Atomic-resolution imaging of rutile TiO₂(110)-(1 × 2) reconstructed surface by non-contact atomic force microscopy

• Daiki Katsube,
• Shoki Ojima,
• Eiichi Inami and
• Masayuki Abe

Beilstein J. Nanotechnol. 2020, 11, 443–449, doi:10.3762/bjnano.11.35

• -AFM and tunneling current for STM), the surface structure sometimes results in different contrasts in both images. In Figure 3, white squares and circles indicate line defects and protrusions, which are considered to be adsorbates or contamination. A line defect was imaged as a likely vacancy by STM

DFT calculations of the structure and stability of copper clusters on MoS₂

• Cara-Lena Nies and
• Michael Nolan

Beilstein J. Nanotechnol. 2020, 11, 391–406, doi:10.3762/bjnano.11.30

• adsorb atop the S atoms. Stability is driven by the number of Cu–Cu interactions and the distance between adsorption sites, with no obvious preference towards 2D or 3D structures. The introduction of a single S vacancy in the monolayer enhances the copper binding energy, although some Cun nanoclusters

• are actually unstable. The effect of the vacancy is localised around the vacancy site. Finally, on both the pristine and the defective MoS2 monolayer, the density-of-states analysis shows that the adsorption of Cu introduces new electronic states as a result of partial Cu oxidation, but the metallic

• particular when the monolayer is defect-rich. MoS2 is known to be naturally high in defects [21][32], in particular S vacancies. It has been predicted that S vacancies in a MoS2 monolayer are most stable when they occur in a row, with a decrease in the vacancy formation energy as the number of vacancies

Nonequilibrium Kondo effect in a graphene-coupled quantum dot in the presence of a magnetic field

• Levente Máthé and
• Ioan Grosu

Beilstein J. Nanotechnol. 2020, 11, 225–239, doi:10.3762/bjnano.11.17

• the Kondo effect for a carbon vacancy in a monolayer of graphene via an effective two-orbital single impurity model using the NRG approach [74]. Vojta et al. applied the pseudogap Kondo and Anderson models using a combination of analytical and numerical renormalization group approaches to study the

Deterministic placement of ultra-bright near-infrared color centers in arrays of silicon carbide micropillars

• Stefania Castelletto,
• Abdul Salam Al Atem,
• Faraz Ahmed Inam,
• Hans Jürgen von Bardeleben,
• Sophie Hameau,
• Ahmed Fahad Almutairi,
• Gérard Guillot,
• Shin-ichiro Sato,
• Alberto Boretti and
• Jean Marie Bluet

Beilstein J. Nanotechnol. 2019, 10, 2383–2395, doi:10.3762/bjnano.10.229

• element method simulations. Our study provides the pathway for device design and fabrication with an integrated ultra-bright ensemble of VSi and NCVSi for in vivo imaging and sensing in the infrared. Keywords: color centers; micropillars; proton irradiation; quantum sensing; silicon carbide; vacancy

• simulations of the nitrogen vacancy, NCVSi(−) (NV), defect in SiC have been recently performed in [35][36][37][38], resulting in ZPLs at 1242, 1241, 1223 and 1180 nm [38]. This emission is very promising as it is further into the infrared compared to the divacancies. The association of ZPL lines with NV

• for the VSi and the nitrogen vacancy (NCVSi) [36]. Micropillars in other materials have been successfully used as photonics structures designed to improve the photoluminescence performance of quantum dots for strong coupling of the emission with the photonics cavity, high photon-extraction efficiency

Nitrogen-vacancy centers in diamond for nanoscale magnetic resonance imaging applications

• Alberto Boretti,
• Lorenzo Rosa,
• Jonathan Blackledge and
• Stefania Castelletto

Beilstein J. Nanotechnol. 2019, 10, 2128–2151, doi:10.3762/bjnano.10.207

• and Technology, University of Wales, Wrexham, United Kingdom Department of Computer Science, University of Western Cape, Cape Town, South Africa School of Engineering, RMIT University, Bundoora, Victoria, Australia 10.3762/bjnano.10.207 Abstract The nitrogen-vacancy (NV) center is a point defect in

