Phosphor BaMgAl10O17 Research Articles

Unveiling highly sensitive Dy3+ doped BaMgAl10O17 phosphor’s thermoluminescence trap features and temperature dependent luminescence for solid state lighting applications

This article explores the structural, morphological, thermoluminescence, and temperature-dependent emission properties of novel Dy3+ doped BaMgAl10O17(BAM-Dy) phosphors. Structural studies reveal that the phosphor has a similar structure to β-alumina. Rod-shaped interlinked surface morphology is a notable characteristic of the BAM-Dy samples. Incorporation of Dy3+ ions lead to the formation of distinct emission peaks (485 nm, 577 nm, and 635 nm) in the PL emission spectra. The effect of dopant concentration on the light output is crucial, and the highest PL intensity is observed for 1.5 mol% of Dy3+ concentration. The potential use of BAM-Dy phosphors for Gamma radiation detection and measurement is tested through thermoluminescence studies, which reveal high sensitivity, low threshold dose values, and exceptional response to low gamma doses, making them suitable for dosimetry applications. The investigation of trap parameters provides useful information about the number of traps, trapping mechanism, and trap energies, which is essential for in-depth study of synthesized phosphors for γ dosimetry application. The study of the effect of temperature on the luminescence behaviour is crucial for the application of phosphors in the light-emitting field. The BAM-Dy samples exhibit excellent thermal stability even at 210 °C, making them suitable for use in the field of White LEDs.

High quantum efficiency and excellent thermal stability in Eu3+ -activated CaY2ZrGaAl3O12 phosphors for wLEDs

There is a high demand for phosphorescent white light-emitting diodes (wLEDs) that possess low correlated color temperature (CCT) and high color rendering index (CRI), as they are considered to be environmentally friendly sources of solid-state illumination. A novel, UV-excited red light emitting Eu3+-activated CaY2ZrGaAl3O12 phosphor was synthesized for the preparation of warm wLEDs with high CRI and low CCT were obtained. Eu3+-doped CaY2ZrGaAl3O12 phosphors were synthesized with varying concentrations of Eu3+ dopant. The luminescence of Eu3+ was thoroughly examined at its optimal concentration of 20 mol%. Surprisingly, CaY2ZrGaAl3O12: 20%Eu3+ exhibits a broad excitation band of 200–550 nm and some sharp excitation peaks, the highest peak is observed at 251 nm. A dazzling red light, ranging from 550 to 750 nm, is emitted by CaY2ZrGaAl3O12: 20%Eu3+ phosphor. The excitation of ultraviolet light at a wavelength of 251 nm was employed, with an impressive internal quantum efficiency of 90.7% and a remarkable thermal quenching resistance. The wLED was packaged with green phosphor (BaMgAl10O17: Eu2+), red phosphor (CaY2ZrGaAl3O12: Eu3+), blue phosphor ((Ba, Sr)2SiO4: Eu2+) and 395 nm NUV LED chip, which emitted a dazzling warm white light when driven at a current of 20 mA. It has excellent CIE color coordinates (0.3893,0.3736), a low correlation color temperature (CCT) of 3738K, and an excellent color rendering index (Ra = 82.1). The application of the prepared new CaY2ZrGaAl3O12: Eu3+ red phosphor in wLED will promote the development of highly efficient luminous materials for healthy solid-state lighting.

Highly emissive 0D Tin(II) hybrid for white LED

The pursuit of environmentally friendly and highly luminescent phosphors for down-conversion white light-emitting diodes (WLEDs) remains a significant focus of research. Here, we present a novel zero-dimensional Sn(II) hybrid exhibiting vibrant orange emission peaking at 598 nm and an outstanding photoluminescence quantum yield of 69%. This hybrid, designated as (C7H8N3)4SnBr6, was synthesized via the reaction of 2-aminobenzimidazole with SnBr2, revealing distinctive self-trapped exciton emission characteristics, contributing to its broad-band emission and prolonged lifetime. Subsequently, a down-conversion WLED was constructed by integrating the Sn(II) hybrid with a green phosphor ((Sr, Ba)2SiO4:Eu2+) and a blue phosphor (BaMgAl10O17:Eu2+), resulting in CIE coordinates of (0.313, 0.331), a correlated color temperature of 6466 K, and an impressive color rendering index of 90.6. This work enriches the family of lead-free hybrid phosphors, showcasing their potential for highly efficient white LED applications.

