterization along with skilled researchers' essential updates on emerging trends and efforts are elucidated at length. It exclusively reviews the red/green/blue organic/inorganic/hybrid phosphorescent materials and the latest advances in the development of novel long afterglow materials that can accelerate the green technology in the world of luminescence.

Energy transfer process in a rare earth (Ce3+ , Dy3+ , Sm3+ )-doped nanocrystalline phosphate phosphor.

This work presents the optimized luminescence spectra for the Ce3+ ,Sm3+ -doped NaSrPO4 phosphor that was synthesized using a wet chemical method. Ce3+ and Sm3+ are activator impurities that show spectral splitting bands that corresponds to the d-f and f-f transitions, respectively. These impurity elements shows the characteristics spectral bands when doped with the NaSrPO4 host lattice. Spectral splitting in the Ce3+ excitation band was monitored in the 240-340 nm range, in which the observed bands were located at 269 nm, 292 nm and 321 nm, and emission bands were observed in the broad spectral range 330-430 nm. However, when Sm3+ ion was doped in the same host lattice we obtained a characteristic emission band at 590 and 645 nm in the orange-red region, under sharp excitation bands located at 345, 361, 375, and 403 nm respectively. Also, we carried out energy transfer analysis in the Ce3+ /Dy3+ -doped NaSrPO4 phosphor. Further crystalline phase and the nanophase nature of the phosphor compound were confirmed using X-ray diffraction and transmission electron microscopy analyses.

Investigations on optical properties of Eu0.5 Sm0.5 (TTA)3 tppo hybrid organic complexes molecularly doped in PMMA and PS matrices.

An attempt has been made to synthesize orange-red light-emitting rare earth-doped polymer matrices Eu0.5 Sm0.5 (TTA)3 tppo (Eu = europium, Sm = samarium, TTA = thenoyltrifluoroacetone, tppo = triphenylphosphine oxide) hybrid organic complex by solution technique. Blended thin films were made by molecularly doping the complex in polymethylmethacrylate (PMMA) and polystyrene (PS) polymers at different weight percentages (5%, 10%). These films were solvated in basic and acidic media to explore the effect of solvent on its luminescence properties. UV-visible absorption spectra of these solvated films portray two peaks corresponding to π→π* and n→π* optical transitions in the range 240-275 nm and 370-390 nm in basic medium. Energy band gap of these thin films in basic medium was found between 3.16 eV to 3.20 eV and 3.12 eV to 3.22 eV in acidic medium. Photoluminescence spectra of all films in dichloromethane showed an intense peak at 614 nm, whereas in formic acid, the same were found at 475 nm, which fell in the orange-red and blue region of the visible spectrum, respectively. CIE coordinates of these solvated films in various solvents and at different weight percentages revealed tunable orange-red to blue light emission with change in polarity of the solvent. Therefore the synthesized complexes blended in the polymers can be shaped into flexible films for fabrication of organic light-emitting diodes (OLEDs) with consistent results, proving their prospect as colour tunable light emissive materials for OLED devices, lasers, displays, and solid-state lighting.

Synthesis and luminescence characterization of Eu3+ -doped Ca7 Mg2 (PO4 )6 phosphor for eco-friendly white light-emitting diodes and thermoluminescence dosimetric applications.

A Eu3+ -activated Ca7 Mg2 (PO4 )6 phosphor was prepared at high temperature (800°C) using a solid-state reaction method. The crystal structure, phase formation of the prepared phosphor was characterized using X-ray diffraction patterns and Fourier transformed infrared analysis. The luminescence properties of the synthesized phosphor were characterized using photoluminescence and thermoluminescence techniques. The prepared phosphor showed two emission peaks at 594 nm with an orange colour due to the 5 D0 →7 F1 transition and at 612 nm a red colour due to the 5 D0 →7 F2 transition under 396 nm near-UV excitation. The prepared phosphors were irradiated with different doses of γ-rays from a 60 Co gamma irradiation source. Thermoluminescence glow curves for this sample phosphor were obtained using a Nucleonix 1009I TL reader. Synthesized phosphor samples were exposed to a 3.6 kGy dose of γ-rays. The thermoluminescence glow curve of the Ca7 Mg2 (PO4 )6 :0.05 mol%Eu3+ phosphor showed maximum intensity at all concentrations of Eu3+ ions. The Ca7 Mg2 (PO4 )6 :0.05 mol%Eu3+ phosphor was irradiated with different doses of 60 Co γ-irradiation and a linear response was observed between 0.6 kGy and 3.6 kGy. Trapping parameters such as activation energy, frequency factor and order of kinetics were calculated. The CIE chromaticity diagram showed the colour coordinates of the synthesized phosphor in the orange and red regions of the visible spectrum; this spectral feature revealed high colour purity and excellent chromaticity coordinate characteristics. Photoluminescence and thermoluminescence properties revealed that the prepared phosphor could be a potential red-emitting phosphor for eco-friendly white light generation and an excellent thermoluminescent dosimeter material for thermoluminescence dosimetric applications.

