7F2 Transition Research Articles

Sol-Gel preparation and luminescent properties of Eu3+ doped Al2O3 hollow microspheres

Rare earth elements have attracted significant attention due to their unique electronic structure. By doping rare earth ions into oxides, they can be used as spectral conversion materials in fields such as photovoltaic power generation and biological probes. In this paper, the performance of Eu3+ doped Al2O3 hollow microspheres by sol-gel method was analyzed by SEM, XRD, IR, TG-DSC, and fluorescence spectrometer. Using aluminum isopropoxide (Al(OC3H7)3) as raw material, PMMA with a particle size of 150nm as the template, PMMA/boehmite particles with core-shell structure can be prepared by sol gel method and template method. After adding Eu3+ and heat treatment, a transition occurred from γ-AlOOH(85°C)→γ-Al2O3(600°C)→θ-Al2O3(1000°C)→α-Al2O3(1200°C) as the temperature increased, and EuAlO3 was generated at 1200°C. Eu3+ occupied the sites without inversion centers inside the host lattice, and the alumina was an effective matrix for the fluorescent properties of Eu3+. Its excitation was caused by the 7F0→5L6 transition, and its luminescence was controlled by the 5D0→7F2 transition, which can convert ultraviolet light into red and orange light. The fluorescence intensity increases with the increase of Eu3+ content, and no quenching was observed at a doping concentration of 10mol% Eu3+.

Fabrication of Eu2O3 doped in high density and transparent silicoborate scintillating glass for synchrotron X-ray radiographic imaging application

In this work, the glass system, xEu2O3 - 10SrO - 20La2O3 - 10Ta2O5 - 10SiO2 - (50-x)B2O3, where x = 0, 1, 3, 5, 7, 9, 11 mol%, was fabricated using the high-temperature melt quenching method. The physical, optical, and luminescence properties of the glass were investigated to determine its suitability as a scintillation material. The transparent glass sample showed a high density and molar volume up to 4.72 g/cm3 and 40.57 cm3/mol, respectively, reflecting that higher NBOs in glass matrix. This result is also supported by X-rays photoelectron spectroscopy (XPS) spectra. Absorption spectra represented peaks in the ultraviolet to near infrared regions, which can be confirmed the presenting of Eu3+ ion in glass matrix. Under UV excitation, the glass doped with 3 mol% of Eu2O3 shows highest intensity while scintillation light (X-rays induced luminescence) was highest performed at 7 mol%. The integral intensity of radioluminescence of glass is 26 % that of commercial BGO scintillator. The photoluminescence quantum yield (PLQY) was measured and the highest PLQY was correspond with emission intensity. The glass scintillator was used for X-ray imaging at beamline 1.2, Synchrotron Light Research Institute (SLRI), Thailand and the spatial resolution was evaluated. Due to the strong light emission at 615 nm from 5D0 → 7F2 transition of Eu3+, this developed scintillating glass has a potential for X-ray imaging material in radiographic application.

Effect of Fuels on Structure, Morphology, and Spectroscopy of Combustion-Synthesized Y2O3:Eu3+ Nanoparticles: Towards Applications in Optoelectronic Devices and Biomedicine

Eu3+ ion doped yttria nanoparticles (Y2O3:Eu3+ NPs) were synthesized by a combustion method using urea (U), glycine (G), and ethylenediaminetetracetic acid (E) as fuels. Combustion parameters including adiabatic flame temperature and emitted heat, were calculated and found to increase with the fuel molecular weight. XRD pattern confirmed a body-centered cubic (BCC) phase with the Ia3 space group where Eu³⁺ ions occupied both C2 and S6 sites. Y2O3:Eu3+ NPs prepared with higher molecular weight fuels, exhibited the superior photoluminescence (PL) of the orange-red (O-R) bands. PL spectra revealed the dominant 5D0→7F2 transitions were driven by the energy transfer process from S6 sites to C2 sites via electric multipolar interactions. Chromaticity parameters confirmed the potential of these Y2O3:Eu3+ NPs for optoelectronic applications, with the strong luminescence in the O-R region, making them suitable for biomedical fluorescence imaging.

