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Pressure measurement in combusting and non-combusting gases using laser-induced grating spectroscopy
摘要： The measurement of pressure using laser-induced thermal grating spectroscopy, LITGS, with improved accuracy and precision is reported. Pressure values are derived from the record of the time-profile of LITGS signals by fitting of modelled signals to experimental data. The procedure is described for accurate modelling of the LIGS signals involving a sequence of calculation steps with appropriate weighting and calibration to determine the best-fit value of pressure-dependent parameters for averaged and single-shot measurements. Results are reported showing application of this model-fitting method to measurements of pressure in static cells using LITGS generated from NO in mixtures containing N2 at pressures in the range 0.5–5.0 bar with accuracy of 1–3% and single-shot precision of 4–7%. Time-resolved measurements of pressure, using LITGS signals generated in toluene-seeded fuel vapour, during the compression and expansion strokes of a motored optically accessible engine are reported with pressure-dependent accuracy ranging from better than 10 to around 20% over the cycle and single-shot precision in the range 5–15% over the same range. Measurements in the engine under firing conditions were obtained over a limited range and slightly increased uncertainties associated with varying composition resulting from exhaust gas residuals. The method was found to be of limited utility for measurements in high temperature flames at around ambient pressures.
关键词： Combustion,Laser-induced thermal grating spectroscopy,Non-combusting gases,Pressure measurement,LITGS
更新于2025-11-25 10:30:42
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Investigations of VO2+ doped SrZn2(PO4)2 nanophosphors by solution combustion synthesis
摘要： VO2+ doped SrZn2(PO4)2 nanophosphor is prepared using solution combustion synthesis. The prepared nanophosphor is studied by structural and spectral characterizations XRD, SEM with EDS, TEM, FT-IR, Optical absorption, EPR, and PL. XRD analyses the monoclinic phase of the prepared sample and the crystallite size determined to be in the order below 60 nm. SEM and TEM micrographs show the agglomerated stone-like structures for VO2+ doped SrZn2(PO4)2 nanophosphors. FT-IR spectrum exhibits various vibrational modes for PO4 3- anionic groups and other related groups. Optical absorption spectrum exhibited characteristic VO2+ bands in visible region and the crystal field and tetragonal field parameters are evaluated as Dq = 1461, Ds = -3035 and Dt = 602 cm-1. EPR spectrum shows well resolved hyperfine octet structure for VO2+ doped nanophosphor. The spin Hamiltonian parameters (g), hyperfine coupling constants (A) are calculated and are satisfying the condition g║<g┴<ge and A║ > A┴. From Optical and EPR data, VO2+ ions with the host ligands are identified as tetragonal distortion in octahedral site symmetry. PL spectrum illustrates, emission peaks in blue and green regions and its CIE and CCT parameters are evaluated, which are useful in LEDs and lightening devices.
关键词： Electron paramagnetic resonance,SrZn2(PO4)2 nanophosphor,Photoluminescence,tetragonal distortion,solution combustion
更新于2025-11-21 11:18:25
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Structural, photoluminescence and thermoluminescence study of novel Li+ co-activated lanthanum oxide activated with Dy3+ and Eu3+ obtained by microwave-assisted solution combustion synthesis
摘要： Stimulated luminescence of novel La2O3 nanophosphors doped with Dy3+ and Eu3+ and co-activated with Li+, prepared by microwave-assisted solution combustion synthesis, was investigated for the very first time. X-ray diffraction results indicated hexagonal La2O3 crystalline phase. Lanthanide and Li+ doping did not affect the La2O3 crystal structure. Scanning electron microscopy images showed nanoparticle morphologies such as plates, rods and irregular shapes. Photoluminescence spectra of La2O3:Dy3+, Li+ exhibited blue and green emission bands due to Dy3+ transitions. For La2O3:Eu3+, Li+, sharp emission lines, corresponding to the optical transitions of Eu3+ were observed. Thermoluminescence glow curve of La2O3:Dy3+, Li+ previously exposed to beta radiation exhibited a prominent glow peak located at ～46 °C, possibly useful for after-glow or persistent luminescence applications, whereas La2O3:Eu3+, Li+ curve, displayed three intense peaks at ～50, ～110 and ～150 °C. Thermoluminescent signal repeatability and decay curve asymptotic behaviour could place La2O3:Eu3+, Li+ as suitable for medium and high-dose radiation dosimetry applications.
