Study of the microscopic structures in 0.72Pb(Mg1∕3Nb2∕3)O3-0.28PbTiO3 relaxor ferroelectrics by means of x-ray diffraction

2007 ◽  
Vol 101 (5) ◽  
pp. 053505 ◽  
Author(s):  
Zhi Guo ◽  
Renzhong Tai ◽  
Hongjie Xu ◽  
Chen Gao ◽  
Haosu Luo ◽  
...  
Keyword(s):  
Relaxor Ferroelectrics ◽  
X Ray Diffraction ◽  
X Ray

Microstructure and electrical properties of 0.5PZN-0.5PZT relaxor ferroelectrics close to the morphotropic phase boundary

2009 ◽  
Vol 24 (6) ◽  
pp. 2029-2034 ◽  
Author(s):  
Lu-Yang Zhao ◽  
Yu-Dong Hou ◽  
Li-Min Chang ◽  
Man-Kang Zhu ◽  
Hui Yan
Keyword(s):  
Phase Boundary ◽  
Morphotropic Phase Boundary ◽  
Oxygen Vacancies ◽  
Rhombohedral Phase ◽  
Relaxor Ferroelectrics ◽  
Arrhenius Law ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Mixing Method

Relaxor ferroelectrics of Pb(Zn1/3Nb2/3)0.5(Zr0.47Ti0.53)0.5O3 (0.5PZN-0.5PZT) were prepared using the conventional oxide mixing method. Both x-ray diffraction analysis and Raman spectroscopy indicate that the amounts of rhombohedral phase are close to tetragonal phase, implying the presence of the morphotropic phase boundary (MPB) in the system of 0.5PZN-0.5PZT, and this result was further confirmed by transmission electron microscopy (TEM) micrographs. At MPB composition, the excellent piezoelectric properties, such as kp (0.66) and d33 (425pC/N), were obtained due to the more possible polarization directions of domains and high dc resistivity of 6.5 × 1010 Ω·cm. Meanwhile, the dielectric studies revealed that the indicator of the degree of diffuseness γ value is 1.73, implying that the relaxor nature of the 0.5PZN-0.5PZT is ceramic. The activation energy related to the dc conductivity was estimated from a linear fitting of the Arrhenius law. The value of 0.09 and 1.04 eV for low and high temperature range corresponds well to the activation energies of migration and first ionization of the oxygen vacancies.

Synthesis, characterization, and properties of lead-based relaxor ferroelectrics

1996 ◽  
Vol 11 (5) ◽  
pp. 1210-1218 ◽  
Author(s):  
Michael M. A. Sekar ◽  
Arvind Halliyal ◽  
K. C. Patil
Keyword(s):  
Thermal Evolution ◽  
Combustion Process ◽  
Diffraction Method ◽  
Relaxor Ferroelectrics ◽  
X Ray Diffraction ◽  
Solution Combustion ◽  
X Ray ◽  
Metal Nitrates ◽  
Different Temperatures ◽  
Solution Combustion Process

Lead-based relaxor ferroelectrics such as Pb(Mg1/3Nb2/3)O3 (PMN), Pb(Zn1/3Nb2/3)O3 (PZN), and their solid solutions with BaTiO3 and PbTiO3 have been prepared by a solution combustion process which involves metal nitrates/oxalate and tetraformal trisazine (TFTA) at 350 °C. Thermal evolution of perovskite relaxors has been investigated at different temperatures of calcination using the powder x-ray diffraction method. Particles are fine and sinter-active at low temperature (1050 °C). Both particulate and dielectric properties are compared.

Search For New Piezoelectrics

2008 ◽  
Vol 1110 ◽  
Author(s):  
Panchapakesan Ganesh ◽  
Ronald Cohen
Keyword(s):  
Density Functional Theory ◽  
Ground State ◽  
First Principles ◽  
Density Functional ◽  
Relaxor Ferroelectrics ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
Chemical Pressure ◽  
X Ray ◽  
Born Effective Charge

AbstractRecent first principles simulations using density functional theory and novel low temperature x-ray diffraction experiments show the existence of a high pressure morphtotropic phase boundary (MPB) in pure PbTiO3. In this paper we apply chemical pressure by substituting smaller atoms in the ABO3 ‘A’ and ‘B’ sites. We find that the ground state of layered PbSnTiO3 (PSnT) is Pmm2, and for rocksalt SnGeTiO3 and PbGeTiO3 is R3m. The polarization of PbSnTiO3 is large (1.13,0,0)C/m2 and is due to the large Born effective charge of the small ‘Sn’ atom. We estimate the d33 for PSnT to be about 2400 pC/N, which is as large as that of currently used relaxor ferroelectrics.

