Modification of Ferroelectric Properties of TGS Crystals Grown under a dc Electric field

2000 ◽  
Vol 658 ◽  
Author(s):  
G. Arunmozhi ◽  
E. Nogueira ◽  
E.de Matos Gomes ◽  
S. Lanceros-Mendez ◽  
M. Margarida ◽  
...  
Keyword(s):  
Dielectric Permittivity ◽  
Electric Field ◽  
Ferroelectric Phase ◽  
Ferroelectric Properties ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
Triglycine Sulphate ◽  
X Ray ◽  
Dc Electric Field ◽  
Diffraction Patterns

ABSTRACTFerroelectric triglycine sulphate crystals have been grown under the influence of an intense electric field of 6×104 V/m. Relative to crystals grown under ambient conditions (TGS) the crystals grown under the electric field (TGS-E) display a dielectric permittivity a factor of two lower. Significant differences are observed in the Curie-Weiss behavior of the ferroelectric phase, in the x-ray diffraction patterns and in the differential calorimetry measurements.

Use of an External Electric Field to Convert the Paraelectric Phase to the Ferroelectric Phase in Ultra-thin Copolymer Films of P(VDF-TrFE)

2000 ◽  
Vol 655 ◽  
Author(s):  
Matt Poulsen ◽  
S. Adenwalla ◽  
Stephen Ducharme ◽  
V.M. Fridkin ◽  
S.P. Palto ◽  
...  
Keyword(s):  
Phase Transition ◽  
Electric Field ◽  
External Electric Field ◽  
Ferroelectric Phase ◽  
Paraelectric Phase ◽  
Continuous Process ◽  
Structural Phase ◽  
X Ray Diffraction ◽  
Layer Spacing ◽  
X Ray

AbstractX-ray diffraction was used to probe the structural changes associated with the conversion of the paraelectric phase to the ferroelectric phase that results from the application of a large external electric field. The samples under study are ultrathin (150 to 250 Å) Langmuir-Blodgett films of the copolymer vinylidene fluoride (70%) with trifluoroethylene (30%) deposited on aluminum-coated silicon. Theta-2theta X-ray diffraction was used to measure the change in inter-layer spacing perpendicular to the film surface. Upon heating at zero external electric field, the crystalline films undergo a structural phase transition, at 100± 5°C, from the all-trans ferroelectric phase to the trans-gauche paraelectric phase. [1,2] Above the phase transition temperature, the non-polar paraelectric phase can be converted back to the polar ferroelectric phase, in a smooth continuous process, using a large external electric field (∼1 GV/m). For example, at 100° C the ferroelectric phase first appears above 0.2 GV/m and increases steadily in proportion while the paraelectric phase decreases until complete conversion to the ferroelectric phase is achieved at approximately 0.6 GV/m.

An x-ray diffraction and EXAFS study of the electric-field-induced ferroelectric phase

1996 ◽  
Vol 8 (11) ◽  
pp. 1615-1620 ◽  
Author(s):  
V A Shuvaeva ◽  
M Yu Antipin ◽  
O E Fesenko ◽  
Yu T Struchkov
Keyword(s):  
Electric Field ◽  
Ferroelectric Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Exafs Study

X-ray diffraction study of the atomic interactions, anharmonic displacements and inner-crystal field in orthorhombic KNbO3

2021 ◽  
Vol 77 (5) ◽  
Author(s):  
Adam I. Stash ◽  
Ekaterina O. Terekhova ◽  
Sergey A. Ivanov ◽  
Vladimir G. Tsirelson
Keyword(s):  
Diffraction Study ◽  
Electron Density ◽  
Ferroelectric Phase ◽  
Ferroelectric Properties ◽  
Structural Disorder ◽  
Space Distribution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Atomic Vibrations

An X-ray diffraction study aimed at establishing the subtle details of the electron density and anharmonicity of the atomic vibrations in a stoichiometric monodomain single crystal of potassium niobate, KNbO3, has been conducted at room temperature (orthorhombic ferroelectric phase Amm2). The cation and anion displacements obtained from the experiment are weakly anharmonic without any manifestation of structural disorder. The chemical bond and interatomic interactions inside and between crystal substructures at the balance of intracrystalline forces are characterized in detail. The role of each of the ions in the formation of the ferroelectric phase was studied and the features of the electron-density deformation in the niobium and oxygen substructures, and the role of each of them in the occurrence of spontaneous polarization are established. The position-space distribution of electrostatic and quantum forces in KNbO3 is restored. It is emphasized that for the completeness of the analysis of the nature of the ferroelectric properties it is necessary to consider both static and kinetic electronic factors, which are of a quantum origin. The experimental results and theoretical estimations by the Kohn–Sham calculation with periodic boundary conditions are in reasonable agreement, thus indicating the physical significance of the findings of this study.

