bluuebunny/crossref_metadata_2025_split huggingface dataset:
Orientation and Composition Dependence of Piezoelectric-Dielectric Properties of Sputtered Pb(Zrx,Ti1-x)O3 Thin Films
Authors: Hiboux S. , Muralt P. , Setter N. 
Published: April 2011

AbstractIn-situ, reactively sputter deposited 300 nm thick Pb(Zrx,Ti1-x)O3 films on Pt/Si based substrates are investigated as a function of composition and texture. (111) PZT is grown on a (111) oriented Pt bottom electrode covered with a very thin TiO2 film. Highly {100} oriented PZT is grown on Pt (111) by means of a 10 nm thick PbTiO3 seed layer. Pronounced deviations from known bulk PZT behavior are observed for the (111) texture. Maximum of d33 and ε are shifted to 40/60 and 45/55 compositions, respectively. (100) textured films exhibit a higher d33. 1.3 μm (100) thick films attain the predicted d33 value of clamped bulk ceramics. Coercive fields and voltage offsets increase strongly with increasing Ti content. In parallel, the as-grown polarization increases. Polarization switching is not possible for x ≤ 0.1. Post-anneals in O2 and hot poling show that oxygen vacancies play an important role in this phenomenon. Ti-rich (100) oriented films exhibit very high and stable pyroelectric and piezoelectric coefficients whithout poling treatments.
Epitaxial PMN-PT Relaxor Thin Films: Dependence of Dielectric and Piezoelectric Properties on Film Thickness
Authors: Nagarajan V. , Alpay S. P. , Ganpule C. S. , Nagaraj B. , Aggarwal S. , Roytburd A. L. , Williams E. D. , Ramesh R. 
Published: April 2011

AbstractThe effect of substrate induced constraint and misfit strain on the structure and piezoelectric properties of epitaxial relaxor ferroelectric lead magnesium niobate-lead titanate (PMN-PT) films were investigated. Relaxor PMN-PT epitaxial 100–400 nm thick films with top and bottom oxide electrodes were grown by pulsed laser deposition on (100) LaAlO3 substrates. A systematic decrease in the temperature of the dielectric maximum with increasing film thickness was observed. This is accompanied by an increase in the room temperature relative dielectric constant. The longitudinal piezoelectric coefficient measured using a scanned probe microscope, increases by almost an order of magnitude with increasing film thickness.
Integrated (Pb,La)(Zr,Ti)O3 Heterostructure Waveguide Devices Fabricated by Solid-Phase Epitaxy
Authors: Nashimoto K. , Nakamura S. , Moriyama H. , Haga K. , Watanabe M. , Morikawa T. , Osakabe E. , Takeda T. 
Published: April 2011

AbstractHeterostructures of a Pb(Zr,Ti)O3 (PZT) waveguide/(Pb,La)(Zr,Ti)O3 (PLZT) system buffer layer were grown on a Nb-doped SrTiO3 (Nb:ST) substrate by solid-phase epitaxy. The propagation loss in the PLZT heterostructure waveguides was on the order of I dB/cm. An electro-optic beam deflection device with an ITO prism electrode on the surface of the PLZT heterostructure waveguide presented efficient deflection of the coupled laser beam by applying a voltage between the electrode and the substrate. A beam deflection greater than 10 mrad at 5 V and frequency response as fast as 13 MHz were observed. An apparent electro-optic coefficient as large as 39 pmJV was estimated from the deflection characteristics for the TE mode and TM mode suggesting the polarization independent nature of the PZT waveguide. For integrating the electrooptic PLZT heterostructure waveguides, channel waveguides were fabricated in the PZT waveguides using a simple wet-etching process. Based on a low-voltage drive structure, lowloss waveguide process, and fine patterning process, a fabricated digital matrix switch showed a – 10 dB cross-talk at a voltage as low as 7.5 V.
Rotating Disk Reactor-Low Pressure Metal Organic Chemical Vapor Deposition (Mocvd) of Optical Films
Authors: McAleese John , Provost L. Gary , Tompa Gary S. , Colibaba-Evulet Andrei , Gulmac Nick G. , Doyle John J. 
Published: April 2011

