scholarly journals Piezoelectricity in perovskite-type pseudo-cubic ferroelectrics by partial ordering of off-centered cations

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Yoshihiro Kuroiwa ◽  
Sangwook Kim ◽  
Ichiro Fujii ◽  
Shintaro Ueno ◽  
Yuki Nakahira ◽  
...  
Keyword(s):  
Electric Field ◽  
Applied Electric Field ◽  
Partial Ordering ◽  
Ferroelectric Ceramics ◽  
Piezoelectric Response ◽  
X Ray Diffraction ◽  
Cubic Symmetry ◽  
X Ray ◽  
Domain Structures ◽  
Perovskite Type

Abstract A large piezoelectric response in ferroelectric ceramics is typically associated with extrinsic contributions from ferroelectric domain structures. However, such domain structures cannot be expected in systems with pseudo-cubic symmetry. In this study, we determine the mechanism of significant piezoelectricity and ferroelectricity in 0.3BaTiO3–0.1Bi(Mg1/2Ti1/2)O3–0.6BiFeO3 ceramic with a perovskite-type pseudo-cubic symmetry. Synchrotron radiation X-ray diffraction reveals that the Bi ions in this ceramic essentially prefer to be off-centered at six sites by approximately 0.4 Å, in the cubic <100> directions. A phase transition occurs at TC ~725 K. However, the crystal seems to present a cubic symmetry even at room temperature. The large piezoelectric response is caused by the combinational partial ordering of the off-centered Bi ions, adapted to any direction of the applied electric field to the ceramic grains. The proposed mechanism for the emergence of a high polarization in the above system will enable designing novel Pb-free ceramics by controlling the fluctuated and off-centered ions under an applied electric field.

Crystal behavior of potassium bromate under compression

2015 ◽  
Vol 71 (6) ◽  
pp. 798-804 ◽  
Author(s):  
David Santamaría-Pérez ◽  
Raquel Chulia-Jordan ◽  
Placida Rodríguez-Hernández ◽  
Alfonso Muñoz
Keyword(s):  
Phase Transition ◽  
Bulk Modulus ◽  
Ab Initio ◽  
X Ray Diffraction ◽  
Pressure Derivative ◽  
Cubic Symmetry ◽  
X Ray ◽  
Reported Data ◽  
Perovskite Type ◽  
Perovskite Type Structure

We report on high-pressure angle-dispersive X-ray diffraction data up to 15 GPa and ab initio total-energy calculations up to 242 GPa for KBrO3. No phase transition was found below 15 Pa in contrast to previously reported data. Its experimental bulk modulus in the quasi-hydrostatic regime is B 0 = 18.8 (9) GPa with a bulk modulus pressure derivative B′0 = 8.2 (4). However, according to our ab initio calculations, KBrO3 significantly reduces its rhombohedral distortion via small cooperative movements of the atoms and the structure progressively approaches the cubic symmetry, where the KBr subarray would adopt a topology similar to that of the corresponding B2-type bromide. This rearrangement of atoms is directly related to the Buerger's mechanism of the B1–B2 phase transition for halides, confirming that cations (second neighbors) do not arrange in an arbitrary way. The O atoms forming the [BrO3] pyramidal units move smoothly with pressure to the center of the [K8] cube faces, where electron localization function calculations present their maxima in other B2-type compounds, eventually adopting the perovskite-type structure at P ≃ 152 GPa. Our data on KBrO3 has been compared with chemically substituted isostructural halates, providing new insights on the compressibility of this family of compounds.

Time-resolved x-ray diffraction study of the piezoelectric crystal response to a fast change of an applied electric field

2010 ◽  
Vol 108 (6) ◽  
pp. 064911 ◽  
Author(s):  
Semen Gorfman ◽  
Oleg Schmidt ◽  
Michael Ziolkowski ◽  
Marc von Kozierowski ◽  
Ullrich Pietsch
Keyword(s):  
Electric Field ◽  
Diffraction Study ◽  
Applied Electric Field ◽  
Piezoelectric Crystal ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Fast Change

Highlights in the history of X-ray topography1

1995 ◽  
Vol 210 (6) ◽  
Author(s):  
A. R. Lang
Keyword(s):  
Magnetic Domain ◽  
Diffraction Theory ◽  
Dislocation Loops ◽  
X Ray Diffraction ◽  
X Ray ◽  
Domain Structures ◽  
Structure Factors ◽  
History Of ◽  
Dislocation Sources ◽  
Non Destructive

AbstractX-ray topography provides a non-destructive method of mapping point-by-point variations in orientation and reflecting power within crystals. The discovery, made by several workers independently, that in nearly perfect crystals it was possible to detect individual dislocations by X-ray diffraction contrast started an epoch of rapid exploitation of X-ray topography as a new, general method for assessing crystal perfection. Another discovery, that of X-ray Pendellösung, led to important theoretical developments in X-ray diffraction theory and to a new and precise method for measuring structure factors on an absolute scale. Other highlights picked out for mention are studies of Frank-Read dislocation sources, the discovery of long dislocation helices and lines of coaxial dislocation loops in aluminium, of internal magnetic domain structures in Fe-3 wt.% Si, and of stacking faults in silicon and natural diamonds.

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