Method for measuring the oxygen content in a gas

The method consists in measuring photoluminescence of a calibrated sensor (3), containing nanocrystalline zirconium dioxide, contacted with tested gas. The sensor is heated to a specific temperature and a beam (11) of electromagnetic radiation is directed on it, then photoluminescence caused by that radiation is measured, whereupon the measurement result is compared with the sensor's calibration data. In the sensor (3) there is used nanocrystalline zirconium dioxide doped with europium (Eu3+) ions at the level of 2 to 10% mol, characterised by an average size of the crystallites no greater than 60 nm. The electromagnetic radiation causing photoluminescence of the sensor, is in a form of a radiation of essentially constant intensity throughout the measurement.