Hostname: page-component-cd9895bd7-dzt6s Total loading time: 0 Render date: 2024-12-24T17:42:57.115Z Has data issue: false hasContentIssue false
  • English
  • Français

The effect of non-stoichiometry on the high-temperature behaviour of MgAl2O4 spinel

Published online by Cambridge University Press:  05 July 2018

F. Nestola ,
L. Secco ,
M. Bruno ,
M. Prencipe ,
F. Martignago ,
F. Princivalle  and
A. Dal Negro
F. Nestola*
Affiliation:
Dipartimento di Geoscienze, Universitá di Padova, Via Giotto 1, 35137 Padova, Italy I.G.G. Unitá di Padova, CNR, I-35137 Padova, Italy
L. Secco
Affiliation:
Dipartimento di Geoscienze, Universitá di Padova, Via Giotto 1, 35137 Padova, Italy
M. Bruno
Affiliation:
Dipartimento di Scienze Mineralogiche e Petrologiche, Universitá di Torino, Via Valperga Caluso 35, 10125 Torino, Italy
M. Prencipe
Affiliation:
Dipartimento di Scienze Mineralogiche e Petrologiche, Universitá di Torino, Via Valperga Caluso 35, 10125 Torino, Italy
F. Martignago
Affiliation:
Dipartimento di Geoscienze, Universitá di Padova, Via Giotto 1, 35137 Padova, Italy
F. Princivalle
Affiliation:
Dipartimento di Scienze della Terra, Universitá di Trieste, Via Weiss 8, 34127 Trieste, Italy
A. Dal Negro
Affiliation:
Dipartimento di Geoscienze, Universitá di Padova, Via Giotto 1, 35137 Padova, Italy
*
* E-mail: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

The effect of cation vacancies upon the thermal expansion and crystal structure of a synthetic defect spinel with composition Mg0.4Al2.4☐0.2O4 was investigated by X-ray diffraction, in situ, at temperatures up to 1273 K. No evidence of symmetry violations from the Fd3m evenat the highest temperature were noted. The volume thermal expansion is markedly less than that of stoichiometric MgAl2O4 spinel, regardless of the degree of inversion. The u oxygen atomic coordinate remains constant throughout the temperature range investigated, with the M–O an dT–O bond lengths showing identical rates of expansivities. An analysis of the evolution of polyhedral volumes with temperature indicates that at 1273 K the octahedron inflates by 0.099 Å3 and the tetrahedron by 0.056 Å3. The expansion of the octahedron is significantly greater than in stoichiometric MgAl2O4 spinel, whereas the expansion of the tetrahedron is similar. The results demonstrate that an excess of Al in the spinel structure accompanied by the formation of cation vacancies strongly affect an important thermodynamic property, in this case, thermal expansion. Such an effect must be considered for those phases stable inthe Earth’s mantle where 4–5 wt.% Al2O3 is thought to be present.

Keywords

spinelsingle crystalhigh temperaturenon-stoichiometry.
Type
Research Article
Information
Mineralogical Magazine , Volume 73 , Issue 2 , April 2009 , pp. 301 - 306
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2009

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Anderson, D.L. (1989) Theory of the Earth. Blackwell Scientific Publications, Boston, USA, pp. 147—177.Google Scholar
Andreozzi, G.B., Princivalle, F., Skogby, H. and Della Giusta, A. (2000) Cation ordering and structural variations with temperature in MgAl2O4 spinel: an X-ray single crystal study. American Mineralogist, 85, 1164—1171.CrossRefGoogle Scholar
Balić-žunić, T. and Vikovic, I. (1996) IVTON — Program for the calculation of geometrical aspects of crystal structures and some crystal chemical applications. Journal of Applied Crystallography, 29, 305—306.CrossRefGoogle Scholar
Basso, R., Carbonin, S. and Della Giusta, A. (1991) Cation and vacancy distribution in a synthetic defect spinel. Zeitschrift für Kristallographie, 194, 111 — 119.Google Scholar
Carbonin, S., Martignago, F., Menegazzo, G. and Dal Negro, A. (2002) X-ray single-crystal study of spinels: in situ heating. Physics and Chemistry of Minerals, 29, 503—514.CrossRefGoogle Scholar
Della Giusta, A., Carbonin, S. and Ottonello, G. (1996) Temperature-dependent disorder in a natural Mg-Al- Fe2+-Fe3+-spinel. Mineralogical Magazine, 60, 603—616.CrossRefGoogle Scholar
Hazen, R.M. (1976) Effects of temperature and pressure on the cell dimension and X-ray temperature factors of periclase. American Mineralogist, 61, 266—271.Google Scholar
Lenaz, D., Skogby, H., Nestola, F. and Princivalle, F. (2008) OH incorporation in nearly pure MgAl2O4 natural and synthetic spinels. Geochimica et Cosmochimica Acta, 72, 475—479.CrossRefGoogle Scholar
Lucchesi, S. and Della Giusta, A. (1994) Crystal chemistry of non-stoichiometric Mg-Al synthetic spinels. Zeitschrift für Kristallographie, 209, 714—719.Google Scholar
Martignago, F., Andreozzi, G.B. and Dal Negro, A. (2006) Thermodynamics and kinetics of cation ordering in natural and synthetic Mg(Al,Fe3+)2O4 spinels. Physics and Chemistry of Minerals, 30, 401—408.Google Scholar
Molin, G., Martignago, F. and Dal Negro, A. (2001) A new radiative micro-furnace for X-ray single-crystal diffractometry. European Journal of Mineralogy, 13, 557—563.CrossRefGoogle Scholar
Nestola, F., Boffa Ballaran, T., Balić-žunić, T., Princivalle, F., Secco, L. and Dal Negro, A. (2007) Comparative compressibility and structural behavior of spinel MgAl2O4 at high pressures: the independency on the degree of cation order. American Mineralogist, 92, 1838 — 1843.CrossRefGoogle Scholar
Nestola, F., Smyth, J.R., Parisatto, M., Secco, L., Princivalle, F., Bruno, M., Prencipe, M. and Dal Negro, A. (2009) The effect of non-stoichiometry at high-pressure: implications for the Earth's mantle mineralogy. Geochimica et Cosmochimica Acta, 73, 489—492.CrossRefGoogle Scholar
Prencipe, M., Belousov, R. and Nestola, F. (2008) First Principles HF/DFT Calculation of Structure and Compressibility of an Al-defective Spinel (Mg2Al3O8). Abstract, 1st SIMP-AIC Joint Meeting. (Sestri Levante). 128 pp.Google Scholar
Redfem, S.A., Harrison, R.J., O’Neill, H.St.C. and Wood, D.R. (1999) Thermodynamics and kinetics of cation ordering in MgAl2O4 spinel up to 1600°C from in situ neutron diffraction. American Mineralogist, 84, 299—310.Google Scholar
Sack, R.O. and Ghiorso, M.S. (1991) Chromian spinels as petrogenetic indicators: thermodynamics and petrological implications. American Mineralogist, 76, 827—847.Google Scholar
Salviulo, G., Carbonin, S. and Della Giusta, A. (2000) Powder and single-crystal X-ray structural refinements on a natural chromite: dependence of site occupancies on experimental strategies. Pp 46—51 in: European Powder Diffraction Proceedings of EPD1C-6 (R. Delhez and E.J. Mittemeijer, editors), Trans Tech Publications, Switzerland.Google Scholar
Sheldrick, F. (1997) SHELXL-97, a program for crystal structure refinement. University of Göttingen, Germany.Google Scholar
Viertel, H.U. and Seifert, F. (1979) Physical properties of defect spinels in the system MgAl2O4-Al2O3. Neues Jahrbuch für Mineralogie Abhandlungen, 134, 167—182.Google Scholar