On the mechanism of piezoresistance in nanocrystalline graphite

• Sandeep Kumar,
• Simone Dehm and
• Ralph Krupke

Beilstein J. Nanotechnol. 2024, 15, 376–384, doi:10.3762/bjnano.15.34

• % strain, a sharper increase in resistance indicates again grain rotation and reorientation, and fracture in the film shown by missing black dots and arrows in Figure 4d, corresponding to point D in the transport curve. The processes of grain movements (increase in distance between grains and rotation

• spectra for 0% (black) and 0.36% (green) strain. (d) Comparison of Raman spectra focused on D and G peaks for 0% (black) and 0.36% (green) curves. Correlation between transport in NCG films and grain rotation and reorientation under strain. Black dots represent the grain position, and arrows represent the

The influence of structure and local structural defects on the magnetic properties of cobalt nanofilms

• Alexander Vakhrushev,
• Aleksey Fedotov,
• Olesya Severyukhina and
• Anatolie Sidorenko

Beilstein J. Nanotechnol. 2023, 14, 23–33, doi:10.3762/bjnano.14.3

• arrangement and force behavior, which caused their reorientation. Analysis of Figure 4 shows that there are significant differences in the spin distributions of an ideal crystalline hexagonal close-packed cobalt (letters (a), (b), (c)) and the nanofilm with structural defects formed as a result of the

• stochastic allocation. Subsequently, the spin temperature fluctuations decrease, and its fluctuations occur near the thermostat target value of 5 K. For an interval of 5–100 ps, the reorientation of spins is slow and mutually consistent, which is reflected in a small change in spin temperature. The system

• material structure. Under an external magnetic field with an induction of 1.0 T, a reorientation of spins along the external magnetic field is observed for crystalline ordered cobalt. Conversely, for cobalt from the nanofilm a more chaotic distribution of spins is characteristic, but also with a

Rapid thermal annealing for high-quality ITO thin films deposited by radio-frequency magnetron sputtering

• Petronela Prepelita,
• Ionel Stavarache,
• Doina Craciun,
• Florin Garoi,
• Catalin Negrila,
• Beatrice Gabriela Sbarcea and
• Valentin Craciun

Beilstein J. Nanotechnol. 2019, 10, 1511–1522, doi:10.3762/bjnano.10.149

• temperature used during RTA, the films became polycrystalline. An increase of the peak intensity with the increase in film thickness to 370 nm can also be noticed (Figure 2), as well as a structural reorientation (decrease of the main peak intensity and the appearance of other peaks in the film structure

Features and advantages of flexible silicon nanowires for SERS applications

• Hrvoje Gebavi,
• Vlatko Gašparić,
• Dubravko Risović,
• Nikola Baran,
• Paweł Henryk Albrycht and
• Mile Ivanda

Beilstein J. Nanotechnol. 2019, 10, 725–734, doi:10.3762/bjnano.10.72

• of the substrate. The pH value of 100% ethanol is 7.33, while the water has a pH value equal to 7. Therefore, we do not expect a significant increase in SERS intensity due to the reorientation of 4-MPBA that could be ascribed to a small change of pH value (see the charge transfer and absorbance in

• as much as it did between 10−6 and 10−5 M. It indicates that there is only a certain number of possible active sites on Ag that can host the analyte molecules. The reorientation of 4-MPBA or a shielding of the first analyte monolayer could also contribute to this effect. At a concentration of 10−6 M

Threshold voltage decrease in a thermotropic nematic liquid crystal doped with graphene oxide flakes

• Mateusz Mrukiewicz,
• Krystian Kowiorski,
• Paweł Perkowski,
• Rafał Mazur and
• Małgorzata Djas

Beilstein J. Nanotechnol. 2019, 10, 71–78, doi:10.3762/bjnano.10.7

• electric field can change the director orientation thereby causing a change in the optical properties. In the absence of an electric field, the orientation of n is determined by anchoring conditions. The field-induced reorientation of the LC director is known as the Frédericksz effect [3]. In the

• the tilt angle θ is small. When the voltage is above Uth, we start to observe the increase of θ [4]. The complete reorientation of the director n, θ = 90°, occurs at higher voltages U > Uth. The reorientation is caused by the anisotropy of the electric permittivity where ε|| and is the electric

