Synthesis, Structural And Optical Properties Of Mn²⁺ Doped 12CaO·7Al₂O₃

In this paper, we use sol-gel method to prepare a set of different concentrations of Mn2+ doped 12CaO·7Al2O3(C12A7:Mn2+)powder samples. We use X-ray diffraction spectroscopy (XRD), micro-Raman spectroscopy and scanning electron microscopy to characterize the micro-structure of C12A7:Mn2+. We also use the excitation spectra, the emission spectra and other testing methods to characterize the optical properties of the samples.According to scanning electron micrographs of the sample, we observed a smooth surface, and its diameter is about 400nm.We also found that the sample has a porous internal structure. We had characterized the sample by XRD and micro-Raman spectroscopy, the XRD shows that the sample has a good match with the standard C12A7 lines. The XRD and micro-Raman spectroscopy do not show other phases than the C12A7 phase, indicating the doping of Mn2+ does not destroy the original lattice structure, which still maintain the unique cage structure of C12A7. According to analyzing anglicizing the results, we believe that the samples are single-phase C12A7: Mn2+ powder.By the excitation spectroscopy, we observed two broad absorption band in 330nm and 350 nm wavelength, which comes from the transition of the 6A1(6S) energy level of Mn2+ to the forbidden energy level 4T1(4P). Using the 350nm wavelength light as emission spectra excitation light to characterize the samples, we found that, with the doping concentration increases, the luminous intensity of powder samples has gradually become stronger and there is a weaker yellow-green band with a 520-650 nm broadband. In the emission spectra, the weaker yellow-green band'peak is at 565nm, due to the space extension of 5d wave function, making the luminescence of Mn2+ become weak broadband emission and decrease its luminous intensity. The weaker yellow-green emission band comes from the radiation transition of 4T1 energy level of Mn2+ to the energy level 6A1.According to the conclusion of our experiment, we think C12A7 is an ideal host material for doping Mn2+. C12A7:Mn2+ not only has broad prospects in luminescent material, but also can be applied in diluted magnetic semiconductors.