CaF₂ ∶ Yb^{3 +} / Mn^{2 +} 体系中 Mn^{2 +} 的上转换发光

Lanthanide-doped upconversion luminescence generally features in narrow emission band and fixed emission wavelength. In order to obtain photo upconversion with wide-spectrum emission characteristic upon near-infrared laser excitation, upconversion luminescence of CaF₂ : Yb^{3 +} and CaF₂ : Yb^{3 +} / Mn^{2 +} materials is investigated. Yb^{3 +} and Mn^{2 +} ions are codoped into CaF₂ materials as activators. CaF₂ : Yb^{3 +} and CaF₂ : Yb^{3 +} / Mn^{2 +} bulky materials are synthesized using high-temperature solid state reactions. The upconversion luminescence properties of Yb^{3 +} doped and Yb^{3 +} -Mn² + codoped CaF₂ materials are investigated upon 980 nm laser excitation. The experimental results indicate that compared with CaF₂ : Yb^{3 +} system, a new upconversion emission peaked at 620 nm is obtained in CaF₂ : Yb^{3 +} / Mn^{2 +} materials. The cooperative energy transfer from Yb^{3 +} -dimers to Mn^{2 +} is considered to be the main reason for populating excited state of Mn^{2 +} ions and the emission peaked at 620 nm comes from its⁴ T₁ 寅⁶ A₁ transition. The cooperative energy transfer from Yb^{3 +} -dimers to Mn^{2 +} is efficient in CaF₂ : Yb^{3 +} / Mn^{2 +} materials to populate excited Mn^{2 +} and to obtain room-temperature upconversion emission of Mn^{2 +} ions.