Preparation and Luminescence Property Study of Red-Emitting Na3.6Y1.8(PO4)3:Eu3+,Li+/K+ Phosphors with Excellent Thermal Stability for Light-Conversion Application.

A series of red-emitting phosphors, Na3.6Y1.8-x(PO4)3:xEu3+, have been synthesized by a high-temperature solid-phase method. The impact of the partial Li+/K+ ion substitution on the crystal structure and photoluminescence (PL) performance of Na3.6Y1.05(PO4)3:0.75Eu3+ phosphor have been investigated. Various techniques have been used for characterization of the as-obtained materials. X-ray diffraction (XRD) analysis was utilized to confirm the composites of these samples, and the morphology and element distribution were examined by scanning electron microscope (SEM) and transmission electron microscope (TEM). This study found that the developed Na3.6Y1.8-x(PO4)3:xEu3+ phosphors exhibited a prominent emission peak at ~620 nm when excited at 393 nm, which corresponded to 5D0 → 7F2 transitions of Eu3+ ions. Furthermore, the robust emission peak at ~705 nm (5D0 → 7F4) of these phosphors enables a better match with plant pigment absorption. Beyond that, the partial substitution of Li+/K+ ions probably changed the crystal structure, and reduces the symmetry around Eu3+, leading to significantly enhanced luminous intensities by 23.24% and 18.29%, with the highest quantum yields (QYs) reaching 99.85% and 96.29%, respectively. Additionally, the prepared phosphors show non-thermal quenching and superior thermal stability at elevated temperatures from 298 to 473 K. These findings and results suggest that Li⁺/K⁺-substituted Na3.6Y1.05(PO₄)₃:0.75Eu3⁺ phosphors can serve as promising red-emitting phosphors for plant lighting applications.

Spectroscopic properties of red-emitting Sr0.9Na0.2ZrO3:Eu3+ phosphors with potential applications in lasers and LEDs

A range of Sr0.9-yNa0.2ZrO3: Eu3+ (SNEZ) nanocrystalline phosphors with high color purity and exceptional laser properties were synthesized using sol-gel technique. The samples were characterized for structural and spectroscopic properties using methods including X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), diffuse reflectance spectroscopy, and photoluminescence (PL) spectroscopy. Structural analysis revealed orthorhombic phase with average crystallite size 28-19 nm, decreasing with increasing Eu3+ concentration. A low phonon energy of 455–495 cm−1 and wide (expanding) band gaps (5.0–5.3 eV) were obtained for the SNEZ phosphors. Under the excitation of 300 nm, the SNEZ phosphor emits strong red light at 614 nm, attributed to the 5D0 → 7F2 transition of the Eu3+ ion. Both XRD and Judd-Ofelt analysis revealed two sites for the Eu3+ ions. Additionally, the optimized SNEZ-7 phosphor achieves a PL internal quantum efficiency of 96 % under UV light at 300 nm excitation. Laser properties such as stimulated emission cross-section, gain bandwidth, branching ratio of the SNEZ phosphor is comparable to those of glasses, fluorides and other oxides for red light emitting laser applications. The CIE coordinate values of the synthesized red phosphor closely match those of commercially available red light-emitting phosphors, with a purity level of about 95 %. This suggests its suitability for various device applications, particularly in high-power white LEDs and lasers, as a red emitter.

Enhancement of luminescence and thermal stability in Eu3+-doped K3Y(BO2)6 with Li+ and Na+ co-doping