• ]. An applied electric field acts to induced dipole moments, which causes reorientation of the flakes [27][28]. The above-mentioned facts are very important features for mixing a nematic liquid crystal with GO flakes in order to improve its physical properties. Here, the nematic liquid crystal compound

Size limits of magnetic-domain engineering in continuous in-plane exchange-bias prototype films

• Alexander Gaul,
• Daniel Emmrich,
• Timo Ueltzhöffer,
• Henning Huckfeldt,
• Hatice Doğanay,
• Johanna Hackl,
• Muhammad Imtiaz Khan,
• Daniel M. Gottlob,
• Gregor Hartmann,
• André Beyer,
• Dennis Holzinger,
• Slavomír Nemšák,
• Claus M. Schneider,
• Armin Gölzhäuser,
• Günter Reiss and
• Arno Ehresmann

Beilstein J. Nanotechnol. 2018, 9, 2968–2979, doi:10.3762/bjnano.9.276

• multilayers is fundamentally based on two energy-transfer mechanisms from the ions to the material system. The predominant effect, the electronic energy transfer (hyperthermal heating), causes a reorientation of the local unidirectional anisotropy. The second and considerably weaker effect is the nuclear

• distribution having the form: Az represents the energy loss per depth unit, σz is the standard deviation of the normal distribution. Since the reorientation of the unidirectional EB anisotropy is attributed to local hyperthermal heating by the electronic interaction of the ion beam with the layer system [53

Magnetism and magnetoresistance of single Ni–Cu alloy nanowires

• Andreea Costas,
• Camelia Florica,
• Elena Matei,
• Maria Eugenia Toimil-Molares,
• Ionel Stavarache,
• Andrei Kuncser,
• Victor Kuncser and
• Ionut Enculescu

Beilstein J. Nanotechnol. 2018, 9, 2345–2355, doi:10.3762/bjnano.9.219

• the field, even in case of such a drastic change of the magnetic configuration (see analogy with Figure 2). When the field is applied perpendicular to the EA (e.g., decreasing from a value above the saturation field), a gradual reorientation of the magnetic moments is expected, leading to a linear

• perpendicular geometry is almost insensitive to values of the stiffness constant, but decreases strongly with the saturation magnetization. The evolution of the spin structure of the wire is similar to one of a magnetic monodomain, with gradual in-field reorientation for almost all spins (only the outermost

Recent highlights in nanoscale and mesoscale friction

• Andrea Vanossi,
• Dirk Dietzel,
• Andre Schirmeisen,
• Ernst Meyer,
• Rémy Pawlak,
• Thilo Glatzel,
• Marcin Kisiel,
• Shigeki Kawai and
• Nicola Manini

Beilstein J. Nanotechnol. 2018, 9, 1995–2014, doi:10.3762/bjnano.9.190

• scaling exponent γ. Hence, shape effects play an important role to explain friction fluctuations associated to particle reorientation observed in nanomanipulation experiments [69]. In part, these shape effects can be related to the particular role that the edge plays within the force-cancellation

Photoluminescence of CdSe/ZnS quantum dots in nematic liquid crystals in electric fields

• Margarita A. Kurochkina,
• Elena A. Konshina and
• Daria Khmelevskaia

Beilstein J. Nanotechnol. 2018, 9, 1544–1549, doi:10.3762/bjnano.9.145

• , Russia 10.3762/bjnano.9.145 Abstract We have experimentally investigated the effect of the reorientation of a nematic liquid crystal (LC) in an electric field on the photoluminescence (PL) of CdSe/ZnS semiconductor quantum dots (QDs). To the LC with positive dielectric anisotropy, 1 wt % QDs with a core

• matrix without reorientation of the LC molecules. With increasing electric field strength, the quenching of QDs luminescence occurred in the active LC matrix, while the PL intensity did not change in the passive LC matrix. The change in the decay time with increasing electric field strength was similar

• the electric field strength. At the same time, no significant changes occurred in the passive LC matrix. With the reorientation of LC molecules from the planar in vertical position in the LC active matrix, quenching of QD luminescence and an increase of the ion current took place simultaneously. The

Formation and development of nanometer-sized cybotactic clusters in bent-core nematic liquid crystalline compounds

• Yuri P. Panarin,
• Sithara P. Sreenilayam,
• Jagdish K. Vij,
• Anne Lehmann and
• Carsten Tschierske