Realization and optimization of bismuth-activated Ba3Ga2O5Cl2 yellow phosphor for high-quality white LEDs

The development of high-quality lighting requires phosphors with excellent performance, and dramatically optimizing the luminescent properties of phosphors is a major challenge. Herein, a novel bismuth-activated yellow phosphor (Ba3Ga2O5Cl2:Bi3+) was firstly prepared by a multi-step solid-state reaction, and the crystal structure, luminescence characteristics, decay time, and thermal stability of the phosphor were systematically studied. Subsequently, the cation substitution strategy (Sr → Ba) was adopted to improve the optical properties. A comparison of the thermal quench performance of the phosphors before and after Sr substitution reveals that this strategy can effectively improve the thermal stability from 17.3 %@423 K to 61.1 %@ 423 K. More importantly, the luminescence intensity of the optimized phosphor was increased by about two times, and the quantum yield was significantly improved from 34.7 % to 85.0 %. Such a large improvement could be rationalized by the modulation of the local structure of Bi3+ ions or the change of band gap when Sr and Ba coexist in the host lattice. In addition, a WLED was prepared by combining Ba2.55Sr0.45Ga2O5Cl2:Bi3+ with commercially available blue phosphor (BaMgAl10O17:Eu2+) and red phosphor (CaAlSiN3:Eu2+) on a 365 nm LED chip, which achieved full-spectrum illumination and demonstrated potential applications.

Zero-Dimensional Hybrid Antimony Chloride with Near-Unity Broad-Band Orange-Red Emission toward Solid-State Lighting.

Zero-dimensional (0D) hybrid metal halides are attractive owing to their distinctive structure as well as photoluminescence (PL) characteristics. To discover 0D hybrid metal halides with high photoluminescence quantum yield and good stability is of great significance for white light-emitting diodes (LEDs). Herein, a novel hybrid antimony chloride (CTP)2SbCl5 is synthesized, which shows a bright broad-band orange-red emission peaking at 620 nm under the low energy excitation (365 nm), achieving an excellent photoluminescence quantum yield of 96.8%. In addition, (CTP)2SbCl5 shows an additional emission peaking at 470 nm when excited at high energy (323 nm). PL spectra and density functional theory results demonstrate that the observed dual-band emission originates from the singlet and triplet self-trapped excitons confined in isolated [SbCl5]2- square pyramids. Moreover, (CTP)2SbCl5 presents relatively superior air stability, and the PL intensity still maintains 78% of the initial PL intensity when exposed to the air for above 2 weeks. Benefiting from high-efficiency PL emission and good stability of (CTP)2SbCl5, a stable warm white LED device with a 92.3% color rendering index was prepared by coating blue phosphor BaMgAl10O17:Eu2+, green (Sr,Ba)2SiO4:Eu2+, and orange-red (CTP)2SbCl5 on a 365 nm LED chip. This work provides an efficient luminescent material and also demonstrates the potential application of 0D hybrid antimony chloride in solid-state lighting.

Antimony-Triggered Tunable White Light Emission in Lead-Free Zero-Dimensional Indium Halide with Ultrastable CCT of White Light Emitting Diodes.