Eu3+-doped and Li+/Na+ co-doped K3Y(BO2)6 (KYBO) phosphors were synthesized through a microwave-assisted sol–gel method, and their structural and photoluminescent (PL) characteristics were examined. X-ray diffraction (XRD) and Rietveld refinement confirm effective dopant incorporation and preservation of the crystalline structure. Fourier Transform Infrared (FTIR) spectroscopy indicates the maintenance of the borate structure, confirming the structural integrity of the phosphors upon doping. The addition of Li+ and Na+ co-dopants notably enhances luminescent efficiency and thermal stability, making these phosphors promising candidates for solid-state lighting (SSL) applications. PL analysis reveals strong red emission peaks at 612 nm, attributed to the 5Do → 7F2 transition of Eu3+ ions. The study indicates that electric dipole-quadrupole interactions are the primary mechanism for energy migration, with a critical distance of approximately 22.68 Å. This mechanism contributes to concentration quenching at higher doping levels. High temperature PL measurements indicated an activation energy of 0.1389 eV for thermal quenching in the Li+ co-doped sample. Additionally, the Na+ co-doped sample exhibited an abnormal thermal stability behavior, with an even higher activation energy of 0.2536 eV. This suggests that Na+ co-doping significantly enhances the thermal resilience of the phosphor, making it more suitable for high-power light-emitting applications that operate under extreme conditions. CIE chromaticity diagrams highlight the potential for optimizing Eu3+ doping levels, combined with Li+ and Na+ co-doping, to improve luminescent performance and thermal stability for advanced SSL applications.

Luminescence, temperature sensing and Judd-Ofelt analysis of Bi2Mo3O12:Eu3+ phosphors and the application in latent fingerprint visualization

Eu3+-activated materials have garnered significant attention due to their outstanding optical characteristics. In this work, the sol–gel method was successfully used to prepare Bi2Mo3O12 phosphors doped with different amounts of Eu3+. The generated samples were identified as orthorhombic Bi2Mo3O12 with a scheelite-like structure by X-ray diffraction analysis of the crystal structure. The sample’s morphology and size were examined using scanning electron microscopy and transmmission electron microscopy, which revealed irregular block morphology and tens to hundreds nanometers scale dimension. From the analysis of the concentration-dependent luminescence intensity of Eu3+, it was confirmed that the exchange interaction was responsible for the quenching of 5D0 fluorescence of Eu3+. When excited at 374 nm, the phosphor emitted brilliant red light, with the highest emission occurring at 616 nm (5D0→7F2 transition), and the calculated color coordinates of the sample were (0.663, 0.336). By examining the temperature dependence of the emission spectra, the temperature sensing performance of the sample and the thermal quenching behavior of Eu3+ luminescence was explored. Furthermore, the optical transition property of Eu3+ was investigated by using the emission spectra and fluorescence lifetime within the context of Judd-Ofelt theory. Ultimately, latent fingerprint visualization of the sample on various object surfaces was studied, thanks to the intense luminescence and small particle size of the Bi2Mo3O12:Eu3+ phosphor. The results indicated that the sample can clearly display the different hierarchical features of fingerprint on different object surfaces.

Development of Dy-doped CaHfO3 single crystal scintillator for X-ray detectors

Dy:CaHfO3 single crystals were synthesized by the floating zone technique and examined for their photoluminescence and scintillation properties. Under excitation at 350 nm, the 3.0 % Dy:CaHfO3 showed the highest quantum yield of 72.5 % among all the samples. Under X-ray irradiation, all the samples showed multiple emission peaks at 480, 575, and 670 nm associated with the 4f–4f transitions of Dy3+. Pulse height spectra of 137Cs as a γ-ray source revealed 3.0 % Dy:CaHfO3 showed the highest light yield of 20,000 photons/MeV among the samples.

Ultraviolet–near infrared luminescence characteristics of Nd:La2Be2O5 single crystals for near-infrared emitting scintillators

The fabrication of 0.1, 0.5, 1.0, and 5.0 % Nd:La2Be2O5 single crystals was carried out by the floating zone method, and photoluminescence (PL) and scintillation properties were measured. The PL spectra showed some emission lines which was derived from the 4f-4f transitions of Nd3+ ions. The scintillation spectra showed a broad emission band originating from some lattice defect and the emission lines due to the 4f–4f transitions of Nd3+ ions. The afterglow levels of Nd:La2Be2O5 were 192.3 (0.1 % Nd), 205.9 (0.5 % Nd), 228.2 (1.0 % Nd), and 315.4 (5.0 % Nd) ppm. The 1.0 % Nd:La2Be2O5 showed the highest intensity in the dose-rate response functions among the samples, and a lower detection limit was 0.003 Gy/h.

