oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Fabrication and Characterization of PZN-4.5PT Inorganic Perovskites Nanoparticles Thin Films Deposited on P-Type Silicon Substrate  [PDF]
Rémi Ndioukane, Moussa Touré, Diouma Kobor, Laurence Motte, Marcel Pasquinelli, Jeanne Solard
Journal of Modern Physics (JMP) , 2018, DOI: 10.4236/jmp.2018.92018
Abstract: This work involves an investigation of nanostructures, microelectronic properties and domain engineering of nanoparticles thin layers of Pb(Zn1/ 3Nb2/3)O3-PbTiO3 (PZN-PT) ferroelectric single crystals deposited on nanostructured silicon substrate. In this study, devices made from PZN-4.5PT nanoparticles thin films successfully deposited on silicon substrate have been studied and discussed. SEM images show the formation of local black circles and hexagonal shapes probably due to the nucleation of a new Si-gel component or phase induced by annealing. Micro Xray Fluorescence mapping shows that the high values of Si and B atoms (7 and 4 normalized unit respectively) can be explained by the fact that the substrate is p-type silicon. The most interesting result of optical measurements is the very good absorption for all the thin films in UV, Visible and NIR regions with values from 70% to 90% in UV, from 75% to 93% in Visible and NIR. Tauc plots present particularities (rarely encountered behavior) with different segments or absorption changes showing the presence of multiple band gaps coming from the heterogeneity of the thin films (nanowires, gel and nanoparticles). Their values are 1.9 and 2.8 eV for DKRN-Gel, 2.1 and 3.1 eV for DKRN-UD and 2.1 and 3.2 eV for DKRN-D) corresponding respectively to the band gap of nanowires and that of the gel while the last ones correspond to the undoped and doped nanoparticles (3.1 and 3.2 eV respectively).
Comparative characterization of rhombohedral and tetragonal PZN-PT single crystals
D. Kobor,M. Tine,A. Hajjaji,L. Lebrun
AIP Advances , 2011, DOI: 10.1063/1.3599587
Abstract: Ferroelectric single crystals Pb(Zn1/3Nb2/3)O3–PbTiO3 (PZN–PT) are promising full materials for nonresonant or large bandwidth transducers due to the large values of their piezoelectric properties (dij, kij) and their mechanical quality factor (Qij). However the properties of these materials depend greatly on the content of titanium which influences very significantly the symmetry of the crystal. In this paper we try to understand the influence of the percentage of Titanium in these crystals by studying the two compositions that are in very different phases at room temperature (rhombohedral and tetragonal symmetries). Crystals of pure PZN–4.5PT and PZN-12PT were grown by a Flux technique. The typical single crystals obtained are brown yellow. The room temperature dielectric permittivity along the <001> direction is about 900 for the PZN-12PT, which is smaller than that of the PZN–4.5PT (5840). The Curie point Tc of the tetragonal crystal is about 220 °C (which is higher than that of the rhombohedral one (166 °C)), while the ferroelectric phase transition temperature is 130 °C for the PZN-4.5PT single crystal. The remnant polarization and coercive field of <001> oriented crystals measured at 1 kHz are around 40 μC/cm2 and 3.30 kV/cm, respectively for the PZN-4.5PT, 27μC/cm2 and 11.1 kV/cm for the PZN-12PT single crystal. The d33 versus uniaxial stress shows that this coefficient is more stable for the single crystal with low Ti than for that with high rate of Ti. The study of temperature stability on these crystals shows a possible presence of an unidentified phase in the low and negative range temperature for the PZN-4.5PT.
Dual structures in PZN-xPT ferroelectric relaxors  [PDF]
Guangyong Xu,H. Hiraka,K. Ohwada,G. Shirane
Physics , 2004, DOI: 10.1063/1.1751216
Abstract: We performed x-ray diffraction studies on a series of (1-$x$)Pb(Zn$_{1/3}$Nb$_{2/3}$)O$_3$-$x$PbTiO$_3$ (PZN-$x$PT) single crystals with different incident photon energies, and therefore different penetration depths. Our results show that outer-layers of $\sim 10$ to 50 $\mu$m thick are present in all samples. The structure of those outer-layers is different from that of the inside of the crystals, by having much greater (rhombohedral) distortions. With increasing $x$, rhombohedral-type lattice distortions develop, both in the outer-layer and the inside.
