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

• (harmonic) interatomic force constants (IFCs), and third-order (anharmonic) IFCs are obtained from the ShengBTE code [28] with the maximum atomic interaction distance of the sixth neighbor in the 4 × 4 × 1 supercell. Here, a dense phonon q-grid of 52 × 52 × 1 is used to compute the thermal conductivity of

• the HSE06 hybrid functional potential, we use the PBE potential to get the electrical transport properties of the MoO3 monolayer in the following work. The phonon dispersion in the high-symmetry directions of the first Brillouin zone of the MoO3 monolayer is plotted in Figure 1c. There is no imaginary

• frequency, ensuring the stability of the MoO3 monolayer. It is well known that the acoustical phonon branches possess large group velocities and mainly determine the thermal conductivity of the lattice [32]. As the dashed lines emphasize in Figure 1c, the acoustic phonon group velocity along the Γ–Y

Remarkable electronic and optical anisotropy of layered 1T’-WTe₂ 2D materials

• Qiankun Zhang,
• Rongjie Zhang,
• Jiancui Chen,
• Wanfu Shen,
• Chunhua An,
• Xiaodong Hu,
• Mingli Dong,
• Jing Liu and
• Lianqing Zhu

Beilstein J. Nanotechnol. 2019, 10, 1745–1753, doi:10.3762/bjnano.10.170

• anisotropic acoustic phonon scatter and elliptic elastic constants (both are relevant to the anisotropic crystalline structure) [31]. One of the consequences of an anisotropic carrier mobility is the anisotropic resistance. Therefore, we also performed angle-resolved DC conductance measurements on the 1T

High-temperature resistive gas sensors based on ZnO/SiC nanocomposites

• Vadim B. Platonov,
• Marina N. Rumyantseva,
• Alexander S. Frolov,
• Alexey D. Yapryntsev and
• Alexander M. Gaskov

Beilstein J. Nanotechnol. 2019, 10, 1537–1547, doi:10.3762/bjnano.10.151

• of zinc oxide contains an intense broad signal, corresponding to the stretching vibrations of Zn–O bonds (635–400 cm−1). The above spectrum also shows the signals from the multi-phonon vibrational modes of the ZnO lattice (990 and 870 cm−1). In accordance with the literature data, such oscillations

Superconducting switching due to a triplet component in the Pb/Cu/Ni/Cu/Co₂Cr_1−xFe_xAl_y spin-valve structure

• Andrey Andreevich Kamashev,
• Nadir Nurgayazovich Garif’yanov,
• Aidar Azatovich Validov,
• Joachim Schumann,
• Vladislav Kataev,
• Bernd Büchner,
• Yakov Victorovich Fominov and
• Ilgiz Abdulsamatovich Garifullin

Beilstein J. Nanotechnol. 2019, 10, 1458–1463, doi:10.3762/bjnano.10.144

• mechanically removed from the areas where the golden wires should be attached using a silver paste. The quality of the Pb layer can be judged from the residual resistivity ratio (RRR): Here, R(T) is the measured resistance at a given temperature T, ρph(300 K) is the phonon contribution to the specific

Kelvin probe force microscopy of the nanoscale electrical surface potential barrier of metal/semiconductor interfaces in ambient atmosphere

• Petr Knotek,
• Tomáš Plecháček,
• Jan Smolík,
• Petr Kutálek,
• Filip Dvořák,
• Milan Vlček,
• Jiří Navrátil and
• Čestmír Drašar

Beilstein J. Nanotechnol. 2019, 10, 1401–1411, doi:10.3762/bjnano.10.138

• (NIs/NPs) into the bulk semiconducting matrices has been proposed [4][5][6] and supported in theoretical works [7][8][9]. Such NIs or NPs are able to enhance ZT via a reduction of the thermal conductivity by phonon scattering [10][11][12][13][14], by modulated carrier doping or by the carrier energy

Construction of a 0D/1D composite based on Au nanoparticles/CuBi₂O₄ microrods for efficient visible-light-driven photocatalytic activity

• Weilong Shi,
• Mingyang Li,
• Hongji Ren,
• Feng Guo,
• Xiliu Huang,
• Yu Shi and
• Yubin Tang

