Study on the synthesis and properties of novel grass green oxides based on Ba4In2-xMnxO7+y.

A new solid solution based on general formula Ba 4 In 2- x Mn x O 7+ y (0 ≤ x ≤ 0.2) has been successfully synthesized by the sol-gel method. The compounds exhibited grass green to olive colors. The origin of the color apparently due to the presence of Mn4+ as a chromophore in square pyramidal coordination. The X-ray diffraction results showed that the space group of all samples is I 4/ mmm. The oxidation state of Mn ion is confirmed to be +4 from the results of magnetization measurements and X-ray photoelectronic spectra (XPS). The color of Ba 4 In 2 O 7 is white. With a small amount of Mn substitution, the color of Ba 4 In 2- x Mn x O 7+ y solid solution changes to grass green, and it turned to olive green when x = 0.2. The UV–Vis absorbance spectra revealed that the absorption peaks are fitted with d3 (Mn4+) configuration in the square pyramid, and the mechanism of color is explained. [Display omitted] • Novel grass green Ba 4 In 2- x Mn x O 7+ y was synthesized by a sol-gel method. • The XPS and magnetic measurement confirmed the existence of Mn4+. • Mn4+ is proved to be in the unique square pyramid coordination. • The grass green color is rooted in the d-d transition of Mn4+ in square pyramids. [ABSTRACT FROM AUTHOR]