Synthesis and study of optical properties of a Gd3+-doped NaYF4 phosphor for phototherapy lamp application.

In recent trends, radiation falls under the narrowband ultraviolet-B region (305-315 nm) widely used in phototherapy lamp applications in the treatment of skin diseases. In this paper, we report a Gd3+-doped NaYF4 luminescent material synthesized for the first time using the low-temperature co-precipitation method. It crystallized into a face-centred cubic structure, as confirmed by X-ray diffraction characterization techniques and Rietveld refinement. The photoluminescence property of the as-prepared sample shows a highly intense, sharp emission band obtained at 311 nm, which belongs to the narrowband ultraviolet-B region and corresponds to the transition of the 6P7/2→8S7/2 level of the Gd3+ ions under 272 nm excitation (8S7/2 to 6IJ). The transitions of the Gd3+ ions are detected entirely with different concentrations of Gd3+ ions. Scanning electron microscopy analysis indicated that the average particle was 288 nm. The critical distance for energy transfer was calculated to be equal to 11.5017 Å. Dipole-dipole interaction is responsible for energy transfer, as analyzed by Dexter theory. These excellent optical characteristics, together with their highly efficient and low-cost synthesis approach, indicate that synthesized NaYF4:Gd3+ phosphors have excessive potential for phototherapeutic lamp applications.

Synthesis and study of luminescence properties of a deep red-emitting phosphor K2 LiAlF6 :Mn4+ for plant cultivation.

Light is the most important component in plant growth and development. This study synthesised a novel Mn4+ -doped K2 LiAlF6 red-emitting phosphor using the coprecipitation method. We observed that on addition of dopant Mn4+ ions to the host K2 LiAlF6 , its phase changed from rhombohedral to cubic due to the change in the lattice position of the atoms. When the atoms are excited at 468 nm, the K2 LiAlF6 :Mn4+ phosphor exhibited a red emission band ranging from 630 to 700 nm, centred at 638 nm, which matched well with the absorption spectra of phytochrome PR. The critical quenching content of Mn4+ ions was ~3 mol%. The critical distance between Mn4+ ions was determined to be 19.724 Å, and non-radiative energy transfer among the nearest-neighbour Mn4+ ions was the mechanism used for the concentration quenching effect. The Commission International de l'Eclairage (CIE) chromaticity coordinates of the K2 LiAlF6 :0.03 Mn4+ sample were (x = 0.7162, y = 0.2837). The luminescence mean decay time was calculated to be 8.29 ms. These results demonstrated the promising prospect of K2 LiAlF6 :Mn4+ as a red-emitting phosphor for application in red light-emitting diodes for plant cultivation.

Assessment of dosimetric impact of interfractional 6D setup error in tongue cancer treated with IMRT and VMAT using daily kV-CBCT.

Background: This study aimed to evaluate the dosimetric influence of 6-dimensional (6D) interfractional setup error in tongue cancer treated with intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) using daily kilovoltage cone-beam computed tomography (kV-CBCT). Materials and methods: This retrospective study included 20 tongue cancer patients treated with IMRT (10), VMAT (10), and daily kV-CBCT image guidance. Interfraction 6D setup errors along the lateral, longitudinal, vertical, pitch, roll, and yaw axes were evaluated for 600 CBCTs. Structures in the planning CT were deformed to the CBCT using deformable registration. For each fraction, a reference CBCT structure set with no rotation error was created. The treatment plan was recalculated on the CBCTs with the rotation error (RError), translation error (TError), and translation plus rotation error (T+RError). For targets and organs at risk (OARs), the dosimetric impacts of RError, TError, and T+RError were evaluated without and with moderate correction of setup errors. Results: The maximum dose variation ΔD (%) for D98% in clinical target volumes (CTV): CTV-60, CTV-54, planning target volumes (PTV): PTV-60, and PTV-54 was -1.2%, -1.9%, -12.0%, and -12.3%, respectively, in the T+RError without setup error correction. The maximum ΔD (%) for D98% in CTV-60, CTV-54, PTV-60, and PTV-54 was -1.0%, -1.7%, -9.2%, and -9.5%, respectively, in the T+RError with moderate setup error correction. The dosimetric impact of interfractional 6D setup errors was statistically significant (p < 0.05) for D98% in CTV-60, CTV-54, PTV-60, and PTV-54. Conclusions: The uncorrected interfractional 6D setup errors could significantly impact the delivered dose to targets and OARs in tongue cancer. That emphasized the importance of daily 6D setup error correction in IMRT and VMAT.

