Dufour effect in superionic copper selenide

Korzhuev, M. A.

doi:10.1134/1.1130276

Cited by 45 publications

(35 citation statements)

References 2 publications

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“…Parameter x tends to decline upon rising temperature. The crystal size increases and the energy band gap declines when x approaches zero [12][13][14][15][16][17][18]. As expected, the change of crystalline structure after annealing of stoichiometric Cu 3 Se 2 compound was observed.…”

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confidence: 49%

Optical investigation and application of copper selenide nanowires

Subas¹

2007

Lithuanian J. Phys.

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Growth and optical properties of copper selenide nanowires (nws) in alumina template were studied and discussed in respect to their application as films doped with semiconductor nanocrystals that provide promising optical properties. The results obtained indicate that nanoscaled copper selenide structures uniformly embedded at the bottom of alumina less than a micron in depth could be useful for mode locking in picosecond YAG type lasers. The operating wavelength of the material was identified by optical characterization. Copper selenide nanowires were examined as saturable absorber to yield passive wave mode-locking in a Nd 3+ / YAG laser (λ = 1.064 µm). Both the deposition conditions and subsequent annealing define the stoichiometry of copper selenides providing a slight shift of absorption spectra. One of the preponderant modern sciences nowadays is nanotechnology. While studying new semiconductor nanomaterials, great interest arrived for copper selenide nanoparticles [1][2][3][4][5][6][7][8][9]. One of their promising applications is optical switching devices, because of the transient bleaching effect [7][8][9]. Size, chemical composition, and crystalline structure of nanoparticles determine the character of light absorption processessame as for indirect p-type semiconductor, copper selenide Cu x Se y . Under ambient conditions the material exists as a series of stable and metastable phases, with the stoichiometry coefficients x and y varying from 1 to 3. Variation in stoichiometry results in change of crystalline structure, absorption spectra, and both direct and indirect band gap E g,dir , E g,indir values [10]. Moreover, the crystalline structure and phase composition of copper selenide leads to different optical and other properties obtainable by annealing of specimens.In recent years, a number of researchers have explored semiconductor nanocrystals as saturable absorbers to create passive mode-locked solid-state lasers [7][8][9]. Nanostructured copper selenide appears to gain shallow absorption centres characterized by the absorp- * The report presented at the 37th Lithuanian National Physics Conference, 11-13 June 2007, Vilnius, Lithuania.tion peak in near-IR, which leads to optical nonlinearity effects [10]. The observed absorption range appears to be consistent with the first harmonic of YAG type solid state laser (wavelength within 1-1.5 µm). We studied here for the first time the nonlinear optical properties and mode-locking performance of porous alumina thin films containing copper selenide. Thus, arrays of nanoscaled Cu 3 Se 2 (umangite) before and after annealing at several different temperatures were fabricated and investigated.Aluminium foil of 100 µm in thickness and 99.995 at% purity from Goodfellow was used to prepare samples of 12 × 12.5 mm 2 in dimensions. Before anodizing, the surface of samples was cleaned by degreasing in acetone, etching in a hot 1.5 M NaOH solution for 20 s, desmutting in 10% HNO 3 , thoroughly rinsing, and drying in nitrogen stream. The growth of porous aluminium ox...

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confidence: 49%

Optical investigation and application of copper selenide nanowires

Subas¹

2007

Lithuanian J. Phys.

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“…[5][6][7] Copper telluride thin films have many applications in various devices such as solar cells, superionic conductors, photodetectors, photothermal conversion, electroconductive electrodes, microwave-shielding coatings, and so forth. [8][9][10] Traditionally, metal tellurides have been synthesized by an elemental reaction at elevated temperatures, typically 500-600 8C, in evacuated tubes, [11] or by the reaction of aqueous metal-salt solutions with a toxic and malodorous gas H 2 Te, [12] or by mechanical alloying from elemental powders. [13] Parkin and co-workers reported a room-temperature route to synthesize Ag and Cu chalcogenides in liquid ammonia.…”

Section: Introductionmentioning

confidence: 99%

Controlled Hydrothermal Synthesis and Growth Mechanism of Various Nanostructured Films of Copper and Silver Tellurides

Zhang

Jia

et al. 2006

Chemistry A European J

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Various nanostructured films of copper and silver tellurides were hydrothermally grown on the corresponding metal substrates through reactions between metal foils and tellurium powder in different media. Interesting morphologies including nanowires, nanorods, nanobelts, nanosheets, and hierarchical dendrites were obtained. The nanostructured films were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM). A growth mechanism was proposed based on the characterization results. This study provides a low-temperature, solution-phase approach to grow low-dimensional, nanostructured metal tellurides with controllable morphologies.

