POLAR AND CHEMICAL DOMAIN STRUCTURES OF LEAD SCANDIUM TANTALATE (PST)

1993 ◽  
Vol 07 (09) ◽  
pp. 609-621 ◽  
Author(s):  
JULIN PENG ◽  
L. A. BURSILL
Keyword(s):  
Domain Walls ◽  
Complex Oxide ◽  
High Resolution Electron Microscopy ◽  
Domain Structures ◽  
Type Complex ◽  
Resolution Electron ◽  
A Site ◽  
First Time ◽  
Functional Ceramics ◽  
The Ideal

The local structure of chemical and polar domains and domain walls is determined directly by atomic resolution high-resolution electron microscopy (HRTEM). Thus the Pb, Ta, and Sc atomic positions may be located in the images of very thin crystals. Furthermore, the Pb cation displacements away from the ideal perovskite A-site have been measured directly for the first time. Local variations in polarization direction may be mapped directly off the images, provided certain electron optical conditions are met. The results are relevant to recent theories of polar-glass behaviour in relaxor-type complex oxide functional ceramics.

The role of ordered A1-site vacancies in belt nano-domains of Pb1−xBaxNb2O6 (PBN) solid solution

1996 ◽  
Vol 11 (3) ◽  
pp. 650-656 ◽  
Author(s):  
Xiaoyue Xiao ◽  
Yan Xu ◽  
Zhigang Zeng ◽  
Zhilun Gui ◽  
Longtu Li ◽  
...  
Keyword(s):  
Solid Solution ◽  
Phase Boundary ◽  
High Resolution Electron Microscopy ◽  
Quasi Equilibrium ◽  
Slow Cooling ◽  
Domain Structures ◽  
Resolution Electron ◽  
A Site ◽  
Anti Phase Boundary ◽  
Site Vacancy

The order-disorder states of the A-site vacancy of PBN solid solution affected by different thermal treatments were studied with the aid of High Resolution Electron Microscopy (HREM). PBN ceramics around the morphotropic phase boundary were prepared through two routes to control ordering degree of the A-site vacancy: (1) samples through quenching processes resulted in chaotic states of the A-site vacancies and misfit anti-phase boundary; (2) samples through slow cooling led to an ordered structure of the vacancies in the A1-site. The ordered A1-site vacancies were modulated by interchanges of the sublattices of the ordered vacancies and the Pb2+ cations in the A1-sites along both and orientations, forming a narrow discommensurate wall between two anti-phase domains. The anti-phase domains were observed as a regular belt structure with dimensions of about 45 nm × (≥120) nm. The belt nano-domain structures were a result of quasi-equilibrium thermodynamic processes.

Possible applications of fraunhofer holography in high resolution electron microscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 222-223 ◽  
Author(s):  
N. Bonnet ◽  
M. Troyon ◽  
P. Gallion
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Transfer Function ◽  
Radiation Damage ◽  
High Resolution Electron Microscopy ◽  
Far Field ◽  
Field Region ◽  
Crystalline Materials ◽  
Resolution Electron ◽  
The Ideal

Two main problems in high resolution electron microscopy are first, the existence of gaps in the transfer function, and then the difficulty to find complex amplitude of the diffracted wawe from registered intensity. The solution of this second problem is in most cases only intended by the realization of several micrographs in different conditions (defocusing distance, illuminating angle, complementary objective apertures…) which can lead to severe problems of contamination or radiation damage for certain specimens.Fraunhofer holography can in principle solve both problems stated above (1,2). The microscope objective is strongly defocused (far-field region) so that the two diffracted beams do not interfere. The ideal transfer function after reconstruction is then unity and the twin image do not overlap on the reconstructed one.We show some applications of the method and results of preliminary tests.Possible application to the study of cavitiesSmall voids (or gas-filled bubbles) created by irradiation in crystalline materials can be observed near the Scherzer focus, but it is then difficult to extract other informations than the approximated size.

scholarly journals Atomic Matching Across Internal Interfaces

1989 ◽  
Vol 153 ◽  
Author(s):  
Karl L. Merkle
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Large Fraction ◽  
High Resolution Electron Microscopy ◽  
Low Energy ◽  
Ideal Lattice ◽  
Interatomic Distances ◽  
Resolution Electron ◽  
Atomic Coordination ◽  
The Ideal

AbstractThe atomic structure of internal interfaces in dense-packed systems has been investigated by high-resolution electron microscopy (HREM). Similarities between the atomic relaxations in heterophase Interfaces and certain largeangle grain boundaries have been observed. In both types of interfaces localization of misfit leads to regions of good atomic matching within the interface separated by misfit dislocation-like defects. It appears that, whenever possible, the GB structures assume configurations in which the atomic coordination is not too much different from the ideal lattice. It is suggested that these kinds of relaxations primarily occur whenever the translational periods along the GB are large or when the interatomic distances are incommensurate. Incorporation of low index planes into the GB appears to lead to preferred, i.e. low energy structures, that can be quite dense with good atomic matching across a large fraction of the interface.