Red-shift of the photoluminescent emission and enhancement of the internal quantum efficiency by co-doping Gd3+ in Tb3Al5O12: Ce3+ phosphors for warm WLEDs

White Light Emitting Diodes (WLEDs) are widely used in our lives as the fourth generation of solid-state lighting sources. However, the phosphors in the WLEDs device lack a red component, resulting in a cool white light, which affects the quality of lighting while damaging the user's eyesight. In this work, the Tb3Al5O12: Ce3+ (TAG: Ce3+) and Tb3Al5O12: Ce3+, Gd3+ (TAG: Ce3+, Gd3+) phosphors were synthesized by sol-gel method. Powder X-ray diffraction analysis confirmed the successful substitution of Ce3+ and Gd3+ in the system, as evidenced by the quantifiable expansion of the unit cell volume when Tb3+ was replaced with Ce3+ and Gd3+. As the increasing of Gd3+ doping concentration in the TAG: 0.025Ce3+, yGd3+ phosphors, the emission peak of Ce3+ (arises from the 5d→4f transition) shifted from 565 nm to 580 nm. The photoluminescence emission intensity of TAG: 0.025Ce3+, 0.6Gd3+ phosphor can be increased by about 192 % compared to TAG: 0.025Ce3+ phosphor (y = 0). The Gd3+-to-Ce3+ energy transfer is robustly supported by the prolonged lifetime of Ce3+ with an increase in Gd3+ content in TAG: 0.025Ce3+, yGd3+. Notably, the energy transfer process from Gd3+ to Ce3+ effectively enhanced the internal quantum efficiency (IQE) of the TAG: 0.025Ce3+, yGd3+ phosphors, up to 70.14 %. Variable-temperature emission spectra indicates that TAG: Ce3+, Gd3+ phosphors prepared by the sol-gel method have excellent luminescent thermal stability. Ultimately, the WLEDs devices assembled with TAG: Ce3+, Gd3+ phosphors can produce warm white light, which indicates that TAG: Ce3+, Gd3+ phosphors are a potential material for warm WLEDs.

Near‐infrared scintillation properties of Nd-doped BaO-Bi2O3-P2O5 glasses

We synthesized BaO-Bi2O3-P2O5 glass samples with different Nd concentrations by the melt-quenching technique. The concentrations were 1.0, 5.0, 10, 15, and 20 %. We obtained transparent and homogeneous samples for 1.0–10 % Nd concentrations. The 15 % Nd-doped sample was inhomogeneous, and the 20 % Nd-doped sample contained a crystalline phase. The photoluminescence (PL) and scintillation properties of the 1.0–10 % Nd-doped samples were investigated. The samples showed PL and scintillation peaks in the near-infrared region, which were due to 4f–4f transitions of Nd3+. We tested the X-ray dose rate response functions of the samples. The 10 % Nd-doped samples showed the most intensive response among the examined samples, and the lower detection limit of dose rate was 0.06 Gy/h with our setup.

Effect of Dopant Concentration on Luminescence Properties of Na3Ca2(SO4)3F: RE (RE = Eu3+, Dy3+) Phosphor for Solid-State Lighting.

A fluoride material phosphor doped with rare earth ions Eu3+ and Dy3+ was studied for its photoluminescence (PL) properties. The material was synthesized using a combustion method and characterized using X-ray diffraction (XRD) and PL techniques. The Na3Ca2(SO4)3F: Eu3+ phosphor exhibits two distinct peaks at 593 nm (orange) and 615 nm (red) at an excitation wavelength of 395 nm. The PL excitation spectrum of the Na3Ca2(SO4)3F: Dy3+ phosphor showed series of peaks, corresponding to the 4f → 4f transitions of Dy3+ ions. Under 350-nm excitation, the PL emission spectrum revealed two prominent bands one at 483 nm (blue region) due to the 4F₉/₂ → 6H₁₅/₂ transition, and another at 573 nm (yellow region) resulting from the 4F₉/₂ → 6H₁₃/₂ transition. These blue and yellow emissions suggest potential applications in solid-state lighting, particularly for mercury-free excitation sources. Rare earth-doped Eu3+/Dy3+ materials exhibit highly efficient PL properties, making them suitable candidates for white light-emitting diodes (LEDs) or other solid-state lighting phosphors.

