Lea Pennacchioni, Naira S. Martirosyan, Anna Pakhomova, Jannes König, Richard Wirth, Sandro Jahn, Monika Koch-Müller, Sergio Speziale
{"title":"Crystal structure and high-pressure phase behavior of a CaCO3–SrCO3 solid solution","authors":"Lea Pennacchioni, Naira S. Martirosyan, Anna Pakhomova, Jannes König, Richard Wirth, Sandro Jahn, Monika Koch-Müller, Sergio Speziale","doi":"10.1007/s00269-023-01252-7","DOIUrl":null,"url":null,"abstract":"<div><p>A synthetic <span>\\(\\hbox {CaCO}_{3}\\)</span>–<span>\\(\\hbox {SrCO}_{3}\\)</span> solid solution with composition <span>\\(\\hbox {Ca}_{0.82}\\hbox {Sr}_{0.18}\\)</span> <span>\\(\\hbox {CO}_{3}\\)</span> was investigated by single-crystal X-ray diffraction in the pressure range between 0 and 22 GPa using different pressure-transmitting media. The samples were compressed in DACs using Ne up to <span>\\(\\sim\\)</span>9 GPa and Ar up to <span>\\(\\sim\\)</span>22 GPa. At ambient conditions, <span>\\(\\hbox {Ca}_{0.82}\\hbox {Sr}_{0.18}\\)</span> <span>\\(\\hbox {CO}_{3}\\)</span> crystallizes in a monoclinic structure, isostructural to <span>\\(\\hbox {CaCO}_{3}\\)</span>-II, Sr-calcite-II (Sr-CC-II), with space group <span>\\(P2_1/c\\)</span>, 4 formula units per unit cell, <i>Z</i>, <span>\\(a = 6.4237(7)\\)</span> Å, <span>\\(b = 5.0176(1)\\)</span> Å, <span>\\(c = 8.1129(1)\\)</span> Å, <span>\\(\\beta = 108.064(1)^\\circ\\)</span> and <span>\\(V=248.60(1)\\)</span> Å<span>\\(^3\\)</span> (where the number in parenthesis is 1<span>\\(\\sigma\\)</span> uncertainties on the last digit). At 1.72(5) GPa, a structural phase transition is observed to a new monoclinic structure, Sr-calcite-IIIc (Sr-CC-IIIc), with space group <span>\\(P2_1/m\\)</span> and <span>\\(Z=8\\)</span> (<span>\\(a~=~6.2683(2)\\)</span> Å, <span>\\(b = 9.9220(5)\\)</span> Å, <span>\\(c = 7.6574(6)\\)</span> Å, <span>\\(\\beta = 103.856(6)^\\circ\\)</span> and <span>\\(V = 462.39(5)\\)</span> Å<span>\\(^3\\)</span>), different from any pure <span>\\(\\hbox {CaCO}_{3}\\)</span> polymorph. At 12 GPa, the sample transformed to a triclinic structure, Sr-calcite-IIIb (Sr-CC-IIIb), with space group <span>\\(P{\\bar{1}}\\)</span> and <span>\\(Z=4\\)</span> ( <span>\\(a=6.059(5)\\)</span> Å, <span>\\(b=6.280(2)\\)</span> Å, <span>\\(c=6.331(2)\\)</span> Å, <span>\\(\\alpha =95.20(3)^\\circ\\)</span>, <span>\\(\\beta =108.89(5)^\\circ\\)</span>, <span>\\(\\gamma =110.52(5)^\\circ\\)</span> and <span>\\(V=207.7(2)\\)</span> Å<span>\\(^3\\)</span>), isostructural to end-member <span>\\(\\hbox {CaCO}_{3}\\)</span>-IIIb. Finally, at 17 GPa, a transition is observed to Sr-calcite-VI (Sr-CC-VI), with space group <span>\\(P{\\bar{1}}\\)</span> and <span>\\(Z=2\\)</span> (<span>\\(a=3.444(3)\\)</span> Å, <span>\\(b=4.985(4)\\)</span> Å, <span>\\(c=5.761(5)\\)</span> Å, <span>\\(\\alpha =77.05(7)^\\circ\\)</span>, <span>\\(\\beta =84.92(7)^\\circ\\)</span>, <span>\\(\\gamma =89.00(7)^\\circ\\)</span> and <span>\\(V=96.0(1)\\)</span> Å<span>\\(^3\\)</span>), isostructural to end-member <span>\\(\\hbox {CaCO}_{3}\\)</span>-VI, which is preserved up to the maximum investigated pressure of 22 GPa. The results of this study show the effect of Sr/Ca cationic substitution on the high-pressure behavior and physical properties of a <span>\\(\\hbox {CaCO}_{3}\\)</span>–<span>\\(\\hbox {SrCO}_{3}\\)</span> solid solution. The phase evolution of <span>\\(\\hbox {Ca}_{0.82}\\hbox {Sr}_{0.18}\\hbox {CO}_3\\)</span> and the crystallization of a new phase, Sr-CC-IIIc, different from the high-pressure polymorphs of end-member <span>\\(\\hbox {CaCO}_{3}\\)</span>, point to the importance of extending the study of carbonates to more complex systems than pure end-member compositions.