Effect of Er-doping on the structural and optical properties of Cd₂V₂O₇

Abstract

The melt-quenching method was used to prepare two groups of samples using CdO and V₂O₅ as starting materials. Taking into account that a crystalline-amorphous phase transition would be expected for the CdO–V₂O₅ system, a first batch was prepared varying the proportions of CdO and V₂O₅ in the intervals 60–95 and 40–5 wt%, respectively. With the aim of investigating the effect of erbium in the phase transition and crystalline quality of the first group of samples, a second batch was fabricated with the same proportions of CdO and V₂O₅, with the addition of 5 wt% of Er(NO₃)5H₂O as source of Er³⁺ ions. It was found that crystalline or amorphous samples could be obtained depending on the relative concentrations of CdO and V₂O₅, and that the borderline between amorphous and crystalline samples was affected by the incorporation of Er. From X-ray diffraction, it was possible to identify the formation of the ternary compound Cd₂V₂O₇ in the crystalline cases. The Raman and infrared bands in these samples were in agreement with the lattice modes of Cd₂V₂O₇. Additionally, an improvement in the crystalline quality of Cd₂V₂O₇ was obtained for the Er-doped samples. The effect of the local environment around the Er³⁺ ions on the room temperature photoluminescence was also investigated for the amorphous and crystalline samples.