Correlation Between the Impurity Content, the Average Charge State of Chromium Cations and Optical Absorption in Sillenite Crystals Doped by Chromium in Wide Range of Concentrations

Effect of Cr doping on the properties and photocatalytic activity of Bi12TiO20

“…It was claimed that chromium cations doped in sillenite (Bi 12 SiO 20 , Bi 12 TiO 20 ) crystals have at least two nonequivalent valence states and the chromium cations have the highest oxidation state (6?) at high doping levels [14]. In this work, however, the BTO was doped with very low concentration of Cr and therefore it is likely that Cr in BTO has a lower oxidation state.…”

“…3). It was found that even a small amount of Cr in BTO strongly affects its optical properties and especially it shifts the absorption edge of BTO toward lower frequency [14]. In addition, the improved photocatalytic activity of Cr-doped BTO under visible light irradiation can be also attributed to its lower combination rate of photogenerated electrons and holes, as compared with undoped BTO (Fig.…”

Chromium-doped bismuth titanate nanosheets as enhanced visible-light photocatalysts with a high percentage of reactive {110} facets

“…It was claimed that chromium cations doped in sillenite crystals have at least two non-equivalent valence states and the chromium cations have the highest oxidation state (6+) at high doping levels. 33 In this work, however, the Bi 4 Ti 3 O 12 nanosheets was doped with very low concentration of Cr and therefore it is likely that Cr in Bi 4 Ti 3 O 12 nanosheets has a lower oxidation state. Similar results were also reported for sillenite compounds doped with low concentration of Cr, presenting that Cr in the this compound is in the Cr 4+ oxidation state.…”

“…The relationship of doping ions and metal oxides as novel photocatalysts has been paid more attention in the previous reports. [32][33][34][35][36][37] In order to reveal the very essential part of the chromium-doped bismuth titanate, the chemical states of as-prepared Bi 4 Ti 2.6 Cr 0.4 O 12 nanosheets were carefully checked by the X-ray photoelectron spectroscopy (XPS), as shown in Fig. 5.…”

“…4 displays FT-IR spectra of the Bi 4 Ti 2.6 Cr 0.4 O 12 nanosheets.The typical characteristics of oxygen metal bonds are observed in the range of 600-850 cm À1 . The two strong peaks near 819 and 580 cm À1 were agreed with the stretching vibrations of Bi-O and Ti-O, respectively,17,19 demonstrating that chromium-doping does not have an effect on the phase of Bi 4 Ti 3 O 12 , which is in agreement with the XRD results.The relationship of doping ions and metal oxides as novel photocatalysts has been paid more attention in the previous reports [32][33][34][35][36][37]. In order to reveal the very essential part of the chromium-doped bismuth titanate, the chemical states of as-prepared Bi 4 Ti 2.6 Cr 0.4 O 12 nanosheets were carefully checked by the X-ray photoelectron spectroscopy (XPS), as shown in Fig.5.…”