High Luminescence Intensity Research Articles

Blue light irradiation-stirred washing high luminescence and highly stable CsPbBrI2 quantum dots modified with CaO for backlight display

Perovskite quantum dots (QDs) have become the star material for liquid crystal display (LCD). However, instability affects its practical application. Herein, CsPbBrI2 quantum dots (CsPbBrI2 QDs) with high quantum efficiency have been successfully precipitated in situ by adding CaO to the Li-Al-Si glass substrate. The photoluminescence quantum yield (PLQY) was adjusted from 64.5 % to 87.5 %. At the same time, we adopted a new strategy of blue light irradiation-stirred water washing. When blue light irradiation and stirred water washing interact synergistically, the naked CsPbBrI2 QDs detached from the glass surface, while smaller CsPbBrI2 QDs continued to grow. This process successfully resulted in CsPbBrI2 QDs with high luminescence intensity and high stability. Moreover, when exposed to 60 °C, 90 % relative humidity (RH), and 2000 nit blue light for 240 hours (h), the treated sample could retain 91.1 % of the original emission intensity. The color gamut of the prepared CsPbBrI2@CsPbBr3@glass@polystyrene (PS) light conversion film covered 122 % of the NTSC 1953 standard and 90 % of the Rec. 2020 standard. It provided great value for the commercialization of QDs in backlight display applications.

Enhanced Stability and Brightness through Co-Substitution: Promoting Plant Growth with Green-Excited Deep Red Phosphor Ca1-zSrzLi1-xMg2xAl3-xN4:yEu2.

The research utilized a strategy of chemical unit co-substitution, successfully developing a novel blue-green to green excited, deep red-emitting phosphor, Ca1-zSrzLi1-xMg2xAl3-xN4:yEu2+ (CLA-2xM-zS:yEu, 0≤x≤0.8, 0.003≤y≤0.01, 0≤z≤1), through the replacement of [Li-Al]4+ by [Mg-Mg]4+. This phosphor uniquely converts unusable green light to growth-enhancing deep red, optimizing it for outdoor agriculture. Doping with Sr creates traps, causing a redshift in emission peaks, as confirmed by 7Li nuclear magnetic resonance (NMR) spectra, indicating Li presence and lattice changes. Ca0.2Sr0.8Li0.5MgAl2.5N4:0.005Eu2+ (CLAM-0.8S) phosphor maintained high luminescence intensity under extreme conditions of 85°C/85% RH, demonstrating excellent photoluminescence performance and chemical stability, compared with conventional SrLi0.5MgAl2.5N4:0.005Eu2+ (SLMA) and SrLiAl3N4:0.005Eu2+(SLA). Experimental results surprised that the unique Ca0.2Sr0.8Li0.8Mg0.4Al2.8N4:0.005Eu2+ (CLA-0.4M-0.8S) prepared light-converting film, which is mainly excited by green light, demonstrated a 20% increase in optical density of Chlorella compared to the PP film and a remarkable 97.5% increase compared to the control group without any film. These findings suggest that this film has significant potential for applications in outdoor agriculture and other fields.

The preparation and luminescence properties of Gd2SiO5:Tb3+@SiO2 core-shell spherical particles

Rare-earth spherical particles (RE-SPs) have garnered significant interest as nanomaterials for biomedical applications due to their high luminescence intensity and tunable luminescence lifetimes. In this study, Tb3+-doped Gd2SiO5@SiO2 (GSO: Tb3+@SiO2) core-shell spherical particles were prepared by coprecipitation and Stöber methods. Firstly, the phase transitions and core-shell structures of GSO:Tb3+@SiO2 SPs during preparation were discussed. The obtained core-shell SPs exhibited excellent dispersion and a well-defined spherical morphology with sizes ranging from 250 to 350nm. Secondly, the luminescence properties of GSO:Tb3+@SiO2 SPs were investigated, delving into the concentration quenching mechanisms of Tb3+ ion and the energy transfer (ET) from Gd3+ to Tb3+ in SPs. Thirdly, the potential biomedical applications of the GSO:Tb3+@SiO2 SPs were evaluated by examining properties such as radioluminescence, luminescence stability and surface charge. The results of present work indicates that the obtained novel spherical particles material with distinct core-shell structures has potential application in X-ray induced photodynamic therapy (X-PDT).

