Heat capacity, structural and thermodynamic properties of synthetic klockmannite CuSe at temperatures from 5 K to 652.7 K. Enthalpy of decomposition

Stølen, Svein; Fjellvåg, Helmer; Grønvold, Fredrik; Sipowska, J.T.; Westrum, Edgar F.

doi:10.1006/jcht.1996.0069

Cited by 29 publications

(17 citation statements)

References 18 publications

(37 reference statements)

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“…Using thermodynamic data for Cu 2 Se (ref. 35 ) and equation (1) , the calculated adiabatic temperature for Cu 2 Se turns out to be about 1,084 K. In comparison to the measured combustion temperature (823–836 K), this is a somewhat higher temperature, indicating that the sample is not truly adiabatic under conditions of the measurement and some heat escapes to the surroundings. Nevertheless, the adiabatic temperature of Cu 2 Se is dramatically lower than the minimal adiabatic temperature viewed previously as critical to sustain the self-propagating nature of the reaction.…”

Section: Resultsmentioning

confidence: 79%

Self-propagating high-temperature synthesis for compound thermoelectrics and new criterion for combustion processing

et al. 2014

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The existing methods of synthesis of thermoelectric (TE) materials remain constrained to multi-step processes that are time and energy intensive. Here we demonstrate that essentially all compound thermoelectrics can be synthesized in a single-phase form at a minimal cost and on the timescale of seconds using a combustion process called self-propagating high-temperature synthesis. We illustrate this method on Cu2Se and summarize key reaction parameters for other materials. We propose a new empirically based criterion for sustainability of the combustion reaction, where the adiabatic temperature that represents the maximum temperature to which the reacting compact is raised as the combustion wave passes through, must be high enough to melt the lower melting point component. Our work opens a new avenue for ultra-fast, low-cost, large-scale production of TE materials, and provides new insights into combustion process, which greatly broaden the scope of materials that can be successfully synthesized by this technique.

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Section: Resultsmentioning

confidence: 79%

Self-propagating high-temperature synthesis for compound thermoelectrics and new criterion for combustion processing

et al. 2014

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“…Point exposure time on the InGaAs array detector was 3 s for a 10 kV acceleration voltage and a 10 nA beam current. The first crystalline binary phase observed is CuSe (PDF 86-1239) 29 which can be tracked by the 006 reflection appearing at around 39 keV. This signal disappears at ∼340°C (20 min process time).…”

Section: Methodsmentioning

confidence: 96%

Chemistry and Dynamics of Ge in Kesterite: Toward Band-Gap-Graded Absorbers

et al. 2017

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The selenization of metallic Cu−Zn−Sn−Ge precursors is a promising route for the fabrication of low-cost and efficient kesterite thin-film solar cells. Nowadays, efficiencies of kesterite solar cells are still below 13%. For Cu(In,Ga)Se 2 solar cells, the formation of compositional gradients along the depth of the absorber layer has been demonstrated to be a key requirement for producing thin-film solar cells with conversion efficiencies above the 22% level. No clear understanding has been reached so far about how to produce these gradients in an efficient manner for kesterite compounds, but among the possible candidates, Ge arises as one of the most promising ones. In the present work, we evaluate the potential of incorporating Ge in Cu 2 ZnSnSe 4 to produce compositional gradients in kesterites. Synchrotron-based in situ energydispersive X-ray diffraction and X-ray fluorescence have been used to study the selenization of Cu−Zn−Sn−Ge metallic precursors. We propose a reaction mechanism for the incorporation of Ge atoms into the kesterite lattice after the formation of Cu 2 ZnSnSe 4 . Electron microscopy reveals that the annealing process leads to Cu 2 Zn(Sn,Ge)Se 4 absorber layers with an increase of Ge content toward the back contact with independence of the original location of Ge in the precursor layer. The effect of the Ge gradient on the optoelectronic properties of the absorber layer has been evaluated with room-temperature cathodoluminescence. The implications of the results for the development of kesterite solar cells are discussed, with the aim of encouraging new synthesis routes for compositionally graded absorbers.

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“…The phase and crystallographic structure of the nanocrystals were characterized using grazing incidence X-ray diffraction (GIXRD) patterns, which were recorded using a Bruker D8 Advance with a fixed θ of 0.5°, scanning rate of 0.2°min −1 , step size of 0.02°, and 2θ range from 10 to 80°, using CuK α radiation (λ ave = 1.54 Å) operating at 40 kV and 40 mA. The starting Rietveld refinement model used CuSe, 46 Se, 47 CuInSe 2 , 48 CuGaSe 2 , 49 and CuIn 0.52 Ga 0.48 Se 2 . 50 The fundamental parameters peak-shape profile was used; a fivecoefficient Chebychev polynomial and 1/x background, zero error, scale factors, unit cell parameters, and crystal size were sequentially refined using the TOPAS V4 program.…”

Section: Methodsmentioning

confidence: 99%

Evolution Pathway of CIGSe Nanocrystals for Solar Cell Applications

Ahmadi¹,

Pramana²,

Xi³

et al. 2012

J. Phys. Chem. C

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CuIn x Ga 1−x Se 2 nanocrystals synthesized via the hot injection route have been used to make thin film solar cells with high power conversion efficiency. Thus, CuIn x Ga 1−x Se 2 nanocrystals have the potential to provide a low cost and high efficiency solution to harvest solar energy. Stoichiometry control of these nanocrystals offers the possibility of tuning the band gap of this material. It is important to understand how the composition of quaternary CuIn x Ga 1−x Se 2 nanocrystals evolves to control the stoichiometry of this compound. We report a systematic study of the growth and evolution pathways of quaternary CuIn 0.5 Ga 0.5 Se 2 nanocrystals in a hot coordination solvent. The reaction starts by the formation of a mixture of binary and ternary nanocrystals, which transforms subsequently to CuIn 0.5 Ga 0.5 Se 2 nanocrystals. These binary and ternary compounds dissolve in the course of the reaction, so as to provide the molecular precursor for monophasic CuIn 0.5 Ga 0.5 Se 2 nanocrystals to form. Here, we study the growth sequence of these spherical, monophasic CuIn 0.5 