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Structural analysis of lead magnesium niobate using synchrotron powder X‐ray diffraction and the Rietveld method
Author(s) -
Bhakar Ashok,
Pandey Adityanarayan H.,
Singh M. N.,
Upadhyay Anuj,
Sinha A. K.,
Gupta S. M.,
Ganguli Tapas
Publication year - 2016
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s2052520616006508
Subject(s) - rietveld refinement , synchrotron , materials science , x ray crystallography , powder diffraction , diffraction , magnesium , x ray , crystallography , metallurgy , optics , chemistry , physics
The room‐temperature synchrotron powder X‐ray diffraction pattern of the single phase perovskite lead magnesium niobate (PMN) has shown significant broadening in the q range ∼ 5–7 Å −1 compared with standard LaB 6 synchrotron powder X‐ray diffraction data, taken under similar conditions. This broadening/asymmetry lies mainly towards the lower 2θ side of the Bragg peaks. Attempts to fit this data with the paraelectric cubic phase () and the local rhombohedral phase ( R 3 m ) corresponding to polar nanoregions (PNRs) are made using the Rietveld method. Rietveld refinements show that neither cubic () nor rhombohedral ( R 3 m ) symmetry can fit this XRD pattern satisfactorily. The two‐phase refinement fits the experimental data satisfactorily and suggests that the weight percentage of the PNRs is approximately 12–16% at room temperature. The unit‐cell volume of these rhombohedral PNRs is approximately 0.15% larger than that of the unit cell volume of the paraelectric cubic phase.