Structural, morphological, and photoluminescence properties of RE (RE = Dy3+ , Eu3+ , Sm3+ )-doped CaAlBO4 phosphor synthesized by combustion method.

The CaAlBO4 :RE (RE = Dy3+ , Eu3+ , Sm3+ ) phosphor were prepared via combustion synthesis and studied by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) analysis, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), photoluminescence (PL) spectra and CIE coordinates. The phase formation of the obtained phosphor was analyzed by XRD and the result was confirmed by standard PDF Card No. 1539083. XRD data successfully indicated pure phase of CaAlBO4 phosphor. The crystal structure of CaAlBO4 phosphor is orthorhombic with space group Ccc2 (37). The SEM image of CaAlBO4 phosphor reveals an agglomerated morphology and non-uniform particle size. The EDS image provides evidence of the elements present and the chemical makeup of the materials. Under the 350 nm excitation, the emission spectrum of Dy3+ activated CaAlBO4 phosphor consists of two main groups of characteristic peaks located at 484 and 577 nm which are ascribed to 4 F9/2 → 6 H15/2 and 4 F9/2 → 6 H13/2 transition of Dy3+ respectively. The PL emission spectra of CaAlBO4 :Eu3+ phosphor shows characteristics bands observed around 591 and 613 nm, which corresponds to 5 D0 → 7 F1 and 5 D0 → 7 F2 transition of Eu3+ respectively, upon 395 nm excitation wavelength. The emission spectra of Sm3+ activated CaAlBO4 phosphor shows three characteristic bands observed at 565, 601 and 648 nm which emits yellow, orange and red color. The prominent emission peak at the wavelength 601 nm, which is attributed to 4 G5/2 → 6 H7/2 transition, displays an orange emission. The CIE color coordinates of CaAlBO4 :RE (RE = Dy3+ , Eu3+ , Sm3+ ) phosphor are calculated to be (0.631, 0.368), (0.674, 0.325) and (0.073, 0.185). As per the obtained results, CaAlBO4 :RE (RE = Dy3+ , Eu3+ , Sm3+ ) phosphor may be applicable in eco-friendly lightning technology.

Thermoluminescence studies of zinc borate (ZnB2 O4 ) phosphor doped with rare earths for dosimetric aspects.

A series of ZnB2 O4 phosphors doped with different concentrations of Eu and Dy (0.05 0.1, 0.2, 0.5, 1.0 mol%) and co-doped with Ce (1, 2, 5, 7, 10 mol%) respectively was prepared via the solid-state reaction technique and the thermoluminescence (TL) behaviour of gamma ray-irradiated samples was studied. The synthesized samples were irradiated with γ-rays for the dose range 0.03-1.20 kGy. The TL intensity variations with dose, dopant concentration, and the effect of co-doping were studied. The TL response curves for ZnB2 O4 :Eu3+ and ZnB2 O4 :Dy3+ , ZnB2 O4 :Eu3 ,Ce3+ and ZnB2 O4 :Dy3+ ,Ce3+ phosphor were observed. It was revealed that ZnB2 O4 :Eu3+ showed a linear TL behaviour for the dose 0.03-1.20 kGy and ZnB2 O4 :Dy3+ showed linearity for the gamma dose range 0.03-0.10 kGy. Furthermore, fading for all the samples was observed to be less than 10% for a storage period of 30 days. In addition to this, the trapping parameters, especially activation energies were evaluated using the Ilich method and the initial rise method. The activation energy values obtained from both methods were in complete agreement with each other.

EVALUATION OF ACCURACY AND INTRINSIC UNCERTAINTY OF AUTOMATED IMAGE REGISTRATION FOR A 6D KV-CBCT IMAGE GUIDANCE SYSTEM: A CONCURRENT ANALYSIS WITH A MACHINE PERFORMANCE CHECK.