• methods, this review presents a survey of the latest advances in NV center nano-MRI. Keywords: nanodiamonds; nanoscale magnetic resonance imaging (nano-MRI); nitrogen-vacancy center; optically detected magnetic resonance; Review Introduction Spin echoes and free induction decays were first detected in

• image resolution on the molecular or even the atomic scale. This has given rise to the investigation of nanoscale magnetic resonance imaging (nano-MRI) [5]. Different nano-MRI technologies have been proposed that are based on different sensors. Some of these technologies use the nitrogen-vacancy (NV

Improvement of the thermoelectric properties of a MoO₃ monolayer through oxygen vacancies

• Wenwen Zheng,
• Wei Cao,
• Ziyu Wang,
• Huixiong Deng,
• Jing Shi and
• Rui Xiong

Beilstein J. Nanotechnol. 2019, 10, 2031–2038, doi:10.3762/bjnano.10.199

• concentration of O vacancy concentrations. Hydrogen-ion intercalation [12] and solar-light irradiation [13] can turn MoO3 into MoO3−x and hence increase the electrical conductivity. Understanding the effect of O vacancies in MoO3 is very beneficial for its thermoelectric applications. Moreover, low-dimensional

• concentration needed to attain the maximum ZT value in the n-type MoO3 monolayer is about 1.16 × 1013 cm−2 (x-axis) and 6.67 × 1013 cm−2 (y-axis). In order to improve the thermoelectric performance of the MoO3 monolayer, we decided to introduce an O vacancy. Therefore, we remove one O atom from the 3 × 3 × 1

• structures exhibit strong Mo–O3–Mo chains along the x-axis and Mo–O2–Mo chains along the y-axis. The anisotropic thermal conductivity of the vacancy-induced MoO3 monolayer can be modified by controlling the O vacancy [34]. For instance, the O3 vacancy mainly disrupts the Mo–O3–Mo chain and reduces the phonon

Kelvin probe force microscopy work function characterization of transition metal oxide crystals under ongoing reduction and oxidation

• Dominik Wrana,
• Karol Cieślik,
• Wojciech Belza,
• Christian Rodenbücher,
• Krzysztof Szot and
• Franciszek Krok

Beilstein J. Nanotechnol. 2019, 10, 1596–1607, doi:10.3762/bjnano.10.155

• transformation from (1×1) to (√5×√5)R26.6°, and in the vicinity of extended defects in a crystal (dislocations) which act as easy conduction paths for electrons. Oxygen vacancy formation, and therefore Ti3+ valence, results in the appearance of new t2g electron states within Ti 3d, which are below the conduction

• equiprobable orientations of (√5×√5)R26.6° domains, both rotated with respect to the (1×1) surface by 26.6 degrees. Those two domains are labeled A and B, both in LEED and STM images. Bright protrusions seen in the STM picture, which also decorate domain boundaries, are either oxygen vacancies/vacancy clusters

Direct observation of oxygen-vacancy formation and structural changes in Bi₂WO₆ nanoflakes induced by electron irradiation

• Hong-long Shi,
• Bin Zou,
• Zi-an Li,
• Min-ting Luo and
• Wen-zhong Wang

Beilstein J. Nanotechnol. 2019, 10, 1434–1442, doi:10.3762/bjnano.10.141

• observations of the oxygen-vacancy formation by in situ spectroscopy and microscopy methods. Therefore, it is desirable to perform in situ microscopy experiments to investigate the generation and evolution of oxygen vacancies at the insulating layer of Bi2WO6 crystals upon an external stimulation, which will

Selective gas detection using Mn₃O₄/WO₃ composites as a sensing layer

• Yongjiao Sun,
• Zhichao Yu,
• Wenda Wang,
• Pengwei Li,
• Gang Li,
• Wendong Zhang,
• Lin Chen,
• Serge Zhuivkov and
• Jie Hu

