Electron trap energy distribution in triphasic ZrO2 nanoparticle and its dosimetric characteristics

Electron trap energy distribution in ZrO₂ prepared by wet chemical synthesis is studied using thermoluminescence (TL). The sample has 70 % monoclinic phase ZrO₂, 25 % cubic phase ZrO₂ and 5 % tetragonal phase ZrO₂. The morphology of its grains is spherical with average size 18.5 ± 3.5 nm as determined by a field-emission scanning electron microscopy. A TL glow curve recorded at 1 ^oC/s following beta irradiation to 10 Gy has an apparently single peak near 75 °C. Kinetic analysis of this glow peak reveals that the peak is composed of several overlapping components. The activation energies of these components lie between 0.40 and 0.80 eV. The activation energies associated with the component traps follow a Gaussian distribution with the maximum at 0.57 ± 0.01 eV and a width of 0.11 ± 0.01 eV. The glow peak shows sublinear dose response between 1 and 15 Gy with the superlinearity index g(D) equal to 0.92 ± 0.01. The glow peak fades with delay between irradiation and measurement. The intensity, noted as peak height decreases by half about 1670 s after irradiation. The glow peak is reproducible. The coefficient of variation of the peak position, peak height and peak area in 20 identical measurements are 1.39, 0.95 and 0.62 % respectively. The TL is attributed to oxygen vacancies (F and F⁺ centres) and intrinsic Ti³⁺ impurities.