A highly efficient and easily tunable luminescence is significant for solid-state luminescent (SSL) materials. However, achieving a photoluminescence quantum yield (PLQY) close to unity and tuning the emission remain challenging tasks. Metal doping strategies enable resolution of these issues. Herein, we report the preparation of a novel organic-inorganic lead-free indium-based metal halide hybrid (MP)3InCl6•EtOH (MP = C4H10ON) with a typical zero-dimension structure. When excited at 320 nm, (MP)3InCl6•EtOH exhibits a dual emission band at 420 and 600 nm, which originates from the organic cation [MP] and the [InCl6]3- octahedral unit. The photoluminescence can be significantly enhanced through Sb3+ doping, resulting in an increase in PLQY from 0.78% to near unity. Multiple emission color tunings have been achieved by regulating the Sb doping level and the radiation wavelength, resulting in a change in emission color from blue → white → orange. Optical characterizations reveal that the significantly enhanced emission centered at 600 nm can be attributed to more efficient absorption, closely associated with an additional 1S0 → 3P1 transition in the inorganic octahedron [In(Sb)Cl6]3- due to Sb3+ doping. With its excellent optical performance, a white light emitting diode (WLED) has been successfully fabricated by coating the mixture of (MP)3InCl6•EtOH:15%Sb3+ with blue phosphor BaMgAl10O17:Eu2+ onto a UV LED chip. The WLED device exhibits perfect white light emission with regard to the International Commission on Illumination (CIE) coordinates of (0.36, 0.34). Significantly, the WLED device maintains a stable correlated color temperature (CCT) range of 4119-4393 K and CIE coordinates (x: 0.37-0.34, y: 0.35-0.33) as the driven current varies from 20 to 200 mA, demonstrating outstanding stability across different power levels. This work not only presents a novel system for achieving remarkably enhanced luminescent performance and tuning emission bands in 0D metal halides but also represents a significant step toward achieving resistance to color drifting for stable WLEDs.

Structure and photoluminescence studies of Rb3GdSi2O7: Eu2+ phosphor used for NUV converted white LEDs

In pursuit of healthy lighting, the exploitation of high-quality Eu2+-activated phosphors available for near-ultraviolet light-emitting diode (NUV-LED) chip-based white LED (WLED) has fetched growing interest. Herein, a novel NUV-light excitable Rb3GdSi2O7: Eu2+ phosphor is successfully synthesized via a high-temperature solid-state reaction method. The crystal structure of Rb3GdSi2O7 is found to be hexagonal, belonging to space group P63/mmc. The Rb3GdSi2O7: Eu2+ phosphor exhibits a broad excitation band in the 300–450 nm wavelength range, and it emits strong yellow-green light with peak at 543 nm upon 365 nm excitation. Benefitting from the high structure rigidity of host matrix, Rb3GdSi2O7: Eu2+ also possesses a desired luminescence thermal stability (423 K, 85.6%). The WLED device fabricated using a 365 nm chip and a blend of the as-prepared Rb3GdSi2O7: Eu2+ yellow-green phosphor and commercial BaMgAl10O17: Eu2+ blue phosphor displays an excellent color-rendering index of 95.9 at a low correlated color temperature of 4373 K. This work confirms the applicative potential of Rb3GdSi2O7: Eu2+ in NUV-converted warm WLEDs, which may promote the development of high-color-quality healthy lighting.

Antimony(III) based hybrid materials toward stable and highly efficient white LED

Zero-dimensional (0D) organic-inorganic hybrid materials have attracted extensive attention due to their facile preparation and excellent optical characteristics. However, achieving superior photophysical properties and excellent stability is still desirable for their practical application. Sb(III)-based metal halides owning 5 S2 lone-pair are prone to form deformable building units, which is beneficial for efficient self-trapped excitons (STE) emission. Herein, a 0D Sb(III)-based metal halides DIPA2SbCl5 (DIPA+ = 4-amino-3,5-diiodopyridin-1-ium) was obtained by solvothermal method at room temperature, which exhibited highly efficient broadband emission at 652 nm with a photoluminescence quantum yield (PLQY) of 87.1% and outstanding stability against moisture. Then, a white-light-emitting diode (WLED) was fabricated by mixing DIPA2SbCl5 with green phosphor ((Sr, Ba)2SiO4: Eu2+) and blue phosphor (BaMgAl10O17:Eu2+), with the CIE coordinates of (0.351, 0.371), a correlated color temperature of 4183 K and a color rendering index of 93.3. This work provides a universal solution to obtain hybrid materials with efficient luminescence properties and potential applications.

