Quick
Search: 		  
advanced search
 GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help 
American Mineralogist Email Content Delivery
JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
American Mineralogist; July 2007; v. 92; no. 7; p. 1038-1047; DOI: 10.2138/am.2007.2099
© 2007 Mineralogical Society of America
This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Schofield, P. F.
Right arrow Articles by Lanfranco, A. M.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

Thermal expansion of deuterated hopeite, Zn3(PO4)2·4D2O

Paul F. Schofield1,*, Kevin S. Knight1,2, Mark E. Hodson1,3 and Anna M. Lanfranco1,{dagger}

1 Department of Mineralogy, Natural History Museum, Cromwell Road, London SW7 5BD, U.K.
2 ISIS Science Division, Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX, U.K.
3 Department of Soil Science, School of Human and Environmental Sciences, The University of Reading, Whiteknights, Reading, RG6 6DW, U.K.

Correspondence: * E-mail: pfs{at}nhm.ac.uk

The lattice parameters extracted from Lebail analysis of neutron powder diffraction data collected between 2 and 300 K have been used to calculate the temperature evolution of the thermal expansion tensor for hopeite, Zn3(PO4)2·2H2O, Pnma, Z = 4 with a = 10.6065(4) Å, b = 18.2977(4) Å, c = 5.0257(2) Å at 275 K. The a lattice parameter shows a negative thermal expansion, the b lattice parameter appears to saturate at 275 K while the c lattice parameter has a more typical positive thermal expansion. At 275 K, the magnitudes of the thermal expansion coefficients are {alpha}a = –1.1(4) x 10–5 K–1, {alpha}b = 2.4(9) x 10–6 K–1 and {alpha}c = 3.6(2) x 10–5 K–1. Under the conditions of these experiments, hopeite begins to dehydrate to the dihydrate between 300 and 325 K, and between 480 and 500 K the monohydrate is formed. The thermal expansion of the dihydrate has been calculated between 335 and 480 and at 480 K the magnitudes of the thermal expansion coefficients are {alpha}a = 1(2) x 10–5 K–1, {alpha}b = 4(1) x 10–6 K–1, {alpha}c = 4(2) x 10–5 K–1, {alpha}ß= 1(1) x 10–5 K–1, and {alpha}V = 2(2) x 10–5 K–1. The thermal expansion of hopeite is described in terms of its crystal structure and possible dehydration mechanisms for the {alpha} and ß modifications of hopeite are discussed.

Key Words: Hopeite • thermal expansion • dehydration • neutron diffraction




This article has been cited by other articles:


Home page
 American MineralogistHome page
M. Tribaudino, M. Bruno, G. Iezzi, G. Della Ventura, and I. Margiolaki
The thermal behavior of richterite
American Mineralogist, October 1, 2008; 93(10): 1659 - 1665.
[Abstract] [Full Text] [PDF]


JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2008 by Mineralogical Society of America