Phosphor Conversion Research Articles

High Luminescence Saturation Y3Al5O12: Ce3+‐Diamond Composite Color Converter for High‐Brightness Laser‐Driven White Lighting

AbstractPhosphor‐converted laser lighting confronts enormous challenges in the development of color converters with high luminescence saturation owing to the thermal issues from laser irradiation and phosphor conversion. Herein, a high luminescence saturation Y3Al5O12: Ce3+‐diamond (YAG‐diamond) composite color converter by introducing diamond particles in phosphor‐in‐glass film (PiGF) coated on transparent sapphire substrate is proposed for high‐brightness laser‐driven white lighting. By optimizing the diamond content to 6 wt.%, the YAG‐diamond converter shows a thermal conductivity (TC) of 14.7 W·m−1·K−1 and displays higher luminescence intensity at 175 °C (1.15 times that at 25 °C). Under laser excitation, the YAG‐diamond converter achieves a luminous flux (LF) of 1990 lm at the laser power density (LPD) saturation threshold (ST) of 24.82 W·mm−2, which is far better than the PiGF@sapphire converter with a LF of 1364 lm@17.64 W·mm−2. The laser‐driven converter yields stable white laser light with a correlated color temperature (CCT) of 5714 K and a chromaticity coordinate of (0.3278, 0.3372) at the ST of 24.82 W·mm−2. Furthermore, the working temperature of the converter is decreased by 59 °C (26.6%) under LPD of 10.89 W·mm−2. These results indicate that the proposed YAG‐diamond composite converter displays excellent opto‐thermal performances, which may be a promising luminescence material in high‐brightness white laser lighting.

Enhancing heat dissipation for laser illumination by utilizing the phosphor in metal combined with vapor chamber (PiMCVC)

Laser-driven illumination has unique advantages in high-power applications. However, the low thermal conductivity of the phosphor converter and high-power density of the laser result in a serious heat dissipation problem. Although the thermal conductivity has been improved in the previous work, the heat transferred from the facula cannot be further dissipated. Herein, a phosphor in metal combined with vapor chamber (PiMCVC) was proposed. A copper foam skeleton structure (CFSS) coated with boron nitride (BN) was welded to an ultra-thin vapor chamber (UTVC). The heat dissipated from the facula can be transferred through the CFSS. The heat dissipation area is significantly enlarged by the UTVC. The facula central temperature of PiMCVC can be maintained below 107.0 °C under a load of 4.92 W while that of the reference sample is 530.18 °C. Even at a laser load of 11.58 W, the PiMCVC can still work normally with a luminous flux of 1568.37 lm. Due to the superior thermal management, under the laser power of 9.20 W, the PiMCVC sample can be stably operated for 720 min with a luminous flux of approximately 1150 lm and a CCT of about 4000 K. This work provides a new approach to the thermal management of high-power laser-driven illumination.

A Cr3+-Yb3+ co-doped high-efficiency near-infrared luminescent phosphor for NIR-II light source applications

Phosphor conversion light-emitting diode (PC-LED) technology has become a focal point of research for portable near-infrared light sources in recent years. One of the crucial aspects is to develop phosphor materials that can be effectively stimulated by commercial available blue light. Unfortunately, efficient phosphors in the NIR-II that can be excited by commercial blue light are particularly scarce. In this study, Mg4Ta2O9:0.04Cr3+,0.03Yb3+,0.07Li+ (MTO:0.04Cr3+,0.03Yb3+,0.07Li+) phosphor was synthesized using the high temperature solid phase method, and its emission spectrum covered the first and second near-infrared windows (700–1200 nm). The internal quantum efficiency (IQE) and external quantum efficiency (EQE) are 88.7 % and 45.6 %, respectively, due to the synergistic effect of energy transfer and Li-ion modification. Additionally, the doping of Yb3+ ions and Li+ ions enhances the thermal stability of luminescence. The thermal stability of MTO:0.04Cr3+,0.03Yb3+,0.07Li+ and MTO:0.04Cr3+,0.03Yb3+ is 9.81 % and 14.43 % higher, respectively, than that of MTO:0.04Cr3+,0.03Yb3+ and MTO:0.04Cr3+. To evaluate its potential applications, we developed a prototype PC-LED utilizing MTO:0.04Cr3+,0.03Yb3+,0.07Li+ phosphor as an emission emitter which demonstrated advantages in biomedical imaging, night vision, and non-destructive testing.

