Synthesis and optical properties of Ni/Co/Cr doped BaMg6Ti6O19

Novel green and blue chromophores based on Ni/Co/Cr doped BaMg 6 Ti 6 O 19 solid solutions are successfully synthesized through a solid-state reaction. The crystal structure of all the samples belongs to the magnetoplumbite structure with the space group of P 6 3 / mmc . The BaMg 6- x /2 Ti 6- x /2 Ni x O 19 (0 ≤  x  ≤ 0.3) compounds exhibit a light green ( x  = 0.1) to yellow-green ( x  = 0.3) color. The oxidation state of Ni is confirmed to be +2 valence and the d-d transition of Ni 2+ in octahedral sites is responsible for color. BaMg 6- x /2 Ti 6- x /2 Co x O 19 (0 ≤  x  ≤ 0.3) series show a blue color and the intensity of blueness is increasing with the increase of Co content. The blue color is due to d-d transitions within Co 2+ present in the tetrahedral sites. For BaMg 6- x /2 Ti 6- x /2 Cr x O 19 (0 ≤  x  ≤ 2) phases the color varies from light green ( x  = 0.2) to green ( x  = 2). Chromium exists in +3 and + 6 oxidation states and the observed color is due to charge transfer transition between Cr 3+ –Ti 4+ and d-d transitions within octahedral Cr 3+ sites resulting in strong absorption in the visible region. The synthesized colored oxides are mixed with PMMA to prepare novel green and blue PMMA polymer composites to evaluate their compatibility in plastics.