The phenomenon of low Al-Si ordering temperatures in aluminosilicate framework structures

Other| April 01, 1996 The phenomenon of low Al-Si ordering temperatures in aluminosilicate framework structures Martin T. Dove; Martin T. Dove University of Cambridge, Department of Earth Sciences, Cambridge, United Kingdom Search for other works by this author on: GSW Google Scholar S. Thayaparam; S. Thayaparam Search for other works by this author on: GSW Google Scholar Volker Heine; Volker Heine Search for other works by this author on: GSW Google Scholar Kenton D. Hammonds Kenton D. Hammonds Search for other works by this author on: GSW Google Scholar American Mineralogist (1996) 81 (3-4): 349–362. https://doi.org/10.2138/am-1996-3-409 Article history first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Martin T. Dove, S. Thayaparam, Volker Heine, Kenton D. Hammonds; The phenomenon of low Al-Si ordering temperatures in aluminosilicate framework structures. American Mineralogist 1996;; 81 (3-4): 349–362. doi: https://doi.org/10.2138/am-1996-3-409 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyAmerican Mineralogist Search Advanced Search Abstract The enthalpy of ordering of Al and Si between tetrahedral sites in framework structures is now known from several studies to be in the range 0.3–1.4 eV per two Al-O-Si linkages, depending on the structure and type of linkage between tetrahedra. On the basis of this value a simple Bragg-Williams model predicts an ordering phase transition at a temperature, Tc, on the order of a few thousand degrees after adjusting the estimate to account for fluctuations in short-range order. However, there are several materials with Tc below 1800 °C (a typical melting point), with some having Tc so low that it cannot be observed because of the slowness of the ordering kinetics, e.g., gehlenite and leucite. We discuss two mechanisms that can reduce Tc substantially: low effective dimensionality and low A1 concentration. The cases of sillimanite, gehlenite, cordierite, and leucite, and some simple demonstration systems, are treated quantitatively with the aid of Monte Carlo computer simulations. Other materials (kalsilite, anorthite, albite, and nepheline) are discussed qualitatively in terms of the same principles. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.