Beilstein J. Nanotechnol. 2018, 9, 1288–1296, doi:10.3762/bjnano.9.121

• Equation 2 and Equation 3, respectively. In the molecular field approximation (MFA), the orientational entropy of a cluster in the nematic phase is the sum of two contributions: the reorientation of the individual molecules and the fluctuation of the cluster directors with respect to the macroscopic

Optical orientation of nematic liquid crystal droplets via photoisomerization of an azodendrimer dopant

• Sergey A. Shvetsov,
• Alexander V. Emelyanenko,
• Natalia I. Boiko,
• Alexander S. Zolot'ko,
• Yan-Song Zhang,
• Jui-Hsiang Liu and
• Alexei R. Khokhlov

Beilstein J. Nanotechnol. 2018, 9, 870–879, doi:10.3762/bjnano.9.81

• . The effects of light-induced director reorientation in the films of NLCs doped with M or G5 occur at light intensities which are three or even four orders of magnitude higher [45]. The polarized absorption spectra were recorded with the help of an MC-122 spectrometer (Proscan Special Instruments). The

Dynamic behavior of nematic liquid crystal mixtures with quantum dots in electric fields

• Emil Petrescu,
• Cristina Cirtoaje and
• Octavian Danila

Beilstein J. Nanotechnol. 2018, 9, 399–406, doi:10.3762/bjnano.9.39

• than the Fréedericksz transition threshold [18][19] is applied transversely to a planar liquid crystal cell, the molecules change their orientation tending to align their director in parallel to the field. This reorientation is illustrated by an intensity variation of a laser beam crossing through the

• parallel with the field direction. During this reorientation process, the refractive index of the sample also changes: where no and ne are, respectively, the ordinary and extraordinary refractive indexes and θ is the angle between the direction of the light and ne. Between the extraordinary and ordinary

Dynamic behavior of a nematic liquid crystal with added carbon nanotubes in an electric field

• Emil Petrescu and
• Cristina Cirtoaje

Beilstein J. Nanotechnol. 2018, 9, 233–241, doi:10.3762/bjnano.9.25

• the moment in which the electric field is switched on. When dynamic evolution is analyzed, we must also take into account the liquid crystal rotational viscosity which slows the molecular reorientation. Thus, an additional dissipative term must be added: The free energy density of the nematic and CNT

Dielectric properties of a bisimidazolium salt with dodecyl sulfate anion doped with carbon nanotubes

• Doina Manaila Maximean,
• Viorel Cîrcu and
• Constantin Paul Ganea

Beilstein J. Nanotechnol. 2018, 9, 164–174, doi:10.3762/bjnano.9.19

• imposed on the CNTs in such a way that the alignment axis of the CNTs is driven by the LC reorientation controlled by an electric field [37]. The concentration and the spatial distribution of charges in the LC matrix will be affected by the presence of CNTs and, hence, the conductivity will be changed [38

Electro-optical characteristics of a liquid crystal cell with graphene electrodes

• Nune H. Hakobyan,
• Hakob L. Margaryan,
• Valeri K. Abrahamyan,
• Vladimir M. Aroutiounian,
• Arpi S. Dilanchian Gharghani,
• Amalya B. Kostanyan,
• Timothy D. Wilkinson and
• Nelson Tabirian

Beilstein J. Nanotechnol. 2017, 8, 2802–2806, doi:10.3762/bjnano.8.279

• due to the reorientation of the LC to be observed (Figure 5). Hence the LC cell can operate as an electrically controlled light valve, where the intensity of the transmitted light is changed from minimum to maximum and vice versa with an associated π-phase shift. The switching time of the light valve

• cell, with different conducting electrodes (i.e., graphene–graphene and ITO–ITO), show almost identical characteristics. A similar pattern was observed during the study of the reorientation and relaxation processes under the influence of an external bipolar pulse voltage (Figure 6). As shown, at the

• initial moment of the pulse action (sharp reorientation oscillation) the system tends to keep its original ordered state. Here, the translation of the highly ordered surface layer into the LC bulk occurs under the influence of elastic forces. However, later, the ordering in the bulk is lost due to the

Thermo- and electro-optical properties of photonic liquid crystal fibers doped with gold nanoparticles

