Symmetry determination on Pb-free piezoceramic 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 using convergent beam electron diffraction method

2014 ◽  
Vol 115 (5) ◽  
pp. 054108 ◽  
Author(s):  
Jinghui Gao ◽  
Lixue Zhang ◽  
Dezhen Xue ◽  
Takayoshi Kimoto ◽  
Minghui Song ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Diffraction Method ◽  
Convergent Beam Electron Diffraction ◽  
Beam Electron ◽  
Convergent Beam

Three-phase structure invariants and structure factors determined with the quantitative convergent-beam electron diffraction method

1999 ◽  
Vol 55 (2) ◽  
pp. 188-196 ◽  
Author(s):  
R. Høier ◽  
C. R. Birkeland ◽  
R. Holmestad ◽  
K Marthinsen
Keyword(s):  
Electron Diffraction ◽  
Phase Structure ◽  
Diffraction Method ◽  
Convergent Beam Electron Diffraction ◽  
Beam Electron ◽  
Structure Factors ◽  
Refinement Method ◽  
Three Phase ◽  
Phase Sensitive ◽  
Convergent Beam

Quantitative convergent-beam electron diffraction is used to determine structure factors and three-phase structure invariants. The refinements are based on centre-disc intensities only. An algorithm for parameter-sensitive pixel sampling of experimental intensities is implemented in the refinement procedure to increase sensitivity and computer speed. Typical three-beam effects are illustrated for the centrosymmetric case. The modified refinement method is applied to determine amplitudes and three-phase structure invariants in noncentrosymmetric InP. The accuracy of the results is shown to depend on the choice of the initial parameters in the refinement. Even unrealistic starting assumptions and incorrect temperature factor lead to stable results for the structure invariant. The examples show that the accuracy varies from 1 to 10° in the electron three-phase invariants determined and from 0.5 to 5% for the amplitudes. Individual phases could not be determined in the present case owing to spatial intensity correlations between phase-sensitive pixels. However, for the three-phase structure invariant, stable solutions were found.

Enantiomorph identification of crystals belonging to the point groups 321 and 312 by convergent-beam electron diffraction

2007 ◽  
Vol 40 (2) ◽  
pp. 241-249 ◽  
Author(s):  
Haruyuki Inui ◽  
Akihiro Fujii ◽  
Hiroki Sakamoto ◽  
Satoshi Fujio ◽  
Katsushi Tanaka
Keyword(s):  
Electron Diffraction ◽  
Diffraction Method ◽  
Convergent Beam Electron Diffraction ◽  
Zone Axis ◽  
The Other ◽  
Zeroth Order ◽  
Beam Electron ◽  
First Order ◽  
Point Groups ◽  
Convergent Beam

The recently proposed CBED (convergent-beam electron diffraction) method for enantiomorph identification has been successfully applied to crystals belonging to the point groups 321 and 312. The intensity asymmetry of zeroth-order Laue zone and/or first-order Laue zone reflections of Bijvoet pairs is easily recognized in CBED patterns with the incidence along appropriate zone-axis orientations for each member of the enantiomorphic pair. The intensity asymmetry with respect to the symmetry line is reversed upon changing the space group (handedness) from one to the other. Thus, enantiomorph identification can be easily performed in principle for all crystals belonging to the point groups 321 and 312.

Convergent-beam electron diffraction studies of domains in tetragonal phase of lead zirconate titanate ceramics

1987 ◽  
Vol 45 ◽  
pp. 26-27
Author(s):  
M.L.A. Dass
Keyword(s):  
Electron Diffraction ◽  
Lead Zirconate Titanate ◽  
Tetragonal Phase ◽  
Diffraction Method ◽  
Rhombohedral Phase ◽  
Lead Zirconate ◽  
Convergent Beam Electron Diffraction ◽  
Beam Electron ◽  
Zirconate Titanate ◽  
Convergent Beam

Lead zirconate titanate Pb(ZrxTi(1-x))O3 (PZT) ceramics are ferroelectrics formed as solid solutions between PbTiO3 and PbZrO3. Among the different phases in the ferroelectric state, the primary ones are the Ti+4 rich tetragonal phase and the Zr+4 rich rhombohedral phase. The coexistence of both T and R phases at the boundary composition has been reported using the convergent beam electron diffraction method. In an attempt to characterize the ferroelectric domains in the different phases, a study on the tetragonal phase is reported here, as such an analysis is useful in identifying the phases at the phase boundary.The ceramic used in this study was prepared by conventional ceramic processing and the composition of the sample examined was Pb(Zr0.55Ti0.45)O3. The structure has been found to be tetragonal with lattice parameters a=4.0155Å and c=4.1033Å using X-ray diffraction studies of powder samples.

Identification of the Chirality and Polarity of Intermetallic Compounds with the Point Groups of 23, 432, 422, and 321 by Electron Diffraction

2007 ◽  
Vol 539-543 ◽  
pp. 1457-1462 ◽  
Author(s):  
Haruyuki Inui ◽  
Katsushi Tanaka ◽  
Kyosuke Kishida ◽  
Satoshi Fujio
Keyword(s):  
Electron Diffraction ◽  
Intermetallic Compounds ◽  
Diffraction Method ◽  
Convergent Beam Electron Diffraction ◽  
Zone Axis ◽  
The Other ◽  
Beam Electron ◽  
Symmetry Line ◽  
Point Groups ◽  
Convergent Beam

A CBED (convergent-beam electron diffraction) method proposed by the present authors for chiral identification of enantiomorphic crystals has been successfully applied to intermetallic compounds with the point groups of 23, 422, 432 and 321. The intensity asymmetry of ZOLZ and/or FOLZ reflections of the Bijvoet pairs is easily recognized in CBED patterns with the incidence along the appropriate zone-axis orientations for each of the two members of the enantiomorphic pair and the intensity asymmetry with respect to the symmetry line is reversed upon changing the space group (handedness) from one to the other. Thus, the generality of the proposed method in identifying the chirality for all crystallographycally possible enantiomorphic crystals is verified.

Sign in / Sign up

Export Citation Format

Share Document