Synthesis And Optical Properties Of 12CaO·7Al₂O₃

The best synthesis conditions of C12A7 polycrystalline powder were determined by a large number of experiments, and pure 12CaO·7Al2O3(C12A7) polycrystalline powder and rare-earth-doped C12A7 polycrystalline powder were synthesized by high temperature solid state method. The results of X-ray diffraction showed that there was no new phase appeared in C12A7 polycrystalline powder. The combination of the results of X-ray diffraction and Ultraviolet-visible absorption spectrum were used to analysis the location of the rare-earth ions.Bright green and weak red color were obtained in Er³⁺-doped C12A7 polycrystalline powder under diode laser excitation of 980 nm, and the upconversion emission intensity of green and red color were all enhanced through increasing the doped Er³⁺ ion concentration. Bright green and red color were obtained in Er³⁺/Yb³⁺-doped C12A7 polycrystalline powder under diode laser excitation of 980 nm, and the upconversion emission intensity of green and red color were all enhanced through increasing the the doped Yb³⁺ ion concentration, but obviously, the red upconversion emission intensity enhanced more than the blue upconversion emission intensity. The green emission peaks centered at 530nm and 550nm are attributed to the ²H_11/2/⁴S_3/2→⁴I_15/2 transitions of the Er³⁺ ions, and the observed red emission peaks centered at 660 nm are attributed to the Er³⁺ ion ⁴F_9/2→⁴I_15/2 transition.White upconversion emission were obtained in Er³⁺/Tm³⁺/Yb³⁺-doped C12A7 polycrystalline powder under diode laser excitation of 980 nm through adjusting the doped Er³⁺/Tm³⁺/Yb³⁺ ions concentrations. The results of experiments showed that the white upconversion emission could well be obtained through increasing the doped Yb³⁺ ion concentration and decreasing the doped Tm³⁺ ion concentration while the doped Er³⁺ ion concentration was fixed. On the contrary, the white upconversion emission could also be obtained through decreasing the doped Yb³⁺ ion concentration and increasing the doped Tm³⁺ ion concentration.