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.

scholarly journals Hydrothermal Synthesis of Iodine-Doped Nanoplates with Enhanced Visible and Ultraviolet-Induced Photocatalytic Activities

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Jiang Zhang ◽  
Zheng-Hong Huang ◽  
Yong Xu ◽  
Feiyu Kang
Keyword(s):  
Photocatalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Oxygen Vacancies ◽  
Diffuse Reflectance Spectroscopy ◽  
Synergetic Effect ◽  
X Ray Diffraction ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Photocatalytic Activities

The iodine-doped Bi2WO6(I-BWO) photocatalyst was prepared via a hydrothermal method using potassium iodide as the source of iodine. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. The photocatalytic activity of I-BWO for the degradation of rhodamine B (RhB) was higher than that of pure BWO and I2-BWO regardless of visible light (>420 nm) or ultraviolet light (<400 nm) irradiation. The results of DRS analysis showed that the I-BWO and I2-BWO catalysts had narrower band gaps. XPS analysis proved that the multivalent iodine species including I0and were coadsorbed on the defect surface of Bi2WO6in I-BWO. The enhanced PL intensity revealed that a large number of defects of oxygen vacancies were formed by the doping of iodine. The enhanced photocatalytic activity of I-BWO for degradation of RhB was caused by the synergetic effect of a small crystalline size, a narrow band gap, and plenty of oxygen vacancies.

Phase Diagram of the W-doped Pb(Zn1/3Nb2/3)O3–BaTiO3– PbTiO3 System Around a Morphotropic Phase Boundary Composition

2002 ◽  
Vol 17 (5) ◽  
pp. 1085-1091 ◽  
Author(s):  
W. Z. Zhu ◽  
M. Yan ◽  
A. L. Kholkin ◽  
P. Q. Mantas ◽  
J. L. Baptista
Keyword(s):  
High Temperature ◽  
Phase Boundary ◽  
Morphotropic Phase Boundary ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electrical Neutrality ◽  
Phase Boundary Composition ◽  
A Site ◽  
Successive Phase

The morphotropic phase boundary (MPB) composition that is characterized by the coexistence of rhombohedral and tetragonal phases in the Pb(Zn1/3Nb2/3)O3–BaTiO3– PbTiO3 system was modified by W-doping at the B site of a perovskite structural block. To maintain the electrical neutrality, creation of A-site vacancies was intentionally introduced in the formulation of the examined compositions. Incorporation of W ions was revealed to stabilize the tetragonal phase against the rhombohedral one, shifting the MPB toward the PZN-rich end at room temperature. High-temperature x-ray diffraction examination in combination with dielectric measurements discloses two successive phase transitions as a sample is cooled from high temperature, namely, paraelectric cubic to ferroelectric rhombohedral followed by ferroelectric rhombohedral to ferroelectric tetragonal. W addition appears to suppress the first transition while promoting the second one.

Solvothermal Synthesis of CeO2 Nanoparticles

2011 ◽  
Vol 236-238 ◽  
pp. 2000-2003
Author(s):  
Yong Cai Zhang ◽  
En Ren Zhang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Absorption Spectrum ◽  
Photoelectron Spectroscopy ◽  
Solvothermal Synthesis ◽  
Oxygen Vacancies ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

Ultrafine CeO2 nanoparticles were synthesized directly via solvothermal treatment of Ce(NO3)3·6H2O powder in toluene at 180 °C for 48 h, and characterized by X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and UV-vis absorption spectrum. The results from XRD, Raman and XPS revealed the formation of pure cubic phase CeO2 with some oxygen vacancies. The TEM image disclosed that the as-synthesized CeO2 comprised nanoparticles of about 5–8 nm. The UV-vis absorption spectrum showed that the as-synthesized CeO2 nanoparticles had a wide UV absorption band centered at around 326 nm (3.8 eV).

scholarly journals Resolving the characteristics of morphotropic phase boundary in the (1−x)Pb(Fe1/2Nb1/2)O3–xPbTiO3 system: A combined dielectric and synchrotron x-ray diffraction study

2008 ◽  
Vol 93 (18) ◽  
pp. 182910 ◽  
Author(s):  
Satendra Pal Singh ◽  
Dhananjai Pandey ◽  
Songhak Yoon ◽  
Sunggi Baik ◽  
Namsoo Shin
Keyword(s):  
Phase Boundary ◽  
Diffraction Study ◽  
Morphotropic Phase Boundary ◽  
X Ray Diffraction ◽  
X Ray ◽  
System A

