The review is devoted to the analysis of the compositional disordering potential of the crystal matrix of a scintillator to improve its scintillation parameters. Technological capabilities to complicate crystal matrices both in anionic and cationic sublattices of a variety of compounds are examined. The effects of the disorder at nano-level on the landscape at the bottom of the conduction band, which is adjacent to the band gap, have been discussed. The ways to control the composition of polycationic compounds when creating precursors, the role of disorder in the anionic sublattice in alkali halide compounds, a positive role of Gd based matrices on scintillation properties, and the control of the heterovalent state of the activator by creation of disorder in silicates have been considered as well. The benefits of introducing a 3D printing method, which is prospective for the engineering and production of scintillators at the nanoscale level, have been manifested.
Technological factors and processes contributing to the scintillation mechanism have been considered in quaternary garnet ceramics doped with Ce(Gd,Lu)3Al2Ga3O12. The super-stoichiometric additive of gadolinium in the material composition or its co-doping with a low concentration of Mg were found to be effective tools to suppress phosphorescence in the quaternary garnet, confirming that it is not an intrinsic property of the material. The Monte-Carlo simulation of electronic excitation transfer demonstrates that the hopping migration along the gadolinium sublattice plays an essential role in forming the scintillation kinetic parameters. Breaking the integrity of the gadolinium sublattice by substitution with heavier lutetium ions increases the role of self-trapped states in the excitation of Ce3+ ions, which ensures both an increase in the fraction of short ~20 ns and very long ~600 ns components in the scintillation kinetics.
This article provides an overview of the latest results in the field of improving the properties of multiatomic inorganic oxide compounds for scintillators. A possibility to control the spatial distribution of nonequilibrium carriers in the ionization track by creating a compositional disorder in the crystalline matrix is in focus. Managing the disorder at the nanoscale level creates an opportunity for the efficient energy loss by carriers during thermalization, smaller spatial dispersion, and, consequently, more efficient binding into excitons and, further, an increase in the scintillation yield. The methods to produce multicationic crystalline scintillation materials have been discussed. The effectiveness of the approach is confirmed for both activated and self-activated scintillation materials.
Luminescent and scintillation ceramic materials with complex shapes, which can be created by stereolithography 3D printing, are of interest for special phosphor and detector applications. Starting powders for such ceramics may possess UV absorption bands; therefore, it is important to study the possible influence of the powders’ luminescent properties on the printing process. This paper deals with complex garnet oxides, Y3Al5O12 and Gd3Al2Ga3O12—well-known hosts for luminescent materials. The photopolymerization rates of slurries based on the luminescent powders produced by various chemical routes are studied, as well as available printing regimes. The slurries containing Ce-doped powders with a broad absorption band in UV have significantly lower photopolymerization rates compared to the undoped ones; a high Ce doping virtually hinders printing with layers thicker than 25–50 μm. Furthermore, the choice of powder synthesis method is shown to influence the printing process. Slurries with Tb-doped powder, with absorption lines at shorter wavelengths, have good photopolymerization activity, close to that of the undoped powder, and can be printed with layer thicknesses of 25–100 μm.