Fluorescence Carbon Dots from Blood-Berries for Sensing Cr6+ Ions in Water and Application in White Light Emitting Diode.

Conventional techniques for identifying heavy metal ions in water are laborious and time-consuming. Therefore, it is necessary to create innovative sensing technologies that can detect with greater sensitivity and speed. Although there have been reports of optical-based assays utilising fluorescent nanomaterials, these assays usually rely on variations in signal strength. However, this approach has significant drawbacks when it comes to environmental monitoring. Fluorescence carbon dots (CDs) have been prepared by facile synthesis from Blood berries. A homemade heavy metal optical detector is constructed to accurately identify heavy metal ions, exclusively Cr6+ ions in a water medium. Their optical emission signature varies based on the specific chromium ions in solution, and the emission intensity also changes depending on its concentration. The quenching behaviour is attributed to the interaction between the metallic cations and the fluorescent surface states of the carbon dots. Another application is the encapsulation of CDs in PVDF polymer to form a flexible film and use it as a phosphor for LED conversion.

Er3+ activated BaLaGaO4 multifunctional green phosphors for optical thermometers and WLEDs

Er3+-doped BaLaGaO4 green phosphors was synthesized through a high-temperature solid-state reaction technique. The phase structure and morphology test results of the phosphor indicate that the BaLaGaO4 material was successfully synthesized and Er3+ ions were successfully doped into the main lattice. This doping does change the basic structure of the crystal. BaLaGaO4:Er3+ phosphor exhibits bright green emission centered at 545 nm when excited by 381 nm ultraviolet light or 980 nm near-infrared light. The optimal doping concentration is found to be x = 0.04. To quantify the temperature sensitivity of the phosphor, the fluorescence intensity ratio method was used. Within the temperature range of 298–473 K, the maximum relative sensitivities are 1.35%/K (298 K, 381 nm) and 1.45%/K (298 K, 980 nm), respectively. The maximum absolute sensitivities are 0.67%/K (473 K, 381 nm) and 0.69%/K (473 K, 980 nm), respectively. Finally, white light-emitting diodes (WLEDs) with a high colour index of Ra = 82 and a relatively low correlated colour temperature of CCT = 5064 K are obtained by integrating the synthesized BaLaGaO4:0.04Er3+ green phosphor into warm WLEDs devices. These results suggest that Er3+-activated BaLaGaO4 multifunctional phosphors hold considerable promise in the areas of optical temperature sensing and WLEDs phosphor conversion.

Enhanced near-infrared II and III emission in Ga2O3: Ni2+ phosphor via charge compensation for NIR spectroscopy application

A novel near-infrared emitting Ga2O3: Ni2+ phosphor was prepared, and its emission characteristics were improved through melting aid and charge balance. Under 410 nm excitation, the Ga2O3: Ni2+ phosphor exhibits broadband near-infrared emission in the second region, with a peak at 1455 nm and a half maximum width of up to 300 nm. At the same time, the crystallinity of the sample was improved and the charge imbalance during substitution between Ga3+ and Ni2+ was eliminated through melting assistance and charge compensation. The results show that the emission intensity of Ga1.97O3: 0.015Ni2+, 0.015Ge4+ phosphor (with added flux H3BO3) is 10 times higher than that of Ga1.985O3: 0.015Ni2+ sample. Its quantum yield is as high as 31.2 %, significantly higher than the reported Ni2+ ion doped phosphors. According to the distinct absorptions of C–H, O–H as well as N–H bonds in the shortwave near-infrared range, samples of ethanol, n-hexanol, water and ammonia demonstrated different absorption peaks under the penetration of the constructed phosphor conversion light-emitting diode, which proved the potential application of Ga2O3: Ni2+, Ge4+-H3BO3 phosphor in composition analysis and detection.