关键词： Dosimetry,Thermoluminescence,Solution combustion synthesis,La2O3 co-doped nanoparticles
更新于2025-10-22 19:40:53
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[IEEE 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC) - Waikoloa Village, HI (2018.6.10-2018.6.15)] 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC) - Improving the performance of thermophotovoltaics using stabilized porous media combustion
摘要： A novel cylindrical porous media combustion-based thermophotovoltaic is proposed and experimentally studied. A mixture of methane-air is burnt at an equivalence ratio of 0.7 in a packed bed made of two layers of different alumina balls which are coated with ytterbia (Yb2O3) and erbia (Er2O3) for spectral control with gallium antimonide (GaSb) photovoltaic (PV) cells. A radiant reflector is used to increase the electrical output and the radiant efficiency. The experiments revealed it was possible to achieve a superadiabatic temperature of 1538 °C and a high radiant efficiency, 63%. Overall, this systematic analysis for lean Air/CH4 mixtures represents a new direction for TPV technology.
关键词： porous media combustion,selective coatings,Thermophotovoltaics
更新于2025-10-22 19:40:53
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Analogous Anti-Ferroelectricity in Y2O3-Coated (Pb0.92Sr0.05La0.02)(Zr0.7Sn0.25Ti0.05)O3 Ceramics and Their Energy-Storage Performance
摘要： Antiferroelectric analogous (Pb0.92Sr0.05La0.02)(Zr0.7Sn0.25Ti0.05)O3 (PSLZSnT) ceramics were prepared by the solid-state sintering method by introducing a Y2O3-coating via the self-combustion method. The synthesized Y2O3-doped PSLZSnT ceramics present pseudo-cubic structure and rather uniform microstructural morphology accompanied by relatively small grain size. Excellent energy-storage performance is obtained in the Y2O3-doped PSLZSnT ceramics, in which the value of the energy-storage density presents a linearly increasing trend within the electric field measurement range. Such excellent performance is considered as relating to the rather pure perovskite structure, high relative density accompanied by relatively small grain size, and the antiferroelectric-like polarization-electric field behavior.
关键词： oxide doping,self-combustion method,energy-storage density,perovskite structure,PSLZSnT antiferroelectric-like ceramics
更新于2025-09-23 15:23:52
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Photocatalytic degradation of phenol by LaFeO3 nanocrystalline synthesized by gel combustion method via citric acid route
摘要： Focusing on the photocatalytic degradation of phenol under visible light, the synthesized lanthanum orthoferrites (LaFeO3) by gel combustion method using citric acid as sacrificial agent were investigated. With the highest reaction temperature of 200 °C, the physicochemical properties of synthesized samples were characterized by X-Ray diffraction (XRD) analysis, Brunauer–Emmet–Teller (BET), and Energy Dispersive X-Ray spectroscopy (EDS). On the other hand, UV–Vis spectroscopy analysis was carried out to determine the phenol photodegradation activities and mechanism. The results suggested the well-defined LaFeO3 nanocrystals with specific area of 28 m2 g?1 were successfully synthesized. Besides that, variations in operating parameters such as pH, catalyst dosage and initial concentration of phenol in synthetic wastewater were also examined. In conclusion, LaFeO3 nanocrystalline exhibited an exceptional photocatalytic activity for phenol degradation, thus providing a perfect alternative for pharmaceutical wastewater treatment.
