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a Chromaticity chart for the nanosamples, while inset manifests physical picture of optimal sample under near UV lamp. b CCT chart of the optimal sample
Source publication
In the present prospective study, a variety of novel rare-earth Dy3+ singly activated Sr6Al4Y2O15 nanoscaled materials were fabricated through ecologically-sound as well as low-temperature facilitated urea-fueled combustion methodology. Monoclinic crystalline phase was recognized via the Rietveld analysis of X-ray powder diffraction (XRPD)-patterns...
Citations
... Figure 11 shows how the observed lifetimes in the Sr 3 Y(PO 4 ) 3 host lattice vary with varying Dy 3+ doping concentrations. As the concentration of activator ions rises from 0.01 mol to 0.15 mol, Table 2 (measured in milliseconds) for the nanophosphor series, the auzel's model provides an explanation for the relationship that reveals the dependency of the obtained lifetime values on the concentration of Dy 3+ ions [30]. ...
Extensive investigations were conducted on the structural and photoluminescence characteristics of the present nanosamples, encompassing PL, TEM, PXRD, EDAX, CCT, and CIE research. PXRD studies established a single phase, and TEM instruments were used to examine the dimensions and topographical behavior. The EDAX analysis examined the magnitude of the different components that were present. Decay lifetimes, radiative and non-radiative energy transfer rates, and a number of intensity limitations have all been found using PL spectra. Two significant peaks were visible in the blue (B) and yellow (Y) regions of the photoluminescence (PL) spectra upon NUV excitation, at 486 nm and 577 nm. At 7 mol% Dy³⁺ ions, the PL intensity peaked. After that, it began to decline as a result of the concentration quenching process brought on by multipolar exchanges (s = 4.1445). The values of 0.86423 ms, 81%, and 226 s⁻¹ were discovered to be the decay life time, non radiative rates, and quantum efficiency of the ideal powder, respectively. Further analysis of Sr3Y0.93Dy0.07(PO4)3 nanocrystals revealed that their chromaticity coordinates (0.305, 0.321), and CCT value (6902 K) matched those of NTSE and commercial LEDs, certifying their use in innovative optoelectronic appliances, particularly single phased WLEDs.
... is the radius of host cations and R d (CN) is the radius of a substitutionally doped ion. The calculated D r of 5.6% for Y 3+ and Eu 3+ ions and 7.8% for Y 3+ and Bi 3+ ions falls within the acceptable range (< 30%) [40][41][42], confirming the substitution of Eu 3+ and Bi 3+ at the Y 3+ site. Moreover, the Y 3+ site in the cubic structure takes two symmetry cation sites, centrosymmetry C 3i (Y 1 ) and non-centrosymmetric C 2 (Y 2 ), which each coordinate with six oxygen. ...
The (0.90)Y2O3:(0.10-x)Eu3+:(x)Bi3+ nanophosphors (0.00 ≤ x ≤ 0.06) are synthesised using chemical combustion citrate route and characterized via X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, UV- visible and photoluminescence spectroscopy. The scanning electron micrographs indicate that the grain size of the phosphors ranges between 40 to 50 nm. The photoluminescence (PL) spectra, acquired under the excitation wavelength of 365 nm of ultraviolet light, show emission peaks at wavelengths 580 nm, 586-598 nm, 610 nm, 629-661 nm and 686-695 nm corresponding to the 5D0 → 7FJ electronic transitions of the Eu3+ ion with J = 0, 1, 2, 3 and 4, respectively. The most intense PL spectra at 611 nm (5D0 → 7F2), showcasing reddish-orange emission, indicate a higher concentration of Eu3+ ions in asymmetric sites within the Y2O3 host matrix. The presence of the distinct electronic transitions of Eu3+ in PL spectra acclaims that Bi3+ ions transfer their energy efficiently to Eu3+ ions in the matrix. Physical and chemical tests are being conducted on nanophosphors with Bi3+ substitutional doping of x = 0.02 and x = 0.04, both demonstrating intense PL emission. Magnetisation measurements suggest the soft magnetic nature of the nanophosphors, attributing it to the presence of Eu3+ ions in the 7F2 state. The highest PL intensity is seen in the nanophosphor (x = 0.04) with substitutional doping of 6% of Eu3+ and 4% of Bi3+ in Y2O3. This nanophosphor also demonstrates excellent optical stability in the investigated conditions and exhibits soft magnetic behaviour, positioning it as a promising material for incorporation as a fluorescent magnetic pigment in security ink applications. These features serve to prevent counterfeiting of secured documents both optically and magnetically.
