High Performance Y_1–<i>x</i>Tb_<i>x</i>TaO₄ Single-Crystal Scintillators for X-ray Detection

In pursuit of a single-crystal scintillator that is free from toxic elements and has scintillation properties comparable to commercial CdWO4 in terms of light yield, afterglow, and stopping power, transparent and colorless Y1–xTbxTaO4 mixed single crystals are grown by the floating-zone technique and investigated for the first time as scintillators. With the substitution of Y3+ by Tb3+, the intrinsic UV photoluminescence from YTaO4, stemming from the Ta–O complex, gradually decreases until only the intraionic Tb3+ emissions remain for a Tb concentration below 5%. The optimum scintillation performance is found for 15% Tb concentration: the light yield is ∼1.5 times that of CdWO4, while the density, the stopping power, and the afterglow are comparable. For concentrations above 15% Tb3+, the quadrupole–quadrupole interaction is found to be responsible for the concentration quenching. These results demonstrate the potential of Y0.85Tb0.15TaO4 single crystals as an environmentally friendly alternative to CdWO4 ones for high-energy X-ray radiography.