• Agata Siarkowska,
• Miłosz Chychłowski,
• Daniel Budaszewski,
• Bartłomiej Jankiewicz,
• Bartosz Bartosewicz and
• Tomasz R. Woliński

Beilstein J. Nanotechnol. 2017, 8, 2790–2801, doi:10.3762/bjnano.8.278

• responsible for the improvement of the response time of the measured PLCF sample. On the other hand, the increase of the fall time with a higher concentration of NPs can be related to hindering of the NP LC reorientation. The presence of a high concentration of NPs could locally disturb the orientation of the

Alternating current magnetic susceptibility of a ferronematic

• Natália Tomašovičová,
• Jozef Kováč,
• Veronika Gdovinová,
• Nándor Éber,
• Tibor Tóth-Katona,
• Jan Jadżyn and
• Peter Kopčanský

Beilstein J. Nanotechnol. 2017, 8, 2515–2520, doi:10.3762/bjnano.8.251

• number of particles capable for magnetic reorientation by the ac testing magnetic field (large aggregates practically do not contribute to χ′). These changes in the particle distribution persist in the isotropic phase, but are annulled at entering into the nematic phase, since the disclinations emerging

Flexible photonic crystal membranes with nanoparticle high refractive index layers

• Torben Karrock,
• Moritz Paulsen and
• Martina Gerken

Beilstein J. Nanotechnol. 2017, 8, 203–209, doi:10.3762/bjnano.8.22

• reorientation of the PEO to the surface–water interface the interfacial free energy is reduced. The modified PDMS surface exhibits a time-dependent water contact angle. It drops rapidly in the first 30 s and is stable after ≈200 s. The contact angle is reduced to 20° at a concentration of about 2% of PEO in the

Scanning probe microscopy studies on the adsorption of selected molecular dyes on titania

• Jakub S. Prauzner-Bechcicki,
• Lukasz Zajac,
• Piotr Olszowski,
• Res Jöhr,
• Antoine Hinaut,
• Thilo Glatzel,
• Bartosz Such,
• Ernst Meyer and
• Marek Szymonski

Beilstein J. Nanotechnol. 2016, 7, 1642–1653, doi:10.3762/bjnano.7.156

• , or at a high coverage limit, molecule–molecule interactions may lead to a reorientation of the molecules). Obviously, it is naïve to claim that a single factor is responsible for the arrangement of molecules in an ordered layer. The form of the final pattern depends on all of the mentioned

• in two coexisting phases with the majority of molecules lying with their plane parallel to the substrate surface. Post-deposition annealing at 200 °C leads to a reorientation of the molecules in the second layer into an upright geometry [43]. When deposited on a TiO2(110) surface, phthalocyanine

• it is no longer present for thick films. When the coverage includes several layers, deprotonation is observed only for molecules in the layer closest to the substrate. The interaction of first layer molecules with the substrate surface seems to be quite strong, despite the reorientation of ZnPPs at

Reorientation of single-wall carbon nanotubes in negative anisotropy liquid crystals by an electric field

• Amanda García-García,
• Ricardo Vergaz,
• José F. Algorri,
• Gianluigi Zito,
• Teresa Cacace,
• Antigone Marino,
• José M. Otón and
• Morten A. Geday

Beilstein J. Nanotechnol. 2016, 7, 825–833, doi:10.3762/bjnano.7.74

• modifications in the electrical and electro-optical properties of liquid crystals. The control of the SWCNT concentration, distribution and reorientation in such self-organized fluids allows for the possibility of tuning the liquid crystal properties. The alignment and reorientation of CNTs are studied in a

• system where the liquid crystal orientation effect has been isolated. Complementary studies including Raman spectroscopy, microscopic inspection and impedance studies were carried out. The results reveal an ordered reorientation of the CNTs induced by an electric field, which does not alter the

• orientation of the liquid crystal molecules. Moreover, impedance spectroscopy suggests a nonnegligible anchoring force between the CNTs and the liquid crystal molecules. Keywords: Anchoring; carbon nanotubes; impedance; liquid crystal; negative anisotropy; Raman spectroscopy; reorientation; single-wall CNTs

Orientation of FePt nanoparticles on top of a-SiO₂/Si(001), MgO(001) and sapphire(0001): effect of thermal treatments and influence of substrate and particle size

