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Title: Composition, response to pressure, and negative thermal expansion in M IIB IVF 6 (M = Ca, Mg; B = Zr, Nb) [Composition, response to pressure, and negative thermal expansion in A IIB IVF 6; A - Ca, Mg, B - Zr, Nb]

CaZrF 6 has recently been shown to combine strong negative thermal expansion (NTE) over a very wide temperature range (at least 10–1000 K) with optical transparency from mid-IR into the UV range. Variable-temperature and high-pressure diffraction has been used to determine how the replacement of calcium by magnesium and zirconium by niobium(IV) modifies the phase behavior and physical properties of the compound. Similar to CaZrF 6, CaNbF 6 retains a cubic ReO 3-type structure down to 10 K and displays NTE up until at least 900 K. It undergoes a reconstructive phase transition upon compression to ~400 MPa at room temperature and pressure-induced amorphization above ~4 GPa. Prior to the first transition, it displays very strong pressure-induced softening. MgZrF 6 adopts a cubic ( Fm$$\bar{3}$$m) structure at 300 K and undergoes a symmetry-lowering phase transition involving octahedral tilts at ~100 K. Immediately above this transition, it shows modest NTE. Its’ thermal expansion increases upon heating, crossing through zero at ~500 K. Unlike CaZrF 6 and CaNbF 6, it undergoes an octahedral tilting transition upon compression (~370 MPa) prior to a reconstructive transition at ~1 GPa. Cubic MgZrF 6 displays both pressure-induced softening and stiffening upon heating. MgNbF 6 is cubic ( Fm$$\bar{3}$$m) at room temperature, but it undergoes a symmetry-lowering octahedral tilting transition at ~280 K. It does not display NTE within the investigated temperature range (100–950 K). Furthermore the replacement of Zr(IV) by Nb(IV) leads to minor changes in phase behavior and properties, the replacement of the calcium by the smaller and more polarizing magnesium leads to large changes in both phase behavior and thermal expansion.
Authors:
 [1] ;  [2] ;  [3] ; ORCiD logo [1]
  1. Georgia Inst. of Technology, Atlanta, GA (United States)
  2. Georgia Inst. of Technology, Atlanta, GA (United States); Northwestern Univ., Evanston, IL (United States)
  3. Argonne National Lab. (ANL), Lemont, IL (United States)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 29; Journal Issue: 2; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22), Scientific User Facilities Division; National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1364648

Hester, Brett R., Hancock, Justin C., Lapidus, Saul H., and Wilkinson, Angus P.. Composition, response to pressure, and negative thermal expansion in MIIBIVF6 (M = Ca, Mg; B = Zr, Nb) [Composition, response to pressure, and negative thermal expansion in AIIBIVF6; A - Ca, Mg, B - Zr, Nb]. United States: N. p., Web. doi:10.1021/acs.chemmater.6b04809.
Hester, Brett R., Hancock, Justin C., Lapidus, Saul H., & Wilkinson, Angus P.. Composition, response to pressure, and negative thermal expansion in MIIBIVF6 (M = Ca, Mg; B = Zr, Nb) [Composition, response to pressure, and negative thermal expansion in AIIBIVF6; A - Ca, Mg, B - Zr, Nb]. United States. doi:10.1021/acs.chemmater.6b04809.
Hester, Brett R., Hancock, Justin C., Lapidus, Saul H., and Wilkinson, Angus P.. 2016. "Composition, response to pressure, and negative thermal expansion in MIIBIVF6 (M = Ca, Mg; B = Zr, Nb) [Composition, response to pressure, and negative thermal expansion in AIIBIVF6; A - Ca, Mg, B - Zr, Nb]". United States. doi:10.1021/acs.chemmater.6b04809. https://www.osti.gov/servlets/purl/1364648.
@article{osti_1364648,
title = {Composition, response to pressure, and negative thermal expansion in MIIBIVF6 (M = Ca, Mg; B = Zr, Nb) [Composition, response to pressure, and negative thermal expansion in AIIBIVF6; A - Ca, Mg, B - Zr, Nb]},
author = {Hester, Brett R. and Hancock, Justin C. and Lapidus, Saul H. and Wilkinson, Angus P.},
abstractNote = {CaZrF6 has recently been shown to combine strong negative thermal expansion (NTE) over a very wide temperature range (at least 10–1000 K) with optical transparency from mid-IR into the UV range. Variable-temperature and high-pressure diffraction has been used to determine how the replacement of calcium by magnesium and zirconium by niobium(IV) modifies the phase behavior and physical properties of the compound. Similar to CaZrF6, CaNbF6 retains a cubic ReO3-type structure down to 10 K and displays NTE up until at least 900 K. It undergoes a reconstructive phase transition upon compression to ~400 MPa at room temperature and pressure-induced amorphization above ~4 GPa. Prior to the first transition, it displays very strong pressure-induced softening. MgZrF6 adopts a cubic (Fm$\bar{3}$m) structure at 300 K and undergoes a symmetry-lowering phase transition involving octahedral tilts at ~100 K. Immediately above this transition, it shows modest NTE. Its’ thermal expansion increases upon heating, crossing through zero at ~500 K. Unlike CaZrF6 and CaNbF6, it undergoes an octahedral tilting transition upon compression (~370 MPa) prior to a reconstructive transition at ~1 GPa. Cubic MgZrF6 displays both pressure-induced softening and stiffening upon heating. MgNbF6 is cubic (Fm$\bar{3}$m) at room temperature, but it undergoes a symmetry-lowering octahedral tilting transition at ~280 K. It does not display NTE within the investigated temperature range (100–950 K). Furthermore the replacement of Zr(IV) by Nb(IV) leads to minor changes in phase behavior and properties, the replacement of the calcium by the smaller and more polarizing magnesium leads to large changes in both phase behavior and thermal expansion.},
doi = {10.1021/acs.chemmater.6b04809},
journal = {Chemistry of Materials},
number = 2,
volume = 29,
place = {United States},
year = {2016},
month = {12}
}