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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: cora.lind@utoledo.edu
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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

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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