BaCa13Mg2(SiO4)8: Ce3+ — A blue phosphor with high brightness, high internal quantum efficiency and excellent thermal stability for w-LEDs

In this paper, a series of Ce3+ ions doped BaCa13Mg2(SiO4)8 blue phosphors were synthesized via a conventional high-temperature solid-state method. Calculations by DFT confirmed that the BaCa13Mg2(SiO4)8 host had a suitable band gap for doping rare earth ions. In terms of luminescence performance, BaCa13Mg2(SiO4)8: Ce3+ blue phosphor with an optimal excitation wavelength of 365 nm can effectively absorb light from 310 to 400 nm and produce a wide emission band centered at 440 nm with an internal quantum efficiency of 71.39%. Based on the analysis of the structure and Gaussian fitting spectra, the Ce3+ ion can occupy all of the Ba2+ and Ca2+ ion lattice positions. After charge compensation by K+ ions, the emission intensity can be increased by 36.8%, and the emission intensity at 140 °C can still maintain 88.7% compared with that at room temperature. Under 365 nm excitation, the integral intensity of the emission spectrum BaCa13Mg2(SiO4)8: 3% Ce3+, 3% K+ sample can reach 90.4% of that of the commercial blue phosphor BaMgAl10O17: Eu2+. When BaCa13Mg2(SiO4)8: Ce3+ phosphors are combined with green (Ba, Sr)2SiO4: Eu2+ phosphors and red CaAlSiN3: Eu2+ phosphors on a 365 nm UV-LED chip, bright LED devices with a correlated color temperature of 4172 K can be obtained. The results show that the blue phosphor BaCa13Mg2(SiO4)8: Ce3+ has great potential for w-LEDs applications.

A broadband yellow-green emitting mixed orthoborate-pyroborate phosphor, Ba2Sc2B4O11:Ce3+, for white light emitting diodes.

The development of yellow-green phosphors for high quality white light emitting diodes (WLEDs) is critical. Herein, we successfully synthesized a mixed orthoborate-pyroborate phosphor, Ba2Sc2B4O11:Ce3+, using a high-temperature solid-state method, which exhibits bright yellow-green emission with a peak located at 540 nm and a full width at half maximum (FWHM) of 130 nm under 410 nm light excitation. In addition, the crystal structure, morphology, and thermal quenching properties of Ba2Sc2B4O11:Ce3+ were investigated in detail. The quantum yield of the optimal sample was found to be 53.3%. The concentration quenching occurred through the energy transition between the nearest-neighbor Ce3+ ions. A WLED with a low correlated color temperature (CCT = 3906 K) and a high color rendering index (Ra = 89) was prepared by coating the mixture of the phosphor Ba2Sc2B4O11:Ce3+, the commercial blue phosphor BaMgAl10O17:Eu2+ and the red phosphor CaAlSiN3:Eu2+ on a 395 nm n-UV LED chip. The results show that the yellow-green phosphor Ba2Sc2B4O11:Ce3+ could be an excellent candidate for WLEDs.

Highly efficient double perovskite (Bi,Gd)-codoped Cs2Ag0.4Na0.6InCl6 phosphors for warm white LEDs

Bi-doped lead-free double perovskite Cs2Ag0.6Na0.4InCl6 phosphors have been proved to be effective for use in white LEDs. To further improve the luminescence effect of this promising material, Bi3+/Gd3+ co-doped lead-free perovskite Cs2Ag0.6Na0.4InCl6 phosphors were successfully synthesized using the oil bath method. The quantum efficiency of orange-emitting Cs2Ag0.6Na0.4InCl6:1% Bi3+ was effectively improved from 79.72% to 87.57% by co-doping Gd3+ ions. White LEDs were prepared by mixing the synthesized phosphor Cs2Ag0.40Na0.60InCl6: 1%Bi3+,10%Gd3+ and commercial blue phosphor BaMgAl10O17:Eu2+. Excellent warm white LEDs with colour coordinates (0.3464, 0.3224), colour rendering index of 93.9, and colour temperature of 4818 K were produced. The results of this study provide a meaningful reference for new lead-free halide perovskite luminescent material systems.