Highly efficient and thermally conductive phosphor in glass based on two-component regulatory and h-BN addition

Achieving laser-driven solid-state lighting with higher brightness and laser power density engenders new requirements for higher-performance phosphor conversion materials. In this study, a highly efficient and thermally conductive tellurite phosphor-in-glass (PIG) added with hexagonal boron nitride (h-BN) was prepared for high-power laser driving. Reduction in the thermal expansion coefficient and refractive index matching with phosphor were realized by two-component regulation of the tellurite glass, which contributed to an enhanced laser irradiation threshold and luminous efficiency of the PIG. Furthermore, the micron h-BN powder, which served as a heat dissipation material and light scattering center, was uniformly dispersed within the PIG by stirring, which increased the thermal conductivity of the composite by 42 %. Microstructural characterization and XRD analysis indicated the ideal compound effect of h-BN and the integrity of the phosphor crystal phase. Notably, under irradiation with a high-power laser, the thermal stability of the composite material was significantly improved, and the luminous efficiency increased to 183.2 lm/W. Therefore, through component regulation and process optimization, the h-BN-added tellurite PIG acquired a high laser irradiation threshold and superior luminous efficiency, making it promising for applications in laser-driven white lighting.

The Biomarkers Associated with Unstable Angina Pectoris (UAP)

Objectives: Coronary artery disease (CAD) is the most common form of CVD that begins as stable angina pectoris (SAP) followed by unstable angina pectoris (UAP) and finally critical stage myocardial infarction (MI), which results from rupture of atherosclerotic plaque and a thrombus that blocks the coronary artery supplying the heart, resulted from the death of part of the heart muscle. The underlying cause of coronary artery disease (CAD) is atherosclerosis, which results from the formation of layers of fatty deposits on the inner walls of the arteries. Early diagnosis of MI has an important role in assisting clinicians in prompt planning for its treatment and thus reducing the number of its deaths. Methods: The present study included 20 UAP patients and 20 healthy individuals (controls). In all the cases and controls, levels of cardiac and inflammatory biomarkers were measured by special kits from Hotgen Company via phosphorous technology using UPT-3A converting phosphor immunological analyzer. Results: The levels of both cardiac and inflammatory biomarkers were significantly increased in UAP cases as compared to controls. Also, there was significant positive correlation between cardiac and inflammatory biomarkers in UAP cases. Conclusions: The positive correlation between most cardiac and inflammatory biomarkers in UAP indicates that inflammation occurs in UAP. Hence it is concluded that inflammatory biomarkers (CRP, Hs-CRP and PCT) and cardiac biomarker (cTnI, H-FABP, CK-MB, NT-proBNP and D-dimer) can be markers of UAP and can be used for diagnostic purposes in patients.

MAS:Eu-YAG:Ce composite phosphor converters with excellent thermal performance and enhanced color rendering index for high-power white LDs