Synthesis and coating of novel cadmium-free MnCsPb(Br0·4/I0.6)3 red perovskite quantum dots

This work introduces a novel synthesis method for MnCsPb (Br0·4/I0.6)3 quantum dots, which demonstrate excellent optical and thermal stability. These quantum dots offer high luminescence intensity and tunable emission wavelengths. By optimizing key factors such as thermal injection temperature, chemical composition, and reaction duration, we were able to improve their crystal quality, reduce defects, and enhance optical properties like luminescence efficiency and emission peak sharpness. Surface treatments with TMOS, APTES, and TEOS further improved their stability, with APTES showing the best results for thermal resistance. In thermal degradation tests, APTES-coated quantum dots retained 76.7 % of their initial luminescence intensity and maintained 95 % of their brightness after 68 h of continuous heating at 85 °C. These quantum dots also showed strong resistance to blue shift in emission wavelength during long-term UV exposure, making them highly durable for applications requiring prolonged performance under harsh conditions.

High photoluminescence quantum yield and stability achieved by encapsulating MAPbBr3 QDs in UIO-66 and their application in LEDs.

Lead halide perovskite quantum dots (QDs) have been extensively studied due to their excellent photoelectric performance. However, the stability of MAPbBr3 QDs is affected by inevitable factors such as light, heat, and moisture, which limits their practical applications. In this work, stable metal-organic framework UIO-66 was synthesized via a solvothermal method, and the composite MAPbBr3@UIO-66 was prepared through an in-situ growth method. Owing to the wide bandgap, small pore size, and regular geometric structure, UIO-66 can confine the size and uniformity of the perovskite QDs encapsulated within the framework, maximally preserving the luminescent properties of the perovskite QDs. Furthermore, UIO-66 isolates the perovskite QDs from contact with polar water molecules in the air, significantly enhancing the stability of the perovskite QDs. The synthesized composite material exhibits high stability and excellent optical performance, with a photoluminescence quantum yield (PLQY) of up to 78.9% in an air environment. After being stored under natural conditions for 35 days, it still retains 65% of its high luminescence intensity and fluorescence quantum efficiency. When packaged into green and white LEDs, the LEDs demonstrate high brightness and good monochromaticity, maintaining stable brightness even after 2.5 hours of continuous operation. These superior characteristics indicate that the composite material MAPbBr3@UIO-66 has great potential for application in LED technology.

Wavelet optical flow velocimetry of a scramjet combustor using high-speed frame-straddling focusing schlieren images

Scramjet combustors feature ultra-high-speed turbulent reacting flows with high temperatures and intense luminescence. Measurement of velocity fields under such extreme conditions presents great challenges. The present work demonstrated a seedless velocimetry approach using focusing schlieren images (FSIs) of high spatiotemporal resolution in a scramjet engine. Two fuel mass flow rates (Case1 and Case2) were investigated with corresponding global equivalence ratios of 0.27 and 0.13, respectively. The FSIs enabled by the employment of a high-speed pulsed LED light source are characterized by an effective exposure of 100 ns, and a 500-ns frame-straddling time interval with full resolution of 1280 × 800 pixels recorded at 76 kHz. The 100-ns exposure allows for capturing of transient high-speed flow motion without blurring, and the 500-ns time interval ensures an appropriate spatiotemporal correlation between subsequent schlieren images for high-speed reacting flows. A wavelet-based optical flow velocimetry (wOFV) algorithm was developed and applied to the FSIs. In contrast to the correlation-based algorithms widely employed in PIV for distinct particles, the wOFV algorithm suits better FSIs with continuous variation in brightness. The maximal velocities in the main duct of the scramjet combustor were measured to be approximately 550 m s-1 and 1100 m s-1 for Case 1 and Case2, suggestively corresponding to subsonic and supersonic combustion modes, respectively. The measured velocity inside the cavity is generally below 200 m s-1 for both cases. Recirculation regions and their dynamic motions inside the cavity were well resolved. In summary, the development of the novel velocimetry approach holds great potential for applications in extreme flow conditions. Novelty and Significance Statement: Present work demonstrates a seedless velocimetry approach based on high-speed frame-straddling focusing schlieren imaging coupled with the novel wavelet optical flow velocimetry (wOFV) algorithm. Velocity field measurement realized in a scramjet combustor with high spatiotemporal resolution (1280 × 800 pixels at 38 kHz) for the first time, showing great abilities to accommodate wide velocity range and to resolve dynamic flow characteristics with potentials for broader future applications.