... Diffuse reflectance spectra (DRS) of the doped Ba 2 Bi 0.95 Sm 0.05 V 3 O 11 nanomaterial and pure Ba 2 BiV 3 O 11 host matrix is exhibited in the inset of Fig. 5a, b which are investigated in the scope of 200-800 nm. Kubelka and Munk expression [38,39] was introduced to compute the band-gap (direct) for Ba 2 Bi 0.95 Sm 0.05 V 3 O 11 nanomaterial and pure Ba 2 BiV 3 O 11 host matrix as: ...
In the present system, Sm³⁺ activated Ba2BiV3O11 nanomaterial series radiating orange-red light was developed via an efficient approach of solution combustion method. The structural examinations using XRD analysis indicate that the sample is crystallized into the monoclinic phase with the P21/a (14) space group. The elemental composition and morphological conduct were studied via energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM) respectively. Also, the formation of nanoparticles was confirmed by transmission electron microscopy (TEM). Photoluminescent (PL) examinations reveal the orange-red emission from the developed nanocrystals via documenting the emission spectra, which reveals the peak at 606 nm due to the ⁴G5/2 → ⁶H7/2 transition. Further, the decay time, non-radiative rates, quantum efficiency, and band gap of the optimal sample were computed as 1.3263 ms, 219.5 s− 1, 70.88%, and 3.41 eV respectively. Finally, the chromatic parameters including color - coordinates (0.5565, 0.4426), 1975 K color correlated temperature (CCT), and color purity (85.58%) reflected their excellent luminous performance. The above-mentioned outcomes endorsed the relevancy of the developed nanomaterials as a propitious agent in the engineering of advanced illuminating optoelectronic appliances.
... The derived CCT (color-temperature) values were found to be below 3000 K (presented in Table 3), which authenticate them as warm sources of light for opto-electronic appliances. [42] Other important parameters related to CIE coordinate, that is, u 0 & v 0 coordinates were also computed via the formula provided next: [43] The derived correlated color-temperature values were found to be below 3000 K, which authenticate them as warm sources of light for opto-electronic appliances. ...
2022) Photoluminescent characterization of trivalent samarium activated aluminates based nano-crystals for advanced photonic applications, Spectroscopy Letters, 55:1, 44-57, ABSTRACT Down-conversion reddish-orange light emanating trivalent samarium doped aluminates-based nano-materials were successfully prepared via ecological urea-combustion approach after sintering at 550 C. X-ray powder diffractometer revealed tetragonal symmetry with P-42 1 m phase group. Non-uniform agglomerated particles of 40-50 nm crystal size were examined by utilizing, scanning electron microscopy and transmission electron microscopy technique. Upon near-ultraviolet excitation, generated phosphors illustrate reddish-orange emanation with a high quantum efficiency (82.2%) and color purity (82.99%). Finally, high emanation performance is measured in terms of chromaticity color parameters like color coordinates (0.5380, 0.4591), 2200.38 K, correlated color temperature, and color purity (82.99%). All these results certified that the generated nano-crystals can be certainly applicable for advanced photonic appliances, signage, lasers, and warm white light-emitting diodes. ARTICLE HISTORY
... It can be clearly observed from this figure that upon exciting the sample at 350 nm excitation wavelength, electrons firstly excite from 6 H 15/2 (ground state) to 6 P 7/2 (excited state) and then relax down via non-radiative mechanism to 4 F 9/2 state. Thereafter, depopulation of excited 4 F 9/2 level takes place via various radiative emissions resulting into 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 transitions sited at 484 nm and 578 nm [35,36]. Photoluminescence (PL) emission band at 488 nm (blue (B) color) in order of magnetic dipole (MD) transition and 578 nm (yellow (Y) color) by results of electric dipole (ED) transition are revealed in 3D emission spectrum of Ba 5 Zn 4 Gd 8 O 21 :Dy 3+ nanomaterials ( Fig. 7(b)) under NUV excitation at 350 nm [26]. ...