Thermoluminescence study of CaNa2 (SO4 )2 phosphor doped with Eu3+ and synthesized by combustion method.

In the present study, the thermoluminescence (TL) properties of an Eu3+ -doped CaNa2 (SO4 )2 phosphor were studied. The Eu3+ -doped CaNa2 (SO4 )2 phosphor was synthesized using the combustion method. The samples were well crystallized in the monoclinic phase. The TL glow curve of the Eu3+ -doped CaNa2 (SO4 )2 phosphor showed a single prominent peak at around 210°C with showed linearity on increasing exposure. The response curve of the synthesized phosphor showed linearity in the range 500-7000 Gy. Trapping parameters of synthesized phosphors such as activation energy, frequency factor, and order of kinetics were calculated in the study. These trapping parameters were determined by different methods such as Chen's peak method, the initial rise method, and Ilich's method. Each characteristic of these outcomes demonstrated that the synthesized Eu3+ -doped CaNa2 (SO4 )2 phosphor had outstanding TL properties and might be valuable for TL dosimetry application.

Upconversion process in BaY2 F8 :Yb3+ ,Ho3+ phosphor for optical thermometry.

A BaY2 F8 :Yb3+ ,Ho3+ phosphor was synthesized using a simple precipitation method. The temperature-sensing properties of BaY2 F8 :Yb3+ ,Ho3+ phosphor were investigated using the fluorescence intensity ratio (FIR) of the thermally coupled energy levels (5 F4 and 5 S2 ) of Ho3+ . Energy transitions 5 F4 →5 I8 and 5 S2 →5 I8 gave rise to emission peaks at 538 nm and 549 nm, respectively. The areas under these two emission peaks were used to calculate the FIR. Temperature-dependent upconversion luminescence was recorded in the temperature range 303-623 K using a 980 nm laser excitation source. The results suggested that the BaY2 F8 :Yb3+ , Ho3+ phosphor has the potential to be used as a non-contact optical temperature sensor.

Enhanced photoluminescence in RE (Eu3+ , Ce3+ and Sm3+ )-activated Ca10 (PO4 )F2 phosphors by double or triple ionized mineral doping: a comparative study.

In this work, RE3+ (Eu, Ce and Sm)-activated Ca10 (PO4 )6 F2 (fluorapatite) phosphors were synthesized by doping with different apatite minerals (SO4 , VO4, WO4 ) using a solid-state diffusion method. Optical and structural characterizations were performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy, and photoluminescence (PL) spectroscopy. XRD characterization showed the crystalline nature of the phosphor. PL properties were investigated under ultraviolet light excitation for all three rare earths. CIE chromaticity revealed the colour emitted in the visible region. Luminescence intensity was enhanced considerably by tuning the host matrices after core-shell formation by substitution with other ions producing promising candidates for white light-emitting diode materials.

Tailoring of thermoluminescent properties and assessment of trapping parameters of natural fluorite samples from Dogargaon fluorite mines, India.

Mineral fluorite or fluorspar (CaF2 ) can host significant quantities of trivalent REE3+ (rare earth element) by substitution with divalent Ca2+ . The fluorites associated with carbonatites are often REE-rich compared to those derived from sedimentary, hydrothermal, or Mississippi Valley-type (MVT) fluorites. The naturally occurring fluorites have several industrial applications one of which is for luminescence. Whether or not REE enriched, the fluorite makes an ideal host for REEs, which are very important phosphors. The naturally occurring fluorites are available in sufficient quantities to cater to the industrial demand. Investigations have been carried out on the fluorites from active fluorite mines at Dongargaon in central India. Thermoluminescence behavior of a natural fluorite sample was investigated using a Nucleonix TL 1009I thermoluminescence reader. Multiple traps formed in the broad thermoluminescent (TL) glow curve were found by TL anal deconvolution software. Trapping parameters for all multiple traps formed on deconvoluting broad TL glow curve were found by different methods like Initial rise method, Chen's Peak shape method and Ilich method.

Investigation of thermoluminescence response and trapping parameters of natural barite samples from Dongargaon mine, India.

