{"title":"Pressure-induced phase transition of CO32−-bearing scapolite by in situ X-ray diffraction and vibrational spectroscopy","authors":"Cheng Qian, Yungui Liu, Xiang Li, Yudong Zhu, Haipeng Song, Xiang Wu","doi":"10.1007/s00269-022-01226-1","DOIUrl":null,"url":null,"abstract":"<div><p>Scapolite Na<sub>2.25</sub>Ca<sub>1.43</sub>K<sub>0.30</sub>Fe<sub>0.02</sub>[Al<sub>4.23</sub>Si<sub>7.77</sub>O<sub>24</sub>]Cl<sub>0.72</sub>(SO<sub>4</sub>)<sub>0.1</sub>(CO<sub>3</sub>)<sub>0.18</sub> has been investigated by single-crystal X-ray diffraction, Infrared and Raman spectroscopy combined with diamond anvil cells (DAC) up to 19.6 GPa at room temperature, to understand its phase stability and the behaviors of CO<sub>3</sub><sup>2−</sup>. The experimental results show that a phase transition from the tetragonal phase (<i>P</i>4<sub>2</sub>/<i>n</i>) to the triclinic phase occurs at 10.7 GPa, which is attributed to the pressure-induced rotation of tetrahedra around the bridging O atoms. The pressure–volume data were fitted to the second-order Birch–Murnaghan equation of state, yielding <i>V</i><sub>0</sub> = 1102.6(8) Å<sup>3</sup> and <i>K</i><sub>0</sub> = 70.3(9) GPa for the tetragonal phase and <i>V</i><sub>0</sub> = 1188.2(16) Å<sup>3</sup> and <i>K</i><sub>0</sub> = 33.0(3) GPa for the triclinic phase. In the triclinic phase, the larger compressibility is due to the increased degree of freedom in the crystal structure, and the anisotropy of the axial compressibility may be related to the ionic radius of the anionic group. From the Infrared absorption and Raman spectroscopy data, we speculate that CO<sub>3</sub><sup>2−</sup> is extruded by the four-membered rings at the (001) plane during the whole pressure range. The high-pressure behavior of CO<sub>3</sub><sup>2−</sup> in scapolite provides a possibility that carbon exists in the Earth’s interior as CO<sub>3</sub><sup>2−</sup> coupled to silicates.</p></div>","PeriodicalId":20132,"journal":{"name":"Physics and Chemistry of Minerals","volume":"50 1","pages":""},"PeriodicalIF":1.2000,"publicationDate":"2022-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Physics and Chemistry of Minerals","FirstCategoryId":"89","ListUrlMain":"https://link.springer.com/article/10.1007/s00269-022-01226-1","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 1
Abstract
Scapolite Na2.25Ca1.43K0.30Fe0.02[Al4.23Si7.77O24]Cl0.72(SO4)0.1(CO3)0.18 has been investigated by single-crystal X-ray diffraction, Infrared and Raman spectroscopy combined with diamond anvil cells (DAC) up to 19.6 GPa at room temperature, to understand its phase stability and the behaviors of CO32−. The experimental results show that a phase transition from the tetragonal phase (P42/n) to the triclinic phase occurs at 10.7 GPa, which is attributed to the pressure-induced rotation of tetrahedra around the bridging O atoms. The pressure–volume data were fitted to the second-order Birch–Murnaghan equation of state, yielding V0 = 1102.6(8) Å3 and K0 = 70.3(9) GPa for the tetragonal phase and V0 = 1188.2(16) Å3 and K0 = 33.0(3) GPa for the triclinic phase. In the triclinic phase, the larger compressibility is due to the increased degree of freedom in the crystal structure, and the anisotropy of the axial compressibility may be related to the ionic radius of the anionic group. From the Infrared absorption and Raman spectroscopy data, we speculate that CO32− is extruded by the four-membered rings at the (001) plane during the whole pressure range. The high-pressure behavior of CO32− in scapolite provides a possibility that carbon exists in the Earth’s interior as CO32− coupled to silicates.
期刊介绍:
Physics and Chemistry of Minerals is an international journal devoted to publishing articles and short communications of physical or chemical studies on minerals or solids related to minerals. The aim of the journal is to support competent interdisciplinary work in mineralogy and physics or chemistry. Particular emphasis is placed on applications of modern techniques or new theories and models to interpret atomic structures and physical or chemical properties of minerals. Some subjects of interest are:
-Relationships between atomic structure and crystalline state (structures of various states, crystal energies, crystal growth, thermodynamic studies, phase transformations, solid solution, exsolution phenomena, etc.)
-General solid state spectroscopy (ultraviolet, visible, infrared, Raman, ESCA, luminescence, X-ray, electron paramagnetic resonance, nuclear magnetic resonance, gamma ray resonance, etc.)
-Experimental and theoretical analysis of chemical bonding in minerals (application of crystal field, molecular orbital, band theories, etc.)
-Physical properties (magnetic, mechanical, electric, optical, thermodynamic, etc.)
-Relations between thermal expansion, compressibility, elastic constants, and fundamental properties of atomic structure, particularly as applied to geophysical problems
-Electron microscopy in support of physical and chemical studies
-Computational methods in the study of the structure and properties of minerals
-Mineral surfaces (experimental methods, structure and properties)