Structural investigation of tungsten bronze-type relaxor ferroelectrics in the BaxSr3−xTiNb4O15 system

2014 ◽  
Vol 29 (S1) ◽  
pp. S15-S18
Author(s):  
Thomas A. Whittle ◽  
Siegbert Schmid
Keyword(s):  
Phase Transition ◽  
Diffraction Data ◽  
Structural Investigation ◽  
Tungsten Bronze ◽  
Relaxor Ferroelectrics ◽  
Cation Ordering ◽  
X Ray Diffraction ◽  
Rietveld Refinements ◽  
X Ray

Compounds in the BaxSr3−xTiNb4O15 series with x = 0.0–3.0 were synthesised. Synchrotron X-ray diffraction data were collected for each member synthesised. Rietveld refinements were performed for all compositions. A composition-dependent phase transition between orthorhombic and tetragonal symmetries was found. Cation ordering was observed between barium and strontium atoms in the two distinct A site cavities

Octahedral tilting in Pb-based relaxor ferroelectrics at high pressure

2010 ◽  
Vol 66 (3) ◽  
pp. 280-291 ◽  
Author(s):  
Bernd J. Maier ◽  
Ross J. Angel ◽  
William G. Marshall ◽  
Boriana Mihailova ◽  
Carsten Paulmann ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Single Crystal ◽  
Ambient Pressure ◽  
Relaxor Ferroelectrics ◽  
Partial Ordering ◽  
X Ray Diffraction ◽  
Threefold Axis ◽  
X Ray ◽  
Octahedral Cation

We have employed a combination of powder neutron diffraction and single-crystal synchrotron X-ray diffraction to characterize the pressure-induced phase transitions that occur in the perovskite-type relaxor ferroelectric PbSc0.5Ta0.5O3 (PST) and Pb0.78Ba0.22Sc0.5Ta0.5O3 (PST-Ba). At ambient pressure the symmetry of the average structure for both compounds is Fm\bar{3}m as a result of partial ordering of the Sc and Ta cations on the octahedral sites. At pressures above the phase transition both the neutron and X-ray diffraction patterns exhibit an increase in the intensities of h,k,l = all odd reflections and no appearance of additional Bragg reflections. Synchrotron single-crystal X-ray diffraction data show that the intensity of hhh peaks, h = 2n + 1, does not change with pressure. This indicates that the structural distortion arising from the phase transition has a glide-plane pseudo-symmetry along the 〈111〉 cubic directions. Rietveld refinement to the neutron powder data shows that the high-pressure phase has either R\bar{3}c or R\bar{3} symmetry, depending on whether the presence of 1:1 octahedral cation ordering is neglected or taken into account, and comprises octahedral tilts of the type a − a − a − that continuously evolve with pressure. The cubic-to-rhombohedral transition is also marked by a large increase in the anisotropy of the displacement ellipsoids of the Pb cations, indicating larger displacements of Pb cations along the rhombohedral threefold axis rather than within the perpendicular plane. For PST the anisotropy of the Pb displacement parameters decreases at approximately 3 GPa above the phase-transition pressure. For both PST and PST-Ba the average magnitudes of Pb-cation displacements expressed in terms of isotropic displacement ellipsoids gradually decrease over the entire pressure range from ambient to 7.35 GPa.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

Ribosome Structural Organization

1974 ◽  
Vol 32 ◽  
pp. 332-333
Author(s):  
James A. Lake
Keyword(s):  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Small Subunit ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Specific Antibodies ◽  
X Ray ◽  
E Coli ◽  
Complete Sequences

The understanding of ribosome structure has advanced considerably in the last several years. Biochemists have characterized the constituent proteins and rRNA's of ribosomes. Complete sequences have been determined for some ribosomal proteins and specific antibodies have been prepared against all E. coli small subunit proteins. In addition, a number of naturally occuring systems of three dimensional ribosome crystals which are suitable for structural studies have been observed in eukaryotes. Although the crystals are, in general, too small for X-ray diffraction, their size is ideal for electron microscopy.

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