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

Abstract

Novel green and blue chromophores based on Ni/Co/Cr doped BaMg6Ti6O19 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 P63/mmc. The BaMg6-x/2Ti6-x/2NixO19 (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 Ni2+ in octahedral sites is responsible for color. BaMg6-x/2Ti6-x/2CoxO19 (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 Co2+ present in the tetrahedral sites. For BaMg6-x/2Ti6-x/2CrxO19 (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 Cr3+–Ti4+ and d-d transitions within octahedral Cr3+ 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.