... Ba 5 Zn 4 Gd 8(1-x) O 21 :8xDy 3+ (x = 1.0, 3.0, 5.0, 7.0, 10.0 mol%) was investigated and then certified via representing the obtained chromaticity coordinates in CIE diagram (shown in Fig. 13). And obtained color coordinates values are catalogued in Table 5, which were found to posses resemblance with the coordinates of the commercial LEDs and NTSE (National Television System Committee) i.e. (0.32, 0.32) & (0.310, 0.316) respectively and shows that coordinates moves from light blue to white region in CIE diagram [35,[36][37][38]. ...
... In which, coordinates of manufactured nanosample, white light and dominated wavelength are depicted via (x, y), (x i , y i ) and (x d , y d ), respectively. On substituting the values mentioned above in Eq. (11), color purity values has been obtained and tabularized in Table 5 and it can be clearly noticed from this table that the optimal composition has the minimum value of color purity i.e. 24.06 × 10 − 2 hence authenticate the purity of the emitted light in the light blue to white region from the targeted sample [36,38,39,27,45]. Moreover, to examine the nature of emitted white light, CCT values were calculated which demonstrates the nature (coolness (CCT above 4000 K) as well as warmth (CCT below 3200 K) of the emanated light in form of temperature. ...
To enhanced the quality of multi-phase WLEDs, a down-converted trivalent dysprosium (Dy 3+) activated Ba 5 Zn 4 Gd 8 O 21 nanocrystals illuminating cool white light were manufactured via eco-friendly methodology i.e. solution combustion methodology. XRD (X-ray diffractometer) instrument and Rietvield refinement investigations over XRD data of the prepared sample discloses the 14/m (87) phase group with tetragonal symmetry in activated sample (Ba 5 Zn 4 Gd 8(1-x) Dy 8x O 21 (x = 1.0, 3.0, 5.0, 7.0, 10.0 mol%). Morphological investigations reported the rod like crystals (35-45 nm) whereas their nano-crystalline behavior was demonstrated by SAED (selected area electron diffraction) profiles. Uniform composition of the element present in the targeted nanocrystals was accomplished via an EDAX (energy dispersive X-ray) analysis. Photoluminescence (PL) spectrum, on NUV excitation depicted two important peaks in the blue (B) & yellow (Y) region at 488 nm and 578 nm. Maximum luminescent intensity was noticed as 3.0 mol% amount of activator (Dy 3+) cations. Band gap, decay life time, quantum efficiency and non radiative rates of optimal powder were found as 4.46 eV, 0.5214 ms, 65.17% and 66.79 s 1 , respectively. Moreover, chromaticity coordinates (0.2850, 0.3021), color purity (24.06 × 10 − 2) & CCT value (8910.6 K) of Ba 5 Zn 4 Gd 7.76 Dy 0.24 O 21 nanocrystals were found resemblance to the coordinates of NTSE and commercial LEDs which certified their utilization in the advanced opt-electronic appliance, especially in single phased WLEDs.
... The average crystallite-size of the particles of fabricated nano-samples can be derived by executing the Scherrer's formula [28]: ...
An orthorhombic symmetry type BaGd 2 ZnO 5 :Dy 3+ nanocrystals with luminance of cool white-color light have been fabricated via urea assisted combustion methodology. Morphological analysis revealed the agglomerated particles with non-uniform shape having crystal-size of 30-40 nm. Optimized amount of dopant (Dy 3+) was examined to be x = 3 mol%, after the occurrence of quenching phenomenon. The logical pathways for quenching mechanism has been determined as non-radiative (NR) relaxations of energy via exchange-type interrelations as validated by Inokuti-Hirayama (I-H) and Dexter's theory. Fabricated nano-powders represents two band located at 492 nm (bluish) and at 581 nm (yellowish). Band gap, decay life time and quantum efficiency of optimal powder were found as 4.71 eV, 0.7049 ms and 93.9% respectively. White-light emanation is reflected in terms of CIE color-parameters like color-coordinates of white regions (0.2869, 0.3876), color purity of 30 × 10 − 2 and CCT values as 7206.2 K, which have been in congruence with standard coordinates of commercial LEDs and NTSE and thus, authenticate their optimistic applicability for advanced illuminating devices.
