Absorption and photoconductivity spectra of amorphous multilayer structures

• Oxana Iaseniuc and
• Mihail Iovu

Beilstein J. Nanotechnol. 2020, 11, 1757–1763, doi:10.3762/bjnano.11.158

• Oxana Iaseniuc Mihail Iovu Institute of Applied Physics, No. 5 Academiei Str., Chisinau, MD-2028, R. Moldova 10.3762/bjnano.11.158 Abstract The experimental results regarding optical absorption and steady-state photoconductivity of amorphous single-layer structures (Al–As0.40S0.30Se0.30–Al, Al

• –Ge0.09As0.09Se0.82–Al, and Al–Ge0.30As0.04S0.66–Al) and of an amorphous heterostructure (Al–As0.40S0.30Se0.30/Ge0.09As0.09Se0.82/Ge0.30As0.04S0.66–Al) at different values of the voltage, with positive or negative polarity, applied to the illuminated top Al electrode are presented and discussed. The complex structure

• of the photocurrent spectra is attributed to the different values of the optical bandgap of the involved amorphous layers (Eg ≈ 2.0 eV for As0.40S0.30Se0.30 and Ge0.09As0.09Se0.82 and Eg ≈ 3.0 eV for Ge0.30As0.04S0.66). The obtained experimental results are discussed taking into account the light

Amorphized length and variability in phase-change memory line cells

• Nafisa Noor,
• Sadid Muneer,
• Raihan Sayeed Khan,
• Anna Gorbenko and
• Helena Silva

Beilstein J. Nanotechnol. 2020, 11, 1644–1654, doi:10.3762/bjnano.11.147

• by direct imaging. In this work, the length of amorphized regions in multiple identical Ge2Sb2Te5 (GST) line cells was extracted from electrical measurements. After each cell was programmed to an amorphous state, a sequence of increasing-amplitude post-reset voltage pulses separated by low-amplitude

• , significant variability arises from the intrinsically unique crystallization and amorphization processes in these devices. For example, cells programmed to an amorphous resistance of approx. 50 MΩ show threshold voltage values of 5.5–7.5 V, corresponding to amorphized length values of 290–395 nm. This

• unpredictable programming feature in phase-change memory devices can be utilized in hardware security applications. Keywords: amorphous materials; drift; electrical breakdown; electrical resistivity; phase-change memory; pulse measurement; stochastic processes; threshold switching; Introduction Phase-change

Optically and electrically driven nanoantennas

• Monika Fleischer,
• Dai Zhang and
• Alfred J. Meixner

Beilstein J. Nanotechnol. 2020, 11, 1542–1545, doi:10.3762/bjnano.11.136

• revealing local structural properties is illustrated in [49], where crystalline and amorphous regions within core–shell silicon nanowires are discerned with an optical resolution of a few nanometers. This study further demonstrates that it is possible to combine polarization angle-resolved experiments with

One-step synthesis of carbon-supported electrocatalysts

• Sebastian Tigges,
• Nicolas Wöhrl,
• Ivan Radev,
• Ulrich Hagemann,
• Markus Heidelmann,
• Thai Binh Nguyen,
• Stanislav Gorelkov,
• Stephan Schulz and
• Axel Lorke

Beilstein J. Nanotechnol. 2020, 11, 1419–1431, doi:10.3762/bjnano.11.126

• amorphous layer (Ar/H2 ≈59, Figure 4d, right panel). Raman spectroscopy was performed to determine the quality (defect density, defect type, and hybridization) of the deposited Pt/CNW layers. All samples produced at sufficiently high pressures and low carrier gas flow rates exhibit the typical spectrum

An atomic force microscope integrated with a helium ion microscope for correlative nanoscale characterization

• Santiago H. Andany,
• Gregor Hlawacek,
• Stefan Hummel,
• Charlène Brillard,
• Mustafa Kangül and
• Georg E. Fantner

Beilstein J. Nanotechnol. 2020, 11, 1272–1279, doi:10.3762/bjnano.11.111

• amorphous silicon bubbles at the surface [34]. Furthermore, focused helium ion beam exposure inside a HIM can be used as a way of locally replicating the harsh radiation conditions found in nuclear fission and fusion reactors, to study the response of structural materials used in the reactors [35]. We

