21 research outputs found
Impact of polishing methods on surface roughness and S. mutans adhesion in composite resins: an in vitro study
No full textAbstract Background This study aimed to evaluate the surface roughness and Streptococcus mutans adhesion on two different composite resin materials following the application of various polishing systems. Methods Eighty disk-shaped specimens (8 mm diameter, 2 mm thickness) were fabricated using nanohybrid (Charisma Topaz) and nanofilled (Tokuyama Estelite Asteria) composite resins (n = 40 each). Each material group was further divided into four groups (n = 10) according to the polishing system used: Mylar strip (control), Sof-Lex™, Clearfil™ Twist Dia, and Opti1Step™. After measuring the surface roughness, the sterilized samples were divided into two subgroups as, “artificial saliva-treated samples” and “non-treated samples.” For each subgroup, solutions containing S. mutans were added, and the samples were incubated at 35–37 °C for 24 h. Determination of adhered bacteria on surfaces depended upon colony counts obtained after incubation, which was presented as CFU/mL. Statistical analyses included two-way ANOVA for surface roughness and three-way ANOVA with Tukey post hoc test for bacterial adhesion. Results SR values ranged from 0.07 ± 0.01 μm to 0.09 ± 0.03 μm across all groups, remaining well below the clinical threshold of 0.2 μm, highlighting that the minor surface variations observed are unlikely to have clinical significance regarding plaque retention. (p > 0.05). S. mutans adhesion values ranged between 2.83 ± 0.25 log CFU/mL and 3.57 ± 0.32 log CFU/mL. No statistically significant differences were found between polishing methods or saliva conditions (p > 0.05). The three-way ANOVA revealed a statistically significant main effect of composite resin material on S. mutans adhesion (F = 29.895, p < 0.001, partial η² = 0.322), indicating that bacterial colonization varied according to the resin material used. Conclusion While different polishing systems did not significantly affect surface roughness or bacterial adhesion, the composite resin type appears to play a crucial role in S. mutans colonization
Dy3+ and Eu3+ co-activated gadolinium aluminate borate phosphor: Synthesis, enhanced luminescence, energy transfer and tunable color
No full textThe synthesis of GdAl3(BO3)4 phosphors incorporated with activators of Dy3+ and Dy3+/ Eu3+was successful and achieved through the gel combustion method. Powder X-ray diffraction (XRD) was employed to identify phase purity and the effects of dopant concentration on the crystallographic structure. The results of Photo-luminescence (PL) measurements revealed that the intensity and lifetime of luminescence properties varied depending on the concentrations of Dy3+ and Eu3+ ions. The dependence of luminescence intensity on doping concentration is investigated with respect to the energy transfer process between Eu3+ and Dy3+ ions. A decrease in luminescence lifetime occurs with increasing concentrations of Eu3+ co-doping. The energy transfer was also investigated using decay curve analysis. The co-doping of Eu3+ significantly boosts the energy transfer efficiency from 26% to 84%. These findings make GdAl3(BO3)4: Dy3+, Eu3+ phosphors an ideal choice for LED applications in solid state lighting and displays.Deanship of Scientific Research at Jazan University, Kingdom of Saudi Arabia [W44-82]The authors thank the Deanship of Scientific Research at Jazan University, Kingdom of Saudi Arabia, for support of this work under grant number W44-82. We honor the memory of those who lost their lives in the 7.8 magnitude earthquake that struck Turkey on February 6, 2022. We stand in solidarity with those who are still struggling to rebuild their lives
Eu3+ and Dy3+ doped La2MoO6 and La2Mo2O9 phosphors: Synthesis and luminescence properties
