Observation of phase decomposition of Sr2FeMoO6 by Raman spectroscopy

Samples of Sr2FeMoO6 were prepared by a solid-state reaction method in an ambient gas of strictly controlled oxygen content. These materials show a room temperature magnetoresistance of 2% in a magnetic field of 1.5 T. The double perovskite phase Sr2FeMoO6 is stable at low oxygen partial pressure. In air at temperatures higher than 400 °C it is unstable and quickly decomposes into SrMoO4 and SrFeO3−x. By means of different techniques such as x-ray diffraction, thermogravimetric analysis (TGA), thermomagnetization (TM) and Raman spectroscopy, we observed phase decomposition of the double perovskite Sr2FeMoO6. The temperature on the sample at the laser spot was estimated based on the ratio of the Stokes and anti-Stokes intensity in the Raman scattering spectra, which were excited by an He–Ne laser beam with power densities ranging from 103 to 104 W cm−2. The estimated temperatures show that the decomposition is greatest around 550 °C. This is in agreement with results obtained from x-ray diffraction, TGA and TM. Copyright © 2001 John Wiley & Sons, Ltd.