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“…The temperature dependence of the effective carrier masses in copper selenides and tellurides can be qualitatively accounted for either by polymorphic transformations a t high temperatures inherent in these materials, or by the complex structure of the valence bands, the existence of which was reported in [45]. α and β are the α and β chalcocite phases.…”

Section: Bulk Chalcogenide Semiconductorsmentioning

confidence: 99%

“…Here Dj is djurelite, and Dg is digenite. Reprinted with permission from refs [45,46]. Neutron diffraction measurements performed on Cu1.75Se and Cu1.98 Se samples for both α--and β--phases by Danilkin et al [47--49] show the dependence on the phase of the kinetics in the copper diffusion in the disordered crystal.…”

Section: Bulk Chalcogenide Semiconductorsmentioning

confidence: 99%

“…Indeed, a direct optical gap was found in the calculations for Cu2S, although the complex energy dependence of the optical absorption could not be calculated, certainly due to the large size of the computation related to the disordered structure. A general overview of the complex phase diagram of Cu2--xSe is reported by Korzhuev in 1998 [45], and is shown in Figure 3 (a). In particular it is clear that around room temperature, and in a wide range of stoichiometries, there are several different stable phases.…”

Section: Bulk Chalcogenide Semiconductorsmentioning

confidence: 99%

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Plasmonics in heavily-doped semiconductor nanocrystals

et al. 2013

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Abstract:Heavily--doped semiconductor nanocrystals characterized by a tunable plasmonic band have been gaining increasing attention recently. Herein, we introduce this type of materials focusing on their structural and photo--physical properties. Beside their continuous--wave plasmonic response, depicted both theoretically and experimentally, we also review recent results on their transient ultrafast response. This was successfully interpreted by adapting models of the ultrafast response of noble metal nanoparticles. IntroductionThe optical features exhibited by metallic nano--systems have been the subject of an intensive theoretical and experimental research, resulting in applications in several fields, from surface--enhanced spectroscopy, to biological and chemical nano--sensing [1]. Such developments are primarily due to the localized surface plasmon resonance (LSPR), which results in intense optical absorption and scattering as well as sub--wavelength localization of large electrical fields in the vicinity of the nano--object [2--10]. The plasmonic response of these metallic nanostructures is strongly dependent on the type of metal of which they are made, on the dielectric function of the surrounding medium, on the particle shape and, even if to a lesser extent, on the particle size. Nanoparticles of several metals, such as Ag, Au, Cu and Pt, exhibiting plasmonic response in the ultraviolet and in the visible regions of the spectrum have been successfully synthesized in the past decades [11--15]. Elongated metallic nanoparticles have been shown to exhibit plasmonic response in the near infrared, due to excitation of the longitudinal plasmon mode [16--18]. It has been recently reported that direct optical excitation of the metal by intense femtosecond laser pulses induces an ultra--fast modulation of the plasmonic resonance, which can be used for ultra--fast modulation of signals [19], paving the way to ultrafast active plasmonics. A quantitative investigation of such dynamical features is therefore crucial for the development of a new generation of ultra--fast nano--devices. Pump--probe spectroscopy, giving access to the electronic excitation and subsequent relaxation processes in the material, is to date the most suitable tool for the experimental study of the ultrafast dynamical features exhibited by plasmonic nanostructures. So far, several noble metal structures have been investigated, including spherical nanoparticles [20--22] and nanorods [23], revealing that the physical processes of excitation and relaxation are actually similar to those observed in bulk (i.e. in thin films) metallic systems, that are the electron--electron, the electron--phonon and the phonon--phonon interactions [24,25].

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Dufour effect in superionic copper selenide

Cited by 45 publications

References 2 publications

Optical investigation and application of copper selenide nanowires

Optical investigation and application of copper selenide nanowires

Controlled Hydrothermal Synthesis and Growth Mechanism of Various Nanostructured Films of Copper and Silver Tellurides

Plasmonics in heavily-doped semiconductor nanocrystals

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