A near UV-excited abnormal broad yellow emission phosphor Ba2CaB2Si4O14:Eu2+ for white-light LEDs

Phosphor-converted white LEDs are realized by combining blue InGaN chips with yellow and red emitting materials. Due to the lack of efficient red phosphor materials, we can design a broadband yellow phosphor material containing as many red components as possible. We found an abnormal broadband yellow-emitting Ba2CaB2Si4O14:Eu2+ borosilicate phosphor inspired by natural minerals, which has been synthesized by traditional high temperature solid-state method. The structural information and photoluminescence characteristics of Ba2CaB2Si4O14:Eu2+ were characterized in detail, and applied to the fabrication of white LED devices. Excited by near ultraviolet light at 365 nm, it displays a wide emission band from 400 to 800 nm centered on the 595 nm peak. White LED devices were fabricated by physically mixing the yellow phosphor Ba2CaB2Si4O14:Eu2+ and synthesized blue phosphor BaMgAl10O17:Eu2+ with 365 nm UV chip as excitation. The correlation color temperature (CCT) value and the chromaticity coordinates of the fabricated WLED devices were found to be 5522 K and (0.3293, 0.3036) respectively. In conclusion, Ba2CaB2Si4O14:Eu2+ has great potential in the preparation of near UV excited white LEDs.

Novel and wide-ranging color tuning photoluminescence properties of Tb3+/Eu3+ doped garnet-type Li3Lu3Te2O12 phosphor: Energy transfer and enhanced thermal stability

In order to promote the development of white light emitting diodes (WLEDs) with improved color reproduction, the challenge by discovering novel photoluminescence color tuning phosphors via energy transfer (ET) is essential. However, the mechanism of energy transfer among dopants and its effect on ET efficiency have not been fully understood. Therefore, the photoluminescence color tuning in a variety of matrix structures based on energy transfer always needs to be discussed further. Herein, a series of wide-ranging color tunable Li3Lu3Te2O12 phosphors doped with Tb3+/Eu3+ were synthesized by high-temperature solid-state reaction for the first time. The crystalline structure, morphology and chemical composition of as-prepared phosphors were characterized. The excitation and emission spectra, fluorescence decay curve, and the relationship among emission intensity, doping concentration of dopants and CIE coordinates were investigated in detail. The results indicate that photoluminescence color tuning from green to red was realized by designing the Tb3+→Eu3+ energy transfer in Li3Lu3Te2O12:Tb3+, Eu3+ phosphors. The approximation theory of Reisfeld and the electric multipole interaction theory of Dexter were used to analyze the ET mechanism, which reveals that the dipole-dipole and dipole-quadrupole interaction is responsible for the ET process of Tb3+→Tb3+ and Tb3+→Eu3+. In addition, the thermal stability of the as-prepared phosphors was also revealed. Unforgettably, the samples with reasonable design ratio of Tb3+/Eu3+ exhibits a wider color tuning range, excellent luminescence intensity under n-UV excitation and outstanding thermal stability comparable to commercial Y2O3:Eu3+ phosphor after surface treatment, whose emission intensity at 150 °C exceeds 70% of the initial value. In addition, a prototype WLED device was fabricated with representative phosphor and commercial blue phosphor BaMgAl10O17: Eu2+ (BAM: Eu2+), which emitted warm-white light with great color rendering index (CRI) of 84.8, softer correlated color temperature (CCT) of 3989 K and the chromaticity coordinates of (0.3647,0.3178). All the results suggest that Li3Lu3Te2O12:Tb3+, Eu3+ phosphors can be conducted as potential alternative for near ultraviolet (n-UV) pumped phosphor-converted white light-emitting diodes (pc-WLEDs).

Broadband near-infrared phosphor BaMgAl10O17:Cr3+ realized by crystallographic site engineering

• The mechanism of unusual broadens BaMgAl 10 O 17 :Cr 3+ was investigated. • The title phosphor has an excellent internal quantum efficiency (94%). • The title phosphor has good thermal stability (63% at 423 K). • The NIR PiG-LD device applies in mechine vision. Near infrared (NIR) light sources play vital roles in bioimaging, medical treatments, food analysis and machine vision. Herein, we report unusual broadband NIR emission in BaMgAl 10 O 17 :Cr 3+ (BAM:Cr 3+ ) via site engineering. Both the emission maximum and spectral bandwidth of BAM:Cr 3+ can be tailored by controlling the site occupancy of Cr 3+ on two different Al sites. The optimal BAM:0.2Cr 3+ phosphor exhibits both a sharp line spectrum (λ em = 696 nm) and a broadband emission centered at 762 nm, having an internal quantum efficiency (IQE) of ~ 94%. A prototype NIR light source was demonstrated by combining a blue laser diode with BAM:Cr 3+ phosphor-in-glass (PiG) and revealed an NIR light output power of 3.4 mW when driven by a 100 mW blue laser diode.

