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

Thermoelectric current in topological insulator nanowires with impurities

• Sigurdur I. Erlingsson,
• Jens H. Bardarson and
• Andrei Manolescu

Beilstein J. Nanotechnol. 2018, 9, 1156–1161, doi:10.3762/bjnano.9.107

• electronic transport properties and also reduce the phonon scattering which then leads to increased efficiency [1]. Interestingly, often the materials that show the best thermoelectric properties on the nanoscale can also exhibit topological insulator properties [2], although the connection between the two

Room-temperature single-photon emitters in titanium dioxide optical defects

• Kelvin Chung,
• Yu H. Leung,
• Chap H. To,
• Aleksandra B. Djurišić and
• Snjezana Tomljenovic-Hanic

Beilstein J. Nanotechnol. 2018, 9, 1085–1094, doi:10.3762/bjnano.9.100

• signals in the emission peaks by suppressing the contributions due to phonon sidebands. Conclusion This study investigated thin films, single crystals and nanopowders of TiO2 via confocal microscopy. For the first time, it has been observed that TiO2 defects exhibit antibunching behaviour within thin

Theoretical study of strain-dependent optical absorption in a doped self-assembled InAs/InGaAs/GaAs/AlGaAs quantum dot

• Tarek A. Ameen,
• Hesameddin Ilatikhameneh,
• Archana Tankasala,
• Yuling Hsueh,
• James Charles,
• Jim Fonseca,
• Michael Povolotskyi,
• Jun Oh Kim,
• Sanjay Krishna,
• Monica S. Allen,
• Jeffery W. Allen,
• Rajib Rahman and
• Gerhard Klimeck

Beilstein J. Nanotechnol. 2018, 9, 1075–1084, doi:10.3762/bjnano.9.99

• harmonic potential underestimates the repulsion at smaller bond lengths and also fails to capture the weakening of atomic forces at large atomic separation [8]. The anharmonic strain parameters were originally optimized to obtain correct Grüneisen parameters for accurate phonon dispersion calculations [7

• and bond-bending coefficient β on the bond length strain, while B describes the dependence of bond-bending coefficient (β) on angle deformation. The anharmonic model was developed to simulate phonon dispersion and transport and the anharmonic strain parameters were optimized to reproduce the Grüneisen

• parameters γi = −(V/ωi)(δωi/δV), which are a measure of the dependence of the phonon mode frequencies on strain. Simulating the strain in quantum dots with the original anharmonic strain parameters produces inaccurate results. In addition, simulating strain in quantum wells with these parameters gives strain

Electro-optical interfacial effects on a graphene/π-conjugated organic semiconductor hybrid system

• Karolline A. S. Araujo,
• Luiz A. Cury,
• Matheus J. S. Matos,
• Thales F. D. Fernandes,
• Luiz G. Cançado and
• Bernardo R. A. Neves

Beilstein J. Nanotechnol. 2018, 9, 963–974, doi:10.3762/bjnano.9.90

• , respectively. Both spectra show two major Raman features: the first-order bond-stretching G band [51] and the two-phonon 2D band [52][53]. The single-Lorentzian shape of the 2D band (≈2690 cm−1) reassures that the graphene piece is a single-layer flake [52][53]. The inset in the upper left corner of Figure 6

The effect of atmospheric doping on pressure-dependent Raman scattering in supported graphene

• Egor A. Kolesov,
• Mikhail S. Tivanov,
• Olga V. Korolik,
• Olesya O. Kapitanova,
• Xiao Fu,
• Hak Dong Cho,
• Tae Won Kang and
• Gennady N Panin

Beilstein J. Nanotechnol. 2018, 9, 704–710, doi:10.3762/bjnano.9.65

• graphene charge carrier density and the effect of the substrate on the electronic and phonon properties of graphene. It was found that adsorption of molecules from the atmosphere onto graphene doped with nitrogen (electron doping) compensates for the electron charge. Furthermore, the atmosphere-induced

