Effect of ferroelectric BaTiO₃ particles on the threshold voltage of a smectic A liquid crystal

• Abbas R. Imamaliyev,
• Mahammadali A. Ramazanov and
• Shirkhan A. Humbatov

Beilstein J. Nanotechnol. 2018, 9, 824–828, doi:10.3762/bjnano.9.76

• features observed in the C–V characteristics are given. Keywords: colloidal systems; dielectric permittivity; ferroelectric BaTiO3 particles; smectic A liquid crystals; threshold voltage; Introduction Interest in liquid crystals (LC) as a unique state of matter arises not only from a scientific point of

• electro-optical cell. The electro-optical effect changes the effective dielectric permittivity of LC, which is reflected a change of capacitance of the electro-optical cell. The electro-optical effect in the investigated LC is the planar–homeotropic transition due to the positive dielectric anisotropy of

• effective dielectric permittivity starts to increase. Note that the latter is determined as the ratio ε = C/C0, where C and C0 are the capacitances of the filled cell and an empty cell, respectively. Figure 3 presents the effective dielectric permittivity as a function of the voltage for pure smectic A LC

Valley-selective directional emission from a transition-metal dichalcogenide monolayer mediated by a plasmonic nanoantenna

• Haitao Chen,
• Mingkai Liu,
• Lei Xu and
• Dragomir N. Neshev

Beilstein J. Nanotechnol. 2018, 9, 780–788, doi:10.3762/bjnano.9.71

• edges, we model the gold bars having rounded corners with a radius of curvature of 5 nm. The permittivity of the gold in the visible and near-infrared spectral region is modeled based on experimental data from [48]. The intensity of the electric field along X direction (I) and phase information (φ) at

Tuning adhesion forces between functionalized gold colloidal nanoparticles and silicon AFM tips: role of ligands and capillary forces

• Sven Oras,
• Sergei Vlassov,
• Marta Berholts,
• Rünno Lõhmus and
• Karine Mougin

Beilstein J. Nanotechnol. 2018, 9, 660–670, doi:10.3762/bjnano.9.61

• moments, α1 = 6.8 × 10−40 C2·m2/J and α2 = 5.8 × 10−40 C2·m2/J are the polarizabilities, ν1 = 2.8 × 1015 Hz and ν2 = 2.1 × 1015 Hz are the ionisation frequencies of silicon and thiol respectivly, kB is Boltzmann’s constant, T = 293 K is the temperature of the medium, ε0 is the vacuum permittivity, ε = 1

• is the relative permittivity and r = 0.165 nm [33] is the typical cut-off distance. According to calculations, the average values of vdW force between the molecules are around 13 nN. This value allows validating AFM measurements (Figure 3b). Therefore, vdW forces remain one of the main interactions

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

• threshold, the deviation angle is very small and the free energy caused by the elastic forces is: where K1 and K3 are the splay and bent elastic constants and θz = ∂θ/∂z. Due to the presence of the QDs, the electric properties of the mixture change. Hence, instead of perpendicular dielectric permittivity

• , , and electric anisotropy, εa, we use the effective perpendicular permittivity, , and effective anisotropy, εaeff. If a small spherical cavity is considered inside the liquid crystal, a polarisation field on the hole surface appears. According to classical theory developed by Landau and Lifshitz [20

• permittivity, is the perpendicular permittivity. In this case H becomes: where d(z) the depolarization coefficient, which for an ellipsoid with almost spherical shape (horizontal axis equal b = R and vertical axis a = R + 0.0005R) is If a quantum dot is placed inside this cavity, another polarization field

Design of polar self-assembling lactic acid derivatives possessing submicrometre helical pitch

• Alexej Bubnov,
• Cyril Vacek,
• Michał Czerwiński,
• Terezia Vojtylová,
• Wiktor Piecek and
• Věra Hamplová

Beilstein J. Nanotechnol. 2018, 9, 333–341, doi:10.3762/bjnano.9.33

• results of the imaginary part, ε”, of complex permittivity versus temperature and versus frequency are presented in Figure 4a,b. The dielectric absorption ε” spectra obtained within the whole temperature range of the ferroelectric SmC* phase at zero bias electric field reveal a strong contribution of the