Photoluminescence and thermally stimulated luminescence properties of Sr3Y(PO4)3 single crystals doped with dy

Sr3Y(PO4)3 (SYPO) is recognized as a highly promising material for dosimetry applications, owing to its dosimetric properties. In this work, we synthesized the SYPO single crystals doped with 0.1, 0.5, 1, and 5 % Dy using the floating zone furnace to evaluate the photoluminescence and thermally stimulated luminescence (TSL) characteristics. All the SYPO single crystals doped with Dy exhibited emission peaks at 480, 580, 670, and 760 nm in PL and TSL spectra. These emission peaks were typical for the 4f–4f transitions of Dy3+ ions. The SYPO single crystal doped with 0.1 % Dy displayed a glow peak in the TSL glow curve at 70 °C. The SYPO single crystals doped with 0.5, 1, and 5 % Dy showed two glow peaks at approximately 70 and 110 °C. The SYPO single crystal doped with 0.5 % Dy exhibited the highest TSL intensity with a lower detection limit of 0.1 mGy. The SYPO single crystal doped with 0.5 % Dy showed a spatial resolution of 50.0 μm after X-ray irradiation of 1Gy.

Crystal growth, luminescence, and radiation response characteristics of undoped and Nd-doped langasite-type Ca3TaGa3Si2O14

Undoped and various concentrations of Nd-doped Ca3TaGa3Si2O14 (CTGS) single crystals were fabricated via the floating zone technique. The luminescence and radiation response characteristics were investigated. A broad intrinsic luminescence was observed at 300–600 nm. Sharp luminescence appeared at 900, 1060, and 1300 nm in Nd-doped samples and they originated from 4f–4f transitions of Nd3+. Photoluminescence quantum yields were calculated to be 44.7, 94.1, 87.4, and 75.5% in 0.1, 0.5, 1, and 2% Nd-doped samples, respectively when monitored at near-infrared (NIR) ranges. Linear responses between dose-rate and scintillation outputs in NIR regions were confirmed in Nd-doped samples. The 0.5% Nd-doped CTGS achieved a detection limit of 1 mGy/h.

An extensive inquisition on the impact of modifier oxides over the luminescent properties of Eu3+ embedded Li-Al tri-former glasses for photonic applications

A novel, tri-former glasses with the composition 45B2O3+12P2O5+8SiO2+3Al2O3+10LiF+20MO+1Eu2O3 with varying metal oxides have been fabricated following the melt-quenching technique. The absorption, luminescence and radiative decay measurements were carried out, and the specific colour emitted by the glass sample was determined employing the CIE chromaticity diagram. While monitoring the excitation at 393 nm, luminescence spectra of all the glass samples exhibit red emission pertaining to the 5D0→7F2 transition at around 615 nm. The local geometry around the Eu3+ ions site and the nature of the Rare Earth ion-ligand bond have been analyzed employing Judd-Ofelt theory and the R/O ratio spectral parameter. The intensity parameters follows the trend as Ω2 > Ω4 > Ω6 and the results are co-related well with the R/O ratio spectral parameter values. Radiative properties such as σPE, βR and AR of every glass in the present series possess higher values, and the FWHM exhibits lower value, indicating the potentiality of the BPSAEu:M glasses for lasing applications. Among the prepared samples, BPSAEu:Ba glass exhibit higher values for σPE and AR as 42.3 × 10−22 cm2 and 641.71 s−1 respectively which are apt for laser applications. The quantum yield pertaining to the 5D0→7F2 transition exhibit more than 65 % for all the samples and particularly Barium oxide incorporated glass BPSAEu:Ba exhibits 84 %. The present study suggests that BPASEu:Ba glass is a promising luminescent material for photonic/LED applications.