The accuracy and uncertainty of the automated image registration (AIR) algorithm in a six-dimensional (6D) kilovoltage cone-beam computed tomography (kV-CBCT) image-guided radiation therapy (IGRT) system were evaluated with a concurrent analysis of machine performance check (MPC). The MPC was performed before (MPCpre) and after (MPCpost) each accuracy and intrinsic uncertainty measurement. The accuracy was evaluated for 25 sets of the known shifts applied to the Catphan-504 phantom through a 6D robotic couch in the head, thorax, and pelvis CBCT acquisition modes. The uncertainty was evaluated for the intensity range, soft tissue, and bone matching filters in the head, thorax and pelvis CBCT acquisition modes. The mean ΔMPC (MPCpost-MPCpre) for all test parameters was within 0.02 ± 0.08 mm and 0.00 ± 0.02°. The overall average accuracy in AIR of 6D kV-CBCT IGRT in all translational and rotational axes was within 0.05 ± 0.76 mm and 0.02 ± 0.07°, respectively, for all CBCT modes. The overall mean population (Mpop), systematic (Σ) and random (σ) errors were within 0.47, 0.53 and 0.24 mm and within 0.03, 0.08 and 0.07° in translational and rotational axes, respectively, for all matching filters in all CBCT modes. The accuracy and intrinsic uncertainty in the AIR of the 6D kV-CBCT IGRT were within acceptable limits for clinical use.

Intensity enhancement of photoluminescence in Tb3+ /Eu3+ co-doped Ca14 Zn6 Al10 O35 phosphor for WLEDs.

This article focuses on the effect of monovalent cation doping on the optical properties of rare earth (RE = Eu3+ , Tb3+ ) co-doped Ca14 Zn6 Al10 O35 which has been synthesized by a low temperature combustion method. Crystalline phase of the Ca14 Zn6 Al10 O35 phosphor was examined and confirmed by X-ray diffraction measurement. Under near-ultraviolet light excitation Eu3+ -doped Ca14 Zn6 Al10 O35 phosphor exhibit characterization of Eu3+ emission bands that are located at a maximum wavelength (λmax ) of approximately 470 nm and other peaks centred at 593 nm and 615 nm, respectively. With Tb3+ -doped Ca14 Zn6 Al10 O35 phosphor showing a green emission band centred at 544 nm under near-ultraviolet range. Furthermore, we studied the energy transfer process in Eu3+ /Tb3+ pair and enhancement in photoluminescence (PL) intensity with doping different charge compensation. Here we obtained the optimum PL emission intensity of the phosphor in broad and intense visible spectral range which may be significant for the fabrication of white light emitting diodes (WLEDs).

Optical and thermal properties of rare earth-doped K4 Ca(PO4 )2 phosphor.

The luminescent properties and energy transfer (ET) mechanism in the Ln3+ pair of the RE3+ (RE = Eu3+ , Ce3+ , Dy3+ and Sm3+ ) doped K4 Ca(PO4 )2 phosphor were successfully investigated using a conventional high-temperature solid-state reaction. In the near infrared (NIR) range, Ce3+ -doped K4 Ca(PO4 )2 phosphor exhibited a UV-Vis. emission band, whereas K4 Ca(PO4 )2 :Dy3+ exhibited characteristic emission bands centred at 481 and 576 nm in the near-ultraviolet excitation range. The possibility of ET from Ce3+ to Dy3+ in K4 Ca(PO4 )2 phosphor was confirmed by a significant increase in the photoluminescence intensity of the Dy3+ ion based on the spectral overlap of acceptor and donor ions. X-ray diffraction, Fourier-transform infrared and thermogravimetric analysis/differential thermal analysis TGA/DTA were carried out to study phase purity, presence of functional groups and amount of weight loss under different temperature regimes. Therefore, the RE3+ -doped K4 Ca(PO4 )2 phosphor may be a stable phosphor host for light-emitting diode applications.

Synthesis and novel emission properties of Bi3+ -doped Ca2 BO3 Cl phosphor for plant cultivation.