• permittivity was measured during cooling using a Schlumberger 1260 impedance analyser in the frequency range of 10 Hz–1 MHz, keeping the temperature of the sample stable during frequency sweeps within ±0.1 K. Differential scanning calorimetry (DSC) plot of heating/cooling runs (indicated by horizontal arrows

• (blue triangle) and KL 4/6 (cyan diamond) as indicated. Temperature dependencies of the helix pitch length p for KL 3/4 (black rectangle), KL 3/5 (red cicle), KL 4/4 (green triangle), KL 4/5 (blue triangle) and KL 4/6 (cyan diamond) as indicated. 3D plots of the imaginary part of complex permittivity

The nanofluidic confinement apparatus: studying confinement-dependent nanoparticle behavior and diffusion

• Stefan Fringes,
• Felix Holzner and
• Armin W. Knoll

Beilstein J. Nanotechnol. 2018, 9, 301–310, doi:10.3762/bjnano.9.30

• interaction energy U(h) of a charged spherical particle at a distance h to a charged plane is given by [23][36]: where κ−1 is the Debye length, ε is the dielectric constant of the medium, ε0 is the vacuum permittivity, a is the radius, and ψP,eff and ψS,eff are the effective surface potentials of plane and

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

• crystal with the electric field (Figure 2) is: where Here is the transverse component of the dielectric permittivity and is the dielectric anisotropy of the liquid crystal. Since D, the electric displacement, is constant, the voltage between the electrodes can be written as: and Equation 7 becomes: If

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

• functions. As a result of doping the ILC with CNT, the electric conductivity increases significantly. Ionic conductivity is dominant and it was indirectly observed through the electrode polarization (EP) effect. The very high dielectric permittivity values and the decrease of the electric conductivity at

• pure and CNT-doped ILC were recorded in the frequency range from 10−1 to 107 Hz and in the temperature range from 293 to 338 K corresponding to the different phases of the ILC (mesophase and isotropic state). The values of the permittivity, dielectric loss and conductivity were deduced from the

• agreement with the DSC and the POM observations for the phase transitions, between 293 and 338 K. The logarithmic permittivity for the pure ILC and the CNT-doped ILC as a function of the temperature is presented in Figure 5. It was found that the permittivity has higher values for the CNT-doped ILC and, in

Electrical properties of a liquid crystal dispersed in an electrospun cellulose acetate network

• Doina Manaila Maximean,
• Octavian Danila,
• Pedro L. Almeida and
• Constantin Paul Ganea

Beilstein J. Nanotechnol. 2018, 9, 155–163, doi:10.3762/bjnano.9.18

• the frequency range from 10−1 to 107 Hz, in a temperature domain from 293 to 350 K. The DS results were obtained by plotting the real and imaginary components of the complex permittivity function ε*(ω) = ε′(ω) − iε″(ω). Here, ε*(ω) is the dielectric permittivity, the real part, ε′(ω), is the

• and ε″(ω) is the dielectric loss, εLF is the low frequency permittivity, ε∞ is the permittivity in the HF limit, and τmax is the characteristic relaxation time of the medium. Figure 6 presents the characteristic relaxation time as a function of the inverse of temperature for the cellulose acetate

• composite system has an important influence on the values of dielectric permittivity (Figure 5). Moreover, because of the interaction with the surface of the CA fibers, the dynamics of the E7 molecules is more or less attenuated, as compared to the pure LC. Thus, as in other composite systems, the phase

Nematic topological defects positionally controlled by geometry and external fields

• Pavlo Kurioz,
• Marko Kralj,
• Bryce S. Murray,
• Charles Rosenblatt and
• Samo Kralj

Beilstein J. Nanotechnol. 2018, 9, 109–118, doi:10.3762/bjnano.9.13

• representative characteristic elastic constant in the single elastic constant approximation, is the external electric field, ε0 is the permittivity of free space, and Δε is the dielectric constant anisotropy. We model conditions at the LC confining boundaries either by [15][16]: or where w is the surface

Growth model and structure evolution of Ag layers deposited on Ge films

• Arkadiusz Ciesielski,
• Lukasz Skowronski,
• Ewa Górecka,
• Jakub Kierdaszuk and
• Tomasz Szoplik