• Martin Schilling,
• Paul Ziemann,
• Zaoli Zhang,
• Johannes Biskupek,
• Ute Kaiser and
• Ulf Wiedwald

Beilstein J. Nanotechnol. 2016, 7, 591–604, doi:10.3762/bjnano.7.52

• SiO2 or crystalline sapphire(0001) supports, highly (001)-textured FePt films can be fabricated by rapid thermal processing driven by stress-induced reorientation [21], while longer annealing times on the order of minutes lead to reorientation towards (111) texture due to surface energy-driven

• patterns. In our experiments, this fact is used to investigate the reorientation of FePt NPs by subsequent annealing. Note that the known substrate structure can be still used as an intrinsic calibration standard for the orientation and the lattice parameter of the NPs. In addition, the appearance of

• possibility of NP reorientation on a single crystalline support by post-deposition annealing. This served as motivation for the in situ RHEED investigations of FePt NPs and films on various substrates. The electron spot in the RHEED experiments has a diameter of about 100 µm where the obtained structural

An adapted Coffey model for studying susceptibility losses in interacting magnetic nanoparticles

• Mihaela Osaci and
• Matteo Cacciola

Beilstein J. Nanotechnol. 2015, 6, 2173–2182, doi:10.3762/bjnano.6.223

• relation: where represents the Néel relaxation time for the particle i and , are the normalized energy barriers (over kBT) for the reorientation of the i-th magnetic moments. The Brownian relaxation time is given by Equation 7, and the effective relaxation time is given by Equation 6. The problem of

Electrical characterization of single molecule and Langmuir–Blodgett monomolecular films of a pyridine-terminated oligo(phenylene-ethynylene) derivative

• Henrry M. Osorio,
• Santiago Martín,
• María Carmen López,
• Santiago Marqués-González,
• Simon J. Higgins,
• Richard J. Nichols,
• Paul J. Low and
• Pilar Cea

Beilstein J. Nanotechnol. 2015, 6, 1145–1157, doi:10.3762/bjnano.6.116

• the dipole transition moment of the chromophore. This result is in agreement with a progressive reorientation of the molecules in the Langmuir film upon compression. Langmuir–Blodgett monomolecular films of 1 were obtained by the transference of Langmuir films onto solid substrates by the vertical

Entropy effects in the collective dynamic behavior of alkyl monolayers tethered to Si(111)

• Christian Godet

Beilstein J. Nanotechnol. 2015, 6, 583–594, doi:10.3762/bjnano.6.60

• dependence of the B2 dipolar strength. For both dissipation mechanisms, the observed linear correlation between activation energy and logarithm of pre-exponential factor is consistent with a multi-excitation entropy model, in which the molecular reorientation path is strongly coupled with a large number of

• ] and measurements can be performed in a well-defined metal/OML/semiconductor planar configuration, which is relevant for molecular electronics devices. Admittance spectroscopy provides insights in the modulation of localized charge density and dipole reorientation in a system submitted to a time

• -dependent electric field. Dissipation (energy loss) mechanisms can be described by using equivalent representations of the complex admittance, including the dielectric permittivity ε* and electrical modulus M*. Dipole reorientation requires an activation of the system with energy barriers related either to

Electrical response of liquid crystal cells doped with multi-walled carbon nanotubes

• Amanda García-García,
• Ricardo Vergaz,
• José F. Algorri,
• Xabier Quintana and
• José M. Otón

Beilstein J. Nanotechnol. 2015, 6, 396–403, doi:10.3762/bjnano.6.39

• consistent with a possible electric contact between the coated substrates of the LC cell caused by the reorientation of the nanotubes. The reversibility of the doped system upon removal of the electric field is quite low. Keywords: carbon nanotubes; Cole–Cole diagrams; impedance; liquid crystal; PEDOT:PSS

• carbon nanotubes (CNTs) and the possibility of reorienting them with external fields [3][4][5][6]. The interest to control this reorientation arises from the possibility of preparing simple devices whose electrical conductivity can be externally controlled and modulated [5][6][7][8][9]. Due to their

• minimize the energy derived from the electric field and the anchoring elastic forces [13]. These LC properties may be used to induce alignment and reorientation on dispersed CNTs. Using this effect, several photonic and electronic devices have been proposed [5] including electrically controlled switches