Hostname: page-component-586b7cd67f-tf8b9 Total loading time: 0 Render date: 2024-11-20T07:38:41.190Z Has data issue: false hasContentIssue false
  • English
  • Français

Polymorphism in the negative thermal expansion material magnesium hafnium tungstate

Published online by Cambridge University Press:  31 January 2011

Amy M. Gindhart ,
Cora Lind  and
Mark Green
Amy M. Gindhart
Affiliation:
Department of Chemistry, The University of Toledo, Toledo, Ohio 43606
Cora Lind*
Affiliation:
Department of Chemistry, The University of Toledo, Toledo, Ohio 43606
Mark Green
Affiliation:
National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102; and Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742-2115
*
a)Address all correspondence to this author. e-mail: [email protected]
Get access

Abstract

Magnesium hafnium tungstate [MgHf(WO4)3] was synthesized by high-energy ball milling followed by calcination. The material was characterized by variable- temperature neutron and x-ray diffraction. It crystallized in space group P21/a below 400 K and transformed to an orthorhombic structure at higher temperatures. The orthorhombic polymorph adopted space group Pnma, instead of the Pnca structure commonly observed for other A2(MO4)3 materials (A = trivalent metal, M = Mo, W). In contrast, the monoclinic polymorphs appeared to be isostructural. Negative thermal expansion was observed in the orthorhombic phase with αa = −5.2 × 10−6 K−1, αb = 4.4 × 10−6 K−1, αc = −2.9 × 10−6 K−1, αV = −3.7 × 10−6 K−1, and αl = −1.2 × 10−6 K−1. The monoclinic to orthorhombic phase transition was accompanied by a smooth change in unit-cell volume, indicative of a second-order phase transition.

Keywords

Crystallographic structureNeutron scatteringX-ray diffraction (XRD)
Type
Articles
Information
Journal of Materials Research , Volume 23 , Issue 1 , January 2008 , pp. 210 - 213
Copyright
Copyright © Materials Research Society 2008

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

REFERENCES

1Korthuis, V., Khosrovani, N., Sleight, A.W., Roberts, N., Dupree, R.Warren, W.W.: Negative thermal-expansion and phase-transitions in the ZrV2−xPxO7 series. Chem. Mater. 7, 412 1995CrossRefGoogle Scholar
2Mary, T.A., Evans, J.S.O., Vogt, T.Sleight, A.W.: Negative thermal expansion from 0.3 to 1050 kelvin in ZrW2O8. Science 272, 90 1996CrossRefGoogle Scholar
3Sleight, A.W.: Negative thermal expansion materials. Curr. Opin. Solid State Mater. Sci. 3, 128 1998CrossRefGoogle Scholar
4Sleight, A.W.: Isotropic negative thermal expansion. Annu. Rev. Mater. Sci. 28, 29 1998CrossRefGoogle Scholar
5Ernst, G., Broholm, C., Kowach, G.R.Ramirez, A.P.: Phonon density of states and negative thermal expansion in ZrW2O8. Nature 396, 147 1998CrossRefGoogle Scholar
6Evans, J.S.O.: Negative thermal expansion materials. J. Chem. Soc., Dalton Trans. 3317 1999Google Scholar
7Mary, T.A.Sleight, A.W.: Bulk thermal expansion for tungstate and molybdates of the type A2M3O12. J. Mater. Res. 14, 912 1999CrossRefGoogle Scholar
8Mittal, R., Chaplot, S.L., Schober, H.Mary, T.A.: Origin of negative thermal expansion in cubic ZrW2O8 revealed by high pressure inelastic neutron scattering. Phys. Rev. Lett. 86, 4692 2001CrossRefGoogle ScholarPubMed
9Forster, P.M.Sleight, A.W.: Negative thermal expansion in Y2W3O12. Int. J. Inorg. Mater. 1, 123 1999CrossRefGoogle Scholar
10Forster, P.M., Yokochi, A.Sleight, A.W.: Enhanced negative thermal expansion in Lu2W3O12. J. Solid State Chem. 140, 157 1998CrossRefGoogle Scholar
11Evans, J.S.O., Mary, T.A.Sleight, A.W.: Negative thermal expansion in a large molybdate and tungstate family. J. Solid State Chem. 133, 580 1997CrossRefGoogle Scholar
12Suzuki, T.Atsushi, O.: Negative thermal expansion in (HfMg)(WO4)3. J. Amer. Ceram. Soc. 87, 1365 2004CrossRefGoogle Scholar
13Rodriguez-Carvajal, J.: Recent advances in magnetic structure determination by neutron powder diffraction. Phys. B: Condens. Matter 192, 55 1993CrossRefGoogle Scholar
14Yim, W.M.Paff, R.J.: Thermal expansion of AlN, sapphire, and silicon. J. Appl. Phys. 45, 1456 1974CrossRefGoogle Scholar
15Shirley, R.: The Crysfire 2002 System for Automatic Powder Indexing: User’s Manual The Lattice Press Guildford 2002Google Scholar
16Visser, J.W.: A fully automatic program for finding the unit cell from powder data. J. Appl. Crystallogr. 2, 89 1969CrossRefGoogle Scholar
17Boultif, A.Louër, D.: Indexing of powder diffraction patterns for low-symmetry lattices by the successive dichotomy method. J. Appl. Crystallogr. 24, 987 1991CrossRefGoogle Scholar
18Werner, P-E., Eriksson, L.Westdahl, M.: TREOR, a semi-exhaustive trial-and-error powder indexing program for all symmetries. J. Appl. Crystallogr. 18, 367 1985CrossRefGoogle Scholar
19Taupin, D.: A powder-diagram automatic-indexing routine. J. Appl. Crystallogr. 6, 380 1973CrossRefGoogle Scholar
20Kohlbeck, F.Hörl, E.M.: Indexing program for powder patterns especially suitable for triclinic, monoclinic and orthorhombic lattices. J. Appl. Crystallogr. 9, 28 1976CrossRefGoogle Scholar