Browsing by Subject "Dysprosium compounds"
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Item Spectral emission of rare earth (Tb, Eu, Dy) doped Y2Sn 2O7 phosphors(2013) Ege A.; Ayvacikli M.; Dinçer O.; Satilmiş S.U.Radioluminescence (RL) characterization of the yttrium stannate (Y 2Sn2O7) phosphors doped with 1 mol% Tb, Eu and Dy was carried out and significant electronic transitions corresponding to doped rare earth ions were observed. It was seen that all parts of these rare earth ions are included in the phosphor material in their trivalent state. The RL measurement indicates that the series of the emission-state 5D 4→7F6, 5D4→ 7F4, 5D4→7F 3, corresponding to the characteristic 4f→4f intra-configuration forbidden transitions of Tb3+are appeared and that main emission peak occurs at about 542 nm. There are in fact multiple emission lines at each of these due to the crystal field splitting of the ground state of the emitting ions. Eu-doped Y2Sn2O7 sample displayed intense and predominant emission peaks located at 580-650 nm corresponding to the 5D0→7Fj (j=l, 2, 3 and 4) transitions. Red emission coming from the hypersensitive Dy doped phosphor presented luminescence emissions with dominating transitions at 4F9/2→6Hj (j=9/2, 11/2, 13/2 and 15/2). The sharp emission properties show that the Y2Sn 2O7 is a suitable host for rare-earth ion doped phosphor material. © 2013 Elsevier B.V.Item Prompt isothermal decay properties of the Sr4Al14O25 co-doped with Eu2+ and Dy3+ persistent luminescent phosphor(Elsevier B.V., 2018) Asal E.K.; Polymeris G.S.; Gultekin S.; Kitis G.Thermoluminescence (TL) techniques are very useful in the research of the persistent Luminescence (PL) phosphors research. It gives information about the existence of energy levels within the forbidden band, its activation energy, kinetic order, lifetime etc. The TL glow curve of Sr4Al14O25:Eu2+,Dy3+ persistent phosphor, consists of two well separated glow peaks. The TL techniques used to evaluate activation energy were the initial rise, prompt isothermal decay (PID) of TL of each peak at elevated temperatures and the glow – curve fitting. The behavior of the PID curves of the two peak is very different. According to the results of the PID procedure and the subsequent data analysis it is suggested that the mechanism behind the low temperature peak is a delocalized transition. On the other hand the mechanism behind the high temperature peak is localized transition involving a tunneling recombination between electron trap and luminescence center. © 2018 Elsevier B.V.Item Thermoluminescence dose and heating rate dependence and kinetic analysis of ZnB2O4:0.05Dy3+ phosphor(Elsevier B.V., 2018) Balci-Yegen S.; Yüksel M.; Kucuk N.; Karabulut Y.; Ayvacikli M.; Can N.; Topaksu M.The intention of this study is to explore the thermoluminescence (TL) behavior of beta irradiated 5% Dy3+ doped zinc borate (Zn(BO2)2:0.05Dy3+) phosphor prepared using the nitric acid method. The TL glow curve corresponding from 1 Gy to 80 Gy beta irradiation (preheated at 140 °C) shows a maxima at c.a. 180 °C. The dependence of heating rate was tested and found out that thermal quenching effect was dominating on TL glow curves as the heating rate increases. The dose response of the phosphor material exposed to beta radiation was investigated. Deconvolution was applied using the peak fit method on the glow curve for optimized conditions. Also peak shape (PS), various heating rates (VHR) and computerized glow curve deconvolution (CGCD) methods were used to evaluate the trapping level parameters, namely trap depth (E), frequency factor (s) and order of kinetics (b) associated with the main glow curve in Zn(BO2)2:0.05Dy3+ phosphor after beta irradiation of 20 Gy. The values of trap depth corresponding with the TL glow peak at 180 °C were found to be 0.93 eV, 0.92 ± 0.05 and 1.05 ± 0.02 respectively. Furthermore W and c parameters characterizing thermal quenching based on the Mott-Seitz theory were determined as 0.31 ± 0.04 eV and 162.55. The TL mechanism appears more likely to get second order kinetics, suggesting the probability of re-trapping of charge carriers by emptied traps. © 2017 Elsevier B.V.Item Detailed luminescence (RL, PL, CL, TL) behaviors of Tb3+ and Dy3+ doped LiMgPO4 synthesized by sol-gel method(Elsevier B.V., 2020) Keskin İ.