Canadian Mineralogist最新文献_第2页

The Hexagonal ↔ Orthorhombic Structural Phase Transition in Claringbullite, Cu4FCl(OH)6 六边形↔ Claringbullite，Cu4FCl（OH）6中的正交结构相变

IF 0.9 4区地球科学

Canadian Mineralogist Pub Date : 2021-05-11 DOI: 10.3749/CANMIN.2000041

M. Welch, J. Najorka, M. Rumsey, J. Spratt

{"title":"The Hexagonal ↔ Orthorhombic Structural Phase Transition in Claringbullite, Cu4FCl(OH)6","authors":"M. Welch, J. Najorka, M. Rumsey, J. Spratt","doi":"10.3749/CANMIN.2000041","DOIUrl":"https://doi.org/10.3749/CANMIN.2000041","url":null,"abstract":"\u0000 Frustrated magnetic phases have been a perennial interest to theoreticians wishing to understand the energetics and behavior of quasi-chaotic systems at the quantum level. This behavior also has potentially wide applications to developing quantum data-storage devices. Several minerals are examples of such phases. Since the definition of herbertsmithite, Cu3ZnCl2(OH)6, as a new mineral in 2004 and the rapid realization of the significance of its structure as a frustrated antiferromagnetic phase with a triangular magnetic lattice, there has been intense study of its magnetic properties and those of synthetic compositional variants. In the past five years it has been recognized that the layered copper hydroxyhalides barlowite, Cu4BrF(OH)6, and claringbullite, Cu4FCl(OH)6, are also the parent structures of a family of kagome phases, as they also have triangular magnetic lattices. This paper concerns the structural behavior of claringbullite that is a precursor to the novel frustrated antiferromagnetic states that occur below 30 K in these minerals. The reversible hexagonal (P63/mmc) ↔ orthorhombic (Pnma or Cmcm) structural phase transition in barlowite at 200−270 K has been known for several years, but the details of the structural changes that occur through the transition have been largely unexplored, with the focus instead being on quantifying the low-temperature magnetic behavior of the orthorhombic phase. This paper reports the details of the structural phase transition in natural claringbullite at 100−293 K as studied by single-crystal X-ray diffraction. The transition temperature has been determined to lie between 270 and 293 K. The progressive disordering of Cu at the unusual trigonal prismatic Cu(OH)6 site on heating is quantified through the phase transition for the first time, and a methodology for refining this disorder is presented. Key changes in the behavior of Cu(OH)4Cl2 octahedra in claringbullite have been identified that suggest why the Pnma structure is likely stabilized over an alternative Cmcm structure. It is proposed that the presence of a non-centrosymmetric octahedron in the Pnma structure allows more effective structural relaxation during the phase transition than can be achieved by the Cmcm structure, which has only centrosymmetric octahedra.","PeriodicalId":9455,"journal":{"name":"Canadian Mineralogist","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2021-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48337955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

A Structure Hierarchy for the Aluminofluoride Minerals 氟化铝矿物的结构层次

IF 0.9 4区地球科学

Canadian Mineralogist Pub Date : 2021-05-11 DOI: 10.3749/CANMIN.2000047

F. Hawthorne, S. Herwig

{"title":"A Structure Hierarchy for the Aluminofluoride Minerals","authors":"F. Hawthorne, S. Herwig","doi":"10.3749/CANMIN.2000047","DOIUrl":"https://doi.org/10.3749/CANMIN.2000047","url":null,"abstract":"\u0000 The structure hierarchy hypothesis states that structures may be ordered hierarchically according to the polymerization of coordination polyhedra of higher bond-valence, and such hierarchies are useful in understanding the general compositional, structural, and paragenetic variations within the structural group of interest. Here we develop a structure hierarchy for the aluminofluoride minerals based on the polymerization of the dominant (AlΦ6) octahedra and their linkage with other strongly bonded complex anionic groups. The minerals are divided first into the following categories: (1) simple aluminofluorides and (2) compound aluminofluorides containing other oxyanions. The minerals are then ordered according to the polymerization of the constituent polyhedra into a coherent structural hierarchy. The chemical composition and crystal-chemical details of the ions of the interstitial complex are a collective function of the Lewis acidity of the interstitial cations; the presence of interstitial anions, both simple [F–, (OH)–] and complex [(SO4)2–]; self-polymerization of the (AlF6)3– octahedra; and polymerization with both Mg(F,OH)6 octahedra and other complex anions: (SO4)2–, (PO4)3–, (CO3)2–.","PeriodicalId":9455,"journal":{"name":"Canadian Mineralogist","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2021-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48576521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Chemical and boron isotope composition of tourmaline from pegmatites and their host rocks, Sierra de San Luis, Argentina 阿根廷圣路易山伟晶岩及其寄主岩石中电气石的化学和硼同位素组成

IF 0.9 4区地球科学

Canadian Mineralogist Pub Date : 2021-05-01 DOI: 10.3749/CANMIN.2000072

Teresita Montenegro, Julieta Gisele Wul, M. L. Luchi, Enrico Ribacki, R. Trumbull

引用次数: 5

The Garies wollastonite deposit, Namaqualand, South Africa: High-Temperature metamorphism of a low-δ18O skarn? 南非Namaquland Garies硅灰石矿床：低δ18O矽卡岩的高温变质作用？

IF 0.9 4区地球科学

Canadian Mineralogist Pub Date : 2021-05-01 DOI: 10.3749/CANMIN.2000071

C. Harris, Lucrecia Maboane

引用次数: 1

Interaction between mafic dike rocks and salt deposits in the Rhine Graben, southwest Germany 德国西南部莱茵地堑镁铁质岩墙岩与盐矿的相互作用