Phosphor converters with excellent thermal performance and high color rendering index (CRI) demonstrate vast application prospects in the field of laser diodes (LDs) lighting. Nevertheless, the significant heat accumulation within the converters and the absence of red spectral components pose challenges in achieving both a high saturation threshold and a high CRI for Y3Al5O12:Ce phosphor converters destined for white LDs. In this work, Mg2Al4Si5O18:Eu/Y3Al5O12:Ce (MAS:Eu/YAG:Ce) composite phosphor converters with excellent thermal performance and enhanced CRI were designed and fabricated for reflective laser lighting. Impressively, MAS:Eu/YAG:Ce phosphor-glass-ceramic composites (PGCC) retained a remarkable 97.8 % of the room temperature emission intensity at 150 °C. The reasons for this could be attributed to the strong thermal quenching resistance exhibited by MAS:Eu phosphors, as well as the ultra-thin glass bonding layer of about 150–200 μm. Meanwhile, by integrating the MAS:Eu/YAG:Ce PGCC with a 450 nm laser source, white LD devices operating in a remote excitation mode were fabricated. These white LDs demonstrated an improved CRI of 76 and maintained a low surface temperature of 131.7 °C under an ultra-high laser power density of 47.8 W/mm2 (laser power ∼ 4.70 W). Moreover, the maximum luminous flux and luminous efficiency of the white LDs were 484 lm and 103 lm/W, respectively. Therefore, the design of MAS:Eu/YAG:Ce composite phosphor converters offers a new approach for the development of high-power white LDs.

Strategy of Charge Compensation for High-Performance Ni2+-Activated MgAl2O4 Spinel Near-Infrared Phosphor Synthesis via the Sol-Gel Combustion Method.

Near-infrared (NIR) phosphor conversion light-emitting diodes (pc-LEDs) have great application potential as NIR light sources in many fields such as food analysis, night vision illumination, and bioimaging for noninvasive medical diagnosis. In general, phosphors synthesized by a high-temperature solid-phase method have large particle sizes and have to be processed to fine powders by a grinding process, which may introduce surface defects and lower the luminous efficiency. Here, we report a sol-gel sintering method with ammonium nitrate and citric acid as the sacrificing agents to synthesize high purity, nanosized (less than 50 nm) Zr4+/Ni2+ codoped MgAl2O4 spinel NIR phosphors, in which MgAl2O4 spinel is the matrix, Ni2+ is the luminous center, and Zr4+ acts as the charge compensator. We systematically characterized the crystal structures and NIR luminescence properties of the Ni2+-doped MgAl2O4 and the Zr4+/Ni2+ codoped MgAl2O4. Under 390 nm light excitation, the emission spectrum of the Ni2+-doped MgAl2O4 phosphor covers 900-1600 nm, the half-peak width is 251 nm, and the peak position is located at 1230 nm. We demonstrated that by incorporating small amounts of Zr4+ as the charge compensator, the NIR emission intensity of the Zr4+/Ni2+ codoped MgAl2O4 nanosized phosphor was doubled over that of the Ni2+-doped MgAl2O4 phosphor. The optimal content of the charge compensator was 2 mol %. More importantly, the inclusion of Zr4+ led to a NIR phosphor with improved thermal stability in luminous properties, and the luminous intensity measured at 100 °C was 33.83% of that measured at room temperature (20 °C). This study demonstrates that NIR phosphor nanomaterials with high-purity and enhanced optical properties can be designed and synthesized through the charge compensation strategy by a sol-gel sintering method.

Exploring potential of quantum dots for high power solid-state lighting protected by transparent ceramics

When quantum dot diffusion plates (QDDPs) are used as phosphor conversion materials for high-power lighting, transparent ceramics (TCs) can be used to prevent thermal damage of QDDPs. The spectral, suitable for diverse lighting environments, can be precisely calibrated by modifying their ratio. The temperature dependent photoluminescence spectra, fluorescence lifetime, Huang Rhys factor and activation energy of TCs were studied in detail. It was evident from the results that the intensity of TCs remained above 89% even at 423 K, while fluorescence lifetime remained stable, nearly 64 ns. Huang-Rhys factor and activation energy were consistently measured at 1.81 and 0.13 eV, respectively. The extraordinary luminescent stability of TCs revealed their integral role in providing reliable protection for QDDPs. The spectra of LEDs/LDs were successfully predicted using Monte Carlo ray tracing method. The service condition under high-energy laser was studied using finite element method. White light with Commission Internationale de l'Eclairage (CIE) of (0.38, 0.39) and (0.31, 0.34) and luminous efficiency of 58 and 150 lm/W were prepared by combining QDDPs/TCs with LEDs/LDs, and the Color Rendering Index (CRI) reached a remarkable 88.4 and 78.8. A detailed exploration of the proficient thermal management was accomplished using finite element analysis, with the simulated outcomes matching closely with the experimental results.