Ç.; Türemiş M.; Katı M.İ.; Gültekin S.; Tuncer Arslanlar Y.; Çetin A.; Kibar R.The un-doped, Tb3+ and, Dy3+ doped LiMgPO4 phosphors were successfully synthesized by the sol-gel method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to characterize the light-emitting phosphors. The XRD spectra verify the phase formation of samples. The luminescence properties were analyzed by radioluminescence (RL), photoluminescence (PL), cathodoluminescence (CL) and, thermoluminescence (TL) spectra. Also, the effect of Tb3+, Dy3+ ions in LiMgPO4 was determined on the luminescence intensity in detail. The RL spectrum of un-doped LiMgPO4 consists of two broad emission bands in the 310–450 nm and 575–850 nm range. The maximum intensities of these bands were observed at 360 nm and 655 nm. The emission spectrum of Dy3+ doped LiMgPO4 under X-ray excitation show characteristic emissions of Dy3+ corresponds to 4F9/2→6Hj transitions. In addition to the 5D4→7Fj (j:6–1) transitions of Tb3+ doped LiMgPO4 phosphor, strong emissions derived from 5D3→7Fj (j:6–3) transitions were observed in the blue region. Also, these blue emissions were seen at RL, PL and, CL spectra. The optical absorption spectra were recorded and the energy band gaps were calculated 3.62 eV, 3.30 eV and, 4,01 eV for un-doped, Dy3+ and, Tb3+ doped LiMgPO4 phosphors, respectively. The phosphors irradiated with UV (254 nm) light. The main TL glow peak was observed at 288 °C for the Dy3+ doped phosphor, and the peaks at 198, 283 °C were observed for the Tb3+ doped phosphor. © 2020 Elsevier B.V.Item Synthesis and competitive luminescence quenching mechanism of Ca3Al2O6:Ln3+ (Ln: Dy and Sm) phosphors(Elsevier Ltd, 2020) Bakr M.; Kaynar Ü.H.; Ayvacikli M.; Benourdja S.; Karabulut Y.; Hammoudeh A.; Can N.Sm3+ and Dy3+ activated Ca3Al2O6 phosphors were produced through a gel combustion method using Urea + β-Alanine, Urea, and Urea + Glycine as fuels. The crystal structure and the phase purity of the obtained materials were characterized by X-ray powder diffraction (XRD). Ca3Al2O6:Sm3+ phosphor shows characteristic emission lines (565 nm, 602 nm, 649 nm, and 714 nm) in the orange red region assigned to 4G5/2→6HJ (J = 5/2, 7/2, 9/2, 11/2) transitions of Sm3+. The strongest peak is located at 602 nm. Emission spectra of Ca3Al2O6:Dy3+ show that there are two dominant peaks centered at 480 nm and 573 nm emitting blue and yellow light. Optimum doping concentrations of Sm(NO3)3 and Dy(NO3)3 are 0.01 % and 0.03 %, respectively. The concentration quenching mechanism is verified to be a dipole-dipole interaction as the type of energy transfer among Sm3+-Sm3+ and Dy3+-Dy3+ ions. The critical distance is also calculated to be 24.19 Å and 16.77 Å, respectively. © 2020 Elsevier LtdItem Robust CsPbBr3 and CdSe / Dy3++CdSe quantum dot doped glass nanocomposite hybrid coupling as color converter for solid-state lighting applications(Elsevier B.V., 2021) Kıbrıslı O.; Erol E.; Çelikbilek Ersundu M.; Ersundu A.E.CsPbX3 (X = Br-, Cl-, I-) and IIB-VIA group quantum dots (QDs) exhibit great potential for diverse opto-electronic applications due to their outstanding photoluminescence features. However, poor long-term stability limits their integration into practical applications. Although various surface modification and encapsulation methods have been proposed to increase their durability, desired stability values along with favorable emission properties could not be achieved yet. In this work, controlled crystallization of CsPbBr3 and CdSe QDs are realized separately in a specially tailored silicate glass matrix to obtain quantum dot doped glass nanocomposite (GNC) layers showing typical bright green