Optical Absorption Spectra of (Mg, Fe)SiO3Silicate Perovskites

✍ Scribed by Guoyin Shen; Yingwei Fei; Ulf Hålenius; Yanbin Wang

• Publisher: Springer-Verlag
• Year: 1994
• Tongue: English
• Weight: 533 KB
• Volume: 20
• Category: Article
• ISSN: 0342-1791
• DOI: 10.1007/bf00203217

✦ Synopsis

Electronic absorption spectra have been measured at room temperature and pressure for polycrystalline samples of (Mg, Fe)SiO 3 silicate perovskites synthesized by multi-anvil device. One strong near-infrared band at about 7000 cm-1 and several weak bands in the visible region were found. The near-infrared band at 7000 cm -1 is assigned to a spin-allowed transition of Fe 2 + at the 8-12 coordinated site in perovskite. However, definite assignments of the weak bands in the visible region are difficult because of their low intensities and the scattering effect at the gain boundaries. Crystal field calculations for Fe 2 § at different sites in perovskite have been carried out based on the crystal structure data. The results agree with the assignment of Fe 2 + to the 8-12 coordinated site in perovskite. Crystal field stabilization energy of Fe 2 + with coordination number of 8 in perovskite is 3332 cm-1 which is small compared to the octahedral site of magnesiowfistite (4320 cm-1), another important lower-mantle mineral.