AbstractOver the past 30 years, the need for transparent conducting oxide coatings has been met almost exclusively by tin doped indium-oxide. As the display market advances in complexity, the demand for alternative transparent materials exhibiting high conductivity and stability has become greater. In this paper, we discuss briefly the merits of using doped ZnO as a superior transparent conducting oxide. We report here our results in scaling our ZnO MOCVD reactor technology from 5° to 12° diameter susceptors. Using Rotating Disk Reactor-Low Pressure Metal Organic Chemical Vapor Deposition, we have been able to obtain large area uniformity on multiple (14 cm × 9 cm) glass sheets per deposition run. Promising film characteristics suggest significant application in the field of flat panel displays and other optical systems may be possible.
Pdlc-Based Device for Optical Limiting
Authors: Feneyrou P. , Genty F. , Chastaing E. , Barny P. Le , Delboulbe A. , Dentan V. , Loiseaux B. , Huignard J P. 
Published: April 2011

AbstractThe scattering properties of polymer dispersed liquid crystal (PDLC) composites are studied and applied to optically addressed devices for the protection against continuous wave laser. The geometry of the device is chosen with respect to its scattering efficiency, linear transmission and response time. The optical limiting performances of this PDLC-based device are measured at 514 nm.
Liquid Crystal Devices for Light Limiting Applications
Authors: Patel J. S. , Zhuang Zhizhong , Kim Young Jin 
Published: April 2011

AbstractIn this paper, we introduce a novel liquid crystal structure, the Inverse Twisted Smectic Structure (ITSS), which has several advantages over the previously reported twisted smectic structure. Both these structures are capable of high-speed, gray scale modulation and phase modulation capability. Additionally, the easy fabrication of the ITSS makes it more attractive for practical applications. We discuss the use of this structure and the fabrication devices using the ITSS. Possible applications, such as the birefringence wavelength filter (BWF), and the digital wavelength filter (DWF) are also discussed and demonstrated experimentally.
Non Linear Optical Properties of Singlewall Carbon Nanotubes for Optical Limiting
Authors: Vivien L. , Anglaret E. , Riehl D. , Hache F. 
Published: April 2011

AbstractOptical limiting properties of singlewall carbon nanotubes suspended in water have been evaluated with 7 ns pulses at 532 and 1064 nm and compared with those of other materials. In order to determine the origin of optical limiting, we carried out a Z-scan experiment at 532 nm and 1064nm at different input energies. We evidenced strong nonlinear scattering and a refractive effect with a negative nonlinear index. The kinetics of nonlinear transmission, from the nanosecond to millisecond time scale, was studied using a pump-probe set-up at 1064nm. We observed cavitation bubbles growth at low input energy. The different nonlinear effects evidenced are discussed in terms of physical origin and in terms of broadband optical limiting efficiency.
Improved Characteristic Temperature (TO) of a 1.3-μm GaInNAs/GaAs Single-Quantum-Well Laser Diode Through Thermal Annealing
Authors: Kitatani T. , Kondow M. , Nakahara K. , Uomi K. , Tanaka T. 
Published: April 2011

AbstractThrough optimal thermal annealing of the active region of a 1.3 μm GaInNAs/GaAs single-quantum-well laser diode, we obtained a characteristic temperature (T0) of 215 K under pulsed operation from 20°C to 80°C. This is the highest yet reported value for a 1.3-μm semiconductor laser. Even under continuous-wave operation, the T0 was as high as 147 K. The lasing-wavelength change with temperature was as small as 0.39 nm/°C, indicating the excellent stability for a GalnNAs laser diode with T0 of over 200 K. These results demonstrate that GaInNAs is a promising material for fabricating long-wavelength laser diodes used for opticalfiber communications.
Spectroscopic Investigations of Dithienyl Polyenes
Authors: Cooper Thomas M. , Sowards Laura A. , Natarajan Lalgudi V. , Kirkpatrick Sean , Chandra Suresh , Mclean Daniel G. , Spangler Charles W. 
Published: April 2011

AbstractTo understand the properties of light-sensitive compounds used in optical limiters having photoinduced charge transfer mechanisms, we have investigated the photophysics of a series of di(2-thienyl-3,4–butyl)polyenes. Spectroscopic measurements were obtained as a function of the number of double bonds(n = 1–8). From analysis of the bandshape of the emission spectra, we found evidence of vibronic coupling between the S1 and S2 excited states. The degree of coupling increased with solvents of high refractive index. The appearance of the cis band in absorption spectra of dithienyl polyenes having 6–8 double bonds suggested equilibria between scis and s-trans conformors. The cis band intensity increased in lower polarity solvents, implying solvent-induced conformation changes in these dyes. Trends in the data reflected the ordering, energy gap between and mixing of 1Bu* and 1Ag* excited state configurations.
Optical Limiting Characteristics of Dendrons and Dendrimers Incorporating Dithienylpolyene Moieties
Authors: Ozer B. , Kang B.-S. , Spangler C. W. 
Published: April 2011

