Effect of Er³⁺ concentration on the upconversion luminescence of GdOCl:Er³⁺ powders with excitation of 514.5nm
2012
Li, Yong | Wei, Xiantao | Tong, Bihai | Liu, Yi | Zhang, Qing | Sun, Wenbin | Yin, Min
GdOCl phosphors doped with different Er³⁺ concentration were prepared by modified solid state reaction. The structure and purity of the powders were analyzed by X-ray diffraction. Upconversion emissions from blue to violet to ultraviolet regions were observed with excitation of 514.5nm. Power-dependence analysis demonstrated that the two-photon upconversion process populated the luminescent levels ⁴G₁₁/₂, ²P₃/₂, ²H₉/₂, and ⁴F₃/₂, ₅/₂. The energy distribution of upconversion spectra depends on doping concentration, and the intensity ratio between involved energy levels changed with increasing Er³⁺ concentration. The dependence of spectral distribution on concentration was possibly ascribed to cross relaxation process of ²P₃/₂+⁴I₁₅/₂→⁴I₁₃/₂+²H₉/₂. Besides the cross concentration, excited state absorption and energy transfer upconversion were proposed to be the possible mechanisms for upconversion.
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