emission and broadband emission that covers red end of the visible spectrum, respectively. Two alternative white LED devices are constructed as a proof-of-concept by coupling CsPbBr3 doped layer with CdSe and Dy3++CdSe doped layers on top of a blue LED chip to demonstrate excellent color conversion performance and challenging color rendering index values up to 85. CsPbBr3 doped GNC layer exhibits photoluminescence quantum yield (PLQY) up to 40.44%, while PLQY of CdSe doped layer is enhanced up to 18.68% via incorporation of Dy3+ ions. PL properties of GNCs are reversible up to 275 °C and stable after 60 days of immersion in water or under 442 nm laser irradiation (5 W/cm2) up to 30 min. Promising thermal, chemical, and photo stability properties reveal that hybrid coupling of GNCs exhibit high potential to be used as color convertors in solid-state lighting applications. © 2021 Elsevier B.V.Item Thermoluminescence glow curve analysis and evaluation of trapping parameters of dysprosium doped lanthanum calcium borate La2CaB10O19(Elsevier B.V., 2021) Bulcar K.; Oglakci M.; Kaynar U.H.; Ayvacikli M.; Souadi G.; Topaksu M.; Can N.The present work elucidates thermoluminescence study of Dy activated lanthanum calcium borate (La2CaB10O19) phosphors and determination of trapping parameters. Two glow curves located at 132 and 295 °C were observed and showed a linear TL response. The kinetic parameters of the glow peaks were evaluated using variable heating rate, repeated initial rise method and Computerized Glow Curve Deconvolution. Analysis of the main dosimetric peaks reveals that the values of the activation energy and pre-exponential factor are found to be 0.78–1.145 eV and 8.59 × 109–8.44 × 1011 s−1, respectively. The sample doped with 1% Dy3+ exhibits a good stability for the reusability. Besides, the found results indicate that the temperature maximum shifts to the higher temperature side as the heating rate increases. Contrary to previously expressed theoretical expectations, anomalous heating rate dependence was observed in Dy3+ doped La2CaB10O19 sample and a semi-localized transition model explaining the anomalous heating rate effect was employed. © 2020 Elsevier B.V.Item Synthesis and enhanced photoluminescence of the BaSiF6:Dy3+ phosphors by Li+ doping via combustion method(Elsevier B.V., 2022) Souadi G.; Kaynar U.H.; Ayvacikli M.; Canimoglu A.; Can N.Undoped BaSiF6, Dy3+ doped BaSiF6, and Dy3+, Li+ co-doped BaSiF6 phosphors were synthesized through a gel-combustion method. The prepared samples were characterized by powder x-ray diffraction (XRD), Fourier transform infrared (FTIR), energy dispersive x-ray spectroscopy (EDS), and photoluminescence (PL) techniques. The XRD data revealed that both the Dy3+ doped and Li + co-doped BaSiF6 phosphors exhibited a single-phase structure belonging to the space group R3m‾ which matched well with the standard JCPDS files (No. 002–6613). FTIR spectra showed absorption bands at 3417 cm−1, 1640 cm−1, and 1620 cm−1 corresponding to water molecules. EDS analysis confirmed the chemical composition of the prepared samples. The PL emission spectra of BaSiF6:Dy3+ by different co-doping concentrations of Li+ exhibited prominent emission peaks at 490 nm, 572 nm, 672 nm and 758 nm. The incorporation of Li+ is beneficial for enhancing the photoluminescence intensity. The optimum Li+ amount was 8% for BaSiF6:Dy3+ and then started to decrease. The enhancement could be due to the occurrence of oxygen vacancies due to the incorporation of Li + ions. The x = 0.301 and y = 0.361 coordinates of this phosphor with varying Li+ dopant concentration determined by the Commission Internationale de l'Eclairage (CIE - 1931) were in the white range. The present work demonstrates how a simple and effective method can be used to prepare novel nanophosphors for applications in the field of visible light emitting devices with enhanced white emission. © 2021 Elsevier B.V.Item Thermoluminescence characterization and kinetic parameters of