Beilstein J. Nanotechnol. 2019, 10, 1360–1367, doi:10.3762/bjnano.10.134

• light. Among these compounds, the spinel-type compound CuBi2O4 has attracted much attention because of its low phonon energy, strong visible-light response and adequate thermal stability [11][12]. Because of these attractive features, CuBi2O4 has been widely studied as a photocatalytic material in the

Synthesis and characterization of quaternary La(Sr)S–TaS₂ misfit-layered nanotubes

• Marco Serra,
• Erumpukuthickal Ashokkumar Anumol,
• Dalit Stolovas,
• Iddo Pinkas,
• Ernesto Joselevich,
• Reshef Tenne,
• Andrey Enyashin and
• Francis Leonard Deepak

Beilstein J. Nanotechnol. 2019, 10, 1112–1124, doi:10.3762/bjnano.10.111

• cm−1 was assigned to the two-phonon bands of the TaS2 slab. The 125 cm−1 peak was assigned to the out-of-phase vibration of the LaS lattice. On the other hand, the 150 cm−1 peak was assigned to the in-phase phonon of LaS. The E2g mode of the TaS2 in the MLC lattice is found in the energy range of

• about 321–325 cm−1. This peak is blue-shifted compared to the pure TaS2 (279 cm−1), which is attributed to the characteristic charge transfer from the LaS slab to that of TaS2. The broad band between ≈240 and 304 cm−1 is attributed to the two-phonon band [52], whereas the 400 cm−1 transition was

CuInSe₂ quantum dots grown by molecular beam epitaxy on amorphous SiO₂ surfaces

• Henrique Limborço,
• Pedro M.P. Salomé,
• Rodrigo Ribeiro-Andrade,
• Jennifer P. Teixeira,
• Nicoleta Nicoara,
• Kamal Abderrafi,
• Joaquim P. Leitão,
• Juan C. Gonzalez and
• Sascha Sadewasser

Beilstein J. Nanotechnol. 2019, 10, 1103–1111, doi:10.3762/bjnano.10.110

• substrates, bare (as-grown) nanodot samples and CdS-covered nanodot samples, as shown in Figure 4. The PL spectra of the bare Si and CIS samples, Figure 4a, show only the common sharp lines related with the Si substrate [41][42]. The observed lines correspond to the phonon replicas (TA, TO and TO+OΓ) of the

• radiative recombination of free excitons (FE) and of bound excitons (B), as well as the no-phonon line of the bound exciton (BNP) as confirmed from PL measurements performed under the same experimental conditions of a Si substrate. After the deposition of a CdS layer on top of the three as-grown nanodot

Electronic properties of several two dimensional halides from ab initio calculations

• Mohamed Barhoumi,
• Ali Abboud,
• Lamjed Debbichi,
• Moncef Said,
• Torbjörn Björkman,
• Dario Rocca and
• Sébastien Lebègue

Beilstein J. Nanotechnol. 2019, 10, 823–832, doi:10.3762/bjnano.10.82

• electronic bandgaps, as obtained with the HSE hybrid functional, range between 3.0 and 7.5 eV and that their phonon spectra are dynamically stable. Additionally, we show that under an external electric field some of these systems exhibit a semiconductor-to-metal transition. Keywords: density functional

• performing phonon calculations. These studies were conducted on bulk materials but little is known on the structural and electronic properties of the corresponding isolated layers. By using a datamining procedure some halides were identified as possible 2D materials [14] but their dynamical stability and

• images. Geometries (cell and atom positions) were relaxed with a threshold on forces of 10−6 eV/Å. The phonon dispersion curves of the single layers, as presented in Supporting Information File 1, were determined with the PHONOPY code [39] with a 5 × 5 × 1 supercell using density functional perturbation

Ultrasonication-assisted synthesis of CsPbBr₃ and Cs₄PbBr₆ perovskite nanocrystals and their reversible transformation

• Longshi Rao,
• Xinrui Ding,
• Xuewei Du,
• Guanwei Liang,
• Yong Tang,
• Kairui Tang and
• Jin Z. Zhang

Beilstein J. Nanotechnol. 2019, 10, 666–676, doi:10.3762/bjnano.10.66

• ) structures of Cs4PbX6 NCs can be achieved, demonstrating a crystalline structure with well-separated octahedra [PbBr6]4− isolated by Cs+ ions [12][13]. This specific structure is expected to result in strong quantum confinement and electron–phonon interactions. This inspires researchers to further explore