关键词： Citric acid,Photocatalytic activity,Lanthanum orthoferrite,Phenol,Gel combustion
更新于2025-09-23 15:23:52
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Combustion synthesis of α-Si3N4 with green additives
摘要： This paper reports the combustion synthesis of α-Si3N4 using green additives of water and alcohol. The addition of water and alcohol is demonstrated to be effective in controlling the reaction kinetics and improving the formation of α-Si3N4 by vapor reactions. With increasing proportion of additives in the starting composition, the content of α-Si3N4 in the product is clearly enhanced. In contrast to the ammonium halides usually employed as additives in the combustion synthesis of α-Si3N4, the green additives used here are nontoxic, noncorrosive, and thus more attractive for industrial applications.
关键词： Silicon nitride,Combustion synthesis
更新于2025-09-23 15:23:52
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A Study of Two Dimensional Tomography Reconstruction of Temperature and Gas Concentration in a Combustion Field Using TDLAS
摘要： Based on tunable diode laser absorption spectroscopy (TDLAS), two-dimensional (2D) distribution reconstructions of gas concentration and temperature are realized using an algebraic reconstruction technique (ART). The influence of the beam distribution and grid size on combustion field reconstruction is investigated to attain optimal reconstruction results with a limited number of beams. Under limited optical-path numbers, it shows that a better spatial resolution is attainable only when the laser beam paths are vertical and parallel to the symmetry axis of the combustion field. Furthermore, experiments with 16 beam paths using one and two flat flame combustion fields are carried out in different fuel-air equivalence ratios under room temperature. The results are in agreement with the simulation results, and the time resolution is less than 1 s.
关键词： tomographic imaging,diode lasers,temperature,spectroscopy,combustion diagnostics,absorption
更新于2025-09-23 15:23:52
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Silica-coating of nano-$$\hbox {Y}_{3} \hbox {Al}_{5} \hbox {O}_{12}{:}\hbox {Ce}^{3+}$$Y3Al5O12:Ce3+ synthesized by self-combustion
摘要： Y2.91Ce0.09Al5O12 is obtained by self-combustion, grinding and sol–gel coating. X-ray diffraction, transmission electron microscopy, photoluminescence and absorption measurements were used to identify the structural and optical properties of each step of the process. The process is composed of a combination of chemical and physico-chemical processes including combustion and thermal steps, followed by grinding, powder dispersion by acidic passivation, stabilization of particle dispersions with citrate ligands and embedding of yttrium aluminium garnet (YAG) particles into SiO2 shells using a seeded growth process before drying. The initial state of the obtained powder is composed of 35 nm crystallites, sintered and agglomerated. The grinding step breaks the sintered bridge, while the passivation and citrate adsorption steps separate the particles by electrostatic repulsion before the silica coating. The optical characterizations are performed and compared separately for the powdered samples that represent the initial and ?nal states of our process, and the dispersion sample represents the intermediate state of our process. The optical measurement revealed an important amount of optical defects at the surface of the particles, compared with micrometric commercial particles. The grinding, nitric acid and citrate steps remove some of these defects. The ?nal state of the sample still possesses lower quantum ef?ciency than that of a micrometric sample, but the SiO2 coating allows for a perfect separation of the particle, suitable for implementation in small devices.
关键词： Self-combustion,YAG,core–shell,SiO2 coating
更新于2025-09-23 15:23:52
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Synthesis of Bismuth Ferrite BiFeO <sub/>3</sub> by solution combustion method
摘要： In this work we describe the synthesis of bismuth ferrite BiFeO3 (BFO) by the method of combustion in solution. Using the techniques of X-ray diffraction (XRD) together with its refinement Rietveld reveals the existence of a distorted rhombohedral perovskite structure (Space group-R3c). The average size of the BFO crystallite was estimated from the half-height width of the X-ray diffraction peaks using the Scherrer’s equation. The morphology of the prepared sample was determined by scanning electron microscopy (SEM) and stoichiometry ratio of BFO was determined by energy dispersive spectroscopy (EDS)
关键词： BFO,X-Ray Diffraction (XRD),Combustion synthesis,Multiferroics
更新于2025-09-23 15:23:52