| Summary: | 碩士 === 國立交通大學 === 應用化學系 === 87 === This research is attempted to investigate the effect of host compositions, activator concentration, crystal structure, and temperature on the luminescent properties of magnetoplumbite-type Sr(Ga1-xAlx)12O19: R ( R = Eu3+ , Tb3+ , Cr3+ , Mn2+ ; 0 ≦x≦1.0) ( SGAO:R ) phosphors. The SGAO:R phases with R = Eu3+ , Tb3+ , Cr3+ , Mn2+ ) were prepared at 1,400℃ in the air via solid-state route, whereas the formation of SGAO:Mn2+ requires additional annealing under H2/Ar atmosphere at 1,000℃. The lattice dimensions of Sr(Ga1-xAlx)12O19: R were found to shrink gradually with increasing content of Al3+ dopant, as indicated by X-ray diffraction analysis.
In addition, SrGa12O19 was found to be self-activating with emission wavelength (λem) of 429 nm, whereas SrAl12O19 is not, as indicated by cathodoluminescence (CL) measurements. On the other hand, with shrunk lattice dimensions the λem corresponding to 2E →4A2 transition in Sr(Ga1-xAlx)12O19:Cr3+ exhibited blue shift, whereas that corresponding to 4T1→6A1 transition in Sr(Ga1-xAlx)12O19:Mn2+ exhibited red shift. These observation can be rationalized by Tanabe-Sugano diagrams for octahedral Mn2+ and Cr3+ ions , respectively. On the contrary, theλem attributed to Sr(Ga1-xAlx)12O19:Eu3+ or Tb3+ phosphors remains unchanged with expanded lattice dimensions.
Furthermore, we have also investigated the effect of activator concentration on the luminescent properties of SrM12O19:Eu3+ or Tb3+ ( M = Al, Ga ) and the optimal concentration was found to be 10 and 3 atom % for phases with Eu3+ and Tb3+ dopants, respectively. Theλem of typical R-lines of Cr3+ in SrM12O19: ( M = Al, Ga) has been determined to be 692.6 and 694.2 nm, respectively, and that attributed to 4T1→6A1 transition observed in SrGa12O19: Mn2+ was found to be 503 nm and highly dependent on the temperature, as indicated by temperature dependent photoluminescence (PL) emission studies.
The PL and CL emission spectra of MgGa2O4: M ( M = Eu3+ , Tb3+ , Mn2+ ) phases were also investigated in this research.
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