Composition Range of Morphotropic Phase Boundary and Electrical Properties of NBT-BT System

2007 ◽  
Vol 336-338 ◽  
pp. 206-209 ◽  
Author(s):  
Ye Jing Dai ◽  
Jin Song Pan ◽  
Xiao Wen Zhang
Keyword(s):  
Dielectric Properties ◽  
Phase Boundary ◽  
Morphotropic Phase Boundary ◽  
Composition Range ◽  
Rhombohedral Phase ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
Air Atmosphere ◽  
Unique Composition ◽  
Narrow Composition Range

(Na0.5Bi0.5)TiO3 (BNT) system ceramics are considered to be an excellent candidate for leadfree piezoelectric ceramics. In this paper, (1–x)Na0.5Bi0.5TiO3-xBaTiO3 (x = 0.03 ~ 0.10) was synthesized by conventional mixed-oxide technique. The powders were calcined at 950oC for 2 h and the pressed disks were sintered at 1145oC for 2 h in air atmosphere. The phase structure was investigated by X-ray diffraction technique (XRD). It is revealed that the morphotropic phase boundary (MPB) lies in a narrow composition range of x=0.05–0.08 but not a unique composition (x = 0.055 or 0.06) as shown before [1-4]. The microstructures of the ceramics were investigated by scanning electron microscopic. In addition, the piezoelectric and dielectric properties of this system were also investigated. It was indicated that both the piezoelectric and dielectric properties are better with the compositions lie near the tetragonal phase within the MPB than that whose compositions lie near the rhombohedral phase.

Dielectric properties anomaly of (1−x)Pb(Ni1/3Nb2/3)O3−xPbTiO3 ceramics near the morphotropic phase boundary

2001 ◽  
Vol 16 (3) ◽  
pp. 834-836 ◽  
Author(s):  
Zhenrong Li ◽  
Liangying Zhang ◽  
Xi Yao
Keyword(s):  
Dielectric Properties ◽  
Phase Boundary ◽  
Morphotropic Phase Boundary ◽  
Composition Range ◽  
The Other ◽  
Dielectric Measurements ◽  
X Ray Diffraction ◽  
Structure Defects ◽  
X Ray ◽  
Dielectric Peak

Dielectric properties and the phase compositions of (1−x)Pb(Ni1/3Nb2/3)O3−xPbTiO3 ceramics were investigated. A morphotropic phase boundary (MPB) in the system between pseudocubic and tetragonal phase regions has been identified to lie in the composition range x = 0.34–0.38 by means of x-ray diffraction and dielectric measurements. The samples of composition lying near the MPB have good dielectric properties, but at the same time, exhibit two dielectric peaks. The possible reasons for the occurrence of dielectric bipeaks are discussed. One dielectric peak is phase transition peak, and the other peak lying in 130–150 °C temperature range is suggested to result from structure defects in the ceramics.

Dielectric and Piezoelectric Properties of Gd-modified (1-x) BiFeO3-xPbTiO3 Ceramics with a Morphotropic Phase Boundary

2013 ◽  
Vol 1507 ◽  
Author(s):  
Dalei Wang ◽  
Shundong Bu ◽  
Guoxi Jin ◽  
RuiDai ◽  
Dengren Jin ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Phase Boundary ◽  
Morphotropic Phase Boundary ◽  
Composition Range ◽  
Piezoelectric Properties ◽  
X Ray Diffraction ◽  
Wide Composition Range ◽  
X Ray ◽  
Dielectric Constant And Loss ◽  
Dielectric And Piezoelectric Properties

ABSTRACT(1-x)(Bi0.8Gd0.2)FeO3-xPbTiO3 (BGF-PT) solid solutions ceramics of x=0.55,0.50,0.4975, 0.49 and 0.45 were prepared by the mixed oxide method. Gd3+ of 20 at% was introduced into the Bi3+ site to improve the dielectric and piezoelectric properties of BFPT without causing the significant reduction of Curie temperature (Tc). X-ray diffraction analysis shows a transformation from the tetragonal (T) to rhombohedral (R) phase with the increase of BGF content. The morphotropic phase boundary was determined by measuring the dielectric and piezoelectric properties of BGF-PT within a wide composition range. BGF-PT for x=0.4975 shows the coexistence of T and R phases with the dielectric constant and loss of about 895 and 0.031 respectively at the frequency of 102 Hz.

