RAMAN-STUDY OF CRYSTAL-STRUCTURE OF GAS-EVAPORATED MOO3 MICROCRYSTALS

MoO3 microcrystals were produced by heating a Mo wire in mixture gas of Ar and O2, and their Raman spectra were measured. Although previous electron microscopic studies revealed only an orthorhombic structure of the microcrystals, the present spectra show additional Raman peaks not attributable to the orthorhombic structure. The intensities of the additional peaks depend strongly on the zone of particle collection, total gas pressure and partial O2 pressure. From a comparison between the present Raman data and previous reports on various types of MoO3 crystals (metastable forms), we find that the additional peaks are due to metastable forms of MoO3 crystals.