• characterized the defects caused by He ion exposure in a correlative AFM–HIM experiment. Amorphous silicon bubbles are created on a crystalline silicon substrate through point exposition with the HIM at 25 kV and 14 pA using doses between 4.2 × 108 and 4.2 × 109 He ions (Figure 3). He ions penetrate deep into

Proximity effect in [Nb(1.5 nm)/Fe(x)]₁₀/Nb(50 nm) superconductor/ferromagnet heterostructures

• Yury Khaydukov,
• Sabine Pütter,
• Laura Guasco,
• Roman Morari,
• Gideok Kim,
• Thomas Keller,
• Anatolie Sidorenko and
• Bernhard Keimer

Beilstein J. Nanotechnol. 2020, 11, 1254–1263, doi:10.3762/bjnano.11.109

• are visible in the RHEED pattern of the Nb layer, which indicate island growth and polycrystallinity (Figure 2d). Subsequently, the Fe/Nb multilayers were grown on the 800 °C Nb buffer. The corresponding RHEED patterns exhibit amorphous growth, i.e., blurred screens (not shown). Increasing the Fe film

• thickness from 2 to 4 nm improves the film quality. The Fe layer becomes polycrystalline while the Nb layer remains amorphous. In contrast, for sample s6, which was grown on the 30 °C Nb buffer, both layers reveal polycrystallinity with a certain texture (Figure 2e,f). Finally, the Pt cap is always

• not observe any antiferromagnetic coupling, neither at room temperature nor in low-temperature measurements. The reason of this disagreement may originate from the amorphous Nb spacers. The proximity of this depth-modulated and weakly magnetic layer to a thick superconductor causes the appearance of

Gas sorption porosimetry for the evaluation of hard carbons as anodes for Li- and Na-ion batteries

• Yuko Matsukawa,
• Fabian Linsenmann,
• Maximilian A. Plass,
• George Hasegawa,
• Katsuro Hayashi and
• Tim-Patrick Fellinger

Beilstein J. Nanotechnol. 2020, 11, 1217–1229, doi:10.3762/bjnano.11.106

• area (SSA) of the anode materials as well as the deposition of amorphous carbon films were shown to reduce irreversible capacity losses [22][23]. Ji et al. found that lower total pore volumes (determined by N2 sorption) gave rise to increased reversible sodium storage capacities for sucrose-derived HCs

• to disordered, amorphous HCs with missing sharp (002) and (101) reflections (Supporting Information File 1, Figure S2). The described features were also found for the RF samples as reported earlier by Hasegawa and co-workers (Supporting Information File 1, Figure S3) [28][29]. The position of the

• only related to the measurable surface area for amorphous electrode materials. One may consider different deposition mechanisms (e.g., van der Merwe layer-by-layer or Volmer–Weber island growth) to explain this. However, it is more likely related to different contributions of porosity that is even

High permittivity, breakdown strength, and energy storage density of polythiophene-encapsulated BaTiO₃ nanoparticles

• Adnanullah Khan,
• Amir Habib and
• Adeel Afzal

Beilstein J. Nanotechnol. 2020, 11, 1190–1197, doi:10.3762/bjnano.11.103

• , respectively, which is attributed to the interactions between β-hydrogens of PTh and oxygen atoms on the BTO surface. X-ray diffraction patterns of BTO, PTh, and core–shell BTO-PTh nanoparticles are presented in Figure 3. Pristine PTh is amorphous in nature and shows a low-intensity broad peak at around 23

• °, which corresponds to the intermolecular π–π stacking structure and amorphous packing of the polymer [19]. The XRD pattern of hydrothermally prepared BTO nanoparticles shows good agreement with the tetragonal perovskite structure (JCPDS No. 05-0626) with the P4mm space group [20][21]. The major

Revealing the local crystallinity of single silicon core–shell nanowires using tip-enhanced Raman spectroscopy

• Marius van den Berg,
• Ardeshir Moeinian,
• Arne Kobald,
• Yu-Ting Chen,
• Anke Horneber,
• Steffen Strehle,
• Alfred J. Meixner and
• Dai Zhang