Dy3+ activated Ca3Y2B4O12(Elsevier B.V., 2022) Hakami J.; Sonsuz M.; Kaynar U.H.; Ayvacikli M.; Oglakci M.; Topaksu M.; Can N.In this study, thermoluminescence (TL) characteristics of Ca3Y2B4O12:xDy (0 ≤ x ≤ 0.07) phosphor samples were studied. The samples were exposed to beta irradiation in the dose range from 0.1 Gy to 100 Gy to investigate TL dose response. The concentration of Dy3+ in Ca3Y2B4O12 phosphor was optimized and found to be 1 mass % in terms of TL signal quality. The TL glow curve appears to be consisted of three peaks which were discernible at 72 °C, 280 °C and 376 °C. The trapping parameters (E, b, and s) were calculated using initial rise (IR), and variable heating rate (VHR) techniques. The trapping parameters, order of kinetics, frequency factor, and figure of merit have been all determined by means of the Glow Curve Deconvolution (GCD) method (tgcd:An R package). Ca3Y2B4O12:Dy phosphor displays efficient thermoluminescence properties. © 2022 Elsevier B.V.Item Thermoluminescence glow curve analysis and kinetic parameters of Dy-doped BaSi2O5 phosphor(Editorial Office of Chinese Rare Earths, 2022) Alajlani Y.; Can N.In this paper, Dy3+ incorporated BaSi2O5 phosphors were synthesized by gel combustion method and characterized by X-ray diffraction (XRD). The effects of various heating rates on thermoluminescence (TL) kinetics and glow peak temperatures of Dy3+ incorporated BaSi2O5 phosphors exposed to β irradiation at room temperature were investigated. The glow curves of the phosphor exposed to β-irradiation (0.1–100 Gy) consist of four main peaks located at 87, 130, 271, and 327 °C and exhibit a good linearity between 0.1 and 100 Gy. Three experimental techniques including variable heating rate (VHR), repeated initial rise (RIR), peak shape (PS) and computerized glow curve deconvolution (CGCD) were employed to determine TL kinetic parameters. Our findings indicate that the TL glow peaks of the phosphor obey first-order kinetics. Analysis of the main dosimetric peaks through the techniques mentioned above indicates that activation energies (E) and pre-exponential factor (s) are in the range of 0.80–1.50 eV and 1.15 × 108–3.28 × 1013 s−1. Additionally, it is found that the temperature of the glow peaks shifts toward the higher temperatures and the TL intensity smoothly decreases as the heating rate increases. The effect on the TL intensities and glow peak temperatures of the heating rate is discussed in terms of thermal quenching. © 2020 Chinese Society of Rare EarthsItem Novel Dy incorporated Ca3Y2B4O12 phosphor: Insights into the structure, broadband emission, photoluminescence and cathodoluminescence characteristics(Elsevier Ltd, 2022) Qaisi A.H.; Kaynar U.H.; Ayvacikli M.; Garcia-Guinea J.; Alajlani Y.; Topaksu M.; Can N.This study reports cathodoluminescence (CL) and photoluminescence (PL) properties of undoped borate Ca3Y2B4O12 and Ca3Y2B4O12:x Dy3+ (x = 0.5, 1, 2, 3, 5, and 7) synthesized by gel combustion method. Micro-X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), CL and PL under electron beam and 359 nm pulse laser excitation, respectively were used to investigate characterization and luminescence studies of synthesized samples in the visible wavelength. As-prepared samples match the standard Ca3Y2BO4 phase that belongs to the orthorhombic system with space group Pnma (62) based on XRD results. Under electron beam excitation, this borate host shows a broad band emission from about 250 to 450 nm, peaked at 370 nm which is attributed to NBHOC. All as-prepared phosphors exhibited the characteristic PL and CL emissions of Dy3+ ions corresponding to 4F9/2→6HJ transitions when excited with laser at 359 nm. The CL emission spectra of phosphors were identical to those of the PL spectra. Concentration quenching occurred when the doping concentration was 1 mol% in both the CL and PL spectra. The underlying reason for the concentration quenching phenomena observed in the discrete orange-yellow emission peaked at 574 nm of