... (5) Å 3 was quit increases from that of pure matrix (V= 520.98 (6) Å 3 ) which is ascribed to the effective replacement of the smaller Gd 3+ cations by larger Sm 3+ cations. This replacement exigency was further verified by computing the equation given below [18]: ...
In the present report, a new series of Sm 3+ doped BaGd 2 ZnO 5 nanomaterials emanating reddish orange light have been manufactured via an ecological, ideal and less energy consuming combustion methodology. Crystallographic investigation reports the orthorhombic symmetry type with Pbnm (62) space group. Morphological analysis examines the non-uniform agglomerated particles of 35-45 nm. Photoluminescent (PL) studies reveals about the orange red emanation from the fabricated nanomaterials by recording the PL emission spectrum, which shows a fine peak at 610 nm and also discloses that the exchange type interrelations as the main mechanism for non-radiative relaxation of energy, as validated by Inokuti-Hirayama (I-H) and Dexter's theory. Band gap, decay life time, quantum efficiency and non radiative rates of optimal powder were found as 4.84 eV, 0.607 ms, 87.84 % and 0.20 ms 1 , respectively. At the last, excellent luminescent performance is reflected in terms of CIE color parameters like color-coordinates (0.579, 0.420), color purity (78.88 %) and 1768 K color correlated temperature (CCT). These magnificent results certified the relevancy of the targeted nanocrystals as an auspicious agent in the manufacturing of advanced illuminating appliances like WLEDs, lasers, photonic devices, solar cell, sensors and various opto-electronic appliances.
A series of Tb3+-activated double perovskite Ba2BiYO6 nanocrystal systems exhibiting a strong green luminescence is produced using an energy-saving solution combustion (SC) method. The crystals formed are found to be cubic and belong to the Fm-3 m (225) space group with irregular shapes and diameters extending from 43 to 67 nm. Morphological aspects are examined via scanning and transmission electron microscopic (SEM and TEM) techniques. When exposed to UV radiation, the nanocrystals emit a vibrant green light at a wavenumber of 18,281 cm−1, caused by the transition from the 5D4 → 7F5 electronic state. The effects of energy transfer are also studied. The highest emission intensity was observed at a concentration of 5.0 mol% Tb3+ ions when excited at 283 nm. This phenomenon can be attributed to the phenomenon of concentration quenching caused by d–d interactions resulting in a decrease in luminescence intensity. The color coordinates fall within the greenish region and the correlated color temperature (CCT) value is measured 5691 K for optimized sample Ba2BiY0.95Tb0.05O6. Consequently, these nanocrystals are well-suited for use in white lighting emitting diodes (WLED) manufacturing, specifically for creating aesthetically pleasing indoor lighting.
In the realm of luminescent materials, white light emitting inorganic nanoparticles offers a promising avenue for creating more efficient and durable light emitting devices. Here the production of cool white light emission from Inorganic Zinc Sulfide (ZnS) nanoparticles have been achieved by simple green co- precipitation method, employing Phyllanthus emblica extract as the capping agent. The structural and optical properties were studied using X-ray diffraction (XRD), Scanning Electron Microscopy with Energy dispersive X-ray analysis (SEM–EDX), Fourier Transform Infrared (FTIR) Spectroscopy, and Transmission Electron Microscopy (TEM) with Selected Area Electron Diffraction (SAED) pattern, UV–visible and photoluminescence (PL) analysis. The XRD analysis confirms the cubic crystalline nature of the sample. The tauc plot study confirms the particle size dependent change in the energy bandgap. Tunable visible emissions are observed from PL spectra and undoped ZnS nanoparticles display cool white emission (x = 0.3056, y = 0.3030) characterized by a high Correlated Color Temperature (CCT = 7255 K) and excellent Color Rendering Index (CRI = 93). These attributes position them as suitable for integration into Light Emitting Diodes (LEDs) as phosphors. Green synthesized ZnS nanoparticles, owing to their tunable structural and optical properties, demonstrate substantial promise in revolutionizing multiple sectors, particularly in advanced lightening and display applications.
