Phosphor properties transition metal doped

State and the equipment for high-pressure generation and control are described. Then, the influence of pressure on basic luminescence properties is discussed. The main part of the review concerns the recent literature, which presents a range of phenomena observable at high pressure where special attention is paid to inorganic phosphors materials doped with transition-metal and rare-earth ions. We conclude with several remarks about the future. 

In this part, single activator-doped systems with multicolor emission are briefly introduced. The luminescent properties of a phosphor are basically determined by the host stmcture and the characteristics of the activator. Rare-earth ions and some transitional-metal ions are usually used as activators of phosphor. The energy-level spectra of some rare-earth ions, such as Eu ", Pr , Tb ", and Dy " contain several metastable multiplets that can offer the possibility of simultaneous emission in the blue, green, orange, red, and infrared wavelengths in different crystalline hosts. In turn, these are strongly affected by the host lattice (phonon frequency as well as the crystal stmcture), and the concentration of the activators decide the different color-emission intensities from 4 -4C transitions. The emissions of other rare-earth ions with —> / transition (Eu ", Ce " ), including transitional metal ions with... 

Semiconductors in nano-crystallized form exhibit markedly different electrical, optical and structural properties as compared to those in the bulk form [1-10]. Out of these, the ones suited as phosphor host material show considerable size dependent luminescence properties when an impurity is doped in a quantum-confined structure. The impurity incorporation transfers the dominant recombination route from the surface states to impurity states. If the impurity-induced transition can be localized as in the case of the transition metals or the rare earth elements, the radiative efficiency of the impurity- induced emission increases significantly. The emission and decay characteristics of the phosphors are, therefore, modified in nanocrystallized form. Also, the continuous shift of the absorption edge to higher energy due to quantum confinement effect, imparts these materials a degree of tailorability. Obviously, all these attributes of a doped nanocrystalline phosphor material are very attractive for optoelectronic device applications. 

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