Eu3+-doped Sr2(Al1−xMgx)(Al1−xSi1+x)O7 phosphors: electronic, crystal structures and photoluminescence properties
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The union of chemical compositions substitution and spectral controlling is of importance for the discovery of new materials or the implementation of properties optimization. In this work, we employed an effective strategy to regulate crystal structures by chemical unit co-substitution. We applied this strategy to Eu3+-doped Sr2(Al1−xMgx)(Al1−xSi1+x)O7 (0 ≤ x ≤ 1) solid solution phosphor, which was successfully synthesized by high temperature solid state reaction. The crystal structure remained the same group, P-421m, with controlling chemical compositions. The excitation peaks shifted between 263 and 270 nm and emission peaks shifted between 612 and 614 nm with a decreasing Stocks shift in overall tendency. The shift trend was clarified by Crystal Field Theory. The energy band structure and density of states of Sr2Al2SiO7 and Sr2MgSi2O7 were calculated by Density Functional Theory using the generalized gradient approximation. The band gap was also analyzed by diffuse reflectance spectrum as a contrast. The morphology was characterized by field emission scanning electron microscopy. Furthermore, the photoluminescence color of phosphors could be tuned from yellow to orange.
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