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Distinctive features of diffusion-controlled radiation defect recombination in stoichiometric magnesium aluminate spinel single crystals and transparent polycrystalline ceramics
摘要： MgAl2O4 spinel is important optical material for harsh radiation environment and other important applications. the kinetics of thermal annealing of the basic electron (F, F+) and hole (V) centers in stoichiometric MgAl2O4 spinel irradiated by fast neutrons and protons is analyzed in terms of diffusion-controlled bimolecular reactions. properties of MgAl2O4 single crystals and optical polycrystalline ceramics are compared. it is demonstrated that both transparent ceramics and single crystals, as well as different types of irradiation show qualitatively similar kinetics, but the effective migration energy Ea and pre-exponent D0 are strongly correlated. Such correlation is discussed in terms of the so-called Meyer-Neldel rule known in chemical kinetics of condensed matter. The results for the irradiated spinel are compared with those for sapphire, MgO and other radiation-resistant materials.
关键词： diffusion-controlled bimolecular reactions,MgAl2O4 spinel,thermal annealing,Meyer-Neldel rule,radiation defect recombination
更新于2025-09-23 15:21:01
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Prepara??o e caracteriza??o de espinélio MgAl2O4 nanoestruturado através de síntese por combust?o em solu??o
摘要： This study aimed to investigate the synthesis and characterization of nanostructured MgAl2O4 spinel by different routes of combustion in solution. The MgAl2O4 spinel was synthesized using aluminum nitrate and magnesium nitrate as the sources of metal cations and sucrose as fuel in continuous combustion system (SCCS), and sequencing batch (CS), followed by heat treatment. The obtained powders were characterized by thermogravimetric analysis, gas adsorption for surface area analysis, laser diffraction for particle size measurement, X-ray diffraction, transmission electron microscopy for crystallographic analysis, and scanning electron microscopy (SEM) for powder morphology analysis. Both routes provided high purity powders and nanosized crystallites in the form of micrometric aggregates, whose properties varied depending on the oxide/fuel ratio. The SEM analyzes confirmed the aggregation of powder particles, as particles with irregular and porous morphology. The SCCS route resulted in a powder with similar properties to the CS route with the advantage of being a continuous process with high potential for industrial scale production.
关键词： nanostructured materials,combustion in solution,MgAl2O4 spinel
更新于2025-09-10 09:29:36