Acta Crystallographica Section B

Structural Science

Volume 65, Part 3 (June 2009)

research papers

Acta Cryst. (2009). B65, 291-299 [ doi:10.1107/S0108768109011057 ]

Structures of K_0.05Na_0.95NbO₃ (50-300 K) and K_0.30Na_0.70NbO₃ (100-200 K)

N. Zhang, A. M. Glazer, D. Baker and P. A. Thomas

Abstract: Rietveld refinement using neutron powder diffraction data is reported for the potential lead-free piezoelectric material K_xNa_1 - xNbO₃ (x = 0.05, x = 0.3) at low temperatures. The structures were determined to be of rhombohedral symmetry, space group R3c, with the tilt system a^-a^-a^- for both compositions. It was found that some of the structural parameters differ significantly in the two structures, and particularly the NbO₆ octahedral strains as a function of temperature. The 300 K profile for K_0.05Na_0.95NbO₃ shows the coexistence of rhombohedral and monoclinic phases, which indicates that the phase boundary is close to room temperature; the phase boundary for K_0.30Na_0.70NbO₃ is found to be at approximately 180 K.

Keywords: Rietveld refinement; neutron powder diffraction; piezoelectric material; phase boundary.


	Rietveld powder data file (CIF format) (102.2 kbytes) [ doi:10.1107/S0108768109011057/wf5039KNN05at50Ksup2.rtv ] Contains datablock KNN05at50K

	Rietveld powder data file (CIF format) (102.1 kbytes) [ doi:10.1107/S0108768109011057/wf5039KNN05at100Ksup3.rtv ] Contains datablock KNN05at100K

	Rietveld powder data file (CIF format) (102.1 kbytes) [ doi:10.1107/S0108768109011057/wf5039KNN05at150Ksup4.rtv ] Contains datablock KNN05at150K

	Rietveld powder data file (CIF format) (102.1 kbytes) [ doi:10.1107/S0108768109011057/wf5039KNN05at200Ksup5.rtv ] Contains datablock KNN05at200K

	Rietveld powder data file (CIF format) (102.1 kbytes) [ doi:10.1107/S0108768109011057/wf5039KNN05at250Ksup6.rtv ] Contains datablock KNN05at250K

	Rietveld powder data file (CIF format) (98.7 kbytes) [ doi:10.1107/S0108768109011057/wf5039KNN30at100Ksup7.rtv ] Contains datablock KNN30at100K

	Rietveld powder data file (CIF format) (98.7 kbytes) [ doi:10.1107/S0108768109011057/wf5039KNN30at120Ksup8.rtv ] Contains datablock KNN30at120K

	Rietveld powder data file (CIF format) (98.7 kbytes) [ doi:10.1107/S0108768109011057/wf5039KNN30at140Ksup9.rtv ] Contains datablock KNN30at140K

	Rietveld powder data file (CIF format) (98.8 kbytes) [ doi:10.1107/S0108768109011057/wf5039KNN30at160Ksup10.rtv ] Contains datablock KNN30at160K

	Rietveld powder data file (CIF format) (98.9 kbytes) [ doi:10.1107/S0108768109011057/wf5039KNN30at180Ksup11.rtv ] Contains datablock KNN30at180K

	Rietveld powder data file (CIF format) (100.2 kbytes) [ doi:10.1107/S0108768109011057/wf5039KNN30at200Ksup12.rtv ] Contains datablock KNN30at200K

	Rietveld powder data file (CIF format) (93.3 kbytes) [ doi:10.1107/S0108768109011057/wf5039KNN05at300Ksup13.rtv ] Contains datablock KNN05at300K

Notes:

To open or display or play some files, you may need to set your browser up to use the appropriate software. See the full list of file types for an explanation of the different file types and their related mime types and, where available links to sites from where the appropriate software may be obtained.

The download button will force most browsers to prompt for a file name to store the data on your hard disk.

Where possible, images are represented by thumbnails.