Influence of annealing on the scintillation properties of zinc oxide powders and ceramics

• Different annealing atmospheres produce different luminescence centers in powders.
• Luminescence of each center is accompanied by specific decay curve.
• Intensity of emission of ceramics can be increased by hydrogenous annealing.
• Depth of hydrogenous annealing effect in ceramics is about 100 μm.

It was shown that annealing ZnO and ZnO:Ga initial powders and ceramics in different atmospheres significantly changes the characteristics of the studied samples. Two main luminescence bands of different origins were observed in powders at 540 nm and 580 nm. Annealing either in vacuum or in Ar:H2 atmosphere increased intensity of green luminescence with peak at 540 nm whereas annealing in air enhanced a luminescence band with peak at 580 nm in the powders. Corresponding changes in luminescence kinetic properties were observed. Annealing of the ceramics in vacuum and air did not affect the luminescence properties, while annealing them in Ar:H2 atmosphere increased green luminescence intensity of undoped ceramics and excitonic luminescence intensity of doped ones. Comparison of the X-ray, gamma-ray and cathode-ray excited luminescence lead to conclusion that the enhancement of luminescence intensity took place in surface layer of about 100 μm thickness.