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1.
Wolfgang H. Binder Laura Petraru Robert Sachenshofer Ronald Zirbs 《Monatshefte für Chemie / Chemical Monthly》2006,137(7):835-841
Summary. The surface modification of nanoparticles via azide/alkine-1,3-dipolar cycloaddition-reactions is described. Ligand exchange onto various nanoparticles was monitored by
1H NMR spectroscopy and formed the basis for the attachment of ligands onto the nanoparticles and their subsequent modification
by dipolar cycloaddition reactions. Nanoparticle-surfaces were monitored by binding onto self-assembled monolayers derivatized
with matching supramolecular interactions after derivatization. 相似文献
2.
The multiferroic properties of ferroelectric tunnel junctions with a composite barrier comprising a fully epitaxial La0.7Sr0.3MnO3/BaTiO3/SrTiO3/La0.7Sr0.3MnO3 heterostructure are reported in this study. The patterned junctions having extended top electrodes show tunnel magnetoresistance ratios ranging from 20% to 110% at 77 K. Furthermore, tunneling electroresistance – induced by ferroelectric polarization switching and showing two‐state memory effect in the dynamic resistance – has also been observed in these junctions. Thus, with the concurrence of tunneling electroresistance and magnetoresistance, these tunnel junctions serve as memory devices with four resistance states. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
3.
A. Petraru V. Nagarajan H. Kohlstedt R. Ramesh D.G. Schlom R. Waser 《Applied Physics A: Materials Science & Processing》2006,84(1-2):67-71
We present a sensitive method to simultaneously acquire the C(V ) characteristics and piezoresponse of sub-micron size ferroelectric capacitors using an Atomic Force Microscope (AFM). Model Pt/(La0.5,Sr0.5)CoO3/PbZr0.4Ti0.6 O3/(La0.5,Sr0.5)CoO3/La:SrTiO3/Si nanocapacitors were fabricated by focused ion beam milling from 100 μm2 down to 0.04 μm2. With this AFM based capacitance measurement technique we show clear “double-humped” C(V ) for all sizes with no significant change in the peak value of the εr down to capacitors with the smallest area of 0.04 μm2. The smallest capacitance measured is only of the order a few femtofarads, demonstrating the high sensitivity of the technique. Simultaneously, the piezoelectric response is recorded for each measurement, thus the technique facilitates simultaneous piezoresponse and dielectric characterization of ferroelectric memory devices. PACS 77.55.+f; 77.90.+k; 85.50.-n; 77.84.-s 相似文献
4.
Good-quality polycrystalline BaTiO3 thin films are deposited on MgO substrates by pulsed laserdeposition. The deposition parameters are optimized to achieve optical-quality films with an attenuation coefficient of 4 dB/cm at the 633-nm wavelength. Thin-film electro-optic Mach-Zehnder modulators are fabricated with standard lithography and ion-beam etching. The waveguides patterned by lithography are the ridge type, and they ensure single-mode propagation in the wavelength range of 633-1550 nm. An electro-optic coefficient of 22 pm/V is estimated for the polycrystalline BaTiO3 films. 相似文献
5.
Ramona Enea Ana-Maria Resmeriţă Laura Petraru Cristian Grigoraş Dan Scutaru Cristofor I. Simionescu Nicolae Hurduc 《Central European Journal of Chemistry》2007,5(4):981-995
This paper presents the syntheses, characterization and photochromic behavior of some new azo-polysiloxanes modified with
uracil, cytosine or nitro-phenolic groups. Taking into consideration the possibility of generating H-bonds or donor/acceptor
interactions, this class of materials present a potential applicability in the immobilization of biomolecules and their nano-manipulations.
Also, such compounds are capable of producing a fluid phase, with directional flowing capacity. For all these polymers, the
molecular modeling simulations have shown disordered structures, which would generate amorphous phases, a very important aspect
for molecules’ nano-manipulation. The photochromic behavior in the presence of UV irradiation was also evaluated.
相似文献
6.