In-situ passivation and anchoring of perovskite quantum dots on KSF:Mn phosphor for liquid crystal display

Perovskite quantum dots (PQDs) hold immense potential for application in backlight liquid crystal display (LCD) owing to their narrow emission spectra, tunable luminous wavelength along with high photoluminescence quantum yield. However, their poor stability severely impedes the practical application of PQDs in optoelectronic devices. Here, we prepare KSF@PQDs composites by in-situ generation of green-emitting MAPbBr3 PQDs on the surface of treated KSF:Mn red phosphors. The surface treatments on KSF:Mn are employed for realization of in-situ passivation and anchoring of MAPbBr3 through chemical interaction between the NH2 group on KSF:Mn and Pb2+ on PQDs, which enables high luminescence intensity, narrow spectral width and simultaneously high photostability of PQDs. Moreover, the ratio of green-to-red emission intensity in KSF@PQDs can be easily modulated by changing APTES content during the surface treatment of KSF:Mn. Further, white light-emitting diode devices consisting of InGaN chip and KSF@PQDs composite achieve luminous efficiency of 41.6 lm·W−1, as well as wide color gamut of 116.6 % for National Television Systems Council standard and 87.2 % for Rec.2020 standard, which paves the way for the application of high stability PQDs in wide color gamut LCD.

Fast response Sc3+-sensitized K2NbF7:Mn4+ phosphors with high luminescence intensity and moisture resistance selected by DFT calculations

Mn4+-activated fluoride phosphors exhibiting broadband excitation and sharp line emission within the sensitivity range of the human eye are extensively utilized as supplementary red phosphors for white light-emitting diodes (WLEDs), and the K2SiF6:Mn4+ phosphor has achieved considerable commercial success. However, the K2SiF6:Mn4+ phosphor has defects in long fluorescence decay life and poor moisture resistance owing to its Mn-doped fluoride composition, which severely restricts its application in fast response commercialized backlight LEDs. Hence, we selected the monoclinic crystal K2NbF7:Mn4+ phosphor with higher zero phonon line (ZPL) emission. Using density functional theory (DFT) calculations, we identified the optimal sensitizer Sc3+ and improved the original synthesis method to develop a new K2NbF7:0.06Mn4+-0.02Sc3+ (KNFMSc) phosphor successfully. The KNFMSc phosphor has an integral luminescence intensity 2.63 times that of K2SiF6:Mn4+, superior moisture resistance performance, which is characterized by maintaining 60.78 % of its initial luminescence intensity after a 12 h water immersion, and a faster fluorescence decay lifetime of 3.79 ms. After being assembled into LEDs, the KNFMSc phosphor emits warm white light with a color rendering index of 93.5 and a correlated color temperature of 3924 K, representing enhanced luminous stability under varying driving currents. Therefore, the prepared KNFMSc phosphor holds considerable potential for application in WLEDs and backlighting LEDs, offering a new alternative to commercial phosphors.

Ultrastable Luminol-OH--(Ni-WOx-CNT) ECL System with High Strength and Its Applications in Sensing.

