The presented work is dedicated to the study and comparison of scintillating properties of zinc oxide samples prepared in different morphologies: whiskers, nanowalls, multipods, and ceramics. It was shown that total transmittance, photo- and radioluminescence spectra, and radioluminescence kinetics can vary significantly depending on sample structure and preparation conditions. The highest total transmittance was registered for ZnO ceramics (>50% at 0.5 mm thickness). Differences in the transmittance of whiskers, nanowalls, and multipods can be attributed to their shape and thickness which affects the amount of light refraction and scattering. The study of radioluminescence demonstrated that all samples, except undoped ceramics and air annealed whiskers, have predominantly fast luminescence with a decay time <1 ns. High transmittance of ceramics opens the way for their use in the registration of high energy X-ray and gamma radiation, where a large volume of scintillators is required. In cases, where large scintillator thickness is not a necessity, one may prefer to use other ZnO structures, such as ensembles of whiskers and nanowalls. Studies of near-band-edge luminescence components at low temperatures showed that the structure is quite similar in all samples except Ga doped ceramics.

This paper discusses the characteristics of ZnO and ZnO:Ga ceramics fabricated by uniaxial hot pressing. The short-wavelength transmission limit of zinc oxide ceramics is in the 370-nm region; the long-wavelength limit is determined by the free-charge-carrier concentration and lies in the interval from 5 to 9 μm. The total transmittance of such ceramics in the visible and near-IR regions is about 70% when the sample is 0.5 mm thick. The luminescence spectrum is represented by a broad emission band with maximum at 580 nm, having a defect nature. The introduction of 0.03–0.1 mass % gallium into the zinc oxide structure inhibits grain growth and increases the free-charge-carrier concentration to 3.44×10¹⁹ cm⁻³. As the gallium concentration increases in the range 0.05–0.1 mass % in a ceramic of composition ZnO:Ga, the defect luminescence band is suppressed and a characteristic exciton luminescence is formed with a maximum corresponding to 389 nm and a damping time constant of 1.1 ns.

Transparent ZnO ceramics are of interest for use as material for high-efficiency fast scintillators. Doping ZnO ceramics in order to improve complex of their properties is a promising direction. In the present research, the role of indium in the ZnO nanopowders surface interactions and in the change of microstructures and photoluminescence (PL) characteristics of sintered cera-mics is considered. Undoped and 0.13 wt% In doped ZnO ceramics are obtained by hot pressing sintering. It has been found that indium leads to the transition of initially faceted ZnO particles to rounded, contributing to good sintering with formation of diffusion active grain boundaries (GBs). Unlike ZnO ceramics, ZnO:In ceramics microstructure is characterised by the trans-crystalline mode of fracture, faceted GBs with places of zig-zag forms and predominant distribution of In at the GBs. Such indium induced modifications of GBs promote removal of point defects and reduce PL parameter α = I _def /I _exc in comparison with the undoped ceramics. Results characterise ZnO:In cera-mics with improved GBs properties as a prospective material for scintillators.

This paper discusses the characteristics of ZnO:Er ceramics fabricated by uniaxial hot pressing. It establishes that the introduction of 0.16–1.0 mass% erbium into the zinc oxide structure reduces the grain size of the ceramic and causes absorption bands to appear in the visible and IR regions, corresponding to interconfiguration transitions from the ground state to the excited states of the $ {\rm Er}^{3 +} $Er³⁺ ions, along with characteristic emission bands in the visible region. Increasing the erbium concentration causes the long-wavelength transmission limit of the ZnO:Er ceramic to shift toward shorter wavelengths by 2–3 µm relative to the undoped ceramic; this is associated with an increase of the charge-carrier concentration from $ 4.9 \times {10^{18}} $4.9×10¹⁸ to $ 1.4 \times {10^{19}}\,\,{\rm cm}^{{ - 3}} $1.4×10¹⁹cm⁻³. Moreover, as the erbium concentration is increased, the defect luminescence band becomes less intense, and the scintillation burst falls off more rapidly.

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Uniaxial hot pressing has been used to obtain ceramics based on zinc oxide, and their optical, x-ray-structure, luminescence, and scintillation characteristics have been studied. It is shown that, by changing the concentration of the dopant (Ga) and the codopant (N), it is possible to change the intensities of the edge band (397.5 nm) and the intraband luminescence (510 nm) of the ZnO luminescence, as well as their ratio. Undoped ZnO ceramic has good transparency in the visible region and fairly high luminous yield: 9050 photons per MeV. Ceramic ZnO:Ga possesses intense edge luminescence with a falloff time of about 1 ns.