Wolfgang H. Binder Laura Petraru Harald Weinstabl Dietrich Gloger Robert Sachsenhofer 《Macromolecular Symposia》2007,254(1):62-66
Summary: Supramolecular gels, made from the combination of telechelic poly (ethyleneglycols) (PEG's) and trivalent poly(isobutylenes) with terminal matching hydrogen bonds were prepared and their rheological properties were investigated. Addition of poly(N-isopropylacrylamide) as thermosensitive polymer was included into the gel-capsules in amounts of 10 w%, producing gels with strongly thermally- responsive properties. Additionally, dansyl-dyes with two different endgroups (either an hydrophobic endgroup or a multiple hydrogen bond) were encapsulated into the gels as mimicks for pharmaceutically active substances. Monitoring their diffusion by UV-dependent measurements allowed to tune the diffusion and thus the release properties of the gel. The generated supramolecular gels will allow the selective encapsulation and triggered release of various pharmaceuticals and biologically active targets. 相似文献
7.
Dominique Farnik Christian Kluger Michael J. Kunz Doris Machl Laura Petraru Wolfgang H. Binder 《Macromolecular Symposia》2004,217(1):247-266
New synthetic methodologies towards hydrogen bonded supramolecular polymers are described. Focus is directed on synthetic work towards telechelics with hydrogen bonds either as side chain moieties or as endgroups. Physical ordering effects related to polymers and particles are discussed citing own and related work in ∼60 references. 相似文献
8.
Crunteanu A. Jänchen G. Hoffmann P. Pollnau M. Buchal C. Petraru A. Eason R.W. Shepherd D.P. 《Applied Physics A: Materials Science & Processing》2003,76(7):1109-1112
We present a method for the selective two- and three-dimensional patterning of sapphire using light ion-beam implantation
to generate severe lattice damage to depths exceeding 1 μm and subsequent selective wet chemical etching of the damaged regions
by hot H3PO4. C-cut sapphire crystals were implanted through contact masks using ion fluences of 1×1016 to 5×1017 He+/cm2 and energies up to 400 keV. The etching process is characterized by a high selectivity and a rate of approximately 19 nm/min.
Whereas an implantation that produces a continuously damaged pathway results in complete etching from the surface, sole in-depth
implantation using only high-energy ions leads to under-etching of the crystalline surface layer. By a combination of these
processes we have fabricated three-dimensional structures such as channels and bridges in sapphire.
Received: 14 October 2002 / Accepted: 15 October 2002 / Published online: 26 February 2003
RID="*"
ID="*"Corresponding author. Fax +41-21/693-3701, E-mail: aurelian.crunteanustanescu@epfl.ch 相似文献
9.
Wolfgang H. Binder Laura Petraru Robert Sachenshofer Ronald Zirbs 《Monatshefte für Chemie / Chemical Monthly》2006,16(3):835-841
The surface modification of nanoparticles via azide/alkine-1,3-dipolar cycloaddition-reactions is described. Ligand exchange onto various nanoparticles was monitored by
1H NMR spectroscopy and formed the basis for the attachment of ligands onto the nanoparticles and their subsequent modification
by dipolar cycloaddition reactions. Nanoparticle-surfaces were monitored by binding onto self-assembled monolayers derivatized
with matching supramolecular interactions after derivatization. 相似文献
10.
T. Schneller H. Kohlstedt A. Petraru R. Waser J. Guo J. Denlinger T. Learmonth Per-Anders Glans K. E. Smith 《Journal of Sol-Gel Science and Technology》2008,48(1-2):239-252
Chemical solution deposited (CSD) complex oxide thin films attract considerable interest in various emerging fields as for example, fuel cells, ferroelectric random access memories or coated conductors. In the present paper the results of soft-X-ray spectroscopy between 280 and 560 eV on the amorphous to crystalline phase transition of ferroelectric Pb(Zr0.3Ti0.7)O3 (PZT) thin films are presented. Five CSD samples derived from the same wafer coated with a PZT film pyrolyzed at 350 °C were heat treated at different temperatures between 400 and 700 °C. At first the samples were morphologically and electrically characterized. Subsequently the soft-X-ray absorption and emission experiments were performed at the undulator beamline 8.0 of the Advanced Light Source of the Lawrence Berkeley National Laboratory. Soft-X-ray absorption spectra were acquired for the Ti L 2,3-, O K-, and C K-edge thresholds by using simultaneously the total electron yield (TEY) and total fluorescence yield (TFY) detection methods. For two samples, annealed at 400 and 700 °C, respectively, the resonant inelastic soft-X-ray spectroscopy (RIXS) was applied for various excitation energies near the Ti L-, O K-edges. We observed clear evidence of a rutile phase at untypically low temperatures. This rutile phase transforms into the perovskite phase upon increasing annealing temperature. These results are discussed in the framework of current microscopic models of the PZT (111) texture selection. 相似文献