In the present work, a series of Bi3+ -activated Ca2 BO3 Cl phosphors was synthesized using the conventional high-temperature solid-state reaction method. The crystal structure of the prepared sample was determined to be monoclinic with space group P21/c. Scanning electron microscopy (SEM) analysis demonstrated the surface morphology with aggregated particles and sizes in the nano range. The presence of vibrational features and their luminescence characteristics were studied using Fourier transform infrared spectroscopy and photoluminescence (PL) techniques, respectively. At the 486 nm excitation wavelength, the PL spectrum revealed a sharp emission centred at 732 nm that was attributed to the 3 P1 →1 S0 transition of Bi3+ . The emission spectra exhibited the highest emission intensity at 0.5 mol% Bi3+ ion concentration, beyond this the emission intensity decreased due to the concentration quenching phenomenon attributed to multipolar interaction. The Commission Internationale de l'éclairage coordinates located at (0.7347, 0.2653) confirmed emission in the deep-red region with a colour purity of 99.98%. The obtained outcomes suggested that the reported material may be a promising candidate as a red-emitting phosphor for w-LEDs and plant growth applications.

Luminescence investigation of Sm3+ ,Eu2+ -activated/co-activated Ba2 AlB4 O7 Cl phosphors: novel red to blue colour tuning in chloroborates.

Borochlorate phosphors have shown their worth in modern day lighting over the last few years. Colour tunability of the phosphor is a modern techniques used to obtain white-light-emitting diodes (WLEDs). In the proposed work, Sm3+ ,Eu2+ -activated/co-activated Ba2 AlB4 O7 Cl phosphors were investigated for WLED applications as well as display devices. A convectional solid-state diffusion method was used to synthesize the proposed phosphors. X-ray diffraction (XRD) of the proposed phosphors confirmed the crystalline nature of the sample. Morphological studies on the samples were carried out using scanning electron microscopy analysis. A photoluminescence study of the colour tunable phosphor showed the characteristic peak of Sm3+ together with one broad peak for Eu2+ ions. Red to blue colour tunability was observed in the proposed phosphor with enhancement of Eu2+ ions. All these results showed the worth of this sample in WLED applications as well as in display devices.

Combustion-assisted Ca8.25 Na1.5 Al6 O18 :Sm3+ phosphors for solid-state lighting and WLED applications.

Aluminate-based phosphors have been the most investigated luminescent phosphors over decades due to their outstanding optical properties. In the proposed work, a series of Sm3+ -doped Ca8.25 Na1.5 Al6 O18 (CNAO) phosphor sample was prepared using a simple combustion technique with the help of two fuels i.e., urea-glycine. The purity of phase and structural analysis of the CNAO phosphors were confirmed using X-ray diffraction analysis. Vibrational features of this phosphors confirmed were via Fourier transform infrared analysis. A photoluminescence study of this phosphor showed a doublet emission at 568 and 576 nm in the yellow region attributable to the 4 G5/2 →6 H5/2 transition of Sm3+ ions, whereas a doublet peak noticed in red region ranged from 600 to 620 nm and was attributable to the 4 G5/2 →6 H7/2 transition of Sm3+ ions. Moreover, Commission Internationale de l'éclairage colour coordinates were also located in the yellowish-red region and confirmed the potential of this phosphor as a yellowish-red component for white light-emitting diodes and display devices applications.

Wet chemical synthesis of BiPO4 :Eu3+ phosphor for w-LED application.

The synthesis of BiPO4 :Eu3+ phosphors has been achieved via a wet chemical process. X-ray diffraction patterns show that the phase of the as-prepared samples matches very well with the standard BiPO4 structure. At 395 nm, the highest excitation intensity was observed. Following 395 nm excitation, two characteristic emission peaks at 592 nm and 616 nm were shown. At 0.5 mol% of Eu3+ ions, concentration quenching occurred. The particle size is within the micrometre range, according to the scanning electron microscope magnification. The chromaticity coordinates for wavelengths 592 nm and 616 nm are (x = 0.586, y = 0.412) and (x = 0.682, y = 0.317), respectively. The findings imply that the prepared phosphor may be used to create white light-emitting diodes.