Beilstein J. Nanotechnol. 2019, 10, 1423–1433, doi:10.3762/bjnano.10.140

• color because of its oxygen vacancy, which is an important reason why WO3 exhibits n-type semiconductor characteristics. WO3 is a multifunctional semiconductor material and widely used in phototropism [1], electrochromism [2], photocatalysis [3], electrochemistry [4], gas sensing [5] and other fields

Gas sensing properties of individual SnO₂ nanowires and SnO₂ sol–gel nanocomposites

• Alexey V. Shaposhnik,
• Dmitry A. Shaposhnik,
• Sergey Yu. Turishchev,
• Olga A. Chuvenkova,
• Stanislav V. Ryabtsev,
• Alexey A. Vasiliev,
• Xavier Vilanova,
• Francisco Hernandez-Ramirez and
• Joan R. Morante

Beilstein J. Nanotechnol. 2019, 10, 1380–1390, doi:10.3762/bjnano.10.136

• sintered lump reference sample. From the analysis of the spectra fine structure, we can conclude that the wire-like sample is closer to the reference spectrum with a more pronounced Sn M4,5 absorption edge fine structure. Also, more noticeable is the "vacancy" feature at ≈487.5 eV observed in SnO2

• in VLS grown single crystals of SnO2 nanowires than in calcinated and partially disoriented particles in powder samples. In the SnO2 powder sample, a decrease is observed between the main Sn M4,5 XANES spectrum maxima and the more developed "vacancy" feature (≈487 eV). This smearing of the fine

Imaging the surface potential at the steps on the rutile TiO₂(110) surface by Kelvin probe force microscopy

• Masato Miyazaki,
• Huan Fei Wen,
• Quanzhen Zhang,
• Yuuki Adachi,
• Jan Brndiar,
• Ivan Štich,
• Yan Jun Li and
• Yasuhiro Sugawara

Beilstein J. Nanotechnol. 2019, 10, 1228–1236, doi:10.3762/bjnano.10.122

• labeled as Os in Figure 4 might be an oxygen vacancy (Osv) [24][25][35], causing another Ti atom to be exposed enhancing the upward local atomic dipole. According to Sasahara et al. [29], the dipole moments are formed in the central direction (horizontal direction) of the upper step by relaxation into the

• , because it has the same in-plane oxygen termination-step geometry as . We rather examine the reduced step configuration, containing an oxygen vacancy directly at step position. This configuration was observed in [35] and is also theoretically consistent [24][25][61]. The LDOS for bridging oxygen closed

• to the step is localized closely to the top of the valence band compared to a more distant oxygen atom, resulting in decrease of oxygen vacancy formation energy and consequent vacancy migration towards the step. This geometry produces a massive positive charge pinned around a vacancy, see Figure 5c

Electronic and magnetic properties of doped black phosphorene with concentration dependence

• Ke Wang,
• Hai Wang,
• Min Zhang,
• Yan Liu and
• Wei Zhao

Beilstein J. Nanotechnol. 2019, 10, 993–1001, doi:10.3762/bjnano.10.100

• denominate donor and acceptor in the doped phosphorenes, the charge density difference Δρ (CDD) is computed as follows [26]: where ρtot, ρvP, and ρd are the electron density of doped phosphorene, black phosphorene with one vacancy, and a dopant atom. The obtained results of Si- and S-doped phosphorenes are

Self-assembly and wetting properties of gold nanorod–CTAB molecules on HOPG

• Imtiaz Ahmad,
• Floor Derkink,
• Tim Boulogne,
• Pantelis Bampoulis,
• Harold J. W. Zandvliet,
• Hidayat Ullah Khan,
• Rahim Jan and
• E. Stefan Kooij