</p></div>","PeriodicalId":20132,"journal":{"name":"Physics and Chemistry of Minerals","volume":null,"pages":null},"PeriodicalIF":1.2000,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Physics and Chemistry of Minerals","FirstCategoryId":"89","ListUrlMain":"https://link.springer.com/article/10.1007/s00269-023-01252-7","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: 0
Abstract
A synthetic \(\hbox {CaCO}_{3}\)–\(\hbox {SrCO}_{3}\) solid solution with composition \(\hbox {Ca}_{0.82}\hbox {Sr}_{0.18}\)\(\hbox {CO}_{3}\) was investigated by single-crystal X-ray diffraction in the pressure range between 0 and 22 GPa using different pressure-transmitting media. The samples were compressed in DACs using Ne up to \(\sim\)9 GPa and Ar up to \(\sim\)22 GPa. At ambient conditions, \(\hbox {Ca}_{0.82}\hbox {Sr}_{0.18}\)\(\hbox {CO}_{3}\) crystallizes in a monoclinic structure, isostructural to \(\hbox {CaCO}_{3}\)-II, Sr-calcite-II (Sr-CC-II), with space group \(P2_1/c\), 4 formula units per unit cell, Z, \(a = 6.4237(7)\) Å, \(b = 5.0176(1)\) Å, \(c = 8.1129(1)\) Å, \(\beta = 108.064(1)^\circ\) and \(V=248.60(1)\) Å\(^3\) (where the number in parenthesis is 1\(\sigma\) uncertainties on the last digit). At 1.72(5) GPa, a structural phase transition is observed to a new monoclinic structure, Sr-calcite-IIIc (Sr-CC-IIIc), with space group \(P2_1/m\) and \(Z=8\) (\(a~=~6.2683(2)\) Å, \(b = 9.9220(5)\) Å, \(c = 7.6574(6)\) Å, \(\beta = 103.856(6)^\circ\) and \(V = 462.39(5)\) Å\(^3\)), different from any pure \(\hbox {CaCO}_{3}\) polymorph. At 12 GPa, the sample transformed to a triclinic structure, Sr-calcite-IIIb (Sr-CC-IIIb), with space group \(P{\bar{1}}\) and \(Z=4\) ( \(a=6.059(5)\) Å, \(b=6.280(2)\) Å, \(c=6.331(2)\) Å, \(\alpha =95.20(3)^\circ\), \(\beta =108.89(5)^\circ\), \(\gamma =110.52(5)^\circ\) and \(V=207.7(2)\) Å\(^3\)), isostructural to end-member \(\hbox {CaCO}_{3}\)-IIIb. Finally, at 17 GPa, a transition is observed to Sr-calcite-VI (Sr-CC-VI), with space group \(P{\bar{1}}\) and \(Z=2\) (\(a=3.444(3)\) Å, \(b=4.985(4)\) Å, \(c=5.761(5)\) Å, \(\alpha =77.05(7)^\circ\), \(\beta =84.92(7)^\circ\), \(\gamma =89.00(7)^\circ\) and \(V=96.0(1)\) Å\(^3\)), isostructural to end-member \(\hbox {CaCO}_{3}\)-VI, which is preserved up to the maximum investigated pressure of 22 GPa. The results of this study show the effect of Sr/Ca cationic substitution on the high-pressure behavior and physical properties of a \(\hbox {CaCO}_{3}\)–\(\hbox {SrCO}_{3}\) solid solution. The phase evolution of \(\hbox {Ca}_{0.82}\hbox {Sr}_{0.18}\hbox {CO}_3\) and the crystallization of a new phase, Sr-CC-IIIc, different from the high-pressure polymorphs of end-member \(\hbox {CaCO}_{3}\), point to the importance of extending the study of carbonates to more complex systems than pure end-member compositions.
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)