Photoluminescence in Er-doped V₂O₅ and Er-doped CdV₂O₆

A group of samples from the CdO-V₂O₅ binary system, particularly with high V₂O₅ content, doped with Er ³⁺ were prepared. The set of samples was fabricated using the conventional melt-quenching method. Depending on the proportion of the used reactants, the existence of V₂O₅ and of CdV ₂O₆ was identified from X-ray diffraction measurements and Raman spectroscopy. Depending on the relative concentrations of CdO and V ₂O₅, different types of morphologies for each sample were found in a scanning electron microscope. Their chemical composition was measured from energy dispersive spectroscopy in the same instrument. An effective Er-doping of the order of 1.0±0.35 at% was found for each sample. From optical absorption data, the composition dependent optical band gap was determined with values between 1.94 and 2.29 eV. Finally, photoluminescence experiments showed, in the samples with the highest V₂O₅ content, wide bands associated to oxygen vacancies. For the rest of the samples emissions from electronic transitions of Er³⁺ ions were detected.