Beilstein J. Nanotechnol. 2018, 9, 66–76, doi:10.3762/bjnano.9.9

• nm thickness has an imaginary part of permittivity lower than 1 within the 315–827 nm range [4]. Therefore, silver is widely used in plasmonic sensors [5][6][7], as substrates for surface enhanced Raman scattering (SERS) [8][9], as inclusion in solar cells [10][11][12] and in other plasmonic devices

• [13][14]. The SPP wave propagation length depends on the permittivity of the metal film, but also on its surface roughness, which is responsible for scattering losses. Thin silver layers deposited on glass substrates usually exhibit an island growth [15]. One way of fabricating smooth and thermally

• spite of scattering loss reduction, the measured imaginary part of permittivity of a 7 nm Al-doped Ag film is three-fold higher than that of a 30 nm pure Ag in the 400–1700 nm spectral range [17]. On the other hand, if silver films are thermally or electron beam (e-beam) evaporated under optimum

Nematic liquid crystal alignment on subwavelength metal gratings

• Irina V. Kasyanova,
• Artur R. Geivandov,
• Vladimir V. Artemov,
• Maxim V. Gorkunov and
• Serguei P. Palto

Beilstein J. Nanotechnol. 2018, 9, 42–47, doi:10.3762/bjnano.9.6

• to the principal refractive index corresponding to the dielectric permittivity tensor component along the LC director ( = 1.751 at 546 nm). Thus, we can conclude that for the given short-period grating we achieve a quite good planar alignment when the pretilt angle (in the cases where it exists) is

Impact of titanium dioxide nanoparticles on purification and contamination of nematic liquid crystals

• Dmitrii Pavlovich Shcherbinin and
• Elena A. Konshina

Beilstein J. Nanotechnol. 2017, 8, 2766–2770, doi:10.3762/bjnano.8.275

• the range from 20 Hz to 1 kHz. In this spectral range, the dispersion of dielectric permittivity is related to ionic conductivity. Figure 1a represents real and imaginary parts of the dielectric permittivity of initially low-contaminated liquid crystals (LC1) and their composites with TiO2

• nanoparticles. The increase of NP concentration led to the enhancement of the real and imaginary parts of the permittivity. We have observed an insignificant change in the spectra shown in Figure 1a. In contrast, the changes in the spectra were significant in the case of the initially high-contaminated LC2

• (Figure 1b). Doping LC2 with TiO2 NPs resulted in a reduction of the real and imaginary parts of the dielectric permittivity. This indicates a decrease of the ionic conductivity of LC2. In this frequency range, the spectra of the dielectric permittivity can be approximated by following equations [24

Enhanced photoelectrochemical water splitting performance using morphology-controlled BiVO₄ with W doping

• Xin Zhao and
• Zhong Chen

Beilstein J. Nanotechnol. 2017, 8, 2640–2647, doi:10.3762/bjnano.8.264

• [22]: where e0 is the electron charge (1.60·10−19 C), ε is the dielectric constant of BiVO4 (68) [23][24], ε0 is the electrical permittivity of vacuum (8.85·10−12 F·m−1), A is the electrode area, Nd is the donor density, V is the potential applied at the electrode, and C is the surface capacitance

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

• , the threshold voltage of the reorientational response is just a few volts, owing to the relatively large anisotropy of the dielectric permittivity. Analogous effects exist with magnetic fields. However, the threshold magnetic fields are high (B = μ0H ≈ 1 T) as a consequence of the small diamagnetic

Substrate and Mg doping effects in GaAs nanowires

• Perumal Kannappan,
• Nabiha Ben Sedrine,
• Jennifer P. Teixeira,
• Maria R. Soares,
• Bruno P. Falcão,
• Maria R. Correia,
• Nestor Cifuentes,
• Emilson R. Viana,
• Marcus V. B. Moreira,
• Geraldo M. Ribeiro,
• Alfredo G. de Oliveira,
• Juan C. González and
• Joaquim P. Leitão

Beilstein J. Nanotechnol. 2017, 8, 2126–2138, doi:10.3762/bjnano.8.212

• capacitance (C) can be estimated considering a metallic cylinder-plane system from [19]: where L is the length of the FET channel, ε0 the vacuum permittivity, εr = 3.9 the relative dielectric constant of the SiO2 insulator layer, h = 300 nm the thickness of the SiO2 layer, and d the nanowire diameter. From