Dy3+ ion-doped Ca3Y2B4O12 phosphor is also discussed. According to these data, we can infer that this new borate can be used as a yellow emitting phosphor in solid-state illumination. © 2022 Elsevier LtdItem Synthesis, characterization and enhanced photoluminescence and temperature dependence of ZrO2:Dy3+ phosphors upon incorporation of K+ ions(Elsevier Ltd, 2023) Can N.; Coban M.B.; Souadi G.; Kaynar Ü.H.; Ayvacikli M.; Garcia Guinea J.; Ekdal Karali E.This study reports the successful synthesis and comprehensive characterization of ZrO2:Dy3+ phosphors with the incorporation of K+ ions. The introduction of Dy3+ and K+ in the ZrO2 lattice as lanthanide activators demonstrates its potential as an efficient host material. The structural integrity of ZrO2 remains unaltered following the doping process. Fourier-transform infrared spectroscopy (FTIR) analysis confirms the presence of Zr-O and O-H stretching, along with H2O bending modes in the phosphor sample. The wide luminescence band seen at 460 nm is attributed to luminescence defects in the ZrO2 induced by oxygen, and the presence of water molecules. Photoluminescence (PL) spectra analysis reveals pronounced emission peaks at 491 and 578 nm, corresponding to 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions, respectively, upon excitation at 349 nm. Optimizing the Dy3+ doping concentration to 0.4 wt% and achieving a critical distance of 31.82 Å resulted in efficient energy transfer. Notably, co-doping K+ as a charge compensator significantly enhances the luminescence intensity. Moreover, at lower temperatures, direct excitation of Dy3+ ions through our pump wavelength, coupled with exciton-mediated energy transfer, leads to a remarkable increase in PL intensity. Tailoring the doping concentrations effectively shifts the emission spectrum of the phosphor mixture, aligning with the standard white light illumination coordinates (0.333, 0.333). This property positions the material as a promising candidate for applications in white light-emitting diodes (WLEDs) and various high-quality lighting applications. The enhanced photoluminescence and temperature dependence observed in ZrO2:Dy3+ phosphors upon the incorporation of K+ ions pave the way for their potential utilization in advanced luminescent devices. © 2023 Elsevier Ltd and Techna Group S.r.l.Item Phase transition and luminescence characteristics of dysprosium doped strontium stannate phosphor synthesized using hydrothermal method(Elsevier Ltd, 2023) Kaynar Ü.H.; Coban M.B.; Madkhli A.Y.; Ayvacikli M.; Can N.A series of strontium stannate (SrSnO3) doped with Dy3+ ions at various wt % concentrations (1, 2, 3 and 5) were synthesized via hydrothermal reaction and analysed using X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), environmental electron scanning microscope (ESEM), photoluminescence (PL) and, cathodoluminescence (CL). The XRD results confirmed that all samples were assigned to cubic perovskite-type SrSnO3 structured with the Pm3m‾ space group. The PL emission spectrum of Dy3+ activated samples consisted of some characteristic peaks located at 481 nm, 572 nm, 660 nm and 753 nm, corresponding to (4F9/2 → 6H15/2, blue), (4F9/2 → 6H13/2, yellow), 660 nm (4F9/2 → 6H11/2, red) and 753 nm (4F9/2 → 6H9/2, red) transitions. The PL emission line intensity is gradually enhanced with an increase in doping concentration up to 3 wt %, followed by concentration quenching. The confinement effects of localized resonant energy transfer might cause higher concentration quenching. PL emission spectra were affected by the temperature range from 10 K to 300 K. PL emission anomalies at 270 K in SrSnO3:Dy3+ have been reported to be consistent with a structural phase transition at this temperature. This work confirms Singh et al.'s observation, revealing that SrSnO3 has a phase transition at 270 K. © 2022 Elsevier Ltd and Techna Group S.r.l.Item Structural and temperature dependence luminescence characteristics of RE (RE=Eu3+, Dy3+, Sm3+ and