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Sm3+, Tb3+ co-doped NaLa(MoO4)2 temperature sensing materials based on the fluorescence intensity ratio
摘要： In optical temperature sensors, the method of measuring temperature based on Fluorescence Intensity Ratio (FIR) has been paid tremendous attention due to its fortissimo anti-excitation power noise and the ability of anti-signal transmission channel to transmit light unsteady [1e10]. The above method has the advantages of non-contact, resistance to high temperature, wide temperature range, quick response and being able to measure small objects. The optical temperature sensing technology based on the FIR is used to detect the temperature through detecting the ratio of emitted fluorescence intensity between a pair of specific thermal coupling energy levels related to the temperature [11e15]. The fluorescence emission efficiency of Sm3+ doped oxide in 4G5/2 energy level was quite high. Sm3+ emits bright orange-red color. Tb3+ doped oxide is the strongest fluorescence branch in emission from 5D4- 7F5 [16,17]. If the thermal-quenching trend of luminescence of Sm3+ and Tb3+ is different, the FIR will change with temperature. So FIR can be used to indicate the temperature. Therefore, intensive study of Sm3+ and Tb3+ co-doped materials has great prospects, because it can reveal broad luminescence color variability from green to red. Molybdate has chemical stability and thermal stability, rare earth ions have strong 4f-4f transition absorption and transition emission in this host. Therefore it is a wally host [18,19]. Based on the above-mentioned reasons, in this paper Sm3+, Tb3+ co-doped NaLa(MoO4)2 samples of different morphology have been prepared and studies the temperature sensing characteristics.
关键词： Phosphor,Optical temperature sensing,Chemical synthesis,Luminescence
更新于2025-09-23 15:22:29
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Prediction of excitation wavelength of phosphors by using machine learning model
摘要： Luminescent materials are the integral part of green revolution helping us in saving the energy. Much effort been made to design and discover the novel phosphors for solid-state lighting. The current paper focuses on the development of machine learning (ML) model based on simple luminescent materials to predict the excitation to the closest possible accuracy using easily accessible key attributes using least absolute shrinkage and selection operator (LASSO) and artificial neural network (ANN) ML approach. These selected attributes expected to correlate with the excitation of material. The style for studying the material property has the potential to turn down the cost and time involved in an Edisonian approach to the lengthy lab experiment to identify excitation.
关键词： Solid-state lighting,Phosphor,Machine learning,Excitation wavelength,Luminescence
更新于2025-09-23 15:22:29
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Improved thermal stability of Y3Al5O12:Ce3+ phosphor by SiO2 coating
摘要： In this paper, a heterogeneous precipitation method was adopted to coat a SiO2 layer on the surface of Y3Al5O12:Ce3+ phosphor. The surface morphologies, crystal phases, defect concentrations, luminescent properties and thermal stability of coated phosphors were investigated and compared with those of uncoated phosphor. A compact and homogeneous SiO2 layer on the surface of phosphor was determined by SEM-EDS, TEM, XRD and FT-IR results. Two thermoluminescent peaks were found at 112 oC and 248 oC on the thermoluminescence spectrum. Their intensities decreased slowly with the increasing coating amounts. It indicated that their corresponding defect concentrations were gradually reduced. Improved thermal stability was obtained by SiO2 coating in spite of a slight weakening of the emission intensity. The optimum theoretical coating amount was identified as 4%. Moreover, a structural modification mechanism on improved thermal stability of SiO2 coated Y3Al5O12:Ce3+ was proposed.
关键词： Y3Al5O12:Ce3+ phosphor,thermal stability,coating,structural modification mechanism
更新于2025-09-23 15:22:29
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Can adaptive post-processing of storage phosphor plate panoramic radiographs provide better image quality? A comparison of anatomical image quality of panoramic radiographs before and after adaptive processing
摘要： Objective: The objective of the present study was to study the effect of adaptive image processing on the visibility of anatomical structures in storage phosphor plate (SPP) panoramic images. Materials and methods: Three hundred SPP panoramic X-ray radiographs of children and adolescents were used. The radiographs were post-processed using general operator processor (GOP) technology, resulting in both a standard-processed and a GOP-processed radiograph. Four specialists in dental radiology compared the structural image quality of all standard-processed and GOP-processed panorama images for six anatomical structures, using a six-point scale for visual grading characteristics (VGC) analysis. Results: For three of the anatomic structures – the root canal space of the mandibular left first premolar, mandibular canal left side and periodontal ligament space of the mandibular right first molar – there was a statistically significant difference to the GOP’s advantage. For the three remaining structures – dentino-enamel junction of the maxillary right first molar, crista alveolaris of the mandibular left molar area and floor of maxillary sinus right side – no significant difference between standard processing and GOP processing was obtained. Conclusions: The study demonstrates that it is possible to improve the quality of SPP radiographs and the visibility of anatomical structures by using the GOP technique. Manufacturers’ image-processing programs can be further developed, as there is a possibility of improving the diagnostic content of an image with external processing.