Beilstein J. Nanotechnol. 2020, 11, 1147–1156, doi:10.3762/bjnano.11.99

• , Germany 10.3762/bjnano.11.99 Abstract Tip-enhanced Raman spectroscopy is combined with polarization angle-resolved spectroscopy to investigate the nanometer-scale structural properties of core–shell silicon nanowires (crystalline Si core and amorphous Si shell), which were synthesized by platinum

• of the Raman peaks of crystalline Si and amorphous Si by applying tip-enhanced Raman spectroscopy, at sample positions being 8 nm apart. The local crystallinity revealed using confocal Raman spectroscopy and tip-enhanced Raman spectroscopy agrees well with the high-resolution transmission electron

• orientational change due to laser-induced temperature variation [20]. Furthermore, crystalline (c-Si) and amorphous (a-Si) Si show different Raman peaks, which can be used to determine the fraction of crystallinity and bond-angle distortion [21][22]. For example, Nikolenko et al. [23] investigated the local

Highly sensitive detection of estradiol by a SERS sensor based on TiO₂ covered with gold nanoparticles

• Andrea Brognara,
• Ili F. Mohamad Ali Nasri,
• Beatrice R. Bricchi,
• Andrea Li Bassi,
• Caroline Gauchotte-Lindsay,
• Matteo Ghidelli and
• Nathalie Lidgi-Guigui

Beilstein J. Nanotechnol. 2020, 11, 1026–1035, doi:10.3762/bjnano.11.87

• . The thermal treatment was carried out to induce both crystallization of the as-deposited amorphous TiO2 into the anatase phase (as discussed in [28][29]) and the formation of AuNPs exploiting dewetting of the Au films. A field-emission scanning electron microscope (FEG-SEM, Zeiss Supra 40) was used to

Microwave-induced electric discharges on metal particles for the synthesis of inorganic nanomaterials under solvent-free conditions

• Vijay Tripathi,
• Harit Kumar,
• Anubhav Agarwal and
• Leela S. Panchakarla

Beilstein J. Nanotechnol. 2020, 11, 1019–1025, doi:10.3762/bjnano.11.86

• nanoparticles of Cu and Ni and one-dimensional nanorods of CuS, ZnF2, and NiF2 protected with fluorinated amorphous carbon. We have also synthesized reduced graphene oxide and partially rolled graphene by this method. Keywords: electric discharges; microwave synthesis; nanomaterials; transmission electron

• of Cu, Ni, und Zn nanoparticles from metal particles. Also, we can control the morphology of the nanomaterials, which has not been achieved before. ZnF2, NiF2, and CuS nanorods covered with amorphous fluorinated carbon were synthesized. We have also extended this procedure to synthesize reduced

• generated after 1 min of microwave treatment of activated Cu and Ni powders in the presence of g-C3N4. The patterns show pure phases of Ni and Cu. The formed nanoparticles are covered with fluorinated amorphous carbon. Figure 3b shows the SEM image of Cu nanoparticles covered with amorphous fluorinated

Gas-sensing features of nanostructured tellurium thin films

• Dumitru Tsiulyanu

Beilstein J. Nanotechnol. 2020, 11, 1010–1018, doi:10.3762/bjnano.11.85

• Dumitru Tsiulyanu CIMAN Research Centre of Department of Physics, Technical University, bul. Dacia 41, MD-2060 Chisinau, Moldova 10.3762/bjnano.11.85 Abstract Nanocrystalline and amorphous nanostructured tellurium (Te) thin films were grown and their gas-sensing properties were investigated at

• the nanocrystalline films. This shortcoming could be solved by using the amorphous nanostructured Te films which, even at 22 °C, exhibited higher gas sensitivity and shorter response and recovery times by more than one order of magnitude in comparison to the nanocrystalline Te films. These results

• aims of the present work were to investigate and improve the gas-sensing parameters of nanostructured Te films by using a mechanical nanostructuring approach. Crystalline and amorphous Te films were grown, respectively, on glass or porous, nanostructured, dielectric substrates. These two physically

