A. V. Sergeeva, L. A. Polevoy, M. B. Golikova, M. A. Nazarova, A. V. Gladyshkina, E. V. Kartasheva, A. A. Kuzmina
{"title":"Spectroscopy of Ammonium Occupying Symmetry-Inappropriate Positions in Crystal Structures of Salts","authors":"A. V. Sergeeva, L. A. Polevoy, M. B. Golikova, M. A. Nazarova, A. V. Gladyshkina, E. V. Kartasheva, A. A. Kuzmina","doi":"10.1007/s10812-024-01753-5","DOIUrl":null,"url":null,"abstract":"<p>The vibrational spectra of the natural ammonium sulfates tschermigite NH<sub>4</sub>Al(SO<sub>4</sub>)<sub>2</sub>(H<sub>2</sub>O)<sub>12</sub>, lonecreekite NH<sub>4</sub>Fe(SO<sub>4</sub>)<sub>2</sub>(H<sub>2</sub>O)<sub>12</sub>, ammoniovoltaite (NH<sub>4</sub>)<sub>2</sub>Fe<sup>2+</sup><sub>5</sub>Fe<sup>3+</sup><sub>3</sub>Al(SO<sub>4</sub>)<sub>12</sub>(H<sub>2</sub>O)<sub>18</sub>, sabieite NH<sub>4</sub>Fe(SO<sub>4</sub>)<sub>2</sub>, ammonioalunite NH<sub>4</sub>Al<sub>3</sub>(SO<sub>4</sub>)<sub>2</sub>(OH)<sub>6</sub>, and ammoniojarosite NH<sub>4</sub>Fe<sub>3</sub>(SO<sub>4</sub>)<sub>2</sub>(OH)<sub>6</sub> were studied to determine the behavior of ammonium in symmetry-inappropriate positions. Disorder of the ammonium cation in salt crystals caused by the need to adjust the tetrahedral cation to the symmetry of the position to preserve the crystal symmetry was revealed. If the symmetry group of the position was not a subgroup of the tetrahedral symmetry group, the NH<sub>4</sub> tetrahedron was distorted by the subgroup <i>H</i>ʹ common for <i>T</i><sub><i>d</i></sub> and <i>H</i>, where <i>H</i> is the symmetry group of the position. Then, a polyhedron corresponding to the symmetry of the position was constructed from <i>N</i> = |<i>H</i>|/|<i>H</i>ʹ| (|<i>H</i>| and |<i>H</i>ʹ| are the orders of these groups) distorted tetrahedra. The disordered ammonium cation had several orientations (<i>N</i>), the superposition of which formally gave a polyhedron corresponding to the local symmetry. The maximum common subgroups for the given salts were <i>C</i><sub>3<i>v</i></sub> and <i>C</i><sub>3</sub>. Distortion of ammonium led to activation of ν<sub>1</sub> and ν<sub>2</sub> [NH<sub>4</sub><sup>+</sup> ] vibrations in the IR spectrum and splitting of ν<sub>3</sub> and ν<sub>4</sub> [NH<sub>4</sub><sup>+</sup> ]. However, the effect was barely noticeable for ammonium in a centrosymmetric position, as in ammonioalunite and ammoniojarosite. The ν<sub>4</sub> [NH<sub>4</sub><sup>+</sup>] band was noticeably split and ν<sub>1</sub> and ν<sub>2</sub> [NH<sub>4</sub><sup>+</sup> ] vibrations were clearly visible in spectra of the ammonium alums, ammoniovoltaite, and sabieite.</p>","PeriodicalId":609,"journal":{"name":"Journal of Applied Spectroscopy","volume":null,"pages":null},"PeriodicalIF":0.8000,"publicationDate":"2024-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Applied Spectroscopy","FirstCategoryId":"92","ListUrlMain":"https://link.springer.com/article/10.1007/s10812-024-01753-5","RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"SPECTROSCOPY","Score":null,"Total":0}
引用次数: 0
Abstract
The vibrational spectra of the natural ammonium sulfates tschermigite NH4Al(SO4)2(H2O)12, lonecreekite NH4Fe(SO4)2(H2O)12, ammoniovoltaite (NH4)2Fe2+5Fe3+3Al(SO4)12(H2O)18, sabieite NH4Fe(SO4)2, ammonioalunite NH4Al3(SO4)2(OH)6, and ammoniojarosite NH4Fe3(SO4)2(OH)6 were studied to determine the behavior of ammonium in symmetry-inappropriate positions. Disorder of the ammonium cation in salt crystals caused by the need to adjust the tetrahedral cation to the symmetry of the position to preserve the crystal symmetry was revealed. If the symmetry group of the position was not a subgroup of the tetrahedral symmetry group, the NH4 tetrahedron was distorted by the subgroup Hʹ common for Td and H, where H is the symmetry group of the position. Then, a polyhedron corresponding to the symmetry of the position was constructed from N = |H|/|Hʹ| (|H| and |Hʹ| are the orders of these groups) distorted tetrahedra. The disordered ammonium cation had several orientations (N), the superposition of which formally gave a polyhedron corresponding to the local symmetry. The maximum common subgroups for the given salts were C3v and C3. Distortion of ammonium led to activation of ν1 and ν2 [NH4+ ] vibrations in the IR spectrum and splitting of ν3 and ν4 [NH4+ ]. However, the effect was barely noticeable for ammonium in a centrosymmetric position, as in ammonioalunite and ammoniojarosite. The ν4 [NH4+] band was noticeably split and ν1 and ν2 [NH4+ ] vibrations were clearly visible in spectra of the ammonium alums, ammoniovoltaite, and sabieite.
期刊介绍:
Journal of Applied Spectroscopy reports on many key applications of spectroscopy in chemistry, physics, metallurgy, and biology. An increasing number of papers focus on the theory of lasers, as well as the tremendous potential for the practical applications of lasers in numerous fields and industries.