Facile synthesis of brownmillerite-type oxides Ba2In2-xMnxO5+x through a microwave-assisted process

Brownmillerite-type oxides Ba 2 In 2-x Mn x O 5+x ( 0 ≤ x ≤ 0.6 ) samples showing intense turquoise to green color were synthesized through a novel microwave assisted rapid sintering method. The properties of as-synthesized samples were compared with samples prepared by previously reported solid state reaction by X-ray diffraction, scanning electronic microscopy, UV-visible absorbance spectra and X-ray photoelectron spectroscopy. The X-ray diffraction patterns showed that the structure symmetry converts from orthorhombic to cubic with the increase in Mn content. And UV-visible absorbance spectra revealed that the color is tuned from turquoise to green color by manganese doping. In the as-synthesized samples, manganese is showing Mn 5+ according to the X-ray photoelectron spectroscopy results.