In traditional luminol electrochemiluminescence (ECL) systems, hydrogen peroxide (H2O2) and dissolved oxygen (DO) are the commonly used coreactants to generate reactive oxygen species (ROS) for ECL emission. However, the self-decomposition of hydrogen peroxide and the limited solubility and content of oxygen in solution undoubtedly restrict the luminescence efficiency and stability of the luminol ECL system. Inspired by the ROS-mediated ECL mechanism, we pioneered hydroxide ion as an advanced luminol ECL coreactant using nickel-doped and carbon nanotube-modified tungsten oxide (Ni-WOx-CNT) as the coreactant accelerator. Owing to the excellent catalytic activity of Ni-WOx-CNT, amounts of ROS were generated from OH- at a low excitation voltage, which subsequently reacted with luminol anion radicals and triggered intense ECL signals. Experiments confirmed an impressive ECL behavior in terms of high luminescent intensity (85,563 a.u.) and super stability over 1300 consecutive tests; both are superior to those recently reported luminol-H2O2 and luminol-DO systems with smaller ECL intensities and consecutive tests less than 25 times. To validate the feasibility and versatility of the developed system in sensor, traditional three-electrodes system and closed bipolar electrodes system with various sensing strategies of direct oxidation, "gate-effect" of molecularly imprinted polymer, immune reaction, and enzyme-catalyzed reaction were proposed to monitor uric acid (UA), C-reactive protein (CRP), immunoglobulin G (IgG), and glucose (Glu). The superior sensing performances confirmed the great application potential of the developed ROS-mediated ECL system.

Highly sensitive and quantitative HiBiT-tagged Nipah virus-like particles: A platform for rapid antibody neutralization studies

Biocontainment regulations restrict the research on NiV to BSL-4 laboratories, thus limiting the mechanistic studies related to viral entry and allied pathogenesis. Understanding the precise process of viral-particle production and host cell entry is critical for designing targeted therapies or particle-based vaccines. In this study, we have synthesized HiBiT-tagged-NiV-VLPs to ease in-vitro BSL-2 particle handling. We propose a simple yet effective approach of generating substantial amount of HiBiT-tagged NiV-VLPs in vitro by co-expressing viral structural proteins in HEK293T cells. Though homologous to parent virus, the incapacitated replication potential facilitates a BSL-2 handling of these particles. The inclusion of a highly sensitive HiBiT tag on these VLPs allows for a quick detection of viral binding and entry, as well as in assessing the efficiency of neutralizing antibodies in vitro using the NanoBiT technology. The HiBiT-tag binds in high affinity with LgBiT (Large BiT an 18 kDa fusion protein and complementary subunit of HiBiT peptide), and the resultant complex elicits high intensity luminescence in the presence of substrate. The VLPs produced were morphologically and functionally identical to the native virus, and the HiBiT-tag permitted their quick application in viral binding, entry, and antibody neutralization assays.“Thus, we report a simple setting for generating HiBiT-NiV VLPs which can be utilized in a BSL-2 laboratory, to concurrently quantify features of NiV assembly, binding and entry. This also offers an alternate-safe and effective platform for viral based antibody neutralization assays in vitro”.

Judd-Ofelt analysis of Sm3+ doped Ca2LiMg2V3O12 phosphors: Unveiling luminescent and thermometric properties for multifunctional applications