Luminescence properties of MgCaAl10 O17 :RE3+ (RE3+ = Sm3+ ,Dy3+ ) phosphor for eco-friendly solid-state lighting applications.

Different concentrations of rare earth Sm3+ - and Dy3+ -activated MgCaAl10 O17 phosphors were synthesized using the combustion route and their detailed luminescence investigations are reported in this paper. The photoluminescence excitation spectra of Sm3+ - and Dy3+ -activated MgCaAl10 O17 phosphor show multiple peaks in the ultraviolet light region of the electromagnetic spectrum. The characteristic emission spectra of the MgCaAl10 O17 :Sm3+ phosphor are located at 563 nm, 594 nm, and 644 nm, with the maximum emission intensity occurring at 594 nm. The emission spectra of the MgCaAl10 O17 :Dy3+ phosphor show two emission peaks, one at 476 nm wavelength in the blue light region and the other at 573 nm wavelength in the yellow region. The above results suggest that the prepared phosphor can be suitable for applications in eco-friendly solid-state lighting.

Luminescence study of Sm3+ ,Eu3+ -doped Y2 Zr2 O7 host: optical investigation of greenish yellow to red colour tunable pyrochlore phosphor.

Pyrochlore phosphors have shown their worth in modern day lighting in the last few years. Colour tunability of the phosphor is one of the modern techniques used to obtain white light-emitting diodes (WLEDs). In the proposed work, Y2 Zr2 O7 :Sm3+ ,Eu3+ phosphors were investigated for WLED applications as well as display devices. A convectional solid-state diffusion method was used to synthesize the proposed phosphors. X-ray diffraction of the proposed phosphors was performed and compared with the standard Inorganic Crystal Structure Database. The crystal structure of the sample was cubic in nature, obtained from Rietveld refinement. Vibrational and morphological studies on the samples were carried out using Fourier transform infrared spectroscopy and scanning electron microscopy analysis. The photoluminescence study of the colour tunable phosphor showed the characteristic peak of Sm3+ together with the two sharp peaks of Eu3+ ions. Greenish yellow to red colour tunability was observed in the proposed phosphor with enhancement of Eu3+ ions. All these results showed the worth of this sample for WLEDs applications as well as in display devices.

Evaluation of kV-CBCT based 3D dose calculation accuracy and its validation using delivery fluence derived dose metrics in Head and Neck Cancer.

PURPOSE: The purpose of this study is to evaluate the dosimetric impact of Hounsfield unit (HU) variations in kilovoltage cone-beam computed tomography (kV-CBCT) based 3D dose calculation accuracy in the treatment planning system and its validation using measured treatment delivery dose (MTDD) derived dose metrics for Volumetric Modulated Arc Therapy (VMAT) and Intensity Modulated Radiotherapy (IMRT) plans in Head and Neck (HN) Cancer. METHODS: CBCT dose calculation accuracy was evaluated for 8 VMAT plans on inhomogeneous phantom and 40 VMAT and IMRT plans of HN Cancer patients and validated using ArcCHECK diode array MTDD derived 3D dose metric on CT and CBCT. RESULTS: The mean percentage dose difference between CBCT and CT in TPS (ΔD(CBCT-CT)TPS) and 3DVH (ΔD(CBCT-CT)3DVH) were compared for the corresponding evaluation dose metrics (D98%, D95%, D50%, D2%, Dmax, D1cc, D0.03cc, Dmean) of all PTVs and OARs in phantom and patients. ΔD(CBCT-CT)TPS and ΔD(CBCT-CT)3DVH for all evaluation dose points of all PTVs and OARs were less than 2.55% in phantom and 2.4% in HN patients. The Pearson correlation coefficient (r) between ΔD(CBCT-CT)TPS and ΔD(CBCT-CT)3DVH for all dose points in all PTVs and OARs showed a strong to moderate correlation in phantom and patients with p < 0.001. CONCLUSIONS: This study evaluated and validated the potential feasibility of kV-CBCT for treatment plan 3D dose reconstruction in clinical decision making for Adaptive radiotherapy on CT in Head and Neck cancer.