AbstractOver the past decade there has been considerable progress in the design of new chromophores for potential optical limiting applications. Most of the focus has been centered on molecules that are capable of efficient excited state absorptions whose cross-sections are larger than the original π–π* excitation cross-section, usually referred to as reverse saturable absorbers (RSAs). The vast majority of chromophores having RSA characteristics depend on efficient intersystem crossing from the excited state singlet (S1) to a highly absorbing and relatively long-lived triplet state (T1). However, much less attention has been paid to alternative excited state absorptions, particularly from charge states such as polaronic radical-ions and bipolaronic diions. In this presentation, we propose that monodisperse dendrimers based on dendron coupling to core molecules such as bisphenol A are potential optical limiting materials based on photo-generation of such charge states in the dendron-attached chromophores, such as dithienylpolyenes. The design and syntheses of these dendrons and dendrimers are presented, and the absorption characteristics of the most likely charge states discussed from an optical limiting perspective.
Effects of Purification and Addition of Electron Acceptor Dyes to Solutions of Macrocyclic Dyes
Authors: Allen W J D , Bahra G S , Healy W 
Published: April 2011

AbstractThis paper will deal with the electronic and physical effects of purification of a macrocyclic dye, 2,3-napthalocyanine bis(trihexylsiloxide) (SiNC), on the optical limiting performance.The changes in optical limiting performance of SiNC, a carbocyanine dye (1,1′,3,3,3′,3′,- Hexamethylindocarbocyanine iodide (HITCI) and two metallated porphyrins upon the addition of an electron acceptor material, methyl viologen dichloride (MV) (1,1′-dimethyl-4,4′ bipyridinium dichloride), are also shown and the results discussed.
Silica-Based Planar Lightwave Circuits
Authors: Himeno Akira 
Published: April 2011

AbstractSilica-based planar lightwave circuits (PLC) provide various important devices for both optical wavelength division multiplexing (WDM) networks and optical access networks. This paper is an overview of recent progress in PLC technology including optical power splitters, arrayed-waveguide gratings, thermo-optic switches, and hybrid integrated PLCs.
Femtosecond to Nanosecond Characterization of Optical Limiting Mechanisms in Power Limiting Liquids and Solids
Authors: Malko A. , Xu S. , Wang H-L. , Kohlman R. , Smilowitz L. , Klimov V. , McBranch D. W. , Nogues J.-L. , Moreshead W. , Hagan D. , Yang S. , Stryland E. Van 
Published: April 2011

AbstractWe present our recent advances toward the development of high-performance solid-state optical limiting devices using reverse saturable absorption (RSA) dyes doped into optical host materials. Femtosecond transient absorption spectroscopy was employed to determine both the spectral regions of strong RSA, and the singlet-triplet excited-state dynamics. The optical limiting in the visible spectrum in both metallo-phthalocyanines and metallo-porphyrins is due to a combination of singlet and triplet RSA. Optical limiting performance was studied for RSA dyes in dual tandem limiters (both in solution and solid-state). Our best results in the solid-state yielded an attenuation of 400x, and a damage threshold of up to several mJ at f/5 focusing. The optical limiting at f/5 is further enhanced, particularly in the solid-state, by self-defocusing thermal nonlinearities.
Processing and Characterization of Inorganic Films for Optical Waveguide Components
Authors: Ponoth S. , Agarwal N. , Huang X. , Persans P. D. , Plawsky J. 
Published: April 2011

AbstractOptical communications are becoming technologically important on progressively shorter length scales. As computer chip speeds increase longer metal wire interconnects become problematic and may limit device performance. Wide bandwidth optical interconnects may be used to address this problem. Silicon oxide and silicon nitride were explored as prospective optical and processing materials in the making of optical interconnects. Etching of slopes, which would be an important process for making optical interconnects, was studied. Slopes with angles ranging from 5 to 50 degrees were fabricated using a silicon oxide / silicon nitride stack.
Molecular Orbital Study of Apatite Nucleation at Silica Bioceramic Surfaces
Authors: Sahai N. , Tossell J. A. 
Published: April 2011

