Thus, the XRD data indicated that as much as 33 mol% EuO1.5 may be present without formation of other crystalline phases such as c-Eu2O3, even after heating at 650 o C. There was no strong trend in h-ZnO unit cellparameters amongst the very similarly sized ZnO:Eu samples, although a very small reduction in unit cell-volume with increased Eu-content from 5 to 20% Eu was observed. The IR spectra gave similar results as the XRD patterns with the 0-10Eu samples showing similar Zn-O peaks and a very weak band associated to Eu-O vibrations, while the 20Eu and more so the 33Eu sample, showed a relatively stronger Eu-O vibration band. The 33Eu sample also stood out with a differently shaped carbonate peak band, compared to the lower Eu-loadings. This indicates that at least 10% Eu can be present as Eu-oxide clusters in the ZnO crystal in a similar fashion as described for the previously studied 5Eu sample, while the 20Eu sample seem to have at least partially some other mode of Eudoping, and the 33%Eu may have a substantial part of the Eu-oxide doping in a different way than found for the 5Eu sample.