scholarly journals Structural and electromechanical study of Bi0.5Na0.5TiO3-BaTiO3 solid-solutions

2013 ◽  
Vol 7 (2) ◽  
pp. 73-80 ◽  
Author(s):  
Biswanath Parija ◽  
Tanmaya Badapanda ◽  
Pratap Sahoo ◽  
Manoranjan Kar ◽  
Pawan Kumar ◽  
...  
Keyword(s):  
Solid Solution ◽  
Raman Spectroscopy ◽  
Phase Boundary ◽  
Morphotropic Phase Boundary ◽  
Solid Solutions ◽  
Structural Changes ◽  
Boundary Region ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
X Ray

Solid solution of (1-x)Bi0.5Na0.5TiO3-xBaTiO3 have been synthesized via conventional solid-state reaction route. Structural changes of the solid-solutions were investigated by using X-ray diffraction, Rietveld refinement Raman spectroscopy and piezoelectric studies. X-ray diffraction analysis shows a distinct 002/200 peak splitting appearing at x = 0.07 showing the coexistence of rhombohedral and tetragonal phase. Raman spectroscopy shows a splitting of (TO3) mode at x = 0.07 confirming the presence of the morphotropic phase boundary region. The dominant bands in the Raman spectra are analyzed by observing the changes in their respective peak positions, widths and intensities as the x increases. The piezoelectric properties of the solid solution increase with rise in BaTiO3 content and shows optimum value at x = 0.07 owing to the co-existence of two ferroelectric phases. Based on these results, it is suggested that the morphotropic phase boundary in the studied system lies in the composition x = 0.07.

Oxygen Vacancies in Perovskite and Related Structures: Implications for the Lower Mantle

2002 ◽  
Vol 718 ◽  
Author(s):  
Catherine A. McCammon ◽  
Ana Isabel Becerro ◽  
Stefan Lauterbach ◽  
Ulrich Bläß ◽  
Stefan Marion ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Lower Mantle ◽  
Oxygen Vacancies ◽  
High Pressures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Vacancy Ordering ◽  
High Pressures And Temperatures ◽  
Electron Energy Loss

AbstractThe oxygen vacancy ordering process and displacive transitions have been characterised in the system CaTiO3-CaFeO2.5 as a function of composition and temperature at atmospheric pressure using X-ray diffraction, Mössbauer spectroscopy, infrared spectroscopy, transmission electron microscopy, electron energy loss spectroscopy, neutron diffraction and electrical conductivity methods. With increasing concentration of vacancies the following sequence is observed: isolated defects → short defect chains → infinite chains in layers. Similar experiments at high pressures and temperatures have been conducted to determine the nature of oxygen vacancies in the lower mantle phases (Mg,Fe)(Si,Al)O3-σ and Ca(Si,Fe)O3-σ perovskite.

Facile Synthesis and Electrical Conductivity of Carbon Nanotube Reinforced Nanosilver Composite

2012 ◽  
Vol 67 (12) ◽  
pp. 679-684 ◽  
Author(s):  
Hemant Pal ◽  
Vimal Sharma ◽  
Rajesh Kumar ◽  
Nagesh Thakur
Keyword(s):  
Electron Microscopy ◽  
Electrical Conductivity ◽  
Industrial Applications ◽  
X Ray Diffraction ◽  
Metal Matrix Nanocomposites ◽  
X Ray ◽  
Transmission Electron ◽  
Silver Matrix ◽  
Mixing Method ◽  
Matrix Nanocomposites

Metal matrix nanocomposites reinforced with carbon nanotubes (CNTs) have become popular in industrial applications. Due to their excellent thermophysical and mechanical properties, CNTs are considered as attractive filler for the improvement in properties of metals. In the present work, we have synthesized noncovalently functionalized CNT reinforced nanosilver composites by using a modified molecular level mixing method. The structure and morphology of nanocomposites are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy dispersive spectroscopy. The electrical conductivity of silver-CNT nanocomposites measured by the four-point probe method is found to be more than that of the pure nanosilver. The significant improvement in electrical conductivity of Ag=CNT nanocomposites stems from homogenous and embedded distribution of CNTs in a silver matrix with intact structure resulting from noncovalent functionalization. The low temperature sintering also enhances the electrical conductivity of Ag=CNT nanocomposites.

Sign in / Sign up

Export Citation Format

Share Document