Novel S, N co-doped Ba2In2-Cr O5+y oxides: Synthesis and optical properties

Abstract

Abstract The (S, N) co-doped Ba2In2-xCrxO5+y (0 ≤ x ≤ 0.5) oxides are successfully obtained by mixing the Ba2In2-xCrxO5+y oxides and thiourea through a simple ball milling method followed by sintering at 400 °C for 3 h. The colors of the compounds change from orange-brown to yellow-green after reacting with thiourea. When Cr amount is small (x = 0.1), the crystal structure of (S, N) co-doped Ba2In2-xCrxO5+y is orthorhombic Ba2In2O5 phase. When x ≥ 0.3, the crystal structure of the sample is cubic BaInO2.5 phase. And this phase transition is the same as Ba2In2-xCrxO5+y. XPS results reveal that Cr6+ in Ba2In2-xCrxO5+y (0 ≤ x ≤ 0.5) oxides are reduced to Cr3+ after sintering. S exists in both cation and anion forms, and N exists in substitutional forms. UV–Vis analysis indicates that the yellow-green hue comes from the d-d transition of Cr3+, and the doping of S, N ions leads to a red shift of the absorption edge of the samples.