Oxide and silicate nanophosphors: soft chemical synthesis routes and luminescence properties

Besides well-known quantum dots, lanthanide- and 3d metal-doped oxide and silicate nanocrystals form a new promising class of nanophosphors. Research is boosted by opto-electronic applications, such as lasers, displays and optical storage media, and medical diagnostic applications, such as scintillators and biological essays. This entry summarizes several soft chemical approaches for the synthesis of oxide and silicate nanophosphors with special emphases on salted sol-gel and combustion techniques. Structure and morphology of phosphor nanoparticles are highlighted as a basis for discussion of luminescence properties. Luminescence emission and lifetime data for several nanophosphors are presented. It is found that the luminescence properties of nanoparticles differ from corresponding bulk materials in several ways: (i) spectroscopic changes, as a systematic broadening of the luminescence bands, resulting from a structural disorder intrinsic to the small size, and (ii) an alternated luminescence lifetimes, due to due to the change in the refractive index and modification of energy transfers and cross relaxation processe