Skip to main content

Polymorphism in the negative thermal expansion material magnesium hafnium tungstate

Gindhart, A.M., Lind, C., Green, M.A. (2008) Polymorphism in the negative thermal expansion material magnesium hafnium tungstate. Journal of Materials Research, 23 (1). pp. 210-213. ISSN 0884-2914. (doi:10.1557/jmr.2008.0013) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided. (Contact us about this Publication)
Official URL
http://dx.doi.org/10.1557/jmr.2008.0013

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 difftaction. 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 α1, = -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. © 2008 Materials Research Society.

Item Type: Article
DOI/Identification number: 10.1557/jmr.2008.0013
Additional information: Unmapped bibliographic data: LA - English [Field not mapped to EPrints] J2 - J Mater Res [Field not mapped to EPrints] AD - Department of Chemistry, The University of Toledo, Toledo, OH 43606, United States [Field not mapped to EPrints] AD - National Institute of Standards and Technology, Gaithersburg, MD 20899-6102, United States [Field not mapped to EPrints] AD - Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742-2115, United States [Field not mapped to EPrints] DB - Scopus [Field not mapped to EPrints]
Uncontrolled keywords: Ball milling, Calcination, Crystal structure, Phase transitions, Polymorphism, Synthesis (chemical), Thermal expansion, Magnesium hafnium tungstate, Negative thermal expansion, Orthorhombic structure, Magnesium compounds
Subjects: Q Science > QC Physics > QC173.45 Condensed Matter
Q Science > QD Chemistry > QD478 Solid State Chemistry
Divisions: Faculties > Sciences > School of Physical Sciences > Functional Materials Group
Depositing User: Giles Tarver
Date Deposited: 15 Oct 2015 11:05 UTC
Last Modified: 29 May 2019 16:09 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/51016 (The current URI for this page, for reference purposes)
  • Depositors only (login required):