Optical-stimulated luminescence properties of undoped and Eu-doped LiCl transparent ceramics synthesized by spark plasma sintering method

The undoped and Eu-doped LiCl transparent ceramics were synthesized, and their photoluminescence (PL) and optical stimulated luminescence (OSL) properties were evaluated. The PL properties of the undoped sample revealed as emission band due to a defect center. Additionally, the Eu-doped samples exhibited an emission band due to the 5d–4f transitions of Eu2+ ions. The OSL phenomenon was observed only in the Eu-doped samples and was not present in the undoped sample. The OSL spectra of the Eu-doped samples showed as emission band at 430 nm under stimulated at 490 nm, which was due to the 5d–4f transitions of Eu2+ ions. Based on the dose response functions, the lower detection limits of the Eu-doped samples were indicated as 10 mGy (0.1% Eu) and 1 mGy (0.5% and 1.0% Eu), and the 0.5% Eu-doped sample exhibited the highest OSL intensity among the Eu-doped samples.

Enhanced hypersensitive (5D0→7F2) transition characteristics of Eu3+ doped β-Ga2O3 microrods

Exploring and realizing the luminescence characteristics of rare earth metal (RE) ions doped gallium oxide (Ga2O3) is crucial for developing optoelectronic device applications. The current research used the solid-state reaction approach to synthesize Ga2O3 microrods doped with various europium (Eu3+) concentrations (0.1, 0.2, 0.3, 0.5, 0.75, and 1 mol). X-ray diffraction (XRD) and Raman spectral analyses confirm the monoclinic structure of β-Ga2O3. The intensity of the Raman phonon modes decreased and a peak shift was observed for Eu:β-Ga2O3. The electron microscopy (SEM, TEM) images depicted a nearly uniform distribution of microrods for undoped and Eu:β-Ga2O3 samples. The interplanar distance (d = 0.290 nm, 0.561 nm, and 0.433 nm), from HR-TEM images, corresponding to (0 0 4), (1 0 0), and (1 0 2) crystallographic orientations confirm the monoclinic structure of β-Ga2O3. The elemental mapping images showed a nearly homogeneous Ga, O, and Eu distribution. The UV–visible diffuse reflectance spectroscopy (UV-DRS) showed a notable reduction in the bandgap as the Eu3+ concentration increased. The emission spectra of Eu: β-Ga2O3 microrods showed a narrow red emission at 612 nm (5D0 → 7F2), which relates to the 5D0 → 7Fj (j = 0, 1, 2, 3) energy level arising from an intra-4f transition of Eu3+ ions upon 394 and 465 nm excitation. The red emission was found to increase with Eu content up to 0.5 mol.%. A quenching of emission due to the multipole–multipole interactions was obtained beyond 0.5 mol.% of Eu. The absolute quantum yield (η) calculated for Eu: β-Ga2O3 (0.5 mol.%) was 3.82 %. The luminescence decay curve using the bi-exponential fit and the average lifetime (τ) of the Eu: β-Ga2O3 (0.5 mol.%) was found to be ∼0.172 ms. CIE chromaticity and correlated color temperature analyses of Eu:β-Ga2O3 microrods yielded a red emission with a superior color purity (93 %). The obtained results suggest that Eu:β-Ga2O3 (0.5 wt.%) microrods could be one of the potential candidates for red light sources.

Study on the properties of Sm3+-Doped CaTbAl3O7 phosphors

New single phase and adjustable emission phosphors have attracted a lot of attention because of the good luminous properties. In this work, Sm3+ doped CaTbAl3O7 phosphors are prepared in air by solid-state method. The crystal structure, concentration dependent spectra, lifetimes, and luminescence properties are investigated. Because of the 4f8 → 4f75d1 and 4f → 4f transitions of Tb3+ ion, host (CaTbAl3O7) shows an excitation spectrum in the range of 220–520 nm under monitored at 544 nm and emits yellow-green light under excitation 248, 284, and 368 nm due to the 5D4 → 7FJ (J = 0, 1, 2, 3, 4, 5, and 6) transitions of Tb3+ ion. CaTbAl3O7:Sm3+ under monitored 598 nm contains the excitation spectral peaks of both CaTbAl3O7 and Sm3+ ion. With excitation at 368 nm, CaTbAl3O7:Sm3+ glows orange-red light, its PL spectrum has both host (CaTbAl3O7) and Sm3+ ion contributing, and the chromaticity coordinates are about (0.5499, 0.4351). Under excitation 402 nm, the red-orange emission of CaTbAl3O7:Sm3+ is only the contribution of Sm3+ ion and the chromaticity coordinates are about (0.5823, 0.4168). The energy transfer process from Tb3+ in host (CaTbAl3O7) to Sm3+ ions can be confirmed via the spectral properties. We explain the luminous mechanism of CaTbAl3O7:Sm3+ by the energy level diagrams of Tb3+ and Sm3+.

