This work shows the results of an optical energy bandgap (Eg) investigation supported by scanning electron microscopy (SEM) of spinel-type zinc stannate (Zn2SnO4) upon doping with rear earth (RE3+) ions (Er3+, Yb3+). The powder samples are synthesized by a mechanochemical solid-state method with the final annealing step at 1200 C. The reference Zn2SnO4 powder sample bandgap (3.87 eV) turning lower upon doping, precisely to 3.5 eV, and 3.37 eV bandgap values found for Er-doped Zn2SnO4 and Er,Yb-codoped Zn2SnO4 powder samples, respectively is a confirmation of the successful incorporation of the RE3+ ions into the Zn2SnO4 host structure. Morphology of the obtained powders shows, in general, the non-uniformly shaped agglomerates, while their particle sizes follow up the bandgap decreasing trend with doping