Enhancement in thermoelectric properties due to Ag nanoparticles incorporated in Bi₂Te₃ matrix

• Srashti Gupta,
• Dinesh Chandra Agarwal,
• Bathula Sivaiah,
• Sankarakumar Amrithpandian,
• Kandasami Asokan,
• Ajay Dhar,
• Binaya Kumar Panigrahi,
• Devesh Kumar Avasthi and
• Vinay Gupta

Beilstein J. Nanotechnol. 2019, 10, 634–643, doi:10.3762/bjnano.10.63

• to unity, it can be improved further with the introduction of nanostructures. The electron and phonon energy spectra can be controlled by tuning the size of nanostructures, which opens up new ways for ZT enhancement [1][2]. Since the introduction of nanotechnology in TE in 1993, various methods have

• applications but these materials are not very efficient because of their low ZT [8][9]. To increase ZT, nanostructures play an important role in the simultaneous increase in power factor and reduction in phonon thermal conductivity (kph) [10]. Recently, Faleev et al. [11] and Zebardaji et al. [12] performed

• is ca. 6.3-times for 10% Ag at 300 K and 1.3-times for 2% Ag at 600 K. The nanoparticles in the semiconductor matrix also lead to a reduction of thermal conductivity through phonon scattering at the interfaces, which in turn increases the figure of merit. The present work shows that during the

Quantification and coupling of the electromagnetic and chemical contributions in surface-enhanced Raman scattering

• Yarong Su,
• Yuanzhen Shi,
• Ping Wang,
• Jinglei Du,
• Markus B. Raschke and
• Lin Pang

Beilstein J. Nanotechnol. 2019, 10, 549–556, doi:10.3762/bjnano.10.56

• reference to estimate the SERS enhancement factor. All spectra were recorded with 5 s acquisition time. The silicon phonon Raman response at 520.7 cm−1 was used to calibrate the spectrometer. Results SERS spectra The spectral range of 900–1200 cm−1 was selected for the study of three characteristic Raman

Temperature-dependent Raman spectroscopy and sensor applications of PtSe₂ nanosheets synthesized by wet chemistry

• Mahendra S. Pawar and
• Dattatray J. Late

Beilstein J. Nanotechnol. 2019, 10, 467–474, doi:10.3762/bjnano.10.46

• fitting the Lorentzian function to the A1g and Eg modes. The temperature coefficient can be calculated by Equation 1 [29]: where ω0 is the peak position of the A1g and Eg mode at zero Kelvin, χ is the temperature coefficient of the A1g and Eg modes, and ω is a Raman phonon frequency. The slope of the

• anharmonicity. The Raman phonon frequency as a function of volume and temperature is given by Equation 2 [30]: where γ is the volume thermal coefficient and K represents the isothermal volume compressibility. The first term on the right hand side, −γ/K (∂lnω/∂P)T, represents the volume contribution at a

• resonance phenomenon can be attributed to several process including absorption of an incident photon, creation of a hole pair, double scattering of a created hole pair by phonon, and recombination of an electron–hole pair with emission of phonon. The temperature coefficient for the Eg and A1g modes was

Raman study of flash-lamp annealed aqueous Cu₂ZnSnS₄ nanocrystals

• Yevhenii Havryliuk,
• Oleksandr Selyshchev,
• Mykhailo Valakh,
• Alexandra Raevskaya,
• Oleksandr Stroyuk,
• Constance Schmidt,
• Volodymyr Dzhagan and
• Dietrich R. T. Zahn

Beilstein J. Nanotechnol. 2019, 10, 222–227, doi:10.3762/bjnano.10.20

• sulfide Cu2ZnSnS4 (CZTS); CuS; Cu-Sn-S; kesterite; phonon; pulsed light crystallization; Raman spectroscopy; secondary phase; SnS; Introduction Affordable and non-toxic solar energy materials having a high absorption coefficient and a bandgap in the solar illumination range are an ever-growing research

• that the laser power does not affect the samples are our recently reported low-temperature measurements (77 K) [34], which revealed no qualitative changes in the spectra except for an expected temperature-induced shift and narrowing of the phonon peaks. The Raman spectra of the ink1-derived films

