Synchrotron x-ray powder diffraction study of the structural phase transition in CaBr{sub 2}

Journal Article · Fri Oct 01 04:00:00 EDT 2004 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PhysRevB.70.144102· OSTI ID:20664909

Kennedy, Brendan J; Howard, Christopher J ^[1]

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1. School of Chemistry, University of Sydney, Sydney NSW 2006 (Australia)

The structures of CaBr{sub 2} have been investigated using high resolution synchrotron powder x-ray diffraction methods between room temperature and 800 deg. C. At room temperature CaBr{sub 2} has an orthorhombic CaCl{sub 2}-type structure (Pnnm Z=2) with a=6.8847(1), b=6.5806(1), and c=4.3477(1) A. Heating above 560 deg. C results in a continuous transition to a tetragonal rutile type structure (P4{sub 2}/mnm Z=2) with a=6.810 95(7) A and c=4.417 70(5) A at 650 deg. C. Investigation, through either spontaneous strain or octahedral tilt angle, suggests that the transition is close to second order in nature, although the contribution from the sixth order term in the Landau potential cannot be neglected.

• OSTI ID: 20664909
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Journal Name: Physical Review. B, Condensed Matter and Materials Physics Journal Issue: 14 Vol. 70; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CALCIUM BROMIDES
CALCIUM CHLORIDES
HEAT TREATMENTS
HEATING
LATTICE PARAMETERS
ORTHORHOMBIC LATTICES
PHASE TRANSFORMATIONS
POWDERS
RUTILE
SYNCHROTRONS
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
TETRAGONAL LATTICES
X-RAY DIFFRACTION