Freezing of the local dynamics in the relaxor ferroelectric PZN-4.5PT  [PDF]
Zhijun Xu,Jinsheng Wen,E. Mamontov,C. Stock,P. M. Gehring,Guangyong Xu
Physics , 2012, DOI: 10.1103/PhysRevB.86.144106
Abstract: We report measurements of the neutron diffuse scattering in a single crystal of the relaxor ferroelectric material 95.5%Pb(Zn1/3Nb2/3)O3-4.5%PbTiO3 (PZN-4.5%PT). We show that the diffuse scattering at high temperatures has a quasielastic component with energy width $\agt$ 0.1 meV. On cooling the total diffuse scattering intensity increases, but the intensity and the energy width of the quasielastic component gradually diminish. At 50 K the diffuse scattering is completely static (i.e.the energy width lies within the limits of our instrumental resolution). This suggests that the dynamics of the short-range correlated atomic displacements associated with the diffuse scattering freeze at low temperature. We find that this depends on the wave vector q as the quasielastic diffuse scattering intensities associated with <001> (T1-type) and <110> (T2-type) atomic displacements vary differently with temperature and electric field.
A two-component model of the neutron diffuse scattering in the relaxor ferroelectric PZN-4.5%PT  [PDF]
Zhijun Xu,Jinsheng Wen,Guangyong Xu,C. Stock,J. S. Gardner,P. M. Gehring
Physics , 2010, DOI: 10.1103/PhysRevB.82.134124
Abstract: We report measurements of the neutron diffuse scattering in a single crystal of the relaxor ferroelectric material 95.5%Pb(Zn$_{1/3}$Nb$_{2/3}$)O$_3$-4.5%PbTiO$_3$ (PZN-4.5%PT). Our results suggest that the nanometer scale structure in this compound exhibits both $<100>$ and $<110>$ polarizations, which contribute to different portions of the total diffuse scattering intensity. These contributions can be distinguished by the differing responses to an electric field applied along [001]. While diffuse scattering intensities associated with $<110>$ (T2-type) polarizations show little to no change in a [001] field, those associated with $<100>$ (T1-type) polarizations are partially suppressed by the field at temperatures below the Curie temperature \emph{T$_C$} $\sim 475$ K. Neutron spin-echo measurements show that the diffuse scattering at (0.05,0,1) is largely dynamic at high temperature and gradually freezes on cooling, becoming mostly static at 200 K.
Fabrication, Physical Properties and Microstructural Characterization of Nanostructured Ferroelectric Films
ZHU Xin-Hua, SONG Ye, HANG Qi-Ming, ZHU Jian-Min, ZHOU Shun-Hua, LIU Zhi-Guo
无机材料学报 , 2010, DOI: 10.3724/sp.j.1077.2010.00966
Abstract: By using pulsed laser deposition method, nanostructured BaTiO3 ferroelectric films (with a thickness of 25 nm) were grown on Si substrates and coated by nanoporous alumina membranes (NAMs) with an average pore size of 25 nm. Metal Pt nanowires were embedded in NAMs as a part of the bottom electrode. The dielectric and ferroelectric properties, and microstructure of the nanostructured BaTiO3 films were characterized. The results show that the dielectric constant of the BaTiO3 nanofilms is decreased slowly from 196 to 190 as the increase of measured frequency from 103 Hz to 106 Hz, and their dielectric loss is increased slowly from 0.005 to 0.007 in the low frequency range from 103 Hz to 105 Hz, whereas quickly increased up to 0.013 at high frequencies over 105 Hz. The remanent polarization and the coercive field of the BaTiO3 nanofilms are 5 uC/cm2 and 680 kV/cm, respectively. Cross-sectional (scanning) transmission electron microscope (TEM) images demonstrate that the BaTiO3 nanofilms contact directly with the Pt nanowires, and the interface between them has some degree of waviness. Suitable post-annealing temperature is the critical processing parameter of fabricating nanostructured ferroelectric films as considering a trade-off between the ordered degree of metal nanowires within NAMs and the crystallinity of ferroelectric nanofilms.
The Technology of Laser-Induced Deposition of Nanostructured Metallic Conductors on the Dielectric Substrate  [cached]
Semenok D.V.,Safonov S.V.,Kochemirovsky V.
Proceedings of the International Conference Nanomaterials : Applications and Properties , 2012,
Abstract: This article describes a new method for planar copper-oxide coatings with controlled topology and the nanostructured surface. The structure obtained by laser-induced deposition of copper-containing aqueous solutions of a semiconductor laser (532 nm) radiation in a continuous mode. The method Energy Dispersive X-Ray spectroscopy to study the composition of the obtained nanoparticles. Particle sizes were determined by scanning electron microscopy.
