Yoon, SonghakMaegli, Alexandra E.Matam, Santhosh KumarTrottmann, MatthiasHisatomi, TakashiLeroy, Celine MarieGraetzel, MichaelPokrant, SimoneWeidenkaff, Anke2013-04-152013-04-152013-04-15201310.1155/2013/507194https://infoscience.epfl.ch/handle/20.500.14299/91505WOS:000315883700001Phase-pure tantalum oxynitride (beta-TaON) powders were synthesized by thermal ammonolysis of Ta2O5 powders. X-ray diffraction revealed an enlargement of the unit cell and an increase of the crystallite size with increasing ammonolysis temperature. Scanning electron microscopy showed reduced particle sizes for beta-TaON synthesized at 800 and 900 degrees C compared to the precursor oxide. With increasing nitridation temperature the Brunauer-Emmett-Teller surface area was reduced and the nitrogen content increased. UV-Vis spectroscopy showed a bandgap energy of 2.6-2.4 eV. The highest oxygen evolution rate of 220 mu mol.g(-1).h(-1) was achieved for beta-TaON synthesized at 800 degrees C. The factors determining the photocatalytic activity of beta-TaON powders were found to be the specific surface area and defects in the beta-TaON.text::journal::journal article::research article