Thermoluminescence properties of β-ray irradiated LuAGG:Ce nanophosphors prepared by sol-gel method for potential applications in dosimetry

In this paper, Lu2.97Al5–xGaxO12:Ce0.03 (x = 0, 1, 2, 3) nanophosphors were synthesized using sol-gel method and calcined at 1100 °C for 3 h. The effect of Ga content on the structural, photoluminescence (PL), and notably thermoluminescence (TL) glow curve, dose response, repeatability and fading properties were investigated. X-ray diffraction (XRD) results indicated that all synthesized samples were crystallized in a pure garnet phase. The PL emission spectra exhibited a broad emission band corresponding to the 5 d → 4f (2F5/2, 2F7/2) transition of Ce3+ ions in the garnet lattice. Furthermore, a significant decrease in emission intensity was observed upon increasing Ga content. The TL characteristics of nanopowders irradiated with β-rays revealed a significant effect of Ga content on the peak position, shape and intensities of TL Glow curves, which can be explained by the reduction of the energy gap and the distribution of trap levels. The dose response linearity in the range of 0.125–100 Gy was examined for different Ga content, revealing a good linear behavior for x = 0 and 1 Ga. Additionally, samples prepared with x = 0, 1, and 2 Ga exhibited a high level of repeatability across a batch of 10 samples. Also, fading studies were performed for 128 h and revealed strong fading in samples synthesized with x = 0 and 1 Ga. These results suggest potential applications of Lu3Al5O12:Ce and Lu3Al4Ga1O12:Ce in ionizing radiation dosimetry.

Synthesis, morphology and dosimetric properties of Cr3+ activated Ca2Al2SiO7 nanophosphor prepared via sol-gel route

In this study, the structural, morphological, photoluminescence (PL), and dosimetric properties of Ca2-xAl2SiO7: xCr3+, at various Cr3+ concentrations (0 ≤ x ≤ 1 mol%) have been studied. The phosphor material was synthesized via sol-gel route with an octadecylamine as a catalyst. The average crystallite sizes were estimated to be in the range 21–30 nm using the modified Scherrer method which are in good agreement with data yielded by TEM micrographs. The energy-dispersive X-ray (EDX) spectra with scanning electron microscope (SEM) data confirm the homogeneous existence, and distribution of constituent elements within the structure and approved the sol-gel preparation method. PL spectra shows that Cr3+ doped Ca2Al2SiO7 structure has shoulder broadening and maximum peaks maintained at 442 ± 3.0 and 491 ± 3.02 nm upon 337 nm excitation which caused by 4F (4A2→4T2), 4F (4A2→4T1), and 4P (4A2→4T1) electronic spin-allowed transitions. Thermoluminescenc (TL) sensitivity characteristics of the obtained samples were scrutinized using Co-60 γ-radiation source. Cr0.4 sample was found to be optimum and its TL intensity increases linearly with increasing γ-doses from 0.5 up to 10 Gy. An accuracy using relative standard deviation (RSD) calculations of the homogenous study for Cr0.4 was found to be 4.02% (<10%, accepted due to ISO rules). Threshold dose of Cr0.4 sample was computed to be about 258 μGy. Acquired results of photon attenuation parameters estimations of Ca2Al2SiO7 composition using Phy-X PSD online program show that this composition is a bone equivalent dosimeter. According to this article, Cr0.4 doped Ca2Al2SiO7 sample can be considered as useful TL-material in various dosimetric applications.