• appeared to be spectrally homogeneous and revealed a strong phonon peak at 333 cm−1 when measured in different spots of the films (Figure 1). In contrast, despite the optically homogeneous surface, the spectra of ink0-derived films showed a variation of the peak position between 328 and 331 cm−1 over the

Graphene–graphite hybrid epoxy composites with controllable workability for thermal management

• Idan Levy,
• Eyal Merary Wormser,
• Maxim Varenik,
• Matat Buzaglo,
• Roey Nadiv and
• Oren Regev

Beilstein J. Nanotechnol. 2019, 10, 95–104, doi:10.3762/bjnano.10.9

• materials by virtue of their high TC (>3500 W/(m∙K) for individual tubes) [18][19], but their performance has proved to be disappointing [20][21][22][23] as a result of phonon scattering at the tube–tube interface. Another graphitic candidate that appears to have good potential as a filler material is

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

• orientation of the nanorods along the [001] crystallographic axis. No notable variation in the XRD patterns of the NRs was observed with respect to growth time. The Raman spectra of the ZnO NRs are shown in Figure 2b, where a strong Raman scattering at 435 cm−1 representing the E2high phonon mode of ZnO is

Disorder in H⁺-irradiated HOPG: effect of impinging energy and dose on Raman D-band splitting and surface topography

• Lisandro Venosta,
• Noelia Bajales,
• Sergio Suárez and
• Paula G. Bercoff

Beilstein J. Nanotechnol. 2018, 9, 2708–2717, doi:10.3762/bjnano.9.253

• activates a TO phonon (“inter-valley” defect-induced electron–hole). On the other hand, the D′ band is activated by a similar double-resonance process that activates an LO phonon (“intra-valley”). Despite the fact that the D band and the D′ band have been widely reported [5][8][9][30][31][32][33] there is

Nanoantenna structures for the detection of phonons in nanocrystals

• Alexander G. Milekhin,
• Sergei A. Kuznetsov,
• Ilya A. Milekhin,
• Larisa L. Sveshnikova,
• Tatyana A. Duda,
• Ekaterina E. Rodyakina,
• Alexander V. Latyshev,
• Volodymyr M. Dzhagan and
• Dietrich R. T. Zahn

Beilstein J. Nanotechnol. 2018, 9, 2646–2656, doi:10.3762/bjnano.9.246

• -wave electromagnetic simulations of the electromagnetic field distribution around the micro- and nanoantennas were employed to realize the maximal SEIRA enhancement for structural parameters of the arrays whereby the LSPR and the NC optical phonon energies coincide. The SEIRA experiments quantitatively

• been extensively examined to date. Recently, A. Toma et al. [21] published the first report on SEIRA for detection of an optical phonon mode (so-called Froehlich mode) from a monolayer of CdSe NCs deposited on Au nanoantenna arrays. The SEIRA enhancement induced by the nanoantennas was estimated to be

• ], nanorings [28], and nanoslits [29]. A detailed description of various nanoantenna geometries can be found in the comprehensive review [30]. In this paper, we report on a systematic study of the effect of SEIRA by the phonon response from monolayers of CdSe, CdS, and PbS NCs deposited on periodic arrays of

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

• structure of bulk and nanoscale objects, illustrating the so-called “phonon bottleneck” phenomenon. The excitation relaxation time is enhanced when the spacing between the size-quantized energy levels ΔE is larger than the vibrational energy ħω. This mechanism is discussed for illustration purposes only

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

• have a D band peak around 1350 cm−1, a G band peak around 1590 cm−1 and G’ band peak in the region of 2700 cm−1. The first is related to the presence of disordered carbon, the second to the tangential vibrations of graphitic carbon and the third one to two-phonon scattering related to long-range order

• higher sample temperature pushing the maximum to a higher fluence [54]. Hence, their data at room temperature agrees well with ours. The peak at 2700 cm−1 in the pristine sample, called G’, is an overtone of the D band and is an additional indicator for damage formation. It is caused by two-phonon

SO₂ gas adsorption on carbon nanomaterials: a comparative study

• Deepu J. Babu,
• Divya Puthusseri,
• Frank G. Kühl,
• Sherif Okeil,
• Michael Bruns,
• Manfred Hampe and
• Jörg J. Schneider

