ESR Study of MoO3 Obtained from Thermal Decomposition of Ammonium Molybdate

The thermal decomposition of ammonium molybdate, between 100–600°C was studied by ESR technique. At 250 °C all ammonium molybdate was decomposed into molybdenum trioxide. Samples taken at 250, 300, 350, 400 and 450 °C all gave ESR signals. Samples at other temperatures (higher and below of this temperature range) did not give any ESR signal. The ESR signals were due to the formation of Mo5+ and Mo3+ ions. The maximum ESR intensity was observed for the sample (MoO3) at 300 °C. The different colouration of molybdenum trioxide formed at different temperature, was due to Mo5+ and Mo3+ ions.