• 2D peak experimental pressure shift can be explained by changes in the corresponding phonon mode energy due to (1) graphene lattice compressibility [5], (2) strain induced by the difference of compressibility values for graphene and substrate [5][14], and (3) possible desorption of atmosphere

• -induced doping groups [3][13]. Thus, the experimental peak shift due to pressure change can be written as: The first term is defined by the following expression [5]: where and are normal G and 2D peak positions, respectively; γG,2D is a Grüneisen parameter for corresponding E2g and A1g phonon modes

Green synthesis of fluorescent carbon dots from spices for in vitro imaging and tumour cell growth inhibition

• Nagamalai Vasimalai,
• Vânia Vilas-Boas,
• Juan Gallo,
• María de Fátima Cerqueira,
• Mario Menéndez-Miranda,
• José Manuel Costa-Fernández,
• Lorena Diéguez,
• Begoña Espiña and
• María Teresa Fernández-Argüelles

Beilstein J. Nanotechnol. 2018, 9, 530–544, doi:10.3762/bjnano.9.51

• attributed to surface state emission, intrinsic band emission, triple ground state emission, dipole emission involving electron–phonon coupling, transition from surface electrons to valence holes, self-trapped excitons and to the presence of small organic molecules. Moreover, the characteristic excitation

Influence of the preparation method on the photocatalytic activity of Nd-modified TiO₂

• Patrycja Parnicka,
• Paweł Mazierski,
• Tomasz Grzyb,
• Wojciech Lisowski,
• Ewa Kowalska,
• Bunsho Ohtani,
• Adriana Zaleska-Medynska and
• Joanna Nadolna

Beilstein J. Nanotechnol. 2018, 9, 447–459, doi:10.3762/bjnano.9.43

• packaged energy levels, which limits the possible efficiency of up-conversion processes [20]. To obtain up-conversion of Nd3+ ions, good crystallization of the host material, revealing also low phonon energy is required [20]. The presence of Nd3+ ions in the Nd2O3 phase or in an environment that is highly

Review: Electrostatically actuated nanobeam-based nanoelectromechanical switches – materials solutions and operational conditions

• Liga Jasulaneca,
• Jelena Kosmaca,
• Raimonds Meija,
• Jana Andzane and
• Donats Erts

Beilstein J. Nanotechnol. 2018, 9, 271–300, doi:10.3762/bjnano.9.29

• 5 V [123]. Here, the switching to the off state is achieved by applying a voltage pulse, presumably causing a phonon heating driven repulsion force [123]. However, practical challenges for the use of CNTs in NEM contact switches still remain, such as dependence of electrical properties of CNTs on

Dopant-stimulated growth of GaN nanotube-like nanostructures on Si(111) by molecular beam epitaxy

• Alexey D. Bolshakov,
• Alexey M. Mozharov,
• Georgiy A. Sapunov,
• Igor V. Shtrom,
• Nickolay V. Sibirev,
• Vladimir V. Fedorov,
• Evgeniy V. Ubyivovk,
• Maria Tchernycheva,
• George E. Cirlin and
• Ivan S. Mukhin

Beilstein J. Nanotechnol. 2018, 9, 146–154, doi:10.3762/bjnano.9.17

• , XB, D0XA and D0XB. As one can see, in our spectra, phonon replicas of exciton transitions related to a longitudinal optical phonon with 93 meV energy [37] (XA – 1 LO, D0XA – 1 LO and D0XB – 1 LO) are observed. Features in the region of 3.43 eV indicate transitions related to structural defects [38

Combined scanning probe electronic and thermal characterization of an indium arsenide nanowire

• Tino Wagner,
• Fabian Menges,
• Heike Riel,
• Bernd Gotsmann and
• Andreas Stemmer

Beilstein J. Nanotechnol. 2018, 9, 129–136, doi:10.3762/bjnano.9.15

• ], then phonon scattering at an additional interface may partly be responsible for the reduced interfacial conductivity to the electrodes. The extracted interfacial thermal conductivities agree well with measured values reported in literature [36][37][38][39]. Conclusion In summary, we have shown that KFM