Beilstein J. Nanotechnol. 2018, 9, 1782–1792, doi:10.3762/bjnano.9.169

• proportional to the presence of defects or disorder in the material and is strongly dependent on the laser excitation energy [32]. The 2D band for sp2-hybridized carbon materials is found between 2500 and 2800 cm−1 and is a double-resonance two-phonon process [33]. The 2D band intensity is found to be

Increasing the performance of a superconducting spin valve using a Heusler alloy

• Andrey A. Kamashev,
• Aidar A. Validov,
• Joachim Schumann,
• Vladislav Kataev,
• Bernd Büchner,
• Yakov V. Fominov and
• Ilgiz A. Garifullin

Beilstein J. Nanotechnol. 2018, 9, 1764–1769, doi:10.3762/bjnano.9.167

• the residual resistivity ratio RRR = R(T = 300 K)/R(Tc= [ρ(300 K) + ρ(Tc)]/ρ(Tc). Since the room-temperature resistivity of the Pb layer is dominated by the phonon contribution ρph(300 K) = 21 μΩ·cm [27] we obtain the ρS values presented below in Table 1. Then with the aid of the Pippard relations [28

Absence of free carriers in silicon nanocrystals grown from phosphorus- and boron-doped silicon-rich oxide and oxynitride

• Daniel Hiller,
• Julian López-Vidrier,
• Keita Nomoto,
• Michael Wahl,
• Wolfgang Bock,
• Tomáš Chlouba,
• František Trojánek,
• Sebastian Gutsch,
• Margit Zacharias,
• Dirk König,
• Petr Malý and
• Michael Kopnarski

Beilstein J. Nanotechnol. 2018, 9, 1501–1511, doi:10.3762/bjnano.9.141

• carriers would quench the PL, which would preferentially affect the larger NCs with least confinement energy. Instead of a PL redshift expected for doped NCs with decreasing T, we observe a small blueshift related to the thermal contraction of the lattice and reduced electron–phonon interaction, which

Electronic conduction during the formation stages of a single-molecule junction

• Atindra Nath Pal,
• Tal Klein,
• Ayelet Vilan and
• Oren Tal

Beilstein J. Nanotechnol. 2018, 9, 1471–1477, doi:10.3762/bjnano.9.138

• conductance steps at 45 ± 1 mV take place at higher voltage than expected for conductance steps due to Ag phonon excitations (<25 mV) [15], and are ascribed to activation of a vibration mode in the molecular junction [13]. The overall distribution of steps as a function of voltage is seen in Figure 2b. The

• transport via the molecular junction, while the overall conductance is the outcome of the parallel molecular and metallic pathways. The zero-voltage feature observed in Figure 2a,c does not allow a clear identification of phonon-induced steps in the conductance via the metallic bridge, which are expected

• G0 (bottom) zero-voltage conductance. The steps in the conductance appear below 25mV and are associated with activation of metal phonon modes [15]. (a,b) Conductance traces measured for the Ag–vanadocene junction (black curve) and the experimentally resolved conductance contributions of the main

Computational exploration of two-dimensional silicon diarsenide and germanium arsenide for photovoltaic applications

• Sri Kasi Matta,
• Chunmei Zhang,
• Yalong Jiao,
• Anthony O'Mullane and
• Aijun Du

Beilstein J. Nanotechnol. 2018, 9, 1247–1253, doi:10.3762/bjnano.9.116

• the same IV–V group combination, we focus our study on two-dimensional SiAs2 and GeAs2 and compare them with their bulk counter parts with regard to electronic band structure, phonon-vibration frequencies, optical properties, band gap modulation behavior and predict their potential applications

• spacing representing the augmentation charges, charge densities and potentials (NGFX, NGFY, NGFZ) so as to get accurate results. The phonon spectrum was computed using the density functional perturbation theory (DFPT) [27] as implemented in the Quantum-ESPRESSO package [28]. The excitonic properties are

• calculated lattice constants for single-layered SiAs2 and GeAs2 are slightly smaller than those calculated for the bulk phases. The lattice constant c is kept constant and greater than 15 Å by adding a vacuum layer. The dynamical stability of SiAs2 and GeAs2 monolayers is evaluated by analysing the phonon