关键词： digital,storage phosphor plate,radiographic image enhancement,radiography,panoramic,Adaptive processing,dental
更新于2025-09-23 15:22:29
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Dynamic Photo-Electro-Thermal Modeling of Light-Emitting Diodes with Phosphor Coating as Light Converter
摘要： Based on the dynamic Photo-Electro-Thermal (PET) theory for LED systems, a comprehensive theory for analyzing and modeling phosphor coating in white light-emitting diodes (LEDs) as a dynamic light converter has been presented in Part-I of this paper. This Part-2 of the work provides the details of the model parameter determination, model setup and experimental verification. The procedures of obtaining the parameters in the experimental setup are explained. Using the comprehensive theory, a dynamic PET computer model of a phosphor-coated LED device has been developed. The simulation results compare well with the practical measurements, confirming the validity of the comprehensive theory in Part-1 of this paper. The new model provides novel equations for new information such as the power loss in phosphor coating and transients of the light emitted from the phosphor coating. Such information can be used for the designs of LED drivers and systems.
关键词： Phosphor-coated light-emitting diodes (PC-LED),complete PET model,photo-electro-thermal (PET) theory,light converter
更新于2025-09-23 15:22:29
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New Dynamic Photo-Electro-Thermal Modeling of Light-Emitting Diodes with Phosphor Coating as Light Converter
摘要： Phosphor-coated light-emitting diode (PC-LED) is the dominant LED technology for public lighting. This paper presents a comprehensive theory for analyzing and modeling phosphor coating in white light-emitting diodes (LEDs) as a dynamic light converter. The new PC-LED model not only obeys the traditional diode equation, it includes the energy-storage and transient effects of the phosphor coating. Major control variables include energy storage in and the luminous flux from the phosphor coating. This new model enables the dynamic variations of luminous flux and energy storage and power loss in phosphor-coating to be accurately predicted. Part-1 of this paper provides the details of the theory and analysis leading to the new PC-LED model under the framework of the photo-electro-thermal theory. Details of the model parameter determination, model setup and experimental verification are included in Part-2. The model offers the important power loss equation of the phosphor coating which highlights the factors affecting the heat loss and the coating’s blackening effects. This equation can be used by engineers to design LED drivers in order to reduce the coating temperature and the blackening effects and to prolong LED lifetime.
关键词： Phosphor-coated light-emitting diodes (PC-LED),flux capacitor,light converter.,photo-electro-thermal (PET) theory,dynamic model of PC-LED
更新于2025-09-23 15:22:29
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Characterization and Photoluminescence Property of a New Eu <sup>3+</sup> -doped Phosphor of the K <sub/>2</sub> [Al(B <sub/>5</sub> O <sub/>10</sub> )] Prepared by Precursor Method
摘要： A new phosphor of the K2[Al(B5O10)]:Eu3+ was prepared by annealing of the as-prepared of the precursor of K2[Al(B5O10)]·4H2O:Eu3+ at 300–400 °C, and which has been synthesized under facile hydrothermal conditions. All the samples were characterized by the EDS, XRD, FT-IR, and SEM. A systematic study on their luminescent properties has been performed by the PL and PLE. A series of influencing factors on the luminescent properties were also investigated. The PL and PLE studies reveal that the phosphor of K2[Al(B5O10)]:Eu3+ with optimal luminescent intensity and higher red-orange ratio were obtained by sintering the precursor at 400 °C for 5.5 h, with 9% doping concentration, which suggests that it might as a potential application of the light display systems.