Nickel nanoparticles supported on a covalent triazine framework as electrocatalyst for oxygen evolution reaction and oxygen reduction reactions

• Secil Öztürk,
• Yu-Xuan Xiao,
• Dennis Dietrich,
• Beatriz Giesen,
• Juri Barthel,
• Jie Ying,
• Xiao-Yu Yang and
• Christoph Janiak

Beilstein J. Nanotechnol. 2020, 11, 770–781, doi:10.3762/bjnano.11.62

• wt %), the characteristic broad reflections for amorphous CTF could also be seen. Size and morphology of the synthesized Ni NPs on CTFs were characterized by transmission electron microscopy (TEM) and SEM. Figure 2 shows TEM images of Ni/CTF-1-600-22 recorded at different magnifications. Ni

Structural optical and electrical properties of a transparent conductive ITO/Al–Ag/ITO multilayer contact

• Aliyu Kabiru Isiyaku,
• Ahmad Hadi Ali and
• Nafarizal Nayan

Beilstein J. Nanotechnol. 2020, 11, 695–702, doi:10.3762/bjnano.11.57

• shows an amorphous structure of the top ITO layer with a strong Ag(111) diffraction peak, showing that the Ag intermediate layer is crystalline, comparable to the work of Kim et al. [31]. There is no diffraction peak of the Al film, which is consistent with the work of Cho et al. [29]. The IAAI film

• appear to be dominant without any traces of SnO2, Sn or SnO peaks. During deposition of the IAAI films, the kinetic energy of the sputtered atoms arriving at the substrate is low, which leads to the amorphous structure. The kinetic energy of the Ag atoms is higher and the Ag film crystallizes already

Soybean-derived blue photoluminescent carbon dots

• Shanshan Wang,
• Wei Sun,
• Dong-sheng Yang and
• Fuqian Yang

Beilstein J. Nanotechnol. 2020, 11, 606–619, doi:10.3762/bjnano.11.48

• of the HTC-processed carbon particles in the range of 250 to 850 °C causes a loss of the photoluminescent characteristics of the CDs without any significant change in the microstructure (amorphous structure) of the carbon particles. The LA processing of the annealed HTC-processed carbon particles

• the nanoparticles. The selected area electron diffraction (SAED) patterns embedded in the figures reveal that all the nanoparticles are amorphous. The EDS and XPS analyses of the HTC-CDs shown in Figure S1 and Table S1 in Supporting Information File 1 confirm that the main component of the HTC-CDs is

• carbon. The annealing at the temperature of 850 °C did not cause the conversion of amorphous carbon nanoparticles to nanocrystals, and the LAL processing of the annealed-HTC carbon particles also produced amorphous carbon nanoparticles. The size distribution of the soybean-derived nanoparticles is

Identification of physicochemical properties that modulate nanoparticle aggregation in blood

• Ludovica Soddu,
• Duong N. Trinh,
• Eimear Dunne,
• Dermot Kenny,
• Giorgia Bernardini,
• Ida Kokalari,
• Arianna Marucco,
• Marco P. Monopoli and
• Ivana Fenoglio

Beilstein J. Nanotechnol. 2020, 11, 550–567, doi:10.3762/bjnano.11.44

• ], while platelet aggregation was observed for amorphous CNPs but not for the small-sized fullerenes [10]. Note however that limited information relating to the physicochemical properties of the materials was given in these studies, making a critical analysis of the results difficult. Moreover, while CNTs

High-performance asymmetric supercapacitor made of NiMoO₄ nanorods@Co₃O₄ on a cellulose-based carbon aerogel

• Meixia Wang,
• Jing Zhang,
• Xibin Yi,
• Benxue Liu,
• Xinfu Zhao and
• Xiaochan Liu

Beilstein J. Nanotechnol. 2020, 11, 240–251, doi:10.3762/bjnano.11.18

• amorphous carbon. The five well-defined diffraction peaks appearing at 2θ values of 14.3, 25.3, 28.9, 33.7 and 53.9° are indexed to the (110), (112), (220), (222) and (422) crystal planes of NiMoO4, respectively, which well correspond to the standard pattern (JCPDS No. 45-0142). In addition to the