High luminous efficiency and excellent thermal performance in rod-shaped YAG:Ce phosphor ceramics for laser lighting.

High power and high brightness laser lighting puts forward new requirements for phosphor converters such as high luminous efficiency, high thermal conductivity and high saturation threshold due to the severe thermal effect. The structure design of phosphor converters is proposed as what we believe to be a novel strategy for less heat production and more heat conduction. In this work, the rod-shaped YAG:Ce phosphor ceramics (PCs) and disc-shaped YAG:Ce PCs as control group were fabricated by the gel casting and vacuum sintering, to comparatively study the luminescence performance for LD lighting, on the premise that the total number of transverse Ce3+ ions and the volume of samples from two comparison groups were same. All rod YAG:Ce PCs with low Ce3+ concentration exhibited the high luminous efficiency and better thermal stability than YAG:Ce discs with high Ce3+ concentration. Under the laser power density of 47.8 W/mm2, the luminous saturation was never observed in all rod-shaped YAG:Ce PCs. The high luminous efficacy of 245∼274 lm/W, CRI of 56.3∼59.5 and CCT of 4509∼4478 K were achieved. More importantly, due to the extremely low Ce3+ doping concentration (0.01 at%), rod-shaped ceramics based LDs devices showed the excellent thermal performance and their surface temperatures were even below 30.5 °C surprisingly under the laser power density of 20.3 W·mm-2 (2 W). These results indicate that the rod shape of phosphor converter is a promising structure engineering for high power laser lighting.

Robust high-efficiency LuAG: Ce phosphor-in-silica glass (PiSG) for high-brightness laser lighting

Blue laser diodes (LDs), owing to their high electro-optical conversion efficiency, strong directivity, and small size under high power, have paved new paths in the semiconductor lighting and display industry. Blue LDs are expected to replace LED lighting in laser displays, automotive headlights, and other advanced lighting fields. In this study, the Lu3Al5O12: Ce3+ phosphor-in-silica glass (LuAG: Ce-PiSG) is fabricated using spark plasma sintering at 1060 °C. This method enables rapid sintering while maintaining the stability of the silica glass matrix, resulting in high transparency and minimal destruction of the crystal structure of the LuAG: Ce phosphor. The phosphor-converted LDs made from LuAG: Ce-PiSG exhibit high luminous efficacy (298 lm·W−1) and luminous flux (1069 lm). The results show that LuAG: Ce-PiSG has significant potential for application as a robust, high-efficiency phosphor conversion material for high-brightness laser lighting applications.

Giant enhancement of photoluminescence in Mn4+-activated Ba2CaWO6 phosphors via heterovalent doping with rare-earth ions

Currently, Mn4+-activated phosphors have attracted extensive attention for their versatile applications in general lighting, display and plant cultivation. Owing to 3d3 electronic configuration of Mn4+ ion, modifying its local coordination environment emerges as a potent method to tailor its luminescence behavior. Herein, a heterovalent substitution strategy is reported to greatly enhance the photoluminescence (PL) of Ba2CaWO6:Mn4+. The effects of the substitution of rare-earth ions (Ln3+ = Lu3+, Y3+, Gd3+, La3+) for Ca2+ ions on the PL properties of the phosphor are studied in detail. The PL spectral change of Mn4+ induced by Ln3+ substitution is clarified in terms of the local structure of [WO6] octahedron and the valence state of Mn. By selection of Ln3+ ions and optimization of Ln3+ doping concentration, the emission intensity of Ba2Ca0.85Gd0.15WO6:0.25Mn4+ phosphor reaches up to 46.3 times as that of Ba2CaWO6:0.25Mn4+. Besides, the Ba2Ca0.85Gd0.15WO6:0.25Mn4+ phosphor exhibits an internal quantum yield of 56.9 % and a thermal stability of 72.6 %@423 K. Finally, Ba2Ca0.85Ln0.15WO6:Mn4+ based phosphor conversion LED devices are demonstrated, which can be potentially employed for indoor plant lighting.

