Ferroelectric transition and structural modulation in Sr2Na(Nb1−xTax)5O15 tungsten bronze ceramics

2021 ◽  
Vol 129 (24) ◽  
pp. 244107
Author(s):  
Ying Wang ◽  
Tu Lai Sun ◽  
Xiao Li Zhu ◽  
Lu Liu ◽  
Xiang Ming Chen
Keyword(s):  
Tungsten Bronze ◽  
Ferroelectric Transition ◽  
Structural Modulation

Effects of B site ions on the relaxor to normal ferroelectric transition crossover in Ba4Sm2Zr4(NbxTa1-x)6O30 tungsten bronze ceramics

2018 ◽  
Vol 112 (26) ◽  
pp. 262904 ◽  
Author(s):  
Wen Bin Feng ◽  
Xiao Li Zhu ◽  
Xiao Qiang Liu ◽  
Xiang Ming Chen
Keyword(s):  
Tungsten Bronze ◽  
Ferroelectric Transition

High-Order Incommensurate Modulations and Incommensurate Superstructures in Transparent Sr0.6Ba0.4Nb2O6(SBN40) Ceramics

1998 ◽  
Vol 31 (5) ◽  
pp. 683-691 ◽  
Author(s):  
Han-Young Lee ◽  
R. Freer
Keyword(s):  
Tungsten Bronze ◽  
Higher Order ◽  
Processing Route ◽  
Microstructural Development ◽  
X Ray Diffraction ◽  
Tetragonal Tungsten Bronze ◽  
Planar Defects ◽  
X Ray ◽  
Transmission Electron ◽  
Structural Modulation

Ceramics of strontium barium niobate (Sr0.6Ba0.4Nb2O6, SBN40), having the tetragonal tungsten bronze (TTB) structure, were prepared by a conventional processing route; sintering at temperatures in the range 1573–1723 K yielded products with three types of microstructure. Incommensurate superstructures were investigated by transmission electron microscopy (TEM). Modulation of the incommensurate superstructure (ICS) depended on microstructural development. The lowest-order ICS modulation was a common feature in all the SBN40 ceramics, regardless of microstructure. (h+1/2,h+1/2,l) reflections and unusually low δ (incommensurability parameter) were observed in SBN40 specimens having abnormally large grains and thus a certain degree ofA-site ordering was expected. Transparent SBN40 ceramics which exhibited large homogeneous grains were characterized by a shortenedcaxis, intense [001] X-ray diffraction reflections, a multiplication of (110) and (001) cell spacings and the appearance of higher-order ICS reflections. Planar defects, having the thickness of one d_{110} spacing, were observed aligned along \{110\}. The development of a higher-order structural modulation and of ICS reflections is believed to reduce the structural energy; the development of planar defects appears to stabilize the incommensurate phase.

Effects of A1/A2-Sites Occupancy upon Ferroelectric Transition in (Sr x Ba1−x )Nb2 O6 Tungsten Bronze Ceramics

2013 ◽  
Vol 97 (2) ◽  
pp. 507-512 ◽  
Author(s):  
C. J. Huang ◽  
K. Li ◽  
X. Q. Liu ◽  
X. L. Zhu ◽  
X. M. Chen
Keyword(s):  
Tungsten Bronze ◽  
Ferroelectric Transition

Role of structural modulation in electrical properties of tungsten bronze (Ca0.28Ba0.72)2.5−0.5Na Nb5O15 ceramics

2015 ◽  
Vol 632 ◽  
pp. 368-375 ◽  
Author(s):  
Bian Yang ◽  
Lingling Wei ◽  
Xiaolian Chao ◽  
Zhongming Wang ◽  
Zupei Yang
Keyword(s):  
Electrical Properties ◽  
Tungsten Bronze ◽  
Structural Modulation

On the assembly and structural modulation of lens fiber junctions

1984 ◽  
Vol 42 ◽  
pp. 110-113
Author(s):  
E.L. Benedetti ◽  
I. Dunia ◽  
Do Ngoc Lien ◽  
O. Vallon ◽  
D. Louvard ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Natural History ◽  
Intercellular Junctions ◽  
Eye Lens ◽  
Membrane Domains ◽  
Functional Polymorphism ◽  
Lens Fiber ◽  
The Past ◽  
Structural Modulation ◽  
Biochemical Difference

In the eye lens emerging molecular and structural patterns apparently cohabit with the remnants of the past. The lens in a rather puzzling fashion sums up its own natural history and even transient steps of the differentiation are memorized. A prototype of this situation is well outlined by the study of the lenticular intercellular junctions. These membrane domains exhibit structural, biochemical and perhaps functional polymorphism reflecting throughout life the multiple steps of the differentiation of the epithelium into fibers and of the ageing process of the lenticular cells.The most striking biochemical difference between the membrane derived from the epithelium and from the fibers respectively, concerns the presence of the 26,000 molecular weight polypeptide (MP26) in the latter membranes.

Local atomic structure of relaxor ferroelectric solids studied by pulsed neutron scattering

1994 ◽  
Vol 52 ◽  
pp. 554-555
Author(s):  
T. Egami ◽  
H. D. Rosenfeld ◽  
S. Teslic
Keyword(s):  
Neutron Scattering ◽  
Atomic Structure ◽  
Argonne National Laboratory ◽  
Relaxor Ferroelectrics ◽  
Relaxor Ferroelectric ◽  
Crystallographic Structure ◽  
Chemical Inhomogeneity ◽  
Distribution Analysis ◽  
Ferroelectric Transition ◽  
Pulsed Neutron

Relaxor ferroelectrics, such as Pb(Mg1/3Nb2/3)O3 (PMN) or (Pb·88La ·12)(Zr·65Ti·35)O3 (PLZT), show diffuse ferroelectric transition which depends upon frequency of the a.c. field. In spite of their wide use in various applications details of their atomic structure and the mechanism of relaxor ferroelectric transition are not sufficiently understood. While their crystallographic structure is cubic perovskite, ABO3, their thermal factors (apparent amplitude of thermal vibration) is quite large, suggesting local displacive disorder due to heterovalent ion mixing. Electron microscopy suggests nano-scale structural as well as chemical inhomogeneity.We have studied the atomic structure of these solids by pulsed neutron scattering using the atomic pair-distribution analysis. The measurements were made at the Intense Pulsed Neutron Source (IPNS) of Argonne National Laboratory. Pulsed neutrons are produced by a pulsed proton beam accelerated to 750 MeV hitting a uranium target at a rate of 30 Hz. Even after moderation by a liquid methane moderator high flux of epithermal neutrons with energies ranging up to few eV’s remain.

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