Bi-layer sandwich film for antibacterial catheters

• Gerhard Franz,
• Florian Schamberger,
• Hamideh Heidari Zare,
• Sara Felicitas Bröskamp and
• Dieter Jocham

Beilstein J. Nanotechnol. 2017, 8, 1982–2001, doi:10.3762/bjnano.8.199

• measurement setup as in Figure 12. The measurement frequency was 1 MHz to minimize the influence of the Warburg capacitance. As the dimensions of the glass slide are known (area, film thickness), the permittivity ε was calculated according to Equation 3: Sandwich layer silver + PPX Analysis To investigate the

Parylene C as a versatile dielectric material for organic field-effect transistors

• Tomasz Marszalek,
• Maciej Gazicki-Lipman and
• Jacek Ulanski

Beilstein J. Nanotechnol. 2017, 8, 1532–1545, doi:10.3762/bjnano.8.155

• insulating material. The capacitance is determined by the dielectric permittivity (ε) and the thickness of the insulating layer. Currently, two types of dielectric materials are commonly employed in transistor design and construction, either inorganic metal oxides (such as Ta2O5, Al2O3, SiO2) or organic

• polymers [13]. However, it was found that the application of an inorganic insulator with high ε significantly decreases the mobility of charge carriers by interaction with the induced polarization in the gate insulator [37]. The effect of dielectric permittivity of the gate insulating material on field

• the linear regime. To summarize, it should be pointed out that an increase of dielectric permittivity of gate insulating material results in a decrease of field effect mobility (Figure 7b). For all dielectric materials applied, the highest values of charge carrier mobility were obtained for xylylene

The effect of the electrical double layer on hydrodynamic lubrication: a non-monotonic trend with increasing zeta potential

• Dalei Jing,
• Yunlu Pan and
• Xiaoming Wang

Beilstein J. Nanotechnol. 2017, 8, 1515–1522, doi:10.3762/bjnano.8.152

• = [2n0c2e2/(εε0kBT)]1/2 (n0 is the original bulk ion concentration of the lubricant, c is the chemical valence of free ions in the lubricant, e is the elementary charge, ε is the lubricant’s relative permittivity, and ε0 is vacuum’s absolute dielectric constant) is the reciprocal of the Debye length, z is

3D continuum phonon model for group-IV 2D materials

• Morten Willatzen,
• Lok C. Lew Yan Voon,
• Appala Naidu Gandi and
• Udo Schwingenschlögl

Beilstein J. Nanotechnol. 2017, 8, 1345–1356, doi:10.3762/bjnano.8.136

• . The electric equation for trigonal structures is exactly the same as for hexagonal structures since the permittivity matrix is the same. Hence, the general method for finding surface optical phonon modes repeats the description of graphene. Qualitatively, there is therefore no difference among the

• ε0 is the vacuum permittivity. Solving the determinantal equation for the 8 × 8 matrix equation as a function of kx specifies a discrete set of (band) eigenfrequencies ωi(kx) and the corresponding eigenmodes fx, fz and , where i denotes the band index. Confined phonon modes An important result

• -meshes. Continuum model: graphene The following parameters are found using DFT calculations as explained above: c11d = 345 Pa·m, c12d = 73 Pa·m, c13d = 0.00387 Pa·m, c33d = 0.531 Pa·m, c44d = 0.0535 Pa·m, c66d = 136 Pa·m, d = 3.4·10−8 m, and ρ2D = 7.61·10−7 kg/m2. For the permittivity data we used the DC

Near-field surface plasmon field enhancement induced by rippled surfaces

• Mario D’Acunto,
• Francesco Fuso,
• Ruggero Micheletto,
• Makoto Naruse,
• Francesco Tantussi and
• Maria Allegrini

Beilstein J. Nanotechnol. 2017, 8, 956–967, doi:10.3762/bjnano.8.97

• resonances on metallic nanometer-scale structures is an intrinsically nanoscale phenomenon, given that the two resonance conditions (i.e., negative dielectric permittivity and large free-space wavelength in comparison with system dimensions) are realized at the same time on the nanoscale. Resonances on

• contributions, where G0 is the coherent contribution and Gf is addressed by the random roughness. The coherent contribution can be expressed by [41]: where is the Hankel function of first kind and order zero, and ε(ω) is the metal electric permittivity (in our case, gold has been considered) described by the

