A method for preparing rare-earth element-doped yttrium oxide phosphor photonic band gap crystals (PBG) is described, which obviates the necessity for multiple infilling of the opal-like template. The method utilizes (i) the re-dissolving and the concentration of previously precipitated spherical phosphor particles made by homogeneous precipitation methods into a viscous precursor phosphor solution, and (ii) formation of an opal-like template of polystyrene or silica spheres. A procedure is outlined that permits the precursor solution to be drawn into the template in a controlled manner that can be easily monitored using an optical microscope. Attenuation of the strong, red cathodoluminescent emission is observed in Y2O3:Eu3+ phosphor PBG crystals that are engineered to have a stopband overlapping the emission bands in the red region. This attenuation results from Bragg diffraction of the light emitted within the PBG phosphor crystals.