Tb3+) in the new gadolinium aluminate borate phosphor(Elsevier Ltd, 2023) Madkhali O.; Kaynar Ü.H.; Alajlani Y.; Coban M.B.; Guinea J.G.; Ayvacikli M.; Pierson J.F.; Can N.GdAl3(BO3)4:Dy3+, Sm3+, Eu3+, and Tb3+ samples were successfully achieved via a sol-gel combustion method. The observed XRD analysis confirms the formation of the desired GAB host, indicating rhombohedral structures that agree well with JPCD card number 72–1985. The FTIR analyses show the detection of B − O stretching and B − O − B bending modes as well as Al − O and Gd − O bonds in the phosphor samples. Energy dispersive spectroscopy (EDS) analysis reveals that Sm, Eu, Dy, and Tb have been successfully doped into GdAl3(BO3)4. The observed broad intrinsic luminescence band can be caused by oxygen-induced luminescence defects in the GAB host with hydrous precursors. The luminescence properties of rare earth ion-doped GdAl3(BO3)4 samples are analysed by photoluminescence spectra, showing their optimal doping concentrations and critical distances of Dy3+, Eu3+, Sm3+ and Tb3+ are 2 wt% − 25.8 Å, 7 wt% − 17 Å, 1 wt% − 32.59 Å, and 7 wt% − 17.03 Å. Additionally, the energy transfer mechanism for luminescence quenching was determined as dipole-dipole (for Dy3+, Eu3+, and Tb3+) or dipole-quadrupole (for Sm3+) and the cross-relaxation process. GdAl3(BO3)4 samples obtained by doping with different RE3+ ions exhibit intense light emissions with different colors originating from different RE3+ ions under 349 nm excitation. When doped with different concentrations of RE3+ ions, the luminescence properties of the samples changed. The synthesized luminescence materials have potential applications in lighting and display technologies. © 2023 Elsevier Ltd and Techna Group S.r.l.Item Low temperature luminescence and tunnelling effect in the Sr4Al14O25 co-doped with Eu2+and Dy3+ persistent luminescent phosphor(Elsevier Ltd, 2023) Karsu Asal E.C.Thermoluminescence (TL) technique is very useful in the research of persistent Luminescence (PL) phosphors. It gives information about the existence of energy levels within the forbidden band and lifetime. The TL glow curve of Sr4Al14O25: Eu2+,Dy3+ persistent phosphor consists of two well-separated glow peaks at around 353 K and 438 K after both UV radiation and beta irradiation. To study the low temperature (≤ room temperature) glow peaks, low temperature TL (LTTL) measurements were performed with a homemade system after exposed to UV radiation. The sample was heated according to T(t)=T∞−(T∞−T0)e−αt equation starting from liquid nitrogen temperature, 77K. Besides the peaks at around 345 and 445 K according to LTTL results, Sr4Al14O25: Eu2+,Dy3+ has two more well-separated low temperature TL peaks at around 170 K and 295 K. The lifetime of the TL glow peaks (at 353 K and 438 K) was calculated according to [Formula presented] and the results were checked with fading tests. Moreover, TL sensitivity tests were carried out both with and without preheating. Finally, tunnelling effect was evaluated by using the results of sensitivity tests and fading tests. Interesting results were observed at sensitivity tests performed with preheating. The results indicates that the behaviour of two glow peaks is very different from each other. The mechanism behind the peak around 438 K is localised transition involving a tunnelling effect. © 2022 Elsevier LtdItem Dy3+ and Eu3+ co-activated gadolinium aluminate borate phosphor: Synthesis, enhanced luminescence, energy transfer and tunable color(Elsevier Ltd, 2023) Madkhali O.; Kaynar Ü.H.; Cam Kaynar S.; Ayvacikli M.; Can N.The 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 LtdItem Structural and photoluminescent analysis of novel Eu3+ and Dy3+ Co-doped ZnO nanoparticles by incorporation of Li+ and K+ ions(Elsevier Ltd, 2024) Altowyan A.S.; Coban M.B.; Kaynar U.H.; Çin E.A.; Ayvacikli M.; Hakami J.; Can N.In this study, we thoroughly investigate the structural and luminescent features of ZnO nanoparticles doped with Eu3+ and co-doped with Dy3+, exploring the impact of Li+ and K+ incorporation during the precipitation process. The synthesized nanoparticles were comprehensively characterized using X-ray diffraction (XRD), Fourier transmission infrared (FTIR), Energy dispersive spectroscopy (EDS), and photoluminescence (PL) techniques. The XRD analysis conclusively verified the presence of the hexagonal wurtzite phase in the ZnO nanoparticles. PL assessment of undoped ZnO revealed a well-defined and narrow exciton band peaked at 390 nm, accompanied by a broad defect-related band spanning from 450 nm to 750 nm. For ZnO:Eu3+ phosphors, distinct emission peaks emerged at 590 nm, 618 nm, and 696 nm when excited at 349 nm, corresponding to the 4f electron transition inherent to Eu3+ ions. The optimized doping level for the ZnO:xEu3+ sample was determined to be 7 wt%. The mechanism of concentration quenching was identified as dipole-quadrupole interaction. Co-doping with Li+ as a charge compensator resulted in a threefold enhancement in the luminescence intensity of the red-emitting ZnO:Eu3+, Li+. As the temperature decreases, the luminescence intensity of Eu3+ transitions in ZnO:7 wt% Eu3+ diminishes due to less efficient energy transfer among Eu3+ ions, while the intrinsic broad band from ZnO fades away, emphasizing the temperature-sensitive nature of the material. The addition of Dy3+ as a co-dopant to ZnO:Eu3+ induces a counterintuitive effect, where an increase in Dy3+ concentration unexpectedly results in a decrease in Eu3+ emission peak intensity. This unconventional behavior highlights a complex interplay between Dy3+ and Eu3+ ions, suggesting the influence of spatial factors, competing processes, and potential dopant aggregation within the ZnO lattice. The CIE analysis conducted on ZnO:Eu3+, Dy3+, and Li+ nanoparticles demonstrated precise control over the emitted light, enabling the fine-tuning of their optical properties for applications in displays. © 2024 Elsevier Ltd and Techna Group S.r.l.Item Enhanced luminescence of Eu3+ in LaAl2B4O10 via energy transfer from Dy3+ doping(Elsevier B.V., 2024) Kaynar U.H.; Coban M.B.; Hakami J.; Altowyan A.S.; Aydin H.; Ayvacikli M.; Can N.In this study, an investigation was conducted on the structural and photoluminescence (PL) characteristics of LaAl2B4O10 (LAB) phosphors initially incorporated with Dy3+ and Eu3+ ions. Subsequently, the impact of varying Eu3+ concentration while maintaining a constant Dy3+ concentration was examined. Structural characterization was performed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and energy-dispersive X-ray spectroscopy (EDS). XRD analysis confirmed the effective embedding of both dopants into the hexagonal framework of the LAB. The PL emission spectra revealed characteristic emissions of Dy3+ (blue and yellow) and Eu3+ (red) ions. The optimized dopant concentrations of both Dy3+ and Eu3+ were observed to be 3 wt%. The dominant mechanism for concentration quenching in doped LAB phosphors was determined to be the electric dipole–dipole interaction. Co-doping with Eu3+ led to a substantial decrease in Dy3+ emission intensity (∼0.18-fold) while enhancing Eu3+ emission intensity (∼3.72-fold). The critical energy transfer distance (RC = 11.64 Å) and the analysis based on the Dexter theory confirmed that the energy transfer mechanism corresponds to dipole–dipole interaction. The color purities and correlated color temperatures (CCT) were estimated, suggesting the potential of these phosphors for warm white and red lighting applications, respectively. The observed energy transfer and luminescence properties, along with the structural and compositional characterization, highlight the promising potential of LAB:Dy3+/Eu3+ co-doped phosphors for advanced lighting and display technologies. © 2024 Elsevier B.V.Item Temperature-responsive insights: Investigating Eu3+ and Dy3+ activated yttrium calcium oxyborate phosphors for structure and luminescence(Elsevier Ltd, 2024) Jabali D.A.; Madkhli