No full textWe report a detailed structural analysis and properties of the photoluminescence (PL) and thermoluminescence (TL) spectra of Eu3+ and Dy3+ incorporated into novel La2MoO6 and La2Mo2O9 phosphors synthesized successfully through gel combustion synthesis. The formation of a tetragonal phase and a cubic structure were verified for La2MoO6 and La2Mo2O9 phosphors via X-ray diffraction (XRD) studies. Dy doped samples exhibited blue and green emissions at 480 nm (4F9/2 ›6H15/2) and 572 nm (4F9/2 › 6H13/2), and also Eu doped samples showed a sharp emission peaks at 612 and 619 nm (5D0 ›7F2) upon 349 nm pulse laser excitation. Peak shape (PS) technique was utilised to determine activation energy, frequency factor and order of kinetics associated with the main glow curves in undoped and Eu and Dy doped samples after X-ray irradiation. The present findings suggest that Eu and Dy incorporated La2MoO6 and La2Mo2O9 phosphors are highly auspicious candidates for applications in solid-state lighting. © 2019 Elsevier Lt
Eu3+ and Dy3+ doped La2MoO6 and La2Mo2O9 phosphors: Synthesis and luminescence properties
No full textWe report a detailed structural analysis and properties of the photoluminescence (PL) and thermoluminescence (TL) spectra of Eu3+ and Dy3+ incorporated into novel La2MoO6 and La2Mo2O9 phosphors synthesized successfully through gel combustion synthesis. the formation of a tetragonal phase and a cubic structure were verified for La2MoO6 and La2Mo2O9 phosphors via X-ray diffraction (XRD) studies. Dy doped samples exhibited blue and green emissions at 480 nm (F-4(9/2) -> H-6(15/2)) and 572 nm (F-4(9/2) -> H-6(13/2)), and also Eu doped samples showed a sharp emission peaks at 612 and 619 nm (D-5(0) -> F-7(2)) upon 349 nm pulse laser excitation. Peak shape (PS) technique was utilised to determine activation energy, frequency factor and order of kinetics associated with the main glow curves in undoped and Eu and Dy doped samples after X-ray irradiation. the present findings suggest that Eu and Dy incorporated La2MoO6 and La2Mo2O9 phosphors are highly auspicious candidates for applications in solid-state lighting
Dy3+ and Eu3+ co-activated gadolinium aluminate borate phosphor: Synthesis, enhanced luminescence, energy transfer and tunable color
No full textThe synthesis of GdAl3(BO3)4 phosphors incorporated with activators of Dy3+ and Dy3+/ Eu3+was successful and achieved through the gel combustion method. Powder X-ray diffraction (XRD) was employed to identify phase purity and the effects of dopant concentration on the crystallographic structure. The results of Photoluminescence (PL) measurements revealed that the intensity and lifetime of luminescence properties varied depending on the concentrations of Dy3+ and Eu3+ ions. The dependence of luminescence intensity on doping concentration is investigated with respect to the energy transfer process between Eu3+ and Dy3+ ions. A decrease in luminescence lifetime occurs with increasing concentrations of Eu3+ co-doping. The energy transfer was also investigated using decay curve analysis. The co-doping of Eu3+ significantly boosts the energy transfer efficiency from 26% to 84%. These findings make GdAl3(BO3)4: Dy3+, Eu3+ phosphors an ideal choice for LED applications in solid state lighting and displays. © 2023 Elsevier Lt
Influence of laser excitation power on temperature-dependent luminescence behaviour of Ce- and Tb-incorporated BaMgAl10O17 phosphors
No full textBaMgAl10O17 (BAM) is a highly suitable host lattice for various rare earth ions with excellent luminescence properties in different spectral regions, including a strong photoluminescence (PL) emission from the visible spectral region. A new Ce- and Tb-incorporated BaMgAl10O17 phase was synthesized successfully using a wet combustion method and it was studied as a function of the temperature and laser excitation power. We further characterize the obtained phosphors with X-ray diffraction at room temperature. Different fuel/oxidant (f/o) ratios were introduced to investigate the optimum synthesis conditions for the BAM phosphors and optimum ratio was found out to be 8. The photoluminescence (PL) spectra were collected under the excitation light generated by a Nd:YLF pulse laser at 349 nm as the temperature was increased from 10 K to 300 K. A strong green emission of Tb3+ was observed in the green region of the spectrum due to the D-5(4)-> F-7(J) transition. We also observed a wide emission band from the Ce3+ ion in the wavelength range of 350-650 nm. The luminescence intensities of all phosphors exhibited different patterns with an increase in the temperature. We also evaluated how the PL spectrum of the rare earth-activated BAM host matrix shifts under various laser excitation powers. The PL intensity of Ce-activated BAM significantly shifted (similar to 30 A) to the blue region of the spectrum with an increase in the laser excitation power, however we did observed no shift forTb(3+) activated BAM. The present findings suggest that Tb-incorporated BaMgAl10O17 can be effective as a green phosphor candidate material with a wide range of applications
