Crystal structure of norsethite-type BaMn(CO3)(2) and its pressure-induced transition investigated by Raman spectroscopy

作者：Liang, Wen^*; Li, Lin; Yin, Yuan; Li, Rui; Li, Zeming; Liu, Xiqiang; Zhao, Chaoshuai; Yang, Shuguang

来源：Physics and Chemistry of Minerals, 2019, 46(8): 771-781.

DOI：10.1007/s00269-019-01038-w

• Norsethite-type BaMn(CO3)(2)
• Single crystal growth
• Single crystal X-ray diffraction
• High-pressure Raman spectroscopy

Single crystals of norsethite-type carbonate BaMn(CO3)(2) up to 200 mu m in size were synthesized in a closed cavity under high pressure-temperature (P-T) conditions. Electron microprobe analyses revealed the composition of 49.00-49.09 wt% BaO and 22.66-22.74 wt% MnO, which correspond well to the ideal formula of Ba1.0Mn1.0(CO3)(2). Accurate crystalline structural data were determined from single crystal X-ray diffraction (XRD). The R (3) over barc space-group with a doubled c-axis and R (3) over barm space-group were used to refine the crystal structure of BaMn(CO3)(2). It is proved that R (3) over barm is the most probable space-group for the BaMn(CO3)(2) crystal structure because no superstructure reflections were observed in the X-ray images. The unit cell parameters were identified to be a = 5.0827(2) angstrom and c = 17.2797(10) angstrom in the rhombohedral symmetry of the R (3) over barm space-group with a final R-value of 0.0184. High-pressure Raman spectroscopy was performed up to 10 GPa at room temperature, and Raman band shifts (dv(i)/dP) were quantified. Each Raman vibration underwent resolvable splitting and the corresponding dv(i)/dP showed a pronounced jump as the pressure reached 3.8 GPa arising from a pressure-induced transition.

• 单位
  中国科学院; 中国科学院研究生院