This study investigated the luminescent and thermometric properties of pure and Sm³⁺-doped Ca₂LiMg₂V₃O₁₂ (CLMV) garnet-type vanadates synthesized by the solid-state reaction method. The synthesized materials, with varying Sm³⁺ concentrations (0.01–0.09 mol%), were comprehensively characterized using powder X-ray diffraction (PXRD) analysis to confirm their phase purity. Diffuse reflectance spectroscopy (DRS) measurements were employed to determine the band gap energy of both pure CLMV and CLMV:0.07Sm³⁺ samples. Photoluminescence (PL) excitation and emission spectra were recorded for the pure and Sm³⁺-doped CLMV phosphors using an excitation wavelength of 345 nm and monitoring the emission at 618 nm. These spectra revealed detailed information about the energy levels involved in light emission processes. An efficient energy transfer from the (VO₄)³⁻ groups to the Sm³⁺ ions was observed, exceeding 48%. This energy transfer process is crucial for achieving high-intensity luminescence in Sm³⁺-doped materials. Judd–Ofelt (J-O) theory was applied from the emission spectra and calculate the Judd–Ofelt intensity parameters, which govern the radiative properties of the Sm³⁺ ions. Based on the J-O analysis, the branching ratio (β) was estimated to be greater than 75%. This value, exceeding the threshold of 50% for display devices, signifies the suitability of the phosphor for solid-state lighting applications due to its efficient light emission. The thermal quenching behavior of both the Sm³⁺ ions and the (VO₄)³⁻ groups was further investigated to explore the optical thermometric characteristics of the Sm³⁺-doped CLMV phosphors. Notably, a maximum absolute sensitivity (Sa) of 0.35 K⁻1 and a relative sensitivity (Sr) of 2.55% K⁻1 were achieved, demonstrating the materials potential for non-contact optical temperature sensing applications. Lifetime decay analysis revealed double exponential decay behavior, indicating the presence of multiple luminescence centers within the phosphor. The average lifetime in the millisecond range further supports the suitability of these materials for practical applications. Finally, the CIE color coordinates, correlated color temperature (CCT), and color rendering index (CRI) values were also reported, providing insights into the colorimetric properties of the Sm³⁺-doped CLMV phosphors. These aspects are crucial for optimizing the materials for solid-state lighting applications.

A Brief Synthesis Methods and Luminescence Development of Rare Earth Activated Borophosphate Phosphor Materials

A Brief Synthesis Methods and Luminescence Development of Rare Earth Activated Borophosphate Phosphor Materials

Low parasitic carrier reservoir of AlGaN-based DUV-LED via controlled-polarization step-graded superlattice electron blocking layer for high luminescence lighting

Achieving high luminescence intensity of deep-ultraviolet light-emitting diode (DUV-LED) is generally performed through the implementation of electron blocking layer (EBL) on the chip’s epilayers. However, the issue of parasitic carrier reservoir that originated from the uncontrolled piezoelectric field polarization has restricted the performance of DUV-LED by reducing the radiative recombination in the active region. This work reports on the numerical computation analysis of the DUV-LED with different types of EBL designs which are reference EBL, conventional superlattice EBL and step-graded superlattice EBL. The analysis of the DUV-LED focuses on the band diagram, carrier concentration at the EBL interfaces, current density of the carrier in the active region, radiative recombination rates, and luminescence spectrum. Remarkably, it is found that the DUV-LED step-graded superlattice EBL provides the polarization-controlled band diagram and emits 272 nm UVC-wavelength in which it is superior in performance compared to the other structures, specifically in terms of its radiated intensity. The parasitic electron and hole reservoir have been reduced by 30% and 60%, respectively. The luminescence intensity was also enhanced by 11% compared with the reference EBL and the IQE obtained by the DUV-LED with step-graded superlattice EBL is 50.12%.

Performance study of Ca3Sc2Si3O12:Ce3+ cyan-green fluorescent converter for laser illumination

To address the problem of cyan-green light deficiency in fluorescent converters for laser diode (LD) illumination applications, Ca3-xSc2Si3O12:xCe3+ (CSS:xCe3+) cyan-green fluorescent ceramics and CSS:Ce3+ phosphor in glass (CSS:Ce3+-PiG) fluorescent converter were successfully prepared. Among them, the CSS:0.08Ce3+ cyan-green fluorescent ceramic and 20 wt% CSS:Ce3+-PiG fluorescent converter had the highest luminescence intensity. At 450 nm excitation, the emission spectra of both materials showed an asymmetric broadband band between 470 nm and 690 nm. And the two fluorescent converters are not appear of luminescence temperature quenching until more than 538 K. The performance of the white LDs synthesized with ceramic and PiG converters was investigated. Under different power excitation, the green emission intensity of both wLD is enhanced with increased incident laser power. The wLDs based on CSS:Ce3+ fluorescent ceramics have a luminous flux of 880 l m and the maximum luminescence efficiency of 176 l m/W at an incident power of 5 W. And the wLDs of PiG fluorescent converters have a maximum luminous flux of 584 l m and luminescence efficiencies of up to 117 l m/W. CSS:Ce3+ ceramics and CSS:Ce3+-PiG are green fluorescent converter with good luminescence performance and thermal stability. It will play an important role in the compensation of the cyan light in LD illumination.

