Low-temperature and high-pressure structural behaviour of NaBi(MoO{sub 4}){sub 2}-an X-ray diffraction study

Journal Article · Fri Jul 15 00:00:00 EDT 2005 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2005.05.001· OSTI ID:20729019

Waskowska, A ^[1]; Gerward, L ^[2]; Staun Olsen, J ^[3]; Maczka, M ^[1]; Lis, T ^[4]; Pietraszko, A ^[1]; Morgenroth, W ^[5]

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1. Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O.B. 1410, 50 950 WrocIaw (Poland)
2. Department of Physics, Technical University of Denmark, 2800 Kongens Lyngby (Denmark)
3. Niels Bohr Institute Oersted Laboratory, University of Copenhagen, 2100 Copenhagen (Denmark)
4. Faculty of Chemistry, University of WrocIaw, 14 F. Joliot-Curie, 50 383 WrocIaw (Poland)
5. Hamburg Synchrotron Radiation Laboratory, Hasylab, at Desy, 22603 Hamburg (Germany)

NaBi(MoO{sub 4}){sub 2} has been characterized by single-crystal and powder X-ray diffraction in the temperature and pressure ranges 13-297K and 0-25GPa, respectively. The domain structure developing below T{sub c}=241K proves that NaBi(MoO{sub 4}){sub 2} undergoes a ferroelastic phase transition associated with tetragonal I4{sub 1}/a to monoclinic I2/a symmetry change. The character of the unit cell evolution as a function of temperature indicates a continuous transition with the spontaneous strain as an order parameter. The structural distortion, due to small displacements of Bi{sup 3+} and Na{sup +} ions, develops slowly. Therefore the overall changes, as measured in single-crystal diffraction at 110 and 13K, appear to be subtle. High-pressure powder X-ray diffraction shows that the elastic behaviour is anisotropic, the linear compressibility along the a- and c-axes of the tetragonal unit cell being {beta}{sub a}=2.75(10)x10{sup -3} and {beta}{sub c}=4.30(10)x10{sup -3}GPa{sup -1}, respectively. The cell contraction, stronger along the c-axis, causes the distances between the MoO{sub 4} layers to be shortened. Consequently, the cation migration in the channels formed by MoO{sub 4} tetrahedra becomes hindered, and any symmetry lowering phase transition is not observed up to 25GPa. The zero-pressure bulk modulus is B{sub 0}=76(5)GPa, and its pressure derivative B{sub 0}{sup '}=5.1(5)

• OSTI ID: 20729019
• Journal Information: Journal of Solid State Chemistry, Vol. 178, Issue 7; Other Information: DOI: 10.1016/j.jssc.2005.05.001; PII: S0022-4596(05)00197-0; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ANISOTROPY
BISMUTH COMPOUNDS
BISMUTH IONS
CATIONS
COMPRESSIBILITY
DOMAIN STRUCTURE
LAYERS
MOLYBDATES
MONOCLINIC LATTICES
MONOCRYSTALS
ORDER PARAMETERS
PHASE TRANSFORMATIONS
PRESSURE RANGE GIGA PA
SODIUM COMPOUNDS
SODIUM IONS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0065-0273 K
TETRAGONAL LATTICES
X-RAY DIFFRACTION