Ba3YB3O9 based phosphor ceramic plates with excellent thermal stability for wLED applications.

A series of Eu3+ and Tb3+ singly doped Ba3YB3O9 phosphors were synthesized by a solution combustion approach. The most luminescent phosphors were selected as the starting materials to fabricate phosphor ceramic plates (PCPs). More intense red and green emission is observed from the PCPs than the corresponding phosphors. The emission colour can be effectively tuned by varying the mass ratio of the red and green phosphors and the excitation wavelength. White light emission was obtained by incorporating the blue-emitting Eu2+ doped BaMgAl10O17 phosphor into the PCP component. The synthesized phosphors and PCPs show robust thermal stability, maintaining more than 80% of emission intensity at 423 K of that at 298 K after a long time operation. The results indicate that the prepared red and green PCPs are promising candidates for high-power wLED applications.

A novel high color purity blue-emitting Tm3+-doped β-Ca3(PO4)2-type phosphor for WLED application

The series of Tm-doped phosphates Ca9-xZnxLa0.9(PO4)7:0.1Tm3+ for phosphor-convertible white LEDs (pc-WLED) with β-Ca3(PO4)2-type structure were synthesized using a standard high temperature route. Intense blue emission in the visible spectrum was observed due to 4f-4f transitions in the Tm3+ ion. The phosphates have been characterized by powder X-ray diffraction (PXRD), second harmonic generation (SHG), and luminescence spectroscopy. These phosphors show a satisfactory blue performance due to the 1D2 – 3F4 (≈ 450 nm) transition of Tm3+ excited by near-UV light (358 nm). The crystal structure transforms R3c → R3¯c upon Ca2+ → Zn2+ substitution, and it leads to growing of the integral intensity in 4 times compared with unsubstituted phosphate. Rising of color purity peaking at x = 1 was also observed. The obtained characteristics are superior to than that for the commercial blue phosphor BaMgAl10O17:Eu2+. Generally, Ca9-xZnxLa(PO4)7:Tm3+ phosphates are a new kind of potential blue emitting phosphors for white light-emitting diodes.

Photoluminescence Properties of Mn4+, Cr3+ co-doped BaMgAl10O17 Phosphor

Mn4+, Cr3+ single-doped and Mn4+, Cr3+ co-doped BaMgAl10O17 phosphors were synthesized via a conventional high-temperature solid-state reaction method. Both Mn4+ and Cr3+ ions show broad excitation band extending from ultraviolet to visible light range, and the emission band peaks at 660 nm for Mn4+ ion and at 694 nm for Cr3+ ion. The relative intensity of the luminescence of Mn4+ and Cr3+ can be adjusted by changing the co-doped Cr3+ or Mn4+ concentration in the Mn4+, Cr3+ co-doped BaMgAl10O17 phosphor to better match the required light for photosynthesis of different plants. Moreover, the specific relationship between the luminous intensity ratio of Mn4+ and Cr3+ and the excitation wavelength in the region of 320 to 530 nm in the co-doped phosphor suggests that the excitation wavelength can be known by measuring the emission integral intensity ratio between Mn4+ and Cr3+. The results show that the Mn4+, Cr3+ co-doped BaMgAl10O17 phosphors can not only be used as plant growth spectral converter, but also wavelength detector.