A.Y.; Souadi G.; Kaynar Ü.H.; Coban M.B.; Madkhali O.; Ayvacikli M.; Amri N.; Can N.An investigation into the luminescent behavior of YCOB (Yttrium Calcium Oxyborate) doped with Eu3+ and Dy3+ ions, synthesized via the combustion method, is presented. The study, employing X-ray diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), and Energy-Dispersive X-ray Spectroscopy (EDS) analyses, confirms the structural integrity and purity of the synthesized nanophosphors. An XRD pattern exhibiting distinct crystalline peaks indicates that the dopant ions were successfully integrated into the YCOB lattice. The photoluminescence (PL) response of YCOB with Eu3+ and Dy3+ ions is thoroughly examined, uncovering distinct excitation and emission spectra. In the case of Eu3+ doping, excitation spectra reveal a significant charge transfer (CT) band at 254 nm, indicative of electron transfer between oxygen and europium ions. This CT transition enhances our understanding of the excitation behavior, with the dominant and Laporte-forbidden 5D0 → 7F2 transition. Characteristic peaks at 345 nm in the excitation spectra efficiently stimulate YCOB:Dy3+ when Dy3+ is used as a dopant. The primary emission peak at 585 nm corresponds to the hypersensitive electric dipole transition 4F9/2–6H13/2. Concentration quenching phenomena are observed, with a maximum Eu3+ concentration of 7 wt % attributed to the dipole-quadrupole interaction. Dy3+ doping, with a maximum concentration of 2 wt % primarily shows multipolar interactions, especially dipole-dipole interactions. The study extends to CIE chromaticity analysis, emphasizing Eu3+ doping's suitability for white light-emitting diode (WLED) applications and ensuring color stability. Conversely, varying Dy3+ concentrations do not yield consistent chromaticity coordinates. These findings have significant implications for the development of advanced phosphor materials across diverse applications, offering a roadmap for optimizing their optical performance. © 2024 Elsevier LtdItem Luminescence characteristics and kinetic parameters of LiBaPO4: Tb3+, Dy3+ phosphors synthesized by sol-gel method(Elsevier B.V., 2024) Katı M.İ.; Gökçe S.; Keskin İ.Ç.; Türemiş M.; Çetin A.; Kibar R.LiBaPO4: Tb3+, Dy3+ phosphors were prepared via sol-gel method by using the stoichiometric amounts of lithium nitrate LiNO3, barium nitrate Ba(NO3)2 and ammonium dihydrogen phosphate NH4H2PO4 as base materials. Morphology by scanning electron microscopy (SEM), structure by X-ray diffraction (XRD), thermal properties by Differential thermal analysis (DTA)/Thermogravimetric Analysis (TGA) and structural characteristics by Fourier transform infrared spectroscopy (FT-IR) were investigated. This paper presents luminescence properties using spectra from radioluminescence (RL), photoluminescence (PL), cathodoluminescence (CL) and, thermoluminescence (TL) and the influence of RE dopants (Tb3+, Dy3+) on the luminescent behavior of LiBaPO4. Computerized Glow Curve Deconvolution (CGCD) and Peak Shape Method were used to determine the kinetic parameters and the obtained results were evaluated. The RL results of un-doped LiBaPO4 showed the presence of a well-defined peak at 417 nm and a weaker band around 685 nm. Strong emissions were detected in the sample doped with Dy3+ correspond to 4F9/2→6Hj transitions. Blue, yellow and red emissions were observed with transitions of 4F9/2 → 6H15/2, 4F9/2 → 6H13/2 and 4F9/2 → 6H11/2, respectively. As for LiBaPO4: Tb3+, green emissions originated from the characteristic transitions (5D3 → 7FJ (j = 6–3) and 5D4 → 7FJ (j = 6–1)) of Tb+3 ion was seen. The RL, PL and CL spectra were identical, suggesting these green emissions. Dy3+ doped sample has three glow curves located at 72 °C, 145 °C and 204 °C, while the main temperature peak is measured at 240 °C for Tb3+ doped sample. Chromotographic studies of LiBa0·98PO4: Dy3+0.02 reveals that calculated x and y color coordinates (0.3122, 0.3233) are very close to the white light. © 2023