title: [Variation of Raman spectra of oligoclase under 1.0-4.4 GPa].
abstract: Variation of crystal structure of oligoclase with pressure was investigated by the approach of diamond anvil cell (DAC) and in situ micro-Raman spectroscopic measurement at room temperature and under pressures from 1.0 to 4.4 GPa. At 2.9 GPa a new peak round 517 cm(-1) appeared, and a new phase was produced. Near 3.4 GPa a major discontinuity occurs in the pressure dependence of 288 cm(-1) peak arising from the stretching mode of M-O, and 517 cm(-1) peak disappeared, it implied that the oligoclase underwent triclinic to monoclinic phase transition completely at about 3.4 GPa. The peaks at 458 and 516 cm(-1) peaks arising from flexural vibrational mode of Si-O-Si shifted linearly with the increasing pressures, the pressure-related slopes are 1.667 cm(-1)/GPa and 3.560 cm(-1)/GPa, respectively, whereas, the flexural vibrational mode of Al-O-Al at 480 cm(-1) did not shifted linearly with the increasing pressures. The position of 288 cm(-1) peak did not change obviously in comparision with 458, 516 and 480 cm(-1) peaks, which shifted to lower frequency during decompression. The phase transition pressure of feldspar relates to the species of cation in the octatomic rings.
authors.affiliation: Institute of Earthquake Science, China Earthquake Administration, Beijing 100036, China. chao.xie0017@163.com
authors.forename: Chao
authors.initials: C
authors.lastname: Xie
authors.forename: Jian-guo
authors.initials: JG
authors.lastname: Du
authors.forename: Yue-ju
authors.initials: YJ
authors.lastname: Cui
authors.forename: Zhi
authors.initials: Z
authors.lastname: Chen
authors.forename: Wei-bin
authors.initials: WB
authors.lastname: Zhang
authors.forename: Li
authors.initials: L
authors.lastname: Yi
authors.forename: Li
authors.initials: L
authors.lastname: Deng