Dosimetry is a technique that quantitatively measures the ionizing radiation absorbed by matter. The present study was conducted on the barites from a mine at Dongargaon in Central India. Morphological and structural analysis of proposed sample was carried out using X-ray diffraction and standard error of the mean. Thermal analysis and chemical composition of the proposed sample were carried out using thermogravimetric analysis and differential thermal analysis, and electron probe microanalysis. Thermoluminescence (TL) studies on a natural barite sample were performed using a Nucleonix TL1009I TL reader following sample irradiation with γ-rays generated from a 60 Co irradiation source. A broad TL glow curve was observed after TL study that was then deconvoluted using TLanal deconvolution software. Trapping parameters from the sample such as activation energy (E), order of kinetics (b), and frequency factor (s) were calculated using Chen's peak shape method, the initial rise method, and Ilich's method. The results indicated that the natural barite sample could be used in high-dose TL dosimetric applications in various fields.

Thermoluminescence dosimetry properties and kinetic analysis of K3 Ca2 (SO4 )3 F:Dy3+ phosphor.

A trivalent Dy3+ -activated K3 Ca2 (SO4 )3 F fluoride-based phosphor was synthesized using a solid-state reaction method and characterized for its thermoluminescence (TL) application. The crystal structure and surface morphology of the as-synthesized material was analyzed using X-ray diffraction and scanning electron microscopy. A series of the K3 Ca2 (SO4 )3 F:Dy3+ phosphor was irradiated using γ-rays from a 60 Co source and TL glow curves were recorded using a Nucleonix 1009I TL reader. The glow curve of the prepared phosphor showed a prominent single peak at 278°C. TL characteristics were maximum intensity at 1 mol% of Dy3+ ion with a single TL glow peak. The TL glow curve revealed linearity with increase in exposure dose range from 0.1 kGy to 3.0 kGy. Theoretical analysis of the TL glow curve of the γ-ray-irradiated sample was carried out using a computerized glow curve deconvolution method and trapping parameters such as activation energy and frequency factor were calculated using the initial rise method and Ilich's method. The synthesized Dy3+ -doped K3 Ca2 (SO4 )3 phosphor revealed excellent TL properties and was found to be a potential candidate for dosimetric applications.

Photoluminescence studies and synthesis of BaSO3 Cl2 :Ce3+ blue-emitting lamp phosphor.

The photoluminescence excitation and emission spectra of BaSO3 Cl2 :Ce3+ phosphor were investigated. Excitation wavelength was 323 nm. The phosphor was prepared using a combustion synthesis method. The emission spectrum exhibited a well defined asymmetric band with a maximum at 445 nm for higher emission concentrations. The prepared samples were characterized by X-ray diffraction, scanning electron microscopy, photoluminescence and Commission Internationale de l'éclairage colour coordinates; emission intensity was related to relative Ce3+ concentration. These developments enabled the rapid and energy-efficient production of fine particles in the powder form with little expenditure. No additional emission band was observed in the emission spectra, demonstrating that the Ce3+ ion occupied one category of site in the prepared host phosphor.

Tunable lanthanide/transition metal ion-doped novel phosphors for possible application in w-LEDs: a review.

Lanthanide-based phosphors have been extensively investigated for their possible applications in solid-state lighting technologies especially for white-light-emitting diodes. In this review article emphasis has been laid on discussing the recent developments of phosphors for warm white-light production based on various optical characteristics such as quantum efficiency, thermal stability, short emission decay time, long-term stability, facile synthesis, and low cost of production. We have tried to cover the essential and latest discoveries of the lanthanide/rare earth-doped phosphors after 2010. New generations of narrow-band phosphors have also been included. The optical and material properties of several novel phosphors and their luminescence characteristics have been thoroughly discussed.

Luminescence characterization of KBaPO4 :RE (RE = Sm3+ ,Eu3+ ,Dy3+ ) phosphors.

KBaPO4 luminescent powdered phosphors doped with rare earth elements (RE = Sm3+ ,Eu3+ ,Dy3+ ) were successfully synthesized using a wet chemical method to identify the most suitable phosphor for solid-state lighting based on the measurement of their emission spectra at excitation wavelengths. The X-ray diffraction pattern of the as-prepared KBaPO4 was well matched with its standard JCPDS file no. 330996, indicating the formation of the desired compound. Scanning electron microscopy images revealed irregular morphology, the material crystallized particles aggregated and were non-uniform with particle sizes ranging from 1 to 100 µm. Photoluminescence excitation and emission spectra clearly indicated that the phosphor containing the Sm3+ -activated KBaPO4 phosphors could be efficiently excited at 403 nm and exhibited an emission mainly including two wavelength peaks at 559 nm and 597 nm. The phosphor containing the Eu3+ -activated KBaPO4 phosphors could be efficiently excited at 396 nm and exhibited a bright red emission mainly including two wavelength peaks at 594 nm and 617 nm. The phosphor containing the Dy3+ -activated KBaPO4 phosphors could be efficiently excited at 349 nm and exhibited wavelength peaks at 474 nm and 570 nm.