Next Generation Chemiluminescent Probes for Antimalarial Drug Discovery.

Malaria is caused by parasites of the Plasmodium genus and remains one of the most pressing human health problems. The spread of parasites resistant to or partially resistant to single or multiple drugs, including frontline antimalarial artemisinin and its derivatives, poses a serious threat to current and future malaria control efforts. In vitro drug assays are important for identifying new antimalarial compounds and monitoring drug resistance. Due to its robustness and ease of use, the [3H]-hypoxanthine incorporation assay is still considered a gold standard and is widely applied, despite limited sensitivity and the dependence on radioactive material. Here, we present a first-of-its-kind chemiluminescence-based antimalarial drug screening assay. The effect of compounds on P. falciparum is monitored by using a dioxetane-based substrate (AquaSpark β-D-galactoside) that emits high-intensity luminescence upon removal of a protective group (β-D-galactoside) by a transgenic β-galactosidase reporter enzyme. This biosensor enables highly sensitive, robust, and cost-effective detection of asexual, intraerythrocytic P. falciparum parasites without the need for parasite enrichment, washing, or purification steps. We are convinced that the ultralow detection limit of less than 100 parasites of the presented biosensor system will become instrumental in malaria research, including but not limited to drug screening.

Comparing Three Methods for Producing Carbon Dots from Mangosteen Peel

Carbon dots are fluorescent nanoparticles that are around 10 nm in size. Carbon dots can be formed via pyrolysis, hydrothermal, and solvothermal procedures from raw materials such as mangosteen peels. Because it contains cyanidin and xanthone, which improve the intensity of carbon dot fluorescence, mangosteen peel waste can be utilized to make carbon dots. The presence of a urea passivation agent is expected to boost carbon dot luminescence intensity. The study aimed to develop carbon dots from mangosteen peel using three different methods: pyrolysis, hydrothermal, and solvothermal, and to assess their ability to produce luminous hues. Carbon dot yield was 21% by the solvothermal method, 5% by the hydrothermal method, and 2% by pyrolysis. All three methods produced blue carbon dot luminescence. The solvothermal method, hydrothermal procedure, and pyrolysis had the highest luminescence intensity. Adding urea as a passivation agent increased the luminescence of carbon dots. The solvothermal approach produced the highest carbon dot production and fluorescence intensity. The hydrothermal and solvothermal carbon dots made emissions at wavelengths of 413 nm and 454 nm, respectively, both corresponding to blue luminescence.

Novel transparent NaLu2F7:Tb3+ glass-ceramics scintillator for highly resolved X-ray imaging

Due to the rapid advancements in medical radiography, nondestructive inspection, and radiation detection, there is an increasing demand for scintillators that offer both cost-effectiveness and high-resolution X-ray imaging. In this study, we have successfully synthesized transparent glass-ceramic scintillator by embedding Tb3+-doped NaLu2F7 nanocrystals in a glass matrix. This scintillator demonstrates excellent spatial resolution of 20 lp/mm in X-ray imaging due to its high transmittance (over 90% at 550 nm) and intense luminescent intensity when excited by X-ray (151% higher than that of the Bi4Ge3O12 scintillator). More significantly, the as-synthesized scintillator exhibits exceptional stabilities at high temperature, moisture levels, and moderate radiation exposure. Notably, any decline in performance caused by long-term exposure to high-dose X-ray can be fully recovered through heat treatment at 350 °C for 30 min. These findings highlight the great potential of NaLu2F7:Tb3+ glass ceramics as suitable options for high-resolution and retrievable X-ray imaging.

