No abstract

One important strategy to further enhance the VUV absorption lies in broadening the light absorption in this VUV wavelength region. The mixing of phosphors is a common solution in the case of obtaining a desired color in the case of WLED. However, the VUV region is very sensitive for the considered materials for such purpose, since the deep penetration is very weak and is very affected by the surface of the grains constituting the phosphor (grain size, morphology) [1]. Consequently the collected fluorescence under VUV excitation is not really representative of the mixture of phosphors when this solution is needed. For this reason, we have explored the possibility to develop strategy where the broadening of the VUV absorption can be reached by one pot synthesis since tunability of the band gap can be allowed simply by modifying the alkali ions in the case of phosphates. Adjusting the ratio between mixed alkali ions in the same material is a promising solution.The luminescence of mixed alkali rare earth cyclo-or poly-phosphates with respective formulas MREP 4 O 12 or MRE(PO 3 ) 4 (M = alkali and RE = rare earth ions) has attracted much attention during the last decades. These compounds are characterized by relatively large cyclic anions or long chains built up by PO 4 3−3tetrahedral connected from each other by at least one or two corners. Such structures are favorable for designing rare-earth (RE)-based

No abstract