Beilstein J. Nanotechnol. 2019, 10, 696–705, doi:10.3762/bjnano.10.69

• sites are observed, which develop following the vacancy regions, and grow as a function of time on various HOPG terraces. Self-assembled layers of CTAB changed the wettability of the surface and facilitated the deposition of gold nanorods on HOPG. Experimental Some of the experimental protocols and

• ) Sequential AFM images depicting the dynamics of self-assembled CTAB stripes on terraces; for reference, a defect which acts as a vacancy nucleation site is indicated by the white arrows. (E) After the large stripes have completely disappeared, a corrugation of the surface is still observed; the inset depicts

Mo-doped boron nitride monolayer as a promising single-atom electrocatalyst for CO₂ conversion

• Qianyi Cui,
• Gangqiang Qin,
• Weihua Wang,
• Lixiang Sun,
• Aijun Du and
• Qiao Sun

Beilstein J. Nanotechnol. 2019, 10, 540–548, doi:10.3762/bjnano.10.55

• (TM = Sc to Zn, Mo, Rh, Ru, Pd and Ag) anchored on the boron vacancy in a BN monolayer as electrocatalysts for CO2 conversion through comprehensive density functional theory (DFT) calculations. Based on the calculated results, single Mo doped onto a BN (Mo-doped BN) monolayer was selected as the

• solvent environment [60], and the dielectric constant was 78.54. To construct the modes, we first built a periodic 5 × 5 BN supercell, whose vacuum region was 15 Å along the z-direction. The single TM atoms were doped at the boron vacancy sites [45]. All of the structures were completely optimized in a

Choosing a substrate for the ion irradiation of two-dimensional materials

• Egor A. Kolesov

Beilstein J. Nanotechnol. 2019, 10, 531–539, doi:10.3762/bjnano.10.54

• required to irradiate supported monolayers desirably avoiding the influence of the substrate (generation of hot electrons in the substrate should also be taken into account here, as discussed later). A basic type of defect produced during 2D material irradiation is a vacancy (for 2D TMDs, the most probable

• vacancy generation event involves chalcogen atom removal) [23]. If the fluence is enough, multiple generated vacancies can subsequently merge through the migration processes [15][24], leading to a creation of more complex defects. Additionally, the incident ion can become embedded into the 2D material

• hot electrons generated in the vicinity of the interface will intensify this mechanism as an additional charge source, leading to a vacancy concentration increase in the irradiated material as long as the threshold for a vacancy formation by electrons is overcome (for example, ≈80 eV for graphene [13

Integration of LaMnO_3+δ films on platinized silicon substrates for resistive switching applications by PI-MOCVD

• Raquel Rodriguez-Lamas,
• Dolors Pla,
• Odette Chaix-Pluchery,
• Benjamin Meunier,
• Fabrice Wilhelm,
• Andrei Rogalev,
• Laetitia Rapenne,
• Xavier Mescot,
• Quentin Rafhay,
• Hervé Roussel,
• Michel Boudard,
• Carmen Jiménez and
• Mónica Burriel

Beilstein J. Nanotechnol. 2019, 10, 389–398, doi:10.3762/bjnano.10.38

• films is expected to be compensated by a mixed valence state of the manganese cation (Mn3+/Mn4+). Particularly, RS in LMO has been reported to be larger for oxygen vacancy-rich films [6][7]. Depending on the oxygen content (δ), the LMO structure changes from orthorhombic to rhombohedral at high δ [8

Sub-wavelength waveguide properties of 1D and surface-functionalized SnO₂ nanostructures of various morphologies

• Venkataramana Bonu,
• Binaya Kumar Sahu,
• Arindam Das,
• Sankarakumar Amirthapandian,
• Sandip Dhara and
• Harish C. Barshilia

Beilstein J. Nanotechnol. 2019, 10, 379–388, doi:10.3762/bjnano.10.37

• efficiently guide visible and UV wavelengths in air and also in water. SnO2 NWs were also used as a short pass filter [6]. Apart from the coupled light, these NWs also guide their oxygen vacancy related visible photoluminescence (PL) towards the end of the NWs [6]. Defects in SnO2 play a crucial role in its