Luminescence enhancement of high temperature hexagonal phase of Ba0.99MgAl10O17: Eu0.01 nanophosphor synthesized at moderately low temperature

Photoluminescent (PL) properties of Eu2+-doped BaMgAl10O17 (BAM:Eu2+) phosphors are significantly influenced by its crystallanity, phase and regular morphology. To obtain a high brightness blue-emitting BAM:Eu2+ nanophosphor, a pH-controlled polymeric gel deflagration method was performed at ~ 600 °C followed by post calcination at 1300 °C for 3 h under mild reducing atmosphere. It is one of the very few reports that depicts the formation of hexagonal phase of BAM:Eu2+ nanophosphor at relatively lower (~600 °C) temperatures, which is otherwise possible at very high (>1500 °C) sintering temperatures. A drastic improvement in crystallanity, phase, morphology and PL intensities has been achieved in BAM:Eu2+ nanophosphors with the addition of ammonium fluoride (NH4F) during post-calcination treatment. The presence of NH4F benefitted the thermal stability of BAM:Eu2+ nanophosphors as well. X-ray diffraction studies confirmed the phase purity while the scanning electron microscopy revealed regular morphology with non-aggregated nanoparticles. The improvement in crystallanity of BAM:Eu2+ nanophosphors led to almost four times increase in PL intensity in comparison to its bulk counterpart synthesized by solid-state reaction method. Intentional gamma irradiation of the samples for the creation of F+ centres is another unique feature studied in the current work. The obtained results clearly indicate that BAM:Eu2+ nanophosphor prepared in the study would be an ideal candidate for enhancing the properties of many active displays.

Photoluminescent properties of red-emitting phosphor BaMgAl10O17:Cr3+ for plant growth LEDs

Abstract Narrow-band red-emitting phosphor Cr3+-doped BaMgAl10O17 (BAM) was successfully synthesized via a sol – gel method. The obtained Cr3+-doped BaMgAl10O17 phosphor with average particle size of about 1 μm emits an intense red light at around 695 nm with two broad excitation bands at 405 and 560 nm. The highest PL intensity is achieved at the Cr3+ doping concentration of 1 mol% and the annealing temperature of 1400 °C. The Tanabe-Sugano diagram reveals that Cr3+ ions are affected by the strong crystal field with the Dq/B ratio value of ~2.7, and the peak at 695 nm is attributed to the 2E→4A2 transitions of Cr3+ ions. A purple LED with colour coordinates of (0.263, 0.148) has been fabricated by coating the Cr3+-doped BaMgAl10O17 phosphor on a violet LED (410 nm) chip. The results indicate that BaMgAl10O17:Cr3+ phosphor could be promising red phosphor for plant growth LEDs.

A novel narrow-band blue-emitting phosphor of Bi3+-activated Sr3Lu2Ge3O12 based on a highly symmetrical crystal structure used for WLEDs and FEDs

Investigating highly efficient narrow-band emission phosphors that have strong excitation bands in the near-ultraviolet (NUV) region is the main goal of the present light-emitting diode (LED) research, especially for Bi3+-activated phosphors. The naked 6s and 6p electrons of Bi3+ are sensitive to the microenvironment, thus leading to broad emission bands, while most Bi3+-activated phosphors suffer from low absorption of NUV-LED chips. Here, we report on a narrow-band blue-emitting garnet-type phosphor of Sr3Lu2Ge3O12: Bi3+ that is available for NUV-LED chips; its full width of the half maximum (FWHM) is limited to 40 nm, which is comparative to rare earth-activated phosphors, such as commercial blue phosphor BaMgAl10O17: Eu2+ (FWHM ≈ 52 nm), and this phenomenon is extremely rare among most Bi3+-activated phosphors. The internal quantum efficiency (IQE) of Sr3Lu2Ge3O12: Bi3+ can reach 57%. Moreover, it is interesting to find that Sr3Lu2Ge3O12: Bi3+ also exhibits exalting cathodoluminescence properties and its narrow-band emission produces brilliant images with high color saturation. The significant luminescent properties of trivalent bismuth are ascribed to the compact and highly symmetrical crystal structure of Sr3Lu2Ge3O12; thus, the discussion of the structure-property relations for Bi3+-activated Sr3Lu2Ge3O12 is the most anticipated part of this work. The results pave the way for the design of better Bi3+-activated phosphors for use as white light emitting diodes (WLEDs) and field emission displays (FEDs).