Effects of Donor Doping on Microstructure and Electrical Properties of Bismuth Layer-Structured Bi4Ti3O12 Ceramics

2007 ◽  
Vol 280-283 ◽  
pp. 259-262 ◽  
Author(s):  
Lina Zhang ◽  
Su Chuan Zhao ◽  
Liao Ying Zheng ◽  
Guo Rong Li ◽  
Qing Rui Yin
Keyword(s):  
Electrical Conductivity ◽  
High Temperature ◽  
Electrical Properties ◽  
Ferroelectric Properties ◽  
Orthorhombic Phase ◽  
X Ray Diffraction ◽  
Suitable Candidate ◽  
X Ray ◽  
Donor Doping ◽  
Diffraction Patterns

A study was conducted on the effects of donor dopants, Nb2O5 and WO3, on microstructure and electric properties of Bi4Ti3O12 (BIT) ceramics. X-ray diffraction patterns of the materials showed a single orthorhombic phase structure. The microstructure results revealed the appearance of plate-like grain. The donor doping decreased the conductivity of BIT by as much as 3 orders of magnitude. The dielectric and ferroelectric properties of doped-BIT materials were also investigated. The decrease in the electrical conductivity allowed the doped samples to be poled to develop piezoelectricity. Thermal annealing studies of the samples indicated the donor-doped BIT were suitable candidate materials for high-temperature piezoelectric applications.

scholarly journals In situ X-ray diffraction investigation of electric-field-induced switching in a hybrid improper ferroelectric

2021 ◽  
Vol 54 (2) ◽  
pp. 533-540
Author(s):  
Gabriel Clarke ◽  
Chris Ablitt ◽  
John Daniels ◽  
Stefano Checchia ◽  
Mark S. Senn
Keyword(s):  
Electric Field ◽  
Simulated Data ◽  
Functional Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Switching Mechanism ◽  
One Step ◽  
Diffraction Patterns ◽  
Ferroelectric Switching

Improper ferroelectric mechanisms are increasingly under investigation for their potential to expand the current catalogue of functional materials whilst promoting couplings between ferroelectricity and other technologically desirable properties such as ferromagnetism. This work presents the results of an in situ synchrotron X-ray diffraction experiment performed on samples of Ca2.15Sr0.85Ti2O7 in an effort to elucidate the mechanism of hybrid improper ferroelectric switching in this compound. By simultaneously applying an electric field and recording diffraction patterns, shifts in the intensity of superstructure peaks consistent with one of the switching mechanisms proposed by Nowadnick & Fennie [Phys. Rev. B, (2016), 94, 104105] are observed. While the experiment only achieves a partial response, comparison with simulated data demonstrates a preference for a one-step switching mechanism involving an unwinding of the octahedral rotation mode in the initial stages of switching. These results represent some of the first reported experimental diffraction-based evidence for a switching mechanism in an improper ferroelectric.

scholarly journals Progressive Polytypism and Bandgap Tuning in Azetidinium Lead Halide Perovskites

2021 ◽  
Author(s):  
Jiyu Tian ◽  
David Cordes ◽  
Alexandra Slawin ◽  
Eli Zysman-Colman ◽  
Finlay Morrison
Keyword(s):  
Linear Variation ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Vegard’S Law ◽  
The Family ◽  
Halide Perovskites ◽  
Diffraction Patterns ◽  
Bandgap Tuning ◽  
Lead Halide

<div><div><div><p>Mixed halide azetidinium lead perovskites AzPbBr<sub>3-<i>x</i></sub>X<i><sub>x</sub></i> (X = Cl or I) were obtained by mechanosynthesis. With varying halide composition from Cl- to Br- to I-; the chloride and bromide analogs both form in the hexagonal 6H polytype while the iodide adopts the 9R polytype. An intermediate 4H polytype is observed for mixed Br/I compositions. Overall the structure progresses from 6H to 4H to 9R perovskite polytype with varying halide composition. Rietveld refinement of the powder X-ray diffraction patterns revealed a linear variation in unit cell volume as a function of the average radius of the anion, which is not only observed within the solid solution of each polytype (according to Vegard’s law) but extends uniformly across all three polytypes. This is correlated with a progressive (linear) tuning of the bandgap from 3.41 to 2.00 eV. Regardless of halide, the family of azetidinium halide perovskite polytypes are highly stable, with no discernible change in properties over more than 6 months under ambient conditions</p></div></div></div>