• commercial application as a gas sensor, transparent conducting electrodes, and catalyst [13][14][15]. SnO2 NSs have been used in several other areas such as sub-wavelength waveguide sensors [4], microelectronics [6], Li-ion batteries [16], and lubricants [17]. Oxygen vacancy related defects in SnO2

• . Then, surface passivation takes place leading to suppression of the luminescence related to the OB vacancy sites. Moreover, luminescence from OP arises at high energy relative to the luminescence OB vacancies. We previously reported a detailed study on OTS functionalization of the SnO2 NPs [19]. It is

Zn/F-doped tin oxide nanoparticles synthesized by laser pyrolysis: structural and optical properties

• Florian Dumitrache,
• Iuliana P. Morjan,
• Elena Dutu,
• Ion Morjan,
• Claudiu Teodor Fleaca,
• Monica Scarisoreanu,
• Alina Ilie,
• Marius Dumitru,
• Cristian Mihailescu,
• Adriana Smarandache and
• Gabriel Prodan

Beilstein J. Nanotechnol. 2019, 10, 9–21, doi:10.3762/bjnano.10.2

• radii (0.74 Å for Zn2+ and 0.71 Å for Sn4+ [21]) and thus each zinc ion replaces a tin ion accompanied by the appearance of an oxygen vacancy (equivalent with two holes) to maintain the crystal electrical neutrality. Moreover, it was hypothesized that part of the zinc ions can also occupy the

• states and VB/CB” (valence band/conduction band) “by adjusting the position of bandgap to obtain an optimized narrow value” [23]. Thus, using a solution-based single-source precursor (Er-doped KSnF3), oxygen-vacancy-rich nanocrystals of co-doped Er and F SnO2 were obtained at low temperature with an

Oriented zinc oxide nanorods: A novel saturable absorber for lasers in the near-infrared

• Pavel Loiko,
• Tanujjal Bora,
• Josep Maria Serres,
• Haohai Yu,
• Magdalena Aguiló,
• Francesc Díaz,
• Uwe Griebner,
• Valentin Petrov,
• Xavier Mateos and
• Joydeep Dutta

Beilstein J. Nanotechnol. 2018, 9, 2730–2740, doi:10.3762/bjnano.9.255

• substrates. The ZnO NRs exhibit a broadband (1–2 µm) near-IR absorption ascribed to the singly charged zinc vacancy VZn−1. The saturable absorption of the ZnO NRs is studied at ≈1 µm under picosecond excitation, revealing a low saturation intensity, ≈10 kW/cm2, and high fraction of the saturable losses. The

• were grown hydrothermally (in oxygen-rich conditions) one can expect the presence of zinc vacancies that have a low formation energy under such conditions. The singly charged zinc vacancy (VZn−1) is typically located at 0.8–0.9 eV above the ZnO valence band (VB) [9][33][34]. This defect site can be a

• at 0.483 µm is due to the radiative capture of an electron from the CB by a zinc vacancy state (VZn−1) located around 0.8–0.9 eV above the VB of ZnO [9][33][34]. The broad green-yellow luminescence from the ZnO NRs is composed of two bands peaking at 0.533 and 0.589 µm. These bands are assigned to

Impact of the anodization time on the photocatalytic activity of TiO₂ nanotubes

• Jesús A. Díaz-Real,
• Geyla C. Dubed-Bandomo,
• Juan Galindo-de-la-Rosa,
• Luis G. Arriaga,
• Janet Ledesma-García and
• Nicolas Alonso-Vante

Beilstein J. Nanotechnol. 2018, 9, 2628–2643, doi:10.3762/bjnano.9.244

• within the range of signals connected to interstitial N, (O–N•–Ti), and has been associated with electron transitions from Ti3+/oxygen vacancy centers to interstitial N atoms [35][37][38][39]. These substitutional N atoms can also be associated with the enhanced signal in the OH group band (531.5 eV) [40