AbstractWe have used Hartree-Fock molecular orbital calculations to model the interactions of Ca2+, H2PO41-, HPO42- and H2O with bioceramic reactive surface sites represented by [Si3O6H6] to determine the reaction sequence for apatite precipitation at bioceramic surfaces. By comparing predicted reaction energies, viberational frequencies, abd NMR shifts for 29Si, and 31P with experimental values we were able to identify stable intermediates during reaction progress.At the pH of blood, our calculations predict that (i) the 3-ring is the active surface site, (ii) formation of [SiO-Ca-OPO3H] bonds is energetically preferred over direct Si-O-P bonds, and (iii) an acidic precursor with bidentate Ca>OPO3H bonds, [Si3O6H5CaHPO4(H2O)3]1-, nucleates rapidly (minutes to 1 hour) at the bioceramic surface. Predicted precursor complex, [Si3O6H5CaHPO4(H2O)3]1-, and young bone share unique IR bands at 631 and 1125–1145 cm-1. Going beyond the scope of our calculations, a literature survey suggests that subsequent slow (1–2 weeks) aggregation of oligomers by H-bonds between surface Si-OH and HPO4 groups results in apatite formation. Analogously, carboxyl and phosphoryl groups on sialoprotein and hydroxyl-terminations on collagen may provide the nucleation and H-bonding sites for natural bone formation in the absence of the bioceramic.
Control and Characterization of Protein Adsorption on Ceramic Surfaces
Authors: Read M. J. , Burkett S. L. , Mayes A. M. 
Published: April 2011

AbstractProtein adsorption to ceramic surfaces is an important early step in the function of implants. The types and amounts of adsorbed protein and the resulting conformational changes could mediate subsequent cell adhesion and inorganic deposition. Microporous silicoalumino-phosphates, which allow variations in surface composition within the same crystal structure, have been used as model surfaces. Effects of surface composition on adsorption isotherms, elutability, and biological activity of the adsorbed protein layer have been studied using lysozyme, a model protein. Control over protein adsorption mechanisms using well-characterized surface properties could be used to predict the biological properties of surfaces, and engineer coatings for a desired response.
Nanocrystalline Apatites for Bone Reconstruction
Authors: Casalbou S. , Midy V. , Tofighi A. , Lee D. , Dard M. , Rey C. 
Published: April 2011

AbstractPoorly crystalline apatites (PCA) are characterized by a non-stoichiometric composition, a high specific surface area and the existence of labile, non-apatitic environments detected by spectroscopic techniques. These environments have been shown to belong mainly to an hydrated layer at the surface of the crystals and determine their surface and bulk reactivity. PCA can be easily synthesized in aqueous media and the amount of labile, non-apatitic environments can be modulated by using apatites at different maturation stage. PCA can adsorb many active proteins or drugs, Growth factors (FGF-2, for example), were strongly bound and remained mostly attached to the surface. Several mineral ions which have been shown to have a biological activity such as strontium, can also be trapped at the surface or into the lattice of poorly crystalline apatites. Due to their reactivity, PCA cannot be shaped easily into materials, however, they have the ability to agglomerate irreversibly into solid body at low temperature. These low temperature ceramics show a variable amount of pores (30 to 60 %) and pore size (5 to 25 nm) in which organic components can be trapped and are released only by the dissolution of the ceramic.
Evidence of Anisotropic Thermoelectric Properties in La2/3Ca1/3MnO3 Thin Films Studied by Laser-Induced Transient Voltages
Authors: Habermeier H.-U. , Li Xiaohang , Zhang Pengxiang 
Published: April 2011

AbstractPulsed UV laser illumination of doped LaMnO3 thin films deposited on vicinal cut SrTiO3 [ STO ] substrates causes unexpected transient voltages at room temperature in remarkable analogy to those observed for intrinsically anisotropic YBa3Cu3O7−x, [YBCO] thin films. The experimental data for La2/3Ca1/3MnO3 [LCMO] thin films are consistent with the description of thermoelectric fields caused by off-diagonal elements of the Seebeck tensor. Systematic measurements of the dependence of the laser-induced signal on the geometry of the sample, the temperature and doping dependence suggest that the anisotropy of the Seebeck tensor is due to combination of long range co-operative Jahn-Teller distortions and substrate-induced biaxial strain effects.
rf Susceptibility of La1−xSrxMnO3 Single Crystals: Magnetic Signatures of Structural Changes
Authors: Parimi P.V. , Srikanth H. , Bailleul M. , Sridhar S. , Suryanarayanan R. , Pinsard L. , Revcolevschi A. 
Published: April 2011

AbstractA sensitive tunnel diode oscillator (TDO) technique operating at 4MHz is used to probe the dynamic response of La1−xSrxMnO3 single crystals for x = 0.125, 0.175, 0.28 and 0.33 doping. Systematics of the measured change in reactance (δX) as a function of temperature (30K < T < 320K) and DC magnetic field (0 < H < 6kOe) reveal distinct temperature and field scales associated with the dynamic response of spin. It is notable that these features are far more striking than the corresponding features in static measurements. The results are discussed in the context of structural changes leading to polaron ordering.
Magnetism and CMR in Electron Doped Perovskite and Layered Manganites
Authors: Maignan A. , Martin C. , Hervieu M. , Raveau B. 
Published: April 2011