A Grease for Domain Walls Motion in HfO2-based Ferroelectrics

2021 ◽  
Author(s):  
Alireza Kashir ◽  
Mehrdad Ghiasabadi Farahani ◽  
Jan Lancok ◽  
Hyunsang Hwang ◽  
Stanislav Kamba
Keyword(s):  
Thin Film ◽  
Domain Walls ◽  
Field Effect Transistors ◽  
Field Measurements ◽  
High Resolution Electron Microscopy ◽  
Polar Regions ◽  
Microscopy Imaging ◽  
Resolution Electron ◽  
Ferroelectric Memories ◽  
Electric Field Measurements

Abstract A large coercive field EC of HfO2 based ferroelectric devices poses critical performance issues in their applications as ferroelectric memories and ferroelectric field effect transistors. A new design to reduce EC by fabricating nanolaminate Hf0.5Zr0.5O2 / ZrO2 (HZZ) thin films is used, followed by an ensuing annealing process at a comparatively high temperature 700 °C. High-resolution electron microscopy imaging detects tetragonal-like domain walls between orthorhombic polar regions. These walls decrease the potential barrier of polarization reversal in HfO2 based films compared to the conventional domain walls with a single non-polar spacer, causing about a 40% decrease in EC. Capacitance vs. electric field measurements on HZZ thin film uncovered a substantial increase of dielectric permittivity near the EC compared to the conventional Hf0.5Zr0.5O2 thin film, justifying the higher mobility of domain walls in the developed HZZ film. The tetragonal-like regions served as grease easing the movement of the domain wall and reducing EC

scholarly journals Sr1/2Ce5/14□1/7WO4: a new modulated ternary scheelite compound

2017 ◽  
Vol 73 (3) ◽  
pp. 466-473 ◽  
Author(s):  
Rafael Hernandez Damascena dos Passos ◽  
Madjid Arab ◽  
Carlson Pereira de Souza ◽  
Christine Leroux
Keyword(s):  
Band Gap ◽  
High Resolution Electron Microscopy ◽  
Partial Ordering ◽  
Promising Candidate ◽  
Atomic Displacements ◽  
Violet Luminescence ◽  
Resolution Electron ◽  
20 Nm ◽  
Cation Sites ◽  
First Time

For the first time, a ternary tetragonal scheelite structure tungstate with strontium and cerium cations, (Sr,Ce)WO4, was synthesized. As much as 35% Ce could be inserted into the structure, leaving 1\over 7 of the (Sr,Ce) cation sites vacant. Partial ordering of Sr and Ce, with atomic displacements, were shown by high-resolution electron microscopy. Two-dimensional incommensurate modulations occur in this material, in small domains 20 nm in size. The band gap of this compound is significantly lower than the band gap of SrWO4and this was related to the distortions of WO4and (Sr,Ce)O8polyhedra. The band gap value of 3.2 eV makes Sr1/2Ce5/14□1/7WO4a promising candidate for violet luminescence.

A study of the ordered structures of the Au–Mn system by high-voltage–high-resolution electron microscopy. II. Two-dimensional antiphase structures based on the DO 22 structure

1981 ◽  
Vol 14 (6) ◽  
pp. 392-400 ◽  
Author(s):  
O. Terasaki ◽  
D. Watanabe ◽  
K. Hiraga ◽  
D. Shindo ◽  
M. Hirabayashi
Keyword(s):  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Antiphase Domain ◽  
Two Dimensional ◽  
Ordered Structures ◽  
Domain Structures ◽  
Resolution Electron ◽  
Specimen Area ◽  
High Resolution Structure ◽  
Resolution Structure

Two-dimensional antiphase domain structures existing in the composition range 20–23 at.% Mn were investigated by a high-resolution structure-imaging technique with a 1 MV electron microscope. The structures are based on the DO 22 structure and consist of parallelogram-shaped domains containing 4 × 3 columns of Mn atoms and lozenge-shaped domains with 4 × 4 and 3 × 3 columns, and the domains are separated by two-dimensional antiphase boundaries parallel to the ({\bar 2}40) and (240) planes of the fundamental face-centred structure. The configuration of the domains changes delicately with a slight change of composition or annealing temperature, and the symmetry of the structure is lowered below about 670 K. The ideal structure models have compositions of about 22.7 at.% Mn. The images of about half of the specimen area of the 22.6 at.% Mn alloy annealed at 570 K do not correspond to these new structures, but bear a resemblance to the image expected from the two-dimensional antiphase structure proposed by Watanabe [J. Phys. Soc. Jpn (1960), 15, 1030–1040] for Au3Mn, which is based on the L12 structure and has boundaries parallel to the (100) and (010) planes.

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