| Summary: | 碩士 === 國立交通大學 === 應用化學系所 === 94 === The discovery and luminescent properties of seven highly saturated red-emitting Mn-activated phosphors are to be described in this thesis. As indicated by the X-ray (XRD) data, Mn was found to substitute for different cation sites. The XRD profiles for both Mn-doped phosphors were found to be in good agreement with those reported in literature. Moreover, the oxidation state of Mn has been confirmed to be 4+ as indicated by core level Mn 2p1/2 and 2p3/2 X-ray photoelectron spectra(XPS) spectra for the Mn4+-activated phosphors.
Furthermore, the comparisons of PLE spectra for the seven Mn4+-activated phosphors reveal that the two excitation bands occuring in near-UV range can be attributed to the 4A2→4T1,2(F) transitions of Mn4+ and the emission was found to be vibronic multiplets attributed to the 2E→4A2 transitions with wavelength ranging from 620 to 700 nm. As indicated by the photoluminescence (PL) spectra, the optimal Mn4+ dopant contents of A, D, F and G were found to be 0.25%, and for B as well as C were found to be 1.0%. Additionally, the optimal Mn4+ dopant contents in E is 0.5%. The C.I.E. chromaticity coordinates of these Mn4+-activated phosphors are exceptionally close to that (i.e., (0.735, 0.265)) of pure red. In summary, as a potential phosphor for white-light LEDs and medical light therapy the Mn4+-activated phosphors showed characteristically purely red emission in the range of 620~700 nm when excited with violet blue radiation.
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