Photoluminescent and scintillant properties of highly transparent [(Y 1‐ x Gd x ) 0.99 Dy 0.01 ] 2 O 3 ( x = 0 and 0.4) ceramics

High‐optical‐quality ternary [(Y 1‐ x Gd x ) 0.99 Dy 0.01 ] 2 O 3 ( x  = 0 and 0.4) ceramics were successfully fabricated by vacuum sintering with in‐line transmittances of 71.4%‐75.1% at 574 nm, the wavelength of Dy 3+ emission (the 4 F 9/2  →  6 H 13/2 transition). Substitution of Gd 3+ for Y 3+ significantly affected the photoluminescent and scintillant properties of the ceramics. Gd 3+ addition effectively increased lattice parameters and theoretical densities of the ceramic samples; this contributed to enhanced X‐ray absorption coefficients. Both [(Y 1‐ x Gd x ) 0.99 Dy 0.01 ] 2 O 3 ( x  = 0 and 0.4) ceramics displayed typical Dy 3+ emissions from 4 F 9/2  →  6 H J ( J =  15/2, 13/2, 11/2) transitions under UV and X‐ray irradiations. By incorporating Gd 3+ into the lattice, a stronger excitation peak of Gd 3+ due to internal f ‐ f transitions relative to Dy 3+ was observed at 276 nm; subsequent ceramics obtained a sharper PL intensity and a warmer hue via effective energy transfer from Gd 3+ to Dy 3+ . Using a Gd 3+ dopant generally reduces the total photoluminescence/photoluminescence excitation intensities and light output; it also delays the lifetime and afterglow of the transparent ceramics.