Anomalous 5D0 ? 7F4 transition induced by alkali ion co-doping in Eu3+-activated K7SrY2(B5O10)3 borates: A Judd-Ofelt and photoluminescence analysis for pc-WLEDs
No full textIn this study, red-emitting K7SrY2(B5O10)(3):Eu3+ phosphors were synthesized via high-temperature solid-state reaction. The effects of Li+ and Na+ co-doping on structural and photoluminescent properties were investigated. XRD and Rietveld refinement confirmed a phase-pure trigonal structure. Under 394 nm excitation, Li+ co-doping induced significant local lattice asymmetry, leading to a remarkable similar to 58-fold enhancement of D-5(0) -> F-7(4) transition, which is typically parity-forbidden. This behavior is further supported by the high Judd-Ofelt Omega(6) parameter (5.42 x 10(-20) cm(2)), indicating enhanced electric dipole character due to symmetry breaking. CIE chromaticity coordinates shifted toward deeper red emission with color purity up to 97.7 % and CCT as low as 2253 K. Temperature-dependent PL confirmed high thermal stability (E-a = 0.190 eV). These results demonstrate that Li+-induced symmetry distortion is a powerful strategy to enhance anomalous red emission, positioning KSYBO:Eu3+,Li+ as a promising red phosphor for pc-WLEDs.Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia [PNURSP2025R16]; Scientific and Technological Research Council of Turkey [223M036]We would like to express our sincere gratitude to the Princess Nourah bint Abdulrahman University Researchers Supporting Project (Project No. PNURSP2025R16), Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia. This study was also financially supported by the Scientific and Technological Research Council of Turkey (TUBITAK, Project No. 223M036)
Judd-Ofelt analysis and photoluminescence behavior of Tb3+-activated K7SrY2(B5O10)3 phosphors modified with alkali co-dopants for solid-state lighting applications
No full textIn this study, the structural and luminescent properties of alkali-modified K7SrY2(B5O10)(3) phosphors activated with Tb3+ ions were systematically investigated for solid-state lighting and photonic applications. A combination of X-ray diffraction (XRD) with Rietveld refinement, vibrational spectroscopy (FTIR and Raman), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) confirmed that the trigonal R32 structure of the host lattice is retained upon doping and co-doping, with Tb3+ ions preferentially occupying Y3+ sites. Photoluminescence (PL) studies revealed intense green emission centered at 540 nm (D-5(4) -> F-7(5) transition), with maximum intensity observed at 3 wt% Tb3+, beyond which concentration quenching occurred. The critical interaction distance (similar to 28 & Aring;) and interaction parameter (theta approximate to 5.55) confirmed that dipole-dipole interactions govern the quenching mechanism. Co-doping with Li+ and Na+ resulted in a significant enhancement in both emission intensity and decay lifetime, with Li+ co-doping at 3 wt% yielding an similar to 11.7-fold enhancement and increasing the average lifetime from 1.48 ms to 1.95 ms. This corresponds to a high radiative efficiency of similar to 93 %, indicating effective suppression of non-radiative losses. These enhancements were attributed to improved crystallinity, suppression of non-radiative defects, and modulation of the local crystal field symmetry. Judd-Ofelt analysis of the well-resolved emission bands yielded Omega(4) and Omega(6) intensity parameters of 0.96 x 10(-20) and 1.12 x 10(-20) cm(2), respectively, indicating moderate asymmetry in the ligand environment. The theoretical radiative lifetime (similar to 1.10 ms) showed excellent agreement with experimental values, indicating high radiative efficiency with minimal non-radiative losses. CIE chromaticity coordinates reached (0.3782, 0.6081) for 3 wt% Tb3+ and shifted toward the blue-green region (e.g., (0.2791, 0.4284) with Li+), demonstrating tunable and stable green emission. This work demonstrates the potential of Li+/Na+ co-doped KSYBO:Tb3+ phosphors as efficient, color-stable, and structurally robust green-emitting components for phosphor-converted white LED and optical display devices.Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia; Scientific Research Project Unit of Manisa Celal Bayar University [2024/122]; Scientific and Technological Research Council of Turkey (TUBITAK) [1001-223M036]; [PNURSP2025R16]We would like to express our sincere gratitude to the Princess Nourah bint Abdulrahman University Researchers Supporting Project (Project No. PNURSP2025R16) , Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia. This study was also financially supported by the Scientific Research Project Unit of Manisa Celal Bayar University (Project No. 2024/122) and by the Scientific and Technological Research Council of Turkey (TUBITAK, Project No. 1001-223M036)
Anomalous dose behaviour of thermoluminescence glow curves and kinetic analysis of beta irradiated YAl3(BO3)4:Tb phosphor
No full textWith the aid of thermoluminescence (TL), we have extensively studied YAl3(BO3)4 host matrices incorporated with Tb3+ at different doping contents, which have been produced by combustion. The measured the TL glow curves exposed to beta rays at different doses consisted of four broad peaks located at around 76, 126, 230, and 378 degrees C. The peak maximum of the 230 degrees C TL peak shifts toward higher temperatures after 5 Gy beta irradiation while the other peak maxima almost remain constant. It is peculiar that 230 degrees C peak maximum shifts to higher temperatures with increased radiation dose and can be attributed to the multiple phases of the sample. A TL glow curve exhibits a proportional increase in intensity with increased the heating rate. A discussion of the possible causes of this pattern is provided. Observed peaks using the TmTstop method are due to the presence of a quasicontinuous distribution of traps. The parameters of the traps have also been estimated using various heating rate methods in excellent agreement with one another
Lattice distortion effects induced by Li plus co-doping on ZnO:Tb3+phosphors: Photoluminescence and unusual hypersensitive 5D4 → 7F0 transition
No full textA series of Tb3+, Li+ co-doped ZnO phosphors were prepared using a precipitation method. X-ray diffraction (XRD) analysis indicated the successful incorporation of Tb3+ into the ZnO lattice. The influence of Tb3+ doping content and Li+ charge compensator on the photoluminescence (PL) properties of ZnO:Tb3+ was investigated. Under UV excitation, emissions corresponding to electron transitions 5D4 -> 7FJ (J = 0,1,2,3,4,5,6) were observed from Tb3+ ions, including an unusual emission transition at 673 nm, which significantly enriches our understanding of Tb3+ luminescence. The critical concentration quenching of Tb3+ in ZnO:Tb3+ occurs at 7 mol%, as explained by the Van Uitert equation, which attributes this phenomenon to dipole-dipole interactions. Surprisingly, incorporating Li+ for charge balancing led to a reduction in the luminescence intensity of ZnO:7 mol% Tb3+, x%Li+ phosphors (x = 0.01 and 0.07) at 544 nm. This reduction highlights an increased degree of lattice distortion due to Li+ inclusion. Furthermore, CIE chromaticity analysis showed that the optimal doping concentration of 0.07 Tb3+ shifted the color coordinates towards vivid green, with a color temperature of approximately 6241 K, indicating of neutral white light.Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia [PNURSP2024R16]; Izmir Bakircay University Scientific Research Projects Coordination Unit [HZP.2023.001]We express our gratitude to Princess Nourah bint Abdulrahman University Researchers Supporting Project number (PNURSP2024R16), Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia. This work was also supported by Izmir Bakircay University Scientific Research Projects Coordination Unit, under grant number HZP.2023.001