An electrochemiluminescence sensor based on lanthanide bimetallic MOFs with a “cascade sensitization mechanism” for the sensitive detection of CA242

Lanthanide metal-organic frameworks (Ln-MOFs) broaden the optical sensing applications of lanthanide ions due to the antenna effect between organic ligands and metals. However, the sensitization ability of the ligand to metal ions is limited, and maximizing the sensitization of the electrochemiluminescence behavior of Eu3+ is still a challenge for the application of Ln-MOFs. Therefore, under the guidance of the “cascade sensitization mechanism” based on the antenna effect sensitizing the electrochemiluminescence of bimetallic Ln-MOFs, we proposed Eu/Tb-MOFs with high luminescence intensity as a signal probe. According to the antenna effect, the conjugated structure and high extinction coefficient of the benzene ring of 2-amino terephthalic acid (NH2-BDC) can enhance the ECL luminescence intensity of Eu/Tb-MOFs. Tb3+ can act as an energy bridge between NH2-BDC and Eu3+, buffering the energy gap. The bimetallic sensitization is formed between Tb3+ and Eu3+, which can inhibit the reverse internal flow of energy and ensure the high luminous efficiency of Eu3+. In addition, the nanosphere mixed valence Fe3O4 as a co-reactant accelerator promotes the formation of transient free radical SO4•- through the valence change of Fe2+/Fe3+. The ECL immunosensor constructed by luminophores Eu/Tb-MOFs and nanosphere Fe3O4 provided a new explanation for the ECL self-luminous of Eu/Tb-MOFs.

Green light activated red luminescence from Y2O3: Eu3+ nanophosphors

The variation of photoluminescence properties of Y1.95Eu0.05O3 nanophosphors, synthesised by the sol-gel combustion technique has been investigated by changing the concentration of the fuel. X-ray diffraction and the Raman spectroscopic studies confirm the bcc bixbyite structure of samples with space group Ia3. EDX analysis and X-ray photoelectron spectroscopy reveal the chemical composition. The significantly high luminescence intensity observed for these red phosphors when excited by green (533 nm) wavelength suggests their possible applications in light conversion technology. Highly intense emission with color coordinates (0.67, 0.33), color temperature of 2255 K, and color purity of 95% have been observed for the optimum sample when excited with 533 nm. The life time of 1.704 ms, obtained from luminescence decay curve analysis and the quantum efficiency of 88%, calculated by Judd- Ofelt analysis distinguish the emission properties of the nanomaterial.

Indexes for evaluation of dynamic characteristics of pressure-sensitive paint based on pressure sensitivity and frequency response

Two evaluation indexes were proposed to select the optimal PSP for unsteady pressure measurement from various PSPs with different pressure sensitivity and frequency response. An effective sensitivity coefficient calculated by pressure sensitivity and gain attenuation due to the response delay was proposed. Furthermore, an effective amount of intensity change was recommended, which takes into account the emission intensity and the effective sensitivity coefficient, because the magnitude of the intensity of a PSP is also important for unsteady-pressure measurement with high-speed sampling. A total of five types of PC-PSPs developed in previous studies were compared: two types of fast-response PC-PSPs using Pt(II) meso-tetra (pentafluorophenyl) porphine (PtTFPP) with poly(isobutyl methacrylate) (poly(IBM)) and ruthenium complex with RTV silicone, respectively, and three types of PC-PSPs using PtTFPP with poly[1-trimethylsilyl)-1-propyne] (poly(TMSP)). A comparison was made using the proposed evaluation indexes under various pressure ranges. The results shows that poly(TMSP)-based PC-PSP has a high effective sensitivity coefficient at pressures less than 20 kPa. On the other hand, poly(IBM)-based PC-PSP has the highest effective sensitivity coefficient at a pressure of 100 kPa. The effective amount of intensity change of poly(TMSP)-based PC-PSP is the highest at 2 kPa, but that of poly(IBM)-based PC-PSP is the highest at a pressure higher than 5 kPa among the evaluated PC-PSPs due to its high luminescence intensity. A PSP with high emission intensity will provide high performance in terms of fluctuation of emission intensity detected by the photodetector when the excitation intensity and the exposure time are limited due to limitations of optical equipment or high-speed sampling.