The Anomalous Skin Effect in Single Crystal Relaxor Ferroelectric PZN-xPT and PMN-xPT  [PDF]
Guangyong Xu,P. M. Gehring,C. Stock,K. Conlon
Physics , 2006,
Abstract: X-ray and neutron scattering studies of the lead-based family of perovskite relaxors PZN-$x$PT and PMN-$x$PT have documented a highly unusual situation in which the near-surface region of a single crystal can exhibit a structure that is different from that of the bulk when cooled to low temperatures. The near-surface region, or "skin" can also display critical behavior that is absent in the crystal interior, as well as a significantly different lattice spacing. By varying the incident photon energy, and thus the effective penetration depth, x-ray measurements indicate a skin thickness of order 10 $\mu$m to 50 $\mu$m for PZN-$x$PT samples with $0 \le x \le 8$%. Neutron residual stress measurements on a large PMN single crystal reveal a uniform lattice spacing within the bulk, but an increased strain near the surface. The presence of this skin effect has led to incorrect phase diagrams for both the PZN-$x$PT and PMN-$x$PT systems and erroneous characterizations of the nature of the relaxor state.
Electrochemical impedimetric biosensor based on a nanostructured polycarbonate substrate
Chen YS, Wu CC, Tsai JJ, Wang GJ
International Journal of Nanomedicine , 2012, DOI: http://dx.doi.org/10.2147/IJN.S27225
Abstract: trochemical impedimetric biosensor based on a nanostructured polycarbonate substrate Original Research (3134) Total Article Views Authors: Chen YS, Wu CC, Tsai JJ, Wang GJ Published Date January 2012 Volume 2012:7 Pages 133 - 140 DOI: http://dx.doi.org/10.2147/IJN.S27225 Received: 10 October 2011 Accepted: 30 November 2011 Published: 06 January 2012 Yu-Shan Chen1, Chia-Che Wu1, Jaw-Ji Tsai2, Gou-Jen Wang1,3 1Department of Mechanical Engineering, National Chung-Hsing University, 2Department of Medical Education and Research, Taichung Veterans General Hospital, 3Graduate Institute of Biomedical Engineering, National Chung-Hsing University, Taichung, Taiwan Abstract: This study integrates the techniques of nanoelectroforming, hot-embossing, and electrochemical deposition to develop a disposable, low-cost, and high sensitivity nanostructure biosensor. A modified anodic aluminum oxide barrier-layer surface was used as the template for thin nickel film deposition. After etching the anodic aluminum oxide template off, a three-dimensional mold of the concave nanostructure array was created. The fabricated three-dimensional nickel mold was further used for replica molding of a nanostructure polycarbonate substrate by hot-embossing. A thin gold film was then sputtered onto the polycarbonate substrate to form the electrode, followed by deposition of an orderly and uniform gold nanoparticle layer on the three-dimensional gold electrode using electrochemical deposition. Finally, silver nanoparticles were deposited on the uniformly deposited gold nanoparticles to enhance the conductivity of the sensor. Electrochemical impedance spectroscopy analysis was then used to detect the concentration of the target element. The sensitivity of the proposed scheme on the detection of the dust mite antigen, Der p2, reached 0.1 pg/mL.
Evolution of the neutron quasi-elastic scattering through the ferroelectric phase transition in 93%\pzn - 7% PbTiO$_3$  [PDF]
G. -M. Rotaru,S. N. Gvasaliya,B. Roessli,S. Kojima,S. G. Lushnikov,P.,Günter
Physics , 2008, DOI: 10.1063/1.2963474
Abstract: We show that the neutron diffuse scattering in relaxor ferroelectric (1-x)PbZn$_{1/3}$Nb$_{2/3}$O$_{3}$ - x PbTiO$_{3}$ (x=0.07) consists of two components. The first component is strictly elastic but extended in q-space and grows below 600 K. The second component, that was not reported before for the (1-x)PbZn$_{1/3}$Nb$_{2/3}$O$_{3}$ - x PbTiO$_{3}$ (x=0.07) relaxor ferroelectrics, is quasi-elastic with a line-width that has a similar temperature dependence as the width of the central peak observed by Brillouin spectroscopy. The temperature dependence of the susceptibility of the quasi-elastic scattering has a maximum at the ferroelectric transition.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.