Synthesis and optical properties of intense blue colors oxides based on Mn5+ in tetrahedral sites in Ba7Al2-xMnxO10+y

Mn-doped Ba 7 Al 2- x Mn x O 10+ y (0 ≤  x  ≤ 0.7) samples with intense blue colors are successfully prepared by solid state reactions. With the increase of Mn content, the colors of compounds are tuned from cyan to ocean blue. FT-IR absorption spectrum and 27 Al NMR spectrum indicate that the structure contains a dominating portion of Al–O tetrahedral sites while a small number of Al–O octahedral sites may also exist. The oxidation state of Mn is proved to be +5. Based on all the analysis, the intense blue shades of the samples are proposed as the d-d transition of Mn 5+ ions in [AlO 4 ] tetrahedral sites.