Hostname: page-component-cd9895bd7-jn8rn Total loading time: 0 Render date: 2024-12-26T01:01:46.675Z Has data issue: false hasContentIssue false
  • English
  • Français

Cation ordering and phase transitions in feldspars along the join CaAl2Si2O8-SrAl2Si2O8: a TEM, IR and XRD investigation

Published online by Cambridge University Press:  05 July 2018

M. Tribaudino ,
M. Zhang  and
E. K. H. Salje
M. Tribaudino*
Affiliation:
Dipartimentodi Scienze della Terra, Universita` di Parma, Viale G.P. Usberti 157/A, I-43100, Parma, Italy
M. Zhang
Affiliation:
Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK
E. K. H. Salje
Affiliation:
Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK
*
* E-mail: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

Two feldspars of composition Ca0.3Sr0.7Al2Si2O8 (An30SrF70) and Ca0.6Sr0.4Al2Si2O8 (An60SrF40) were synthesized from gel and annealed at temperatures between 1150 and 1480ºC for durations between 0.025 (1.5 min) and 1073 h. The An60SrF40 feldspar is triclinic for all annealing temperatures, whereas the An30SrF70 possesses, at room temperature, a monoclinic symmetry, C2/m in the shortest annealing runs and I2/c after slightly longer heating, and becomes triclinic after prolonged annealing. A TTT plot for the triclinic–monclinic transition shows an activation energy of 101±12 kcal, less than, but still close to, that observed for Al-Si order in anorthite. TEM investigation shows antiphase domains and Carlsbad twins the size of which increases with annealing. IR spectroscopy was performed on a series of samples of An30SrF70, annealed at T = 1350ºC. The linewidth in hard mode is related to the spontaneous strain of the monoclinic–triclinic transition via . The evolution of the order parameter with time can be modelled as lnt, as predicted in order-disorder processes at intermediate degrees of order. It is shown that even after the longest annealing runs in An30SrF70, equilibrium was not obtained whereas, under the same conditions, equilibrium Al-Si order can be obtained in anorthite and Sr-feldspar.

Keywords

feldsparsphase transitionAl-Si order-disorderspontaneous strainIR spectroscopy.
Type
Research Article
Information
Mineralogical Magazine , Volume 73 , Issue 1 , February 2009 , pp. 119 - 130
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

Atkinson, A.J., Carpenter, M.A. and Salje, E.K.H. (1999) Hard mode infrared spectroscopy of plagio- clase feldspars. European Journal of Mineralogy, 11, 7–21.CrossRefGoogle Scholar
Benna, P. and Bruno, E. (2003) Single-crystal in situ high-temperature structural investigation of the R- 121cphase transition in Ca02Sr08Al2Si2O8 feldspar. American Mineralogist, 88, 1532–1541.Google Scholar
Benna, P., Tribaudino, M. and Bruno, E. (1995) Al-Si ordering in Sr-feldspar SrAl2Si2O8: IR, TEM and single-crystal XRD evidences. Physics and Chemistry of Minerals, 22, 343–350.CrossRefGoogle Scholar
Benna, P., Nestola, F., Ballaran, T.B., Balic-Zunic, T., Lundegaard, L.F. and Bruno, E. (2007) High- pressure structural configurations of Ca02Sr08Al2Si2O8 feldspar: The R —121cand I2/ c—P21 /cphase transitions. American Mineralogist, 92, 1190—1199.Google Scholar
Carpenter, M.A. (1991a) Mechanisms and kinetics of Al-Si ordering in anorthite: I. Incommensurate structure and domain coarsening. American Mineralogist, 76, 1110—1119.Google Scholar
Carpenter, M.A. (1991b) Mechanisms and kinetics of Al-Si ordering in anorthite: II. Energetics and a Ginzburg-Landau rate law. American Mineralogist, 76, 1120—1133.Google Scholar
Carpenter, M.A. (1992) Equilibrium thermodynamics of Al/Si ordering in anorthite. Physics and Chemistry of Minerals, 19, 1—24.CrossRefGoogle Scholar
Carpenter, M.A and Salje, E.K.H. (1989) Time dependent Landau theory for order-disorder processes in minerals. Mineralogical Magazine, 53, 483—504.CrossRefGoogle Scholar
Carpenter, M.A., Angel, R.J. and Finger, L.W. (1990) Calibration of Al/Si order variations in anorthite. Contributions to Mineralogy and Petrology, 104, 471—480.CrossRefGoogle Scholar
Copreaux, J., Gandais, M. and Dujon, S.C. (1989) Growth and ordering processes in synthetic hydrothermal anorthite. Physics and Chemistry of Minerals, 16, 545—550.CrossRefGoogle Scholar
Dove, M.T. and Redfern, S.A.T. (1997) Lattice simulation studies of the ferroelastic phase transitions in (Na,K)AlSi3O8 and (Sr,Ca)Al2Si2O8 feldspar solid solutions. American Mineralogist, 82, 8—15.CrossRefGoogle Scholar
Malcherek, T., Kroll, H., Schleiter, M. and Salje, E.K.H. (1995) The kinetics of the monoclinic to monoclinic phase transition in BaAl2Ge2O8-feldspar. Phase Transitions, 55, 199—215.CrossRefGoogle Scholar
Malcherek, T., Carpenter, M.A., Kroll, H. and Salje, E.K.H. (1999) Cation ordering in BaAl2Ge2O8- feldspar: implications for the H — CĪphase transition in anorthite. Physics and Chemistry of Minerals, 26, 354—366.Google Scholar
McGuinn, M.D. and Redfern, S.A.T. (1994) Ferroelastic phase transition along the join CaAl2Si2O8- SrAl2Si2O8. American Mineralogist, 79, 24—30.Google Scholar
McGuinn, M.D. and Redfern, S.A.T. (1997) High- temperature ferroelastic strain below the I2/c—I1transition in Ca1—xSrxAl2Si2O8 feldspars. European Journal of Mineralogy, 9, 1159—1172.Google Scholar
Nestola, F., Boffa-Ballaran, T., Benna, P., Tribaudino, M. and Bruno, E. (2004) High-pressure phase transitions in Ca0.2Sr0.8Al2Si2O8 feldspar. American Mineralogist, 89, 1474—1479.Google Scholar
Phillips, B.L., McGuinn, M.D. and Redfern, S.A.T. (1997) Si-Al order and the H —12/cstructural phase transition in synthetic CaAl2Si2O8—SrAl2Si2O8 feldspar: A 29Si MAS-NMR spectroscopy study. American Mineralogist, 82, 1 —7.Google Scholar
Redfern, S.A.T. (1992) The effect of Al/Si disorder on the H —P1co-elastic SrAl2Si2O8 phase transition in Ca-rich plagioclase. Physics and Chemistry of Minerals, 19, 246—254.Google Scholar
Redfern, S.A.T. and Salje, E.K. (1992) Microscopic dynamic and macroscopic thermodynamic character of the IĪ —Pī phase transition in anorthite. Physics and Chemistry of Minerals, 18, 526—533.CrossRefGoogle Scholar
Rocquefelte, X., Clabau, F., Paris, M., Deniard, P., Le Mercier, T., Jobic, S. and Whangbo, M.H. (2007) Resolving the aluminum ordering in aluminosilicates by a combined experimental/theoretical study of Al- 27 electric field gradients. Inorganic Chemistry, 46, 5456—5458.CrossRefGoogle Scholar
Sorrell, C.A. (1962) Solid state formation of barium, strontium and lead feldspars in clay-sulfate mixtures. American Mineralogist, 47, 291— 309.Google Scholar
Topel-Schadt, J., Muller, W.F. and Pentinghaus, H. (1978) Transmission electron microscopy of SrAl2Si2O8: feldspar and hexacelsian polymorphs. Journal of Material Science, 13, 1809—1816.CrossRefGoogle Scholar
Tribaudino, M. (1994) Al-Si ordering in Sr-rich feldspars of the join CaAl2Si2O8—SrAl2Si2O8: spontaneous strain and TEM data. Pp. 51—58 in: Kinetics of Cation Ordering, (A. Putnis editor), European Science Foundation Workshop, Cambridge, UK.Google Scholar
Tribaudino, M., Benna, P. and Bruno, E. (1993) Iī —I2/c phase transition in alkaline-earth feldspars along the CaAl2Si2O8—SrAl2Si2O8 join: Thermodynamic behaviour. Physics and Chemistry of Minerals, 20, 221—227.CrossRefGoogle Scholar
Tribaudino, M., Benna, P. and Bruno, E. (1995) Iī —I2/c phase transition in alkaline-earth feldspars: Evidence from TEM observations of Sr-rich feldspars along the CaAl2Si2O8—SrAl2Si2O8 join. American Mineralogist, 80, 907—915.CrossRefGoogle Scholar
Tribaudino, M., Benna, P. and Bruno, E. (2000) TEM observations on the Pī —Iī phase transition in feldspars along the join CaAl2Si2O8—SrAl2Si2O8. American Mineralogist, 85, 963—970.Google Scholar
Tribaudino, M., Benna, P., Nestola, F., Meneghini, C. and Bruno, E. (2005) Thermodynamic behaviour of the high temperature Pī —Iī phase transition along the CaAl2Si2O8—SrAl2Si2O8 join. Physics and Chemistry ofMinerals, 32, 3 4—32 .Google Scholar
Xu, H.F., Buseck, P.R. and Carpenter, M.A. ( 997) Twinning in synthetic anorthite: a transmission electron microscopy investigation. American Mineralogist, 82, 25— 30.Google Scholar
Zhang, M., Wruck, B., Graeme-Barber, A.G., Salje, E.K.H. and Carpenter, M.A. ( 1 996) Phonon spectra of alkali feldspars: phase transitions and solid solutions. American Mineralogist, 81, 92—104.Google Scholar
Zhang, M., Salje, E.K., Carpenter, M.A., Parsons, I., Kroll, H., Reed, S.J.B. and Graeme-Barber, A.G. (1997) Exsolution and Al-Si disorder in alkali feldspars: their analysis by infrared spectroscopy. American Mineralogist, 82, 849—857.Google Scholar