Advanced nanocrystalline ZrO2 for optical oxygen sensors

It was shown that ZrO₂ nanopowders and nanoceramics can be used as an optical oxygen sensor, where the luminescence signal is proportional to the partial oxygen pressure in gases. The nanopowders were obtained in a hydrothermal microwave driven process followed by annealing at 750°C. Nanoceramics were obtained by sintering at pressures up to 6 GPa and at 250°C so that grain growth did not occur. Luminescence of both materials depends linearly on the oxygen content in nitrogen-oxygen mixtures for 2.1% - 25 vol% oxygen content. For luminescence excitation using an electron beam, the luminescence intensity decreases as oxygen pressure increases. For excitation with a laser beam, the opposite effect is observed - the lower the oxygen pressure, the lower the luminescence signal. The experimental results are explained in terms of luminescence centers being distorted lattice sites close to vacancies.