关键词： Precursor method,Luminescent property,Eu3+ doped phosphor,Aluminoborate
更新于2025-09-23 15:22:29
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Synthesis and mechanoluminescent property of (Eu2+, Dy3+)-co-doped strontium aluminate phosphor by soft mechanochemistry-assisted solid-state method
摘要： (Eu2+, Dy3+)-co-doped strontium aluminate (SrAl2O4:Eu2+, Dy3+) powder as a mechanoluminescent (ML) phosphor was synthesized via soft mechanochemical pretreatment of precursor mixtures in a stirred media mill and subsequent calcination. Effect of soft mechanochemical pretreatment of precursors on the synthesis process as well as the photoluminescent (PL) and ML properties of SrAl2O4:Eu2+, Dy3+ phosphor was investigated. The precursor mixtures unground and ground at different time and the resultant phosphors were characterized by laser particle size analysis, X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, Fourier transfer infrared spectroscopy and optical property measurement. The results reveal that soft mechanochemical pretreatment of precursor mixture promotes the crystal growth, and reduces the subsequent calcination temperature. SrAl2O4:Eu2+, Dy3+ phosphor can be obtained via calcining at 1200 oC for precursor mixture ground at 60 min, but formed via calcining at 1400 oC for unground precursor mixture. The phosphor synthesized with precursor mixture ground at 60 min has the maximum PL and ML intensities due to the enhancement of Eu2+ and Dy3+ ions into the crystal lattice to form more electron traps. The measurements by a designed ML instrument indicate that the ML intensity increases with increasing impact stress, and decreases with multiple applications of the same impact stress on phosphor disks.
关键词： Phosphor,Soft mechanochemistry,(Eu2+, Dy3+)-co-doped strontium aluminate,Solid-state method,Mechanoluminescence
更新于2025-09-23 15:22:29
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Structure and cathodoluminescent properties of ultraviolet emitting Zn(Al<inf>1-x</inf> Ga<inf>x</inf>)<inf>2</inf> O<inf>4</inf> alloy phosphor
摘要： The goal is to control the band gap by replacing the Al site of zinc aluminate having a spinel structure with Ga, and to control the emission wavelength, and aim for application as a light source in sterilization, skin treatment and the like. Zn(Al1-xGax)2O4 phosphor was prepared by a solid phase synthesis method. A plurality of samples with different Al/Ga ratio were prepared, and their crystal structures and luminescent properties were evaluated. In X-ray diffraction, formation of a single phase was confirmed in the sample fired at 1300 oC. It was confirmed that the diffraction peak shifted to the lower angle side by increasing the Ga ratio. In the cathode luminescence method, it was confirmed that ultraviolet emission of ZnAl2O4 was confirmed at about 250 nm, and it was confirmed that the emission wavelength shifted to the long wavelength side by increasing the Ga ratio. It is suggested that substituting Ga for the Al site of ZnAl2O4 is useful for shifting the emission wavelength although the emission intensity is unstable.
关键词： Cathodoluminescence,Zn(Al,Ga)2O4,Alloy phosphor,Ultra-Violet emission
更新于2025-09-23 15:21:21
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Effects of composition modulation on the structural and luminescence properties of Mn2+ doped Na2Mg1-xCaxSiO4 green-emitting phosphors
摘要： On the basis of the crystalline structural information that the matrix material has excellent physical-chemical stabilization, green-emitting Na2(Mg1-xCax)SiO4:Mn2+ (NMCS:Mn2+) phosphors were synthesized by a traditional solid-state method and systematically optimized, and their photoluminescence properties were studied. The luminescence properties of NMCS:Mn2+ phosphors as a function of Ca2+ concentrations were investigated. The structure of the as-prepared phosphors was identified by the X-ray diffraction (XRD) and the luminescent properties were characterized by the luminescence spectra, decay curve and CIE chromaticity coordinates. The emission peaks at 520nm generated by 4T1(4G)→6A1(6S) transition of the Mn2+ doped NMCS phosphors can provide a green component in the tri-color system. The emission intensity would be enhanced greatly by Ca2+-substitution and it can be observed that these emission peaks would shift to shorter wavelengths (blue-shift) with the increasing of Ca2+ content. The large enhancement of emission intensity and the shift of emission peaks due to Ca2+ substitution may provide a reference in the research of new type and more efficient phosphors for NUV-LEDs.
关键词： green phosphor,luminescence properties,Na2(Mg1-xCax)SiO4:Mn2+
更新于2025-09-23 15:21:21