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Dense and transparent ceramic samples of a (Gd,Y)3Al2Ga3O12:Ce scintillator were obtained by using stereolithography-based Digital Light Processing (DLP) 3D printing for compacting, subsequent burnout, and pressureless sintering. The effects of stoichiometric deviations and green body compaction methods (uniaxial pressing versus DLP 3D printing) on the optical, luminescent, and scintillation properties of ceramics were analyzed. An excess of Y and Gd in the composition led to an increase in transmittance and to the acceleration of the scintillation kinetics. Moreover, transparent ceramics made of 3D-printed green bodies were found to be superior in light yield to the samples, which were prepared from the same powders and densified by uniaxial pressing.

Compositionally disordered crystalline material (Gd,Y,Tb,Ce)3Al2Ga3O12 was demonstrated to be a highly effective converter of corpuscular ionizing radiation into light. The material was found to be radiation-tolerant to an intense 10 MeV electron beam and had a low temperature dependence on light yield. These findings open an opportunity to utilize the developed material to create long-living, high-flux sources of optical photons under the irradiation of isotope sources. Besides the purposes of the measurement of ionizing radiation by the scintillation method in a harsh irradiation environment, this puts forward the exploiting of the developed material for indirect isotope voltaic batteries and the consideration of a photon engine for travel beyond the solar system, where solar wind force becomes negligible.

The production of scintillating ceramics can require the utilization of the phosphorus compounds at certain stages of 3D-printing, such as vat polymerization, applied for the formation of green bodies before sintering. The effect of phosphorus additive on the microstructure, optical, and scintillation parameters of Gd1.494Y1.494 Ce0.012Al2Ga3O12 (GYAGG:Ce) ceramics obtained by pressureless sintering at 1650 °C in an oxygen atmosphere was investigated for the first time. Phosphorus was introduced in the form of NH4H2PO4 into the initial hydroxycarbonate precipitate in a wide concentration range (from 0 to 0.6 wt.%). With increasing of phosphorus concentration, the density and the optical transmittance of garnet ceramics show a decrease, which is caused by an increase in the number of pores and inclusions. The light yield of fast scintillation, which is caused by Ce3+ ions, was found to be affected by the phosphorus additive as well. Moreover, an increase in phosphorescence intensity was recognized.