ENHANCED MULTIFERROIC PROPERTIES OF BiFeO3 CERAMICS BY Mo DOPING

2011 ◽  
Vol 25 (18) ◽  
pp. 1521-1528 ◽  
Author(s):  
X. ZHANG ◽  
G. Q. ZHANG ◽  
J. MIAO ◽  
X. G. XU ◽  
Y. JIANG
Keyword(s):  
Electrical Properties ◽  
Electric Field ◽  
Phase Structure ◽  
Ferroelectric Properties ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Multiferroic Properties ◽  
Mo Doping ◽  
Polarization Electric Field

We have investigated the magnetic and electrical properties of multiferroic BiFe 1-x Mo x O 3 ceramics ( BFMO , x = 0.0%, 0.2%, 0.5% and 0.8%) prepared by the sol–gel method. The phase structure of BFMO samples were confirmed by X-ray diffraction. It was found that the substitution of Mo is responsible for the increasing of the magnetization in BFMO ceramics. Moreover, both dielectric and polarization-electric field properties suggest that the Mo doping could improve the dielectric and ferroelectric properties in BFMO ceramic.

Thermal expansion of nano–boron carbide under constant DC electric field: An in situ energy dispersive X-ray diffraction study using a synchrotron probe

2020 ◽  
Vol 35 (1) ◽  
pp. 90-97
Author(s):  
Hülya Biçer ◽  
Enver Koray Akdoğan ◽  
İlyas Şavklıyıldız ◽  
Christopher Haines ◽  
Zhong Zhong ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Electric Field ◽  
Boron Carbide ◽  
Diffraction Study ◽  
Energy Dispersive ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dc Electric Field ◽  
Image Position

Abstract

Ferroelectric Properties and Crystal Structure of YBa2Cu3O7/BaxSr(1−x)TiO3 Heterostructures

1997 ◽  
Vol 493 ◽  
Author(s):  
CH. Schwan ◽  
F. Martin ◽  
G. Jakob ◽  
J. C. Martinez ◽  
H. Adrian
Keyword(s):  
Domain Walls ◽  
Ferroelectric Phase ◽  
Ferroelectric Properties ◽  
Rf Sputtering ◽  
Superconducting Transition ◽  
X Ray Diffraction ◽  
Weiss Temperature ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force

ABSTRACTEpitaxial YBa2Cu3O7/Ba0.5Sr0.5TiO3 (YBCO/BST) and YBCO/BaTiO3 (BTO) heterostructures were prepared by dc and rf sputtering on SrTiO3 and MgO substrates. The YBCO/BTO bilayers exhibit an inductive superconducting transition temperature of 85 K and the ferroelectric phase transition of BST shows a Curie-Weiss temperature of 310 K. Microstructure was investigated by x-ray-diffraction and atomic force microscopy. In this work we also studied the insulator's conductivity and the contribution of domain walls to permittivity.

Relaxor Ferroelectricity and Electrostrictive Behavior of KNN-ST Ceramics

2010 ◽  
Vol 654-656 ◽  
pp. 1978-1981
Author(s):  
Hui Qing Fan ◽  
Zhuo Li ◽  
Peng Rong Ren ◽  
Gang Cheng Jiao
Keyword(s):  
Electric Fields ◽  
High Dielectric Constant ◽  
Narrow Range ◽  
Ferroelectric Properties ◽  
Lead Magnesium Niobate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lead Magnesium ◽  
Diffraction Patterns ◽  
High Dielectric

The new electrostrictive ceramics have been produced from the (1-x) K0.5Na0.5NbO3-xSrTiO3 (KNN-ST, x=0.1-0.25) system by using conventional mixed-oxide methods. Sintering temperatures rise with increasing SrTiO3 content (x=0.1-0.25) and are in a very narrow range. The x-ray diffraction patterns indicate that with the increasing of SrTiO3 up to 0.25, KNN-ST ceramics with a single perovskite structure exhibit a transition from orthorhombic to cubic and no other impure phase appeared. The dielectric and relaxor ferroelectric properties of KNN-ST ceramics are investigated with the different SrTiO3 content. Also, the strain of these ceramics induced by applied electric fields have been studied. The electrostrictive response is similarly as in the classical PMN (lead magnesium niobate), but lower (order of the 10-5) than PMN (order of the 10-3). Furthermore, this system shows translucent, high dielectric constant, thus suggests possible applications in electric-optic devices, electromechanical transducer applications.

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