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A strong greenish-light photoluminescence (PL) emission was measured at room temperature for disordered and ordered powders of CaMoO 4 prepared by the polymeric precursor method. The structural evolution from disordered to ordered powders was accompanied by XRD, Raman spectroscopy, and TEM imagery. Highlevel quantum mechanical calculations in the density functional framework were used to interpret the formation of the structural defects of disorder powders in terms of band diagram and density of states. Complex cluster vacancies) were suggested to be responsible to the appearance of new states shallow and deeply inserted in the band gap. These defects give rise to the PL in disordered powders. The natural PL emission of ordered CaMoO 4 was attributed to an intrinsic slight distortion of the [MoO 4 ] tetrahedral in the short range.

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