Study on luminescence properties of Ce3+ and Eu3+ ions in a nanocrystalline hexagonal Zn4 Al22 O37 novel system.

The present communication is strongly focused on the investigation of synthesis, structural and luminescence properties of cerium (Ce3+ )- and europium (Eu3+ )-activated Zn4 Al22 O37 phosphors. Ce3+ - and Eu3+ -doped Zn4 Al22 O37 novel phosphors were prepared using a solution combustion synthesis route. Structural properties were studied using powder X-ray diffraction and high-resolution transverse electron microscopy. The optical properties were studied using ultraviolet-visible light spectroscopy and Fourier transform infrared spectroscopy; luminescence properties were studied using a photoluminescence (PL) technique. The crystal structure of the prepared Zn4 Al22 O37 host and Ce3+ - and Eu3+ -activated Zn4 Al22 O37 phosphors was investigated and was found to have a hexagonal structure. The measured PL emission spectrum of the Ce3+ -doped Zn4 Al22 O37 phosphor showed an intense and broad emission band centred at 421 nm under a 298 nm excitation wavelength. By contrast, the Eu3+ -doped Zn4 Al22 O37 phosphor exhibited two strong and intense emission bands at approximately 594 nm (orange) and 614 nm (red), which were monitored under 395 nm excitation. The Commission Internationale de l'Eclairage (CIE) colour coordinates of the Ce3+ -doped Zn4 Al22 O37 were investigated and found to be x = 0.1567, y = 0.0637 (blue) at 421 nm and for Eu3+ -doped Zn4 Al22 O37 were x = 0.6018, y = 0.3976 (orange) at 594 nm and x = 0.6779, y = 0.3219 (red) at 614 nm emission. The luminescence behaviour of the synthesized phosphors suggested that these phosphors may be used in lighting applications.

A review: X-ray excited luminescence of gadolinium based optoelectronic phosphors.

X-ray excited fluorescence tomography is an emerging field in the application of bio-imaging and computer tomography. Some rare-earth doped inorganic phosphors like gadolinium oxide (Gd2 O3 ), yttrium oxide (Y2 O3 ), zinc tungstate (ZnWO4 ), cesium fluoride (CsF), barium fluorochloride (BaFCl), lanthanum oxybromide (LaOBr) are shown outstanding applications for X-ray excited phosphors. Gadolinium (Gd)-based inorganic phosphors show extraordinary applications in the field of X-ray chromatography and computer chromatography. In this review article, we discussed the general information about X-ray excited luminescence (XEL) phosphor. Further, we discussed importance, synthesis, structural and photoluminescence (PL) properties of rare-earth (Europium (Eu)) doped Gd2 O3 . To elaborate the scope of the review, we have discussed synthesis, structural and optical properties of lithium (Li) doped Gd2 O3 :Eu. At the end of the review, synthesis, structural and optical properties of Eu doped lutetium oxide (Lu2 O3 ) have been discussed and the results compared with Eu doped Gd2 O3 . The comparison provided the understanding of structural and optical peak position of host and the dopant (Eu).

Response of TLD-600/TLD-700 and CR-39 to neutrons for medical dosimetry.

In this study, thermoluminescence detectors (TLD)-600 and TLD-700 were used under different conditions to study neutron dosimetry for its application in medical dosimetry as albedo dosimeters. 6 LiF has a high cross-section for neutrons and is more sensitive to neutrons than to gamma radiation. Conversely, TLD-700 showed a better response to gamma radiation. Therefore, to obtain the response for neutrons, the responses for TLD-600 and TLD-700 were subtracted. A cadmium sheet was used to absorb incident thermal neutrons so that detector measured only backscattered neutrons from the albedo dosimeter. A Perspex sheet was used as a moderator to thermalize the fast neutron source Am-Be used in the experiment. CR-39 was used to detect fast neutrons and act as an albedo dosimeter when covered with a 10 B disc. Both TLD and CR-39 dosimeters were successful in detecting scattered neutrons in radiotherapy rooms.