The effects of Ca<sub>14</sub>Mg<sub>2</sub>(SiO<sub>4</sub>)<sub>8</sub>:Eu<sup>2+</sup> phosphor on white light emission quality of LED-phosphor packages

Ca14Mg2(SiO4)8: Eu2+ (CMS:Eu2+) green phosphor is used for creating the white-light emitting diode (W-LED) packages with conversion phosphor materials. The phosphor shows the broadband green emission that peaks at 505 nm in the blue wavelength. The phosphor introduces the improvement in the blue and green emission spectra, which helps to heighten the luminous flux. Moreover, that the concentration of CMS:Eu2+ increases, the scattering events are enhanced to benefits the color blending for lower color variations or better color uniformity. The color renditions reduce with the rising green-phosphor concentration. The green-light amount becomes surplus and redundant for balancing color elements of white light emission. Thus, it should adjust and keep the concentration of CMS:Eu2+ in the range of ~2–8 wt%, to get the average number of color rendering index (CRI) (73–75), and color quality scale (CQS) (60–64). The CMS: Eu2+, hence, is suitable for white light realization, and the W-LED aiming at high-luminescence white light emission with improved color uniformity, and average rendering performances.

Multicolour LED lighting achieved by an array phosphor-converted film and blue-LED chip

A multicolour LED is a miniaturized, long-lasting, and easy-to-achieve colour adjustable emission light source. It is widely used in outdoor displays and room lighting fields. However, the increase in the cost and the decrease in luminous efficiency when adjusting lighting colours have constrained the development of multicolour LEDs. In this study, we initially designed a phosphor conversion pixel array through optical simulation and then prepared the phosphor conversion pixel arrays with different layouts using a semi-cured template method. Finally, we packaged the phosphor conversion pixel array with the blue LED array as a remote phosphor LED. The measurement of the luminous performance indicated that the colour gamut of multicolour LEDs was included in the simulated colour gamut, and the colour of the light was consistent with the design guidelines. Notably, the multicolour LED emission efficiency packaged with a phosphor conversion pixel array could reach 125 lm/W, and the hexagonal phosphor conversion pixel array had better emission performance than the square phosphor conversion pixel array.

Anomalous 5D0→7F4 Transition of Eu3+‐Doped BaLaGaO4 Phosphors for WLEDs and Plant Growth Applications

AbstractEuropium (Eu3+) doped phosphors typically exhibit orange or red emission and are used in lighting and display applications, originating from the 5D0→7F1 and 5D0→7F2 transitions of Eu3+. However, BaLaGaO4: xEu3+ deep‐red phosphor, when excited by near‐ultraviolet light, is mainly 5D0→7F4 transition (703 nm). Meantime, the BaLaGaO4: 0.30Eu3+ exhibits a high I423K/I298K value of 71% and a high quantum yield of 82.54%. Furthermore, the prepared samples are mixed with commercial blue and green phosphors in a certain proportion to make white light‐emitting diodes (WLEDs). The color coordinate of the fabricated WLEDs is (0.3208, 0.3436), with a color rendering index of 91.9 and an R9 value of 73. Based on the unique spectral characteristics of this compound, a prototype device of a deep‐red LED with phosphor conversion is developed, which exhibits color coordinates (0.6294, 0.3581) and a color purity of 96.4%. The conducted germination experiments with plant seeds have provided compelling evidence regarding the considerable positive effects of the deep‐red LEDs on plant growth. These findings further emphasize the highly promising potential application of BaLaGaO4: Eu3+ deep‐red phosphor in WLEDs and plant growth lighting.