Improved catalytic combustion of methane using CuO nanobelts with predominantly (001) surfaces

• Qingquan Kong,
• Yichun Yin,
• Bing Xue,
• Yonggang Jin,
• Wei Feng,
• Zhi-Gang Chen,
• Shi Su and
• Chenghua Sun

Beilstein J. Nanotechnol. 2018, 9, 2526–2532, doi:10.3762/bjnano.9.235

• discussed in an early publication [28], surface oxygen is often actively involved and may cleave H from CHx to form –OH and H2O, generating an oxygen vacancy (OV), which can be filled with reactant O2, leading to its dissociation and further oxidizing CHx intermediates, as shown in Figure 4d–f. With oxygen

• reference. According to the results, the early oxidation to release the first H2O (oxygen is from the surface) is exothermic and generates an OV (see Figure 4c). This is followed by O2 dissociation which occurs over the vacancy with a maximum energy barrier of 0.91 eV. This is informative because it

• ) Heating profile (Tmax = 600 °C) for NBs tested for three cycles, labelled as C1, C2 and C3. CH4 oxidation mechanism by computational calculations. (a) Clean (001); (b) CH4 physical adsorption; (c) CH4 dissociative adsorption; (d) CH2* with oxygen vacancy (OV) presented; (e) CH2* with O2 adsorbed; (f) CH2

Lead-free hybrid perovskites for photovoltaics

• Oleksandr Stroyuk

Beilstein J. Nanotechnol. 2018, 9, 2209–2235, doi:10.3762/bjnano.9.207

• PCE of 0.2% for MAGeI3-based cells (Table 1). A DFT study of CsGeI3 HP showed that the iodide vacancy in this material can serve as a deep hole trap, in contrast to the corresponding Pb- and Sn-based HPs resulting in a reduction of the Voc [141]. These results indicate that efforts should be applied

Metal-free catalysis based on nitrogen-doped carbon nanomaterials: a photoelectron spectroscopy point of view

• Mattia Scardamaglia and
• Carla Bittencourt

Beilstein J. Nanotechnol. 2018, 9, 2015–2031, doi:10.3762/bjnano.9.191

• vertically aligned boron–carbon–nitrogen (BCN) nanotubes [61]. Similar to nitrogen, boron can take a substitutional position with three-fold coordination or form a vacancy complex changing the bond lengths in the carbon lattice. These configurations respond differently to a gaseous analyte [29]. Wu et al

• higher kinetic energies, the cross section for vacancy creation decreases and more complex defect configurations are created, such as di-vacancies and distortions (Figure 5) [83][86][87]. The effect of different ion kinetic energies on supported graphene has been highlighted in the case of CF4 plasma

• exhibits a vacancy as neighbor. The different nitrogen configurations are easily distinguished by XPS according to the binding energy of the N 1s core level spectra. The pyridinic configuration is usually found at 398–399 eV, the pyrrolic configuration and other defective components at 399.5–400.5 eV, and

Defect formation in multiwalled carbon nanotubes under low-energy He and Ne ion irradiation

• Santhana Eswara,
• Jean-Nicolas Audinot,
• Brahime El Adib,
• Maël Guennou,
• Tom Wirtz and
• Patrick Philipp

Beilstein J. Nanotechnol. 2018, 9, 1951–1963, doi:10.3762/bjnano.9.186

• improved mechanical properties which is similar to the one of collagen found in nature [7]. Vacancy formation and interconnections forming between CNTs have also been observed in molecular dynamics (MD) simulations during the irradiation of SWCNTs supported by silica [8]. MD simulations have been used to

Cr(VI) remediation from aqueous environment through modified-TiO₂-mediated photocatalytic reduction

• Rashmi Acharya,
• Brundabana Naik and
• Kulamani Parida

Beilstein J. Nanotechnol. 2018, 9, 1448–1470, doi:10.3762/bjnano.9.137