Solid state diffusion and amalgamating anionic exchange at a KNaSO4 phosphors activated with Eu3+ , Dy3+ and Sm3+ rare earth ions to enhance w-LED performance.

In present work, KNa(SO4 ) phosphors doped with different concentrations of rare earth Eu3+ , Sm3+ and Dy3+ ions (0.05, 0.1, 0.3, 0.5, 0.7, 1 mol%) were synthesized using a solid-state diffusion technique. Photoluminescence (PL) investigations were carried out for the whole range of Eu3+ , Sm3+ and Dy3+ -doped phosphors; rare earth ions that retained maximum PL intensity were selected for advanced anionic exchange. In the present investigation, phosphors KNa(SO4 ):Eu3+ (1 mol%), KNa(SO4 ):Dy3 + (0.5 mol%) and KNa(SO4 ):Sm3+ (0.3 mol%) had the highest PL intensity, and were therefore selected for further anionic substitution of sulphate anions with different concentrations of vanadate, phosphate, and tungstate anions, such as KNa(SO4 )1-x (MO4 )x : W (where W = Eu3+ 1 mol%, Dy3+ 0.5 mol% and Sm3+ 0.3 mol%; MO4 = PO4 , VO4 , WO4 ; and x = 0.1, 0.3, 0.5, 0.7, 1). Structural and molecular environments of the substituted phosphors were characterized individually using X-ray diffraction and Fourier transform infrared spectroscopy. In-depth morphological investigations of the prepared phosphors were undertaken using scanning electron microscopy. For the principal investigation on enhancement of white light-emitting diode (w-LED) performance, the PL properties of all the synthesized phosphors were studied analytically. Emission intensity ratios for KNa(SO4 ):Eu3+ 1 mol%, KNa(SO4 )0 (PO4 )1 :Eu 1 mol%, KNa(SO4 )0.9 (VO4 )1 :Eu 1 mol%, and KNa(SO4 )0.9 (WO4 )0.1 :Eu 1 mol% were 1:1.15:1.23:0.08. PL intensity ratios for the phosphors KNaSO4 :Dy 0.5 mol% and KNa(SO4 )0.9 (PO4 )0.1:Dy 0.5 mol% was 1:2. The ratio of PL intensity was 1:3.2:0.8 for KNa(SO4 ):Sm 1 mol%, KNa(SO4 )0.5 (PO4)0.5 :Sm 0.3 mol%, and KNa(SO4 )0.7 (VO4 )0.3 :Sm 0.3 mol% phosphors, respectively. Chromaticity investigations were carried out using Commission Internationale de l'Éclairage colour co-ordinate diagrams, which suggested that the prepared Eu3+ -doped and Sm3+ -doped phosphors would be prospective candidates for red and green LEDs, respectively, whereas Dy3+ -doped phosphors showed emission in the blue and yellow regions. The entire study indicated that amalgamation of anionic exchange at a KNaSO4 phosphor activated with Eu3+ , Dy3+ and Sm3+ rare earth ions could generate and enhance white light emission.

Green Synthesis of Nanomaterials Using Plant Extract: A Review.

For the last two decades, extensive research is conducted on metal and metal oxide nanoparticles and their application in the field of medical, cosmetics, catalysts, packaging, photonics, agriculture and electronics. However, these nanoparticles show toxicity to the environmental, human and animal health. The toxicity effects of nanoparticles are mainly due to their size, which can easily pass through physiological barriers and also due to the synthesis procedure. The toxicity due to their size cannot be avoided, but toxicity due to the synthesis process can be nullified by adopting the biosynthesis process. Bacteria, fungus, fish scales, plant extracts and algae are used to synthesize metal and metal- oxide nanoparticles such as silver, gold, iron-oxide, zinc-oxide, zirconia, etc. For the last few years, researchers have been working on synthesis methods of plant extracts to produce stable, cost-effective and economical nanoparticles. In this review, we focus on the biosynthesis of nanoparticles using different parts of plant extracts. The review contains a summary of selected papers from 2018-20 with a detailed description of the process of synthesis, mechanism, characterization and their application in various fields of biosynthesized metal and metal oxide nanoparticles.