• , permittivity of the environment, ε = 1 (air). Supporting Information Supporting Information File 172: Additional Green’s function calculations. Acknowledgements The authors would like to thank the bilateral Italy-Japan project, CNR-JSPS “Fluctutation-phonon-mediated assisted nanophotonic fabrication and

Computing the T-matrix of a scattering object with multiple plane wave illuminations

• Martin Fruhnert,
• Ivan Fernandez-Corbaton,
• Vassilios Yannopapas and
• Carsten Rockstuhl

Beilstein J. Nanotechnol. 2017, 8, 614–626, doi:10.3762/bjnano.8.66

• , which is characterized by the permittivity ε(ω) and the permeability μ(ω). The complex expansion coefficients anm(ω) and bnm(ω) are called scattering coefficients and the coefficients pnm(ω) and qnm(ω) are called incident coefficients. Together they contain all relevant information about the interaction

• are zero. Let us consider a single dielectric sphere with a radius of 100 nm and a relative permittivity of 16 in vacuum. The Mie-coefficients of this sphere for the first two orders are non-negligible at 600 THz. Such a high-permittivity sphere is nowadays at the focus of interest since it sustains a

• experimental data for the dispersive permittivity of silver [43]. Such objects can be fabricated in large quantities by self assembly methods, e.g., by connecting commercially available metal nanospheres with a linker molecule [44]. We set N = 2, because the higher orders do not contribute notably. For general

Advances in the fabrication of graphene transistors on flexible substrates

• Gabriele Fisichella,
• Stella Lo Verso,
• Silvestra Di Marco,
• Vincenzo Vinciguerra,
• Emanuela Schilirò,
• Salvatore Di Franco,
• Raffaella Lo Nigro,
• Fabrizio Roccaforte,
• Amaia Zurutuza,
• Alba Centeno,
• Sebastiano Ravesi and
• Filippo Giannazzo

Beilstein J. Nanotechnol. 2017, 8, 467–474, doi:10.3762/bjnano.8.50

• relevant for the fabrication of a FET where the properties of the gate dielectric (e.g., permittivity, leakage current, critical breakdown field) are crucial for the device operation. Results and Discussion Low temperature gate dielectric In our experiments we developed a 100 °C PE-ALD process using a PE

Impact of contact resistance on the electrical properties of MoS₂ transistors at practical operating temperatures

• Filippo Giannazzo,
• Gabriele Fisichella,
• Aurora Piazza,
• Salvatore Di Franco,
• Giuseppe Greco,
• Simonpietro Agnello and
• Fabrizio Roccaforte

Beilstein J. Nanotechnol. 2017, 8, 254–263, doi:10.3762/bjnano.8.28

• ≈ 9.1 × 10−5 F/m2 (ε0 is the vacuum dielectric constant, εox = 3.9, tox = 380 nm, the permittivity and the thickness of the SiO2 film, respectively), on the capacitance of the MoS2 depletion region, Cs, as well as on the capacitance associated with MoS2/SiO2 interface traps, Cit [5]. In the depletion

Tunable plasmons in regular planar arrays of graphene nanoribbons with armchair and zigzag-shaped edges

• Cristian Vacacela Gomez,
• Michele Pisarra,
• Mario Gravina and
• Antonello Sindona

Beilstein J. Nanotechnol. 2017, 8, 172–182, doi:10.3762/bjnano.8.18

• correction in mind, we can introduce the inverse dielectric matrix: The zeros in the real part of the macroscopic dielectric function (permittivity) provide the condition for a plasmon resonance to occur, stated as: The imaginary part of the inverse permittivity is proportional to so-called energy loss (EL

• real permittivity, satisfying the condition given by Equation 7. It has been further demonstrated that extrinsic 4ZGNR presents only an intraband plasmon structure, independently on the positive doping level used (below ca. 1 eV), while both intraband and interband plasmons coexist in 5AGNR [31]. To

• in energy, with the zeroes of the real permittivity being hidden by the Landau damping mechanism, associated to single-particle excitation processes [25][46][47][48]. In 11AGNR the same modes strongly interfere and largely dominate with respect to single-particle excitations. A similar interplay was