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Rapid synthesis of AlON powders by low temperature solid-state reaction
摘要： High synthesis temperatures and long soaking times are generally required to fabricate AlON powders, which can cause coarsening and aggregation of the powder. Solid-state reaction methods form AlON powders by a direct reaction of Al2O3 and AlN, enabling rapid synthesis of AlON powder at low temperatures. In this work, single phase AlON powders were fabricated by a solid-state reaction method using Al2O3 and AlN powders as raw materials. To lower the synthesis temperature and shorten the soaking time, the raw materials particle sizes and the homogeneity of the Al2O3/AlN mixture were investigated. The effects of AlN content, synthesis temperature, and soaking time on the synthesis of AlON powders were examined. When the AlN content was 27 mol %, single phase AlON powders were synthesized by calcining Al2O3/AlN mixture at 1680 °C for 20 min. After ball-milling at 250 rpm for 24 h, the synthesized AlON powder was ground into a single phase fine AlON powder with an average particle diameter of 320 nm, a narrow size distribution, and good dispersibility. Transparent AlON ceramics with dimensions of Φ100 mm × 1 mm were fabricated by pressureless sintering the produced fine AlON powder.
关键词： B.Grain size,Aluminum oxynitride,A. Powders: solid-state reaction
更新于2025-11-19 16:56:35
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A development of new red phosphor based on europium doped as well as substituted Barium Lanthanum Aluminate (BaLaAlO4: Eu3+)
摘要： New red emitting Eu3+ doped and substituted BaLaAlO4 phosphor powders were synthesized by simple modified solid state reaction method. BaLaAlO4 crystal phase formation studied through powder X-ray diffraction (XRD) analysis. Fourier Transform - Infra Red (FT-IR) analysis was performed to study the formation of the host with respect to temperature increment and metal-oxygen bond vibrations of BaLaAlO4 host lattice. Morphology of the phosphor was appeared as irregular in shapes with agglomeration. Photoluminescence (PL) analysis was performed to study the PL excitation and emission characteristics of the phosphor. It dictates that synthesized phosphors exhibited a strong red emission at 626 nm. Substitution effect of Eu3+ in BaLaAlO4 with various compositions such as Ba(1-x)LaAlO4: Eux3+, BaLa(1-y)AlO4: Euy3+ and BaLaAl(1-z)O4: Euz3+ were studied for PL enhancement. Luminescence decay time of the phosphors was also determined. PL thermal quenching and Commission Internationale de l'Eclairage (CIE) chromaticity analysis were carried out to find thermal stability and colour purity of the phosphor sample respectively. The Judd- Ofelt parameters (Ω2 & Ω4) obtained from the emission spectra of Eu3+ ions in BaLaAlO4 host lattice were evaluated and discussed.
关键词： BaLaAlO4,Eu3+,Red phosphor,Substitution effect,Solid state reaction
更新于2025-11-14 15:13:28
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Fabrication of alkali metal sulfate–doped zinc tungstate and their photoluminescence
摘要： The enhancement of photoluminescence of alkali metal sulfate-doped zinc tungstate was investigated. All samples were prepared by solid-state reaction at 800 °C using ZnO, WO3, and alkali metal sulfates as starting powders. The zinc tungstate phase was confirmed from the samples by X-ray diffraction. The emission peak of the samples excited at 275 nm was observed at 465 nm. Rb2SO4 > K2SO4 > Cs2SO4 > undoped > Na2SO4 > Li2SO4 was the order of peak emission intensity of alkali metal sulfate-doped samples. Alkali metals with a large ionic radius (K, Rb, Cs) enhanced the emission of intrinsic luminescence in the blue wavelength region. Moreover, sulfates had the potential to change the luminescence activities of the samples.
