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An EXAFS study of cation site distortions through the P2/c-P1̄ phase transition in the synthetic cuproscheelite-sanmartinite solid solution

Published online by Cambridge University Press:  05 July 2018

P. F. Schofield ,
J. M. Charnock ,
G. Cressey  and
C. M. B. Henderson
P. F. Schofield
Affiliation:
Department of Geology, University of Manchester, Oxford Road, Manchester M13 9PL, UK
J. M. Charnock
Affiliation:
Department of Geology, University of Manchester, Oxford Road, Manchester M13 9PL, UK
G. Cressey
Affiliation:
Department of Mineralogy, Natural History Museum, Cromwell Road, London SW7 5BD, UK
C. M. B. Henderson
Affiliation:
Department of Geology, University of Manchester, Oxford Road, Manchester M13 9PL, UK
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Abstract

EXAFS spectroscopy has been used to monitor changes in divalent cation site geometries across the P2/c-P1̄ phase transition in the sanmartinite (ZnWO4)-cuproscheelite (CuWO4) solid solution at ambient and liquid nitrogen temperatures. In the ZnWO4 end member, Zn occupies axially-compressed ZnO6 octahedra with two axial Zn-O bonds at approximately 1.95 Å and four square planar Zn-O bonds at approximately 2.11 Å. The substitution of Zn by Cu generates a second Zn environment with four short square planar Zn-O bonds and two longer axial Zn-O bonds. The proportion of the latter site increases progressively as the Cu content increases. Cu EXAFS reveals that the CuO6 octahedra maintain their Jahn-Teller axially-elongate geometry throughout the majority of the solid solution and only occur as axially-compressed octahedra well within the stability field of the Zn-rich phase with monoclinic long-range order.

Keywords

EXAFS spectroscopysanmartinitecuproscheelitephase transition
Type
Experimental Mineralogy
Information
Mineralogical Magazine , Volume 58 , Issue 391 , June 1994 , pp. 185 - 199
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1994

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Footnotes

*

Present Address: Department of Mineralogy, Natural History Museum, Cromwell Road, London SW7 5BD, UK

References

Abrahams, S. C. (1967) Crystal structure of the transition-metal molybdates and tungstates. HI Diamagnetic xZnMoO4. J. Chem. Phys., 46, 2052–63.Google Scholar
Brown, G. E. Jr., Calas, G., Waychunas, G. A. and Petiau, J. (1988) X-ray absorption spectroscopy: Applications in mineralogy and geochemistry. In Spectroscopic Methods in Mineralogy and Geology. Mineralogical Society of America, Reviews in Mineralogy, 18, (Hawthorne, F. C, ed.), 431-512.Google Scholar
Binsted, N., Campbell, J. W., Gurman, S. J. and Stephenson, P. C. (1990) SERC Daresbury Laboratory EXCVRVE90 program. Google Scholar
Calas, G., Manceau, A., Combes, J-M. and Farge, F. (1990) Application of EXAFS in mineralogy. In Absorption Spectroscopy in Mineralogy. (Mottana, A. and Burragato, F., eds.), 172-5.Google Scholar
Combes, J. M., Manceau, G. and Calas G. (1986) Study of the structure in poorly-ordered precur-sors of iron oxi-hydroxides. J. Physique, 47, 697–70.Google Scholar
Eisenberger, P. and Brown, G. S. (1979) The study of disordered systems by EXAFS: Limitations. Sol. Stat. Commun., 29, 481–4.Google Scholar
Eisenberger, P. and Lengeler, B. (1980) Extended X-ray absorption fine structure determinations of coordination numbers: Limitations. Phys. Rev., B22, 3551–62.Google Scholar
Filipenko, O. S., Pobedimskay, E. A. and Belov, N. V. (1968) The crystal structure of ZnWO4. Sov. Phys. Crystallogr., 13, 127–9.Google Scholar
Forsyth, J. B., Wilkinson, C. and Zvyagin, A. I. (1991) The antiferromagnetic structure of copper tungstate, CuW04. J. Phys.: Condens. Matter, 3, 8433–0.Google Scholar
Gurman, S. J., Binsted, N. and Ross, I. (1984) A rapid, exact, curved wave theory for EXAFS calculations. J. Phys. C: Solid State Phys., 17, 143–51.Google Scholar
Joyner, R. W., Martin, K. J. and Meehan, P. (1987) Some applications of statistical tests in analysis of EXAFS and SEXAFS data. J. Phys. C: Solid State Phys., 20, 4005–12.Google Scholar
Kihlborg, L. and Gebert, E. (1970) CuWO4 a distorted wolframite-type structure. Ada Crystallogr., B26, 1020–5.Google Scholar
Klein, S. and Weitzel, H. (1975) PERNOD — ein Programm zur von Kristallstructurparameterrn aus Neutronenbeugungspulverdiagrammen. J. Appl. Crystallogr., 8, 54–9.Google Scholar
Lee, P. A. and Pendry, J. B. (1975) Theory of the extended X-ray absorption fine structure. Phys. Rev., 811, 2795-811.Google Scholar
Schofield, P. F. and Redfern, S. A. T. (1992) Ferroelastic phase transition in the sanmartinite (ZnWO4)-cuproscheelite (CuWO4) solid solution. J. Phys.: Condens. Matter, 4, 375–88.Google Scholar
Schofield, P. F. and Redfern, S. A. T. (1993) Temperature and composition-dependence of the ferroelastic phase transition in (CuxZn] JWO4. J. Phys. Chem. Solids, 54, 161–70.Google Scholar
Schofield, P. F., Henderson, C. M. B., Redlern, S. A. T. and van der Laan, G. (1993) Cu 2/> absorption spectroscopy as a probe for the site occupancies of (ZnxCu!_x)WO4 solid solution. Phys. Chem. Minerals, 20, 375–81.+absorption+spectroscopy+as+a+probe+for+the+site+occupancies+of+(ZnxCu!_x)WO4+solid+solution.+Phys.+Chem.+Minerals,+20,+375–81.>Google Scholar
Simonov, M. A., Sandomerskii, P A., Egorov-Tismenko, Yu. K. and Belov, N. V. (1977) Crystal structure of willemite, Zn2SiO4. Sov. Phys. Dokl, 22, 622–3.Google Scholar