Thermoluminescence study in fossils of dinosaur bones and eggshells.

In this study, thermoluminescence (TL) characterization of fossils of sauropod dinosaur bone, dinosaur eggshells, and associated sediments were recorded for the first time. The fossil bone was collected from the Bagwanya intertrappean sediments in the Dhar district of Madhya Pradesh, India. TL was recorded using 60 Co gamma ray exposure at different doses. Fossils of dinosaur bone, dinosaur eggshells, and associated sediments were irradiated using 60 Co gamma rays at different doses from 0.15 kGy to 19 kGy. The linear dose-response curve of the irradiated sample was obtained for a dose ranging from 0.15 kGy to 9.5 kGy. These geological samples were characterized further using X-ray diffraction for confirmation with phase, scanning electron microscopy, Fourier transform infrared spectroscopy, and wavelength dispersive-X-ray fluorescence for determination of the elemental composition in parts per million to percentage levels.

Intense green-, red-emitting Tb3+ , Tb3+ /Bi3+ -doped and Sm3+ , Sm3+ /La3+ -doped Ca2 Al2 SiO7 phosphors.

This paper focuses on an optical study of a Tb3+ /Bi3+ -doped and Sm3+ /La3+ - doped Ca2 Al2 SiO7 phosphor synthesized using combustion methods. Here, Ca2 Al2 SiO7 :Sm3+ showed a red emission band under visible light excitation but, when it co-doped with La3+ ions, the emission intensity was further enhanced. Ca2 Al2 SiO7 :Tb3+ shows the characteristic green emission band under near-ultraviolet light excitation wavelengths, co-doping with Bi3+ ions produced enhanced photoluminescence intensity with better colour tunable properties. The phosphor exhibited better phase purity and crystallinity, confirmed by X-ray diffraction. Binding energies of Ca(2p), Al(2p), Si(2p), O(1s) were studied using X-ray photoelectron spectroscopy. The reported phosphor may be a promising visible light excited red phosphor for light-emitting diodes and energy conversion devices.

Study of thermoluminescence in turtle shell fossils using radiation dosimetry.

The present study describes for the first time thermoluminescence (TL) characterization of turtle shell. A fossil shell was collected from the Dongargaon area in the Chandrapur district of Maharashtra, India. TL was recorded and a comparative study of TL for the above material was performed to understand the special TL characteristics of the shell. The shell was irradiated with 60 Co γ-radiation to study its TL properties. The sample displayed two good TL peaks at 135°C and 255°C. A linear dose-response curve for the irradiated sample was produced for the dose range 0.79-28.5 kGy; this sample of turtle shell (fossil) may be useful as a high dose dosimetry phosphor in this range. This geological sample was further characterized using X-ray diffraction to confirm its phase structure and by scanning electron microscopy , Fourier transform infrared and wavelength dispersive X-ray fluorescence spectroscopy to determine morphology, vibration, and elemental composition as ppm or percentage of the sample, respectively. Kinetic parameters of the TL glow peak were calculated using three different methods.

Synthesis and photoluminescence properties of Eu3+ -activated Ba2 Mg(PO4 )2 phosphor.

In this paper, we have reported the photoluminescence (PL) properties of the Ba2 Mg(PO4 )2 :Eu3+ phosphor synthesized using a wet chemical method. The preliminary scanning electron microscopy (SEM) investigation of the sample revealed irregular surface morphology with particle sizes in the 10-50 µm range. The strongest PL excitation peak was observed at 396 nm. The emission spectra indicated that this phosphor can be effectively excited by the 396 nm wavelength. Upon 396 nm excitation, the emission spectrum showed characteristics peaks located at 592 nm and 615 nm. These intense orange-red emission peaks were obtained due to f→f transitions of Eu3+ ions. The emission peak at 592 nm is referred to as the magnetic dipole 5 D0 →7 F1 transition and the emission peak at 615 nm corresponded to the electric dipole 5 D0 →7 F2 transition of Eu3+ . The Commission Internationale de l'Eclairage (CIE) coordinates of the Ba2 Mg(PO4 )2 :Eu3+ phosphor were found to be (0.586, 0.412) for wavelength 592 nm and (0.680, 0.319) for wavelength 615 nm situated at the edge of the CIE diagram, indicating high colour purity of phosphors. Due to the high emission intensity and a good excitation profile, Eu3+ -doped Ba2 Mg(PO4 )2 phosphor may be a promising orange-red phosphor candidate for solid-state lighting applications.