AbstractFrom the magnetic phase diagrams established for Ln1−xAExMnO3 manganites with x>0.5, it is shown that the magnetoresistance is only obtained for compositions of smallest average Asite cations <rA>. The magnetic structure study reveals that the small <rA> favors the coexistence of ferromagnetism with G-type antiferromagnetism. It is also shown that ferromagnetism can be induced in the Ln2−xAExMnO4 type electron doped manganites by using compositions with small Ln and AE cations and x values close to 1.90. Finally, manganse site doping by Cr, Co, Ni can be used to weaken the charge-ordering of the Mn4+ rich perovskite manganites (0.5<x≤0.8) and thus to induce CMR properties.
Transport Properties and Magnetism of β-MnO2
Authors: Sato H. , Enoki T. , Wakiya K. , Isobe M. , Ueda Y. , Kiyama T. , Wakabayashi Y. , Nakao H. , Murakami Y. 
Published: April 2011

AbstractA comprehensive study of transport properties and magnetism on β-MnO2reveals the strong coupling between the conduction electrons and the localized spins which are supposed to form a magnetic helix below TN∼ 92 K. We also show the direct evidences of the helical magnetism by means of the measurements of the anisotropy in the magnetic susceptibility and the observation of x ray magnetic scatterings on a single crystal of β-MnO2. These results are consistent with proper-type helix model proposed by Yoshimori [J. Phys. Soc. Jpn. 14, p. 807 (1959)]. This model also qualitatively agrees with the anisotropy in magnetoresistance that appears belowTN. The pitch of the magnetic helix is not commensurate to the lattice and it is slightly temperature dependent. The intensity of several Bragg peaks drastically changes atTNsuggesting that the magnetic ordering is accompanied by a lattice distortion.
Anomalous Magnetoresistance Effect in Strained Manganite Ultrathin Films
Authors: Li Qi , Wang H. S. , Hu Y. F. , Wertz E. 
Published: April 2011

AbstractMagnetotransport properties of strained epitaxial Pr2/3Sr1/3MnOz (PSMO) ultrathin films have been studied. The strains are controlled by growing PSMO films on different lattice-mismatched substrates which impose biaxial compressive-, tensile-, and very little strain in the films, respectively. Distinctive magnetoresistance effects in low magnetic field (LFMR) have been observed in films with different types of strain. The films with compressive strain show very large negative LFMR (> 1000 % at 2500 Oe) and significant magnetoresistance hysteresis when a magnetic field is applied perpendicular to the film plane. In a parallel field, the LFMR is much smaller with almost no hysteresis. In contrast, the tensile-strained ultrathin films show positive LFMR at low temperatures in a perpendicular field and a negative LFMR in a parallel field. In comparison, the almost strain-free ultrathin films show very small LFMR (< 2 %) as in single crystal samples at similar temperatures and magnetic fields. In the compressive-strained samples, the large LFMR decreases rapidly with increasing film thickness. These results are interpreted based on spin dependent scattering at the domain walls and domain-rotation.
Artificial Control of Magnetic and Magnetoresistive Properties in the Perovskite Manganites Superlattices and Their Multilayers With Organics
Authors: Tabata H. , Ueda K. , Matsui H. , Saeki H. , Kawai T. 
Published: April 2011

AbstractArtificial superlattice of LaFeO3-LaMnO3 have been formed on SrTiO3(111), (110) and (100) substrates with various stacking periodicity using pulsed laser deposition. Their magnetic properties have been controlled by altering the ordering of magnetic ions (Fe or Mn). Charge disproportionate behaviors are also observed in these superlattices. For the superlattices on (111) plane, all the samples showed ferromagnetic (or ferrimagnetic) behaviors and the same Curie temperature of 230K. In the case of other superlattices formed on (110) and (100), oh the other hand, the increase of the spin frustration effect between LFO-LMO interface with decrease of the stacking periodicity causes reduction of Tc and magnetization. Specially, spin glass like behaviors observed in the superlattices of less than 3/3 stacking periodicity Furthermore, we have constructed heterostructures of Organic/Inorganic multilayers with a sequence of Copper phthalocyanine(CuPc), BaTiO3 and (LaSr)MnO3. In this system, magnetoresistant properties have been controlled by the photo irradiation through the lattice strain and/or induced charges caused by the piezo effect and electric field effect. That is magnetoresistance in the (LaSr)MnO3 layer can be controlled by the shining the light.