Thermally-stable AlN-based green and red composite ceramic phosphor wheel for LD lighting with high CRI

Phosphor conversion materials with excellent thermal stability and broad-spectrum is critical to obtaining laser lighting devices with high luminous flux and CRI. In this paper, high thermally stable green AlN-Lu3Al5O12:Ce (ASL) and red AlN–CaAlSiN3:Eu (ASR) composite phosphor ceramics were prepared by embedding phosphor into AlN ceramic matrix. With mass ratio of phosphor increasing, luminescence intensity and quantum efficiency gradually increased, and the maximum internal quantum efficiency reached 62.8 % and 78.9 % for ASL and ASR, respectively. Under laser exciting in reflection mode, ASL-20 and ASR-50 got the max luminous emittance of 2827.5 lm/mm2 and 268.7 lm/mm2 with a saturation laser power density of 60.4 W/mm2 and 16.7 W/mm2, respectively. The diffusion coefficient of Ca, Al, Si between AlN and CASN grains was 2–4 magnitude higher than that of Lu, O, N between AlN and LuAG grains, confirming facile solid solubility of AlN and CASN. Finally, luminescence performances of green-red color wheel fabricated by ASL and ASR were evaluated. When the area ratio of green to red was 2:1, the color wheel yielded the biggest CRI of 82.6. This work presents a facile strategy for fabricating high thermally stable AlN-based composite phosphor ceramic and its application in high-quality laser lighting and display devices.

MgF2-doped MgO-YAG:Ce composite ceramics prepared by pressureless vacuum sintering for laser-driven lighting

Laser-driven solid-state lighting has attracted much attention in recent years. However, the super-high luminous flux under high-power-density laser irradiation is accompanied by an enormous amount of heat. Here, to enhance the thermal robustness of phosphor converter materials, we prepared composite ceramics of YAG:Ce combined with high-thermal-conductivity MgO via simply vacuum sintering. 1.0 mol% MgF2 was employed as the liquid-phase sintering additive to accelerate the densification process. The optimum temperature proves to be 1400 °C, at which MgO-YAG:Ce composites exhibit highly dense composite structure, without obvious reaction between MgO and YAG phases. Additionally, low sinterability of commercial YAG:Ce particles dragged down the densification process, which limits the YAG:Ce content of the composites. As a result, MgF2-doped MgO-10 vol% YAG:Ce composite ceramic (MYF10) sintered at 1400 °C exhibits the highest relative density of 99.33 % and thermal conductivity of 42.05 W/(m·K). Under 34.06 W/mm2 blue laser excitation in a reflection mode, a stable laser-driven white light is obtained with the luminous flux of 2834 lm and luminous efficiency of 166 lm/W, respectively.

An ultra broadband NIR phosphor LiScSnO4:Cr3+ with emission wavelength peaking at 900 nm for component analysis

Near-infrared phosphor conversion light-emitting diode (NIR pc-LED) is a widely used ideal NIR light source due to its unique advantages of low cost, energy saving, compactness and long operational lifetime. However, there is currently a scarcity of appropriate phosphor for NIR light sources utilized in spectral detection, with emission peak larger than 850 nm and steady spectrum output of ultra broadband spectra. Here, a broadband Cr3+ activated LiScSnO4 (LSS) phosphor (λex-max = 460 nm) matching the pump band of commercial blue LED chips has been developed, which shows a long wavelength NIR emission peaking at 900 nm. Cr3+ simultaneously replace the Wyckoff site co-occupied by Sc and Sn in LSS. Due to the difference of local environment of the specific crystal field, two different wide emission bands are caused. These two broad emission bands both contribute to the broadband luminescence with a full width at half maximum (FWHM) of 227 nm. Benefiting from the crystallography consistent Wyckoff position occupation of Cr3+ ions, the spectral distribution of LSS:Cr3+ exhibit excellent stability over a wide temperature span (80–423 K). The broadband NIR pc-LED prototype based on LSS:Cr3+ shows great potential in NIR spectrum detection, night vision imaging applications.