关键词： Solid-state reaction,Alkali metal,Zinc tungstate,Sulfate,Photoluminescence
更新于2025-09-23 15:23:52
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Tunable photoluminescence properties and energy transfer of Ca5(BO3)3F: Tb3+/Eu3+ phosphors for solid state lighting
摘要： A series of Ca5(BO3)3F: Tb3+/Eu3+ phosphors have been prepared via solid-state reaction. Phase purity and crystal structure of as-prepared samples are confirmed by X-ray diffraction measurements. The emission intensity of Ca5(BO3)3F: Tb3+ with Li+, Na+, K+ as charge compensators are remarkably enhanced, and the sample in presence of Na+ exhibits the strongest emission intensity. The emission spectra and fluorescence decays confirm the presence of efficient energy transfers from Tb3+ to Eu3+ in Ca5(BO3)3F: Tb3+/Eu3+ phosphors. The energy transfer mechanism between Tb3+ and Eu3+ has been proven to be resonant type via the electric dipole-dipole interaction. The thermal quenching temperature T50 obtained from the temperature-dependent emission spectra is 478 K, demonstrating a high thermal stability of the as-obtained Ca5(BO3)3F: Tb3+/Eu3+ phosphors. Moreover, by increasing the molar ratio of Eu3+ to Tb3+, the emission colors of Ca5(BO3)3F: Tb3+/Eu3+ phosphors can be tuned from green to orange, and then to red. These results demonstrate that the as-obtained Ca5(BO3)3F: Tb3+/Eu3+ phosphors may have potential applications in solid-state lighting fields.
关键词： Energy transfer,Ca5(BO3)3F,Phosphors,Tunable luminescence,Solid-state reaction
更新于2025-09-23 15:23:52
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Fraction of Rare-Earth (Sm/Nd)-Lanthanum Ferrite-Based Perovskite Ferroelectric and Magnetic Nanopowders
摘要： Multiferroic compound, especially LaFeO3-based perovskite nanopowders that exhibit robust simultaneous ferromagnetism and ferroelectricity, are widely investigated and applied in different applications. In this work, we report the synthesis and characterization pertaining to fraction of rare-earth (Sm/Nd)-substituted lanthanum ferrite based perovskite nanopowders via solid-state technique. The multiferroic phenomenon is the fundamental approach to combine both the ferromagnetic and ferroelectric properties in a single system. Reduction in crystallite size, as well as some lattice distortion effects, are included to show the possibilities of tuning the lattice structure, electrical, optical as well as the magnetic properties which are closely connected to the ferroelectric behavior and magnetism. At room temperature, the ferroelectric behavior of La0.9(Sm/Nd)0.1FeO3 exhibiting a P-E hysteresis loop became more and more pronounced, indicating the electrical leakage is greatly reduced. The canted antiferromagnetic hysteresis loop shows that the rare-earth (Sm/Nd) ion can significantly affect the magnetic parameters of the materials.
关键词： Lanthanum ferrite,x-ray diffraction,optical and magnetic properties,solid-state reaction,ferroelectric,UV–Vis spectroscopy
更新于2025-09-23 15:23:52
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Exploration of structural, vibrational and spectroscopic properties of self-activated orthorhombic double molybdate RbEu(MoO4)2 with isolated MoO4 units
摘要： RbEu(MoO4)2 is synthesized by the two-step solid state reaction method. The crystal structure of RbEu(MoO4)2 is defined by Rietveld analysis in space group Pbcn with cell parameters a=5.13502(5), b=18.8581(2) and c=8.12849(7) ?, V=787.13(1) ?3, Z=4 (RB=0.86%). This molybdate possesses its phase transition at 817 K and melts at 1250K. The Raman spectra were measured with the excitation at l =1064 and 514.5nm. The photoluminescence spectrum is evaluated under the excitation at 514.5nm. The absolute domination of hypersensitive 5D0(cid:1)7F2 transition is observed. The ultranarrow 5D0(cid:1)7F0 transition in RbEu(MoO4)2 is positioned at 580.2nm being 0.2nm blue shifted, with respect to that in Eu2(MoO4)3.
关键词： Rietveld refinement,rubidium europium molybdate,Raman luminescence,solid state reaction,DSC
更新于2025-09-23 15:23:52
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Shock synthesis of Sr2Si5N8:Eu2+ phosphor
摘要： A new approach to synthesise the red-emitting nitridosilicate phosphor Sr2Si5N8:Eu2+ using shock waves is described. The solid state reaction of a mixture of Si3N4, Sr3N2 and EuN was induced using a detonation-driven shock wave apparatus. The obtained products consist of Sr2Si5N8:Eu2+ with a purity of 80–89 %, containing 7–9 % of SrSi7N10 and 4–11 % α-Si3N4, according to Rietveld analyses. Crystallites with sizes of 240–310 nm are formed, yielding particles of 2–3 μm grain size. The luminescence properties are similar to conventionally produced Sr2Si5N8:Eu2+ phosphors.
关键词： High-pressure,Phosphors,Luminescence,Solid state reaction
更新于2025-09-23 15:23:52
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A comparative study of Sr-doped LaMnO <sub/>3</sub> synthesised via solid-state reaction and sol–gel methods
摘要： This work deals with the synthesis of hole-doped La1-xSrxMnO3 (x = 0.25 and 0.33) perovskite via two different ways, namely a solid-state reaction method and a sol–gel process. Various properties of the samples have been investigated and compared by means of different techniques, namely X-ray diffraction (XRD), temperature-dependent resistivity measurements in the temperature range 25–300 K using a closed cycle refrigerator and vibrating sample magnetometry (VSM). All samples have orthorhombic crystal symmetry and an irregular variation in unit-cell volume with increase in Sr content. The average crystallite size was determined from the XRD data and found to lie in the range 19–22 nm. Metal–insulator transitions (MIT) were observed in all the samples via low-temperature electrical characterisations. The magnetic measurements confirm that the magnetisation does not saturate for the 25% Sr doped samples up to the available field of 10 kOe. The magnetic response also supports the interpretation of XRD and resistivity data. The obtained results are explained on the basis of double-exchange and super-exchange mechanisms.
关键词： CMR,manganites,metal to insulator transition (MIT),sol–gel method,Solid-state reaction
更新于2025-09-23 15:22:29
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Engineering of hollow AlAu2 nanoparticles on sapphire by solid state dewetting and oxidation of Al
摘要： The Al-Au binary diffusion couple is a classic example of the system exhibiting Kirkendall voiding during interdiffusion. We demonstrate that this effect, which is a major reason for failures of the wire bonds in microelectronics, can be utilized for producing hollow AlAu2 nanoparticles attached to sapphire substrate. To this end, we produced the core-shell Al-Au nanoparticles by performing a solid state dewetting treatment of Al thin film deposited on sapphire substrate, followed by the deposition of thin Au layer on the top of dewetted sample. Annealing of the core-shell nanoparticles in air resulted in outdiffusion of Al from the particles, formation of pores, and growth of the AlAu2 intermetallic phase in the particles. We demonstrated that the driving force for hollowing is the oxidation reaction of the Al atoms at the Au-sapphire interface, leading to the homoepitaxial growth of newly formed alumina at the interface. We developed a kinetic model of hollowing controlled by diffusion of oxygen through the Au thin film, and estimated the solubility of oxygen in solid Au. Our work demonstrates that the core-shell nanoparticles attached to the substrate can be hollowed by the Kirkendall effect in the thin film spatially separated from the particles.
关键词： Diffusion,Nanovoid,Solid state reaction,Kirkendall effect,Nanoparticles
更新于2025-09-23 15:22:29
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Visible light photocatalytic dye decomposition behaviour of solid state reaction grown Zn <sub/>2</sub> TiO <sub/>4</sub> nanoparticles
摘要： In this investigation, visible photocatalytic dye decomposition is carried out with compound semiconductor nanoparticles of zinc orthotitanate (Zn2TiO4). These nanoparticles were grown by the solid state reaction method and characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, diffuse reflectance spectroscopy, photoluminescence study, and Brunauer–Emmett–Teller (BET) study. The BET surface area of the Zn2TiO4 nanoparticles was found to be 8.78 m2/g. The photocatalytic activity is carried out by using a 500 W halogen light source having a spectrum in the range of 450 to 860 nm and the reaction kinetics was found to be the pseudo first order. The reaction rate constant was found to be 0.069 min?1. Discussion is given on the possible mechanism of the observed visible photocatalytic dye decomposition activity. The cost of the material used is very low, so it could be very useful for visible photocatalytic dye decomposition.
关键词： visible photocatalysis,zinc orthotitanate,solid state reaction,dye decomposition,nanoparticles
更新于2025-09-23 15:22:29