The overviw of trivalent Pr3+++.doc

The overview of trivalent Pr3+ ion single-doped or co-doped into some host lattices as red emitting phosphors 1 Introductions of trivalent Pr3+ and its schematic energy level diagram Pr3+ ion has rich emission spectral lines in ultra-violet, visible, infrared regions due to its intricate energy level scheme. Pr6011 is composed by PrO2 and Pr2O3. Therefore, Pr3+ doped materials have several applications, such as fiber laser amplifier, red-emitting phosphors, visible lasers and mid-infrared laser. element Atomic number Electronic configuration M M2+ M3+ M4+ Pr 59 4f15d16s2 [4f2] 4f1 4f0 Table 1 Electronic configurations of Pr element It is well-known that exoteric electric field, magnetic field and ligand field have almost no influences on the 4f shell of Pr3+ due to its well-shielding effect by 5s and 5p outside shells, leading to little effect of crystal filed on the energy levels also. Among different rare earth ions, especially Pr3+ ion has unique properties as it offers the possibility of simultaneous blue (3P0→3H4), green (3P1→3H5), red (3P0→3F2), and deep red (3P0→3F4) emission. Additionally, Pr3+-doped inorganic phosphors can be applied in optical displays due to the strong emission from 3P0→3F2 band. This transition is very important, because it can improve the color rendering index in white LEDs. In general, the emission property of a phosphor is usually influenced by the crystal field strength, which is a function of the structure of the host material, the coordination number of the activator, and the electro-negativity of the constituents. In a series of trivalent Pr3+ ion single-doped or co-doped into some host lattices, the Pr3+ ion exhibits a prominent red luminescence from the meta-stable 1D2 level upon ultra-violent (UV) or blue phonon excitation, with partial and even total quenching of the otherwise emitting 3P0 level. Also, this quenching may have different origins: intersystem crossing through a low-lying 4f15d1 state, multi-phonon rel