In this study, blue‐emitting AlN:Eu2+ spherical phosphors were successfully synthesized for the first time by the carbothermal reduction nitridation (CRN) method, assisted with high nitrogen pressure, appropriate synthesis temperature, and the addition of CaF2. The influence of typical experimental parameters, such as N2 pressure, heating temperature, CaF2 content and Eu2+ concentration on the morphologies and luminescence properties of AlN phosphors were comprehensively investigated. The formation mechanism of spherical morphology were significantly proffered, indicating that sufficient liquid Ca‐aluminates during the AlN growth stage were essential for the spheroidization process under the action of surface tension. The synthesized AlN:Eu2+ spherical phosphors presented an intense blue emission band centered in the range of 427‐ 476 nm relative to the reaction temperature. The lifetime of AlN:Eu2+ phosphor was calculated to be around 1.89 μs. The temperature‐dependent PL spectra suggested that the emission band did not shift until 225°C. In addition, the spectral analysis strongly suggested that the luminescence property of AlN:Eu2+ phosphors was significantly enhanced by the large particle size, spherical morphology, reduced impurity content, and appropriate Eu2+ concentration.
h i g h l i g h t sThe skeletal mechanism of n-heptane combustion was developed and validated. n-Heptane/oxygen were investigated by the developed skeletal mechanism. The maximum soot volume fraction increases as f v,max / P 2 with increasing pressure.n-Heptane/oxygen flame height decreased with increasing pressure.
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b s t r a c tA skeletal reaction mechanism of n-heptane combustion is developed and validated. The axisymmetric laminar co-flow diffusion flames of n-heptane/oxygen are simulated using the skeletal mechanism at elevated pressure, and the chemical reaction paths in three reaction zones of flame are presented. The n-heptane/oxygen flame height decreases from 8.8 to 5.6 mm with the increase of pressure from 0.1 to 2 MPa, and the Roper's formulation is not expected for the prediction of n-heptane/oxygen flame height.The maximum volume fraction of soot increases with pressure as f v,max / P 2 . The ratio of flame height to soot oxidation length of the n-heptane/oxygen flames is close to unity (1.037-1.121).
The environment-friendly synthesis and property modulation of two-dimensional organic–inorganic halide perovskite (2D OHP) single crystals with large sizes and high quality are important for the fabrication of optoelectric devices.
Measurement of the oxygen dissociation fraction in RF low pressure oxygen/argon plasma using optical emission spectrometry is presented. The oxygen dissociation fraction and its evolutions as functions of operational parameters were determined using argon as the actinometer. At a pressure of 30 Pa, the oxygen dissociation fraction decreased from 13.4% to 9.5% as the input power increased from 10 W to 70 W. At an input power of 50 W, the oxygen dissociation fraction decreased from 12.3% to 7.7% when the gas pressure increased from 10 Pa to 40 Pa. The influences of operational parameters on the generation of atomic oxygen were also discussed.
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