Rational design of block copolymer self-assemblies in photodynamic therapy

• Maxime Demazeau,
• Laure Gibot,
• Anne-Françoise Mingotaud,
• Patricia Vicendo,
• Clément Roux and
• Barbara Lonetti

Beilstein J. Nanotechnol. 2020, 11, 180–212, doi:10.3762/bjnano.11.15

• ]. Cristallinity Albertsson’s team published a study comparing semi-crystalline to amorphous vectors based on ε-caprolactone (CL), ʟ-lactide (LA) or ε-decalactone (DL) copolymers. All polymers formed micelles ranging from 25 to 60 nm but only those incorporating DL were amorphous. The study showed that the

• critical aggregation concentration was higher for amorphous systems and that the loading of aniline pentamer was better in the amorphous vector [132][133]. A similar loading improvement in amorphous vectors for indomethacin was described by Alexander and co-workers [134]. Morphology/size Morphology

Synthesis of amorphous and graphitized porous nitrogen-doped carbon spheres as oxygen reduction reaction catalysts

• Maximilian Wassner,
• Markus Eckardt,
• Andreas Reyer,
• Thomas Diemant,
• Michael S. Elsaesser,
• R. Jürgen Behm and
• Nicola Hüsing

Beilstein J. Nanotechnol. 2020, 11, 1–15, doi:10.3762/bjnano.11.1

• Abstract Amorphous and graphitized nitrogen-doped (N-doped) carbon spheres are investigated as structurally well-defined model systems to gain a deeper understanding of the relationship between synthesis, structure, and their activity in the oxygen reduction reaction (ORR). N-doped carbon spheres were

• temperatures. The overall nitrogen content of the graphitized N-doped carbon spheres is lower than that of the amorphous carbon spheres, however, also the microporosity decreases strongly with graphitization. Comparison with the electrocatalytic behavior in the ORR shows that in addition to the N-doping, the

• microporosity of the materials is critical for an efficient ORR. Keywords: amorphous carbon; graphitized carbon; hydrothermal carbonization; nitridation; nitrogen doping; oxygen reduction reaction (ORR); porosity; Introduction Fuel cells and metal–air batteries are important renewable energy technologies

Abrupt elastic-to-plastic transition in pentagonal nanowires under bending

• Sergei Vlassov,
• Magnus Mets,
• Boris Polyakov,
• Jianjun Bian,
• Leonid Dorogin and
• Vahur Zadin

Beilstein J. Nanotechnol. 2019, 10, 2468–2476, doi:10.3762/bjnano.10.237

• approximately 15 nN, and the dislocations continue to nucleate in the region close to the fixed end. Besides the existing twin boundaries, a deformation twin could also be observed (Figure 8iii). The interaction of continuously nucleated dislocations will form an amorphous layer, similar to a grain boundary

• . With the increased concentration of the deformations surface necking occurs, which will lead to the ductile fracture of the NW. Upon unloading, some dislocations may retract and annihilate at the free surface, which is promoted by the existing twin boundaries [31] and the amorphous atomic layer and

Self-assembly of a terbium(III) 1D coordination polymer on mica

• Quentin Evrard,
• Giuseppe Cucinotta,
• Felix Houard,
• Guillaume Calvez,
• Yan Suffren,
• Carole Daiguebonne,
• Olivier Guillou,
• Andrea Caneschi,
• Matteo Mannini and
• Kevin Bernot

Beilstein J. Nanotechnol. 2019, 10, 2440–2448, doi:10.3762/bjnano.10.234

• . Initially, amorphous structures appeared on the surface that can be attributed to the gradual evaporation of solvent and moisture (Figure 2a). More interesting is the morphology observed after the aging of the samples under controlled moisture conditions. Needle-like objects (Figure 2b) with lengths of

• tetragonal Si/Al atoms present on the (001) mica surface. Some disordered objects that are roughly 1.5 nm high are also present on the surface, which could be due to residual amorphous [Tb(hfac)3·2H2O] formed by a less controlled evaporation of the solvent in these areas. Under elevated moisture conditions

Coating of upconversion nanoparticles with silica nanoshells of 5–250 nm thickness

• Cynthia Kembuan,
• Maysoon Saleh,
• Bastian Rühle,
• Ute Resch-Genger and
• Christina Graf

Beilstein J. Nanotechnol. 2019, 10, 2410–2421, doi:10.3762/bjnano.10.231

• . Accordingly, the broad signal of the amorphous silica at 2θ = 20–25° becomes more dominant with increasing thickness of the silica shell. These data indicate that the crystal structure of the UCNP cores is not changed during the silica shell formation process. Figure 3 shows the upconversion luminescence (UCL

Semitransparent Sb₂S₃ thin film solar cells by ultrasonic spray pyrolysis for use in solar windows

• Jako S. Eensalu,
• Atanas Katerski,
• Erki Kärber,
• Lothar Weinhardt,
• Monika Blum,
• Clemens Heske,
• Wanli Yang,
• Ilona Oja Acik and
• Malle Krunks

Beilstein J. Nanotechnol. 2019, 10, 2396–2409, doi:10.3762/bjnano.10.230

• demonstrated that by adapting a two-step sequence, whereby amorphous Sb2S3 layers are first deposited by USP and then crystallized by thermal annealing, compact Sb2S3 thin films with uniform thickness can be fabricated [46]. Similarly, a two-step procedure to grow compact Sb2S3 thin films has become common

• and back contact is needed to attain an AVT in excess of 20% for the complete solar cell. As-deposited Sb2S3 layers on glass/ITO/TiO2 substrate were amorphous (Figure 1d), as only signals of anatase-TiO2 and In2O3 from the substrate were detected by X-ray diffraction (XRD). In contrast, the XRD

• pattern of the vacuum-annealed sample matched orthorhombic Sb2S3 (ICDD PDF 01-075-4012). The Raman spectrum of the as-deposited Sb2S3 layer contains two broad bands (Figure 1e), which are characteristic of amorphous Sb2S3 [28][46]. After vacuum annealing, characteristic narrower bands of Sb2S3 are

Design and facile synthesis of defect-rich C-MoS₂/rGO nanosheets for enhanced lithium–sulfur battery performance

• Chengxiang Tian,
• Juwei Wu,
• Zheng Ma,
• Bo Li,
• Pengcheng Li,
• Xiaotao Zu and
• Xia Xiang

Beilstein J. Nanotechnol. 2019, 10, 2251–2260, doi:10.3762/bjnano.10.217

• composite with both large surface area and high porosity for the use as advanced electrode material in lithium–sulfur batteries. Double modified defect-rich MoS2 nanosheets are successfully prepared by introducing reduced graphene oxide (rGO) and amorphous carbon. The conductibility of the cathodes can be

• improved through the combination of amorphous carbon and rGO, which could also limit the dissolution of polysulfides. After annealing at different temperatures, it is found that the C-MoS2/rGO-6-S composite annealed at 600 °C yields a noticeably enhanced performance of lithium–sulfur batteries, with a high

• adsorption of polysulfides [23][24]. However, the low conductivity of MoS2 often results in incomplete conversion of polysulfides. Thus, MoS2 is usually combined with carbon materials and annealing treatment is also considered [25][26]. Hence, double modification of defect-rich MoS2 nanosheets with amorphous

Targeted therapeutic effect against the breast cancer cell line MCF-7 with a CuFe₂O₄/silica/cisplatin nanocomposite formulation

• B. Rabindran Jermy,
• Vijaya Ravinayagam,
• Widyan A. Alamoudi,
• Dana Almohazey,
• Hatim Dafalla,
• Lina Hussain Allehaibi,
• Abdulhadi Baykal,
• Muhammet S. Toprak and
• Thirunavukkarasu Somanathan

Beilstein J. Nanotechnol. 2019, 10, 2217–2228, doi:10.3762/bjnano.10.214

• < 0.001; **** p < 0.0001 versus control. N.S. indicates non-significant. Results and Discussion Figure 1 shows the PXRD patterns of 30 wt % CuFe2O4 loaded onto HYPS using the dry impregnation technique. The presence of broad peaks due to the amorphous nature of the siliceous framework of HYPS was observed