Hostname: page-component-848d4c4894-2pzkn Total loading time: 0 Render date: 2024-05-16T04:51:34.968Z Has data issue: false hasContentIssue false
  • English
  • Français

I1̄ – I2/c ferroelastic phase transition in the Ca0.2Pb0.8Al2Si2O8 feldspar as a function of temperature

Published online by Cambridge University Press:  05 July 2018

P. Benna ,
M. Tribaudino  and
E. Bruno
P. Benna*
Affiliation:
Dipartimento di Scienze Mineralogiche e Petrologiche, Via Valperga Caluso 35, I-10125 Torino, Italy Centro di Studi sulla Geodinamica delle Catene Collisionali (C.N.R.), Via Accademia delle Scienze 5, I-10123 Torino, Italy
M. Tribaudino
Affiliation:
Dipartimento di Scienze Mineralogiche e Petrologiche, Via Valperga Caluso 35, I-10125 Torino, Italy
E. Bruno
Affiliation:
Dipartimento di Scienze Mineralogiche e Petrologiche, Via Valperga Caluso 35, I-10125 Torino, Italy Centro di Studi sulla Geodinamica delle Catene Collisionali (C.N.R.), Via Accademia delle Scienze 5, I-10123 Torino, Italy
*
*E-mail: benna@dsmp.unito.it
Get access Rights & Permissions [Opens in a new window]

Abstract

Feldspar of composition Ca0.2Pb0.8Al2Si2O8 (PbF80An20) was synthesized from melt and subsequently isothermally annealed at T = 960°C for 4 days. In situ HT X-ray powder spectra of PbF80An20 feldspar, triclinic I1̄ at room temperature, were collected in the temperature range 20–800°C, and a displacive continuous ferroelastic transition to a I2/c monoclinic phase was observed. An analysis of the symmetry-required components of the spontaneous strain tensor reveals the second order character (β = 0.46 ± 0.02) of the transition with TC = 680 ± 15°C. A linear coupling was observed between the e4 and e6 components of the spontaneous strain. The transition is analogous to those observed, with increasing temperature, along the join An–SrF and in disordered Na-rich alkali feldspars. A comparison with Ca0.2Sr0.8Al2Si2O8 feldspar (TC = 680°C, McGuinn and Redfern, 1997) shows that PbF80An20 has a higher spontaneous strain (εs = 0.028 in PbF80An20vs 0.020 in Ca0.2Sr0.8Al2Si2O8) and a higher e4 component, possibly related to the higher distortion of the non-tetrahedral polyhedron in lead feldspar.

Keywords

lead feldsparphase transformationsHT unit-cell parameters
Type
Research Article
Information
Mineralogical Magazine , Volume 64 , Issue 2 , April 2000 , pp. 285 - 290
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2000

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

Bambauer, H.U. and Nager, H.E. (1981) Gitterkonstanten und displazive Transformationen synthetischer Erdalkalifeldspäte. I. System Ca[Al2Si2O8]– Sr[Al2Si2O8]– Ba[Al2Si2O8]. Neues Jahrb. Mineral Abh., 141, 225–39.Google Scholar
Benna, P., Tribaudino, M. and Bruno, E. (1995) Al-Si ordering in Sr-feldspar SrAl2Si2O8: IR, TEM and single-crystal XRD evidences. Phys. Chem. Min., 22, 343–50.CrossRefGoogle Scholar
Benna, P., Tribaudino, M. and Bruno, E. (1996) The structure of ordered and disordered lead feldspar (PbAl2Si2O8). Amer. Mineral., 81, 1337–43.CrossRefGoogle Scholar
Bown, M.G. and Gay, P. (1958) The reciprocal lattice geometry of the plagioclase feldspar structures. Zeits. Kristallogr., 111, 1–14.Google Scholar
Bruno, E. and Gazzoni, G. (1968) Feldspati sintetici della serie CaAl2Si2O8 – SrAl2Si2O8 . Atti dell ’Accademia delle Scienze di Torino, 102, 881–93.Google Scholar
Carpenter, M.A. (1988) Thermochemistry of aluminium/silicon ordering in feldspar minerals. Pp. 265–323 in: Physical Propert ies and Thermodynamic Behaviour of Minerals (Salje, E.K.H., editor). NATO ASI series C/225, Reidel, Dordrecht, The Netherlands.CrossRefGoogle Scholar
Carpenter, M.A. (1991) Mechanisms and kinetics of Al–Si ordering in anorthite: I. Incommensurate structure and domain coarsening. Amer. Mineral., 76, 1110–9.Google Scholar
Dove, M.T. and Redfern, S.A.T. (1997) Lattice simulation studies of the ferroelastic phase transitions in disordered (Na,K)AlSi3O8 and ordered (Sr, Ca)Al2Si2O8 feldspar solid solutions. Amer. Mineral., 82, 8–15.CrossRefGoogle Scholar
Hayward, S.A. and Salje, E.K.H. (2000) Twin memory and twin amnesia in anorthoclase. Mineral. Mag., 64, 195–200.CrossRefGoogle Scholar
Hayward, S.A., Salje, E.K.H. and Chrosch, J. (1998) Local fluctuations in feldspar frameworks. Mineral. Mag., 62, 639–45.CrossRefGoogle Scholar
Keppler, U. (1988) Thermal expansion of silicon. Z. Metallkunde, 79, 157–8.Google Scholar
Kroll, H., Bambauer, H.U. and Schirmer, U. (1980) The high albite-monalbite and analbite-monalbite transitions. Amer. Mineral., 65, 1192–211.Google Scholar
McGuinn, M.D. and Redfern, S.A.T. (1994) Ferroelastic phase transition along the join CaAl2Si2O8 – SrAl2Si2O8 . Amer. Mineral., 79, 24–30.Google Scholar
McGuinn, M.D. and Redfern, S.A.T. (1997) Hightemperature ferroelastic strain below the I2/c- I1̄ transition in Ca1−xSrxAl2Si2O8 feldspars. Eur. J. Mineral., 9, 1159–72.CrossRefGoogle Scholar
Nager, H.E. (1969) Strontiumfeldspat und die Mischreihe (Sr,Ca)[Al2Si2O8]. Diplomarbeit, Univ. Münster.Google Scholar
Nager, H.E., Hoffmann, W. and Nissen, H.U. (1969) Die Mischreihe (Ca,Sr)[Al2Si2O8]. Naturwissenschaften, 56, 136.CrossRefGoogle Scholar
Nager, H.E., Bambauer, H.U. and Hoffmann, W. (1970) Polymorphie in der Mischreihe (Ca,Sr)[Al2Si2O8]. Naturwissenschaften, 57, 86–7.CrossRefGoogle Scholar
Redfern, S.A.T. and Salje, E. (1987) Thermodynamics of plagioclases II: Temperature evolution of the spontaneous strain at the I1̄– P1̄ phase transition in anorthite. Phys. Chem. Min., 14, 189–95.CrossRefGoogle Scholar
Salje, E. (1985) Thermodynamics of sodium feldspar I: order parameter treatment and strain induced coupling effects. Phys. Chem. Min., 12, 93–8.CrossRefGoogle Scholar
Salje, E. (1986) Raman spectroscopic investigation of the order parameter behaviour in hypersolvus alkali feldspar: displacive phase transition and evidence for Na-K site ordering. Phys. Chem. Min., 13, 340–6.CrossRefGoogle Scholar
Salje, E. (1987) Towards a thermodynamic understanding of feldspars: order parameter of Na-feldspar and the I1̄ -P1̄ phase transition in anorthite. Pp. 1–16 in: Structural and Magnetic Phase Transitions in Minerals (Ghose, S., Coey, J.M.D. and Salje, E.K.H., editors). Advances in Physical Geochemistry, Springer-Verlag, Berlin.Google Scholar
Salje, E., Kuscholke, B., Wruck, B. and Kroll, H. (1985) Thermodynamics of sodium feldspar II: experimental results and numerical calculations. Phys. Chem. Min., 12, 99–107.CrossRefGoogle Scholar
Tribaudino, M., Benna, P. and Bruno, E. (1993) I1̄ – I2/cphase transition in alkaline-earth feldspars along the CaAl2Si2O8-SrAl2Si2O8 join: Thermodynamic behaviour. Phys. Chem. Min., 20, 221–7.CrossRefGoogle Scholar
Tribaudino, M., Benna, P. and Bruno, E. (1998) Structural variations induced by thermal treatment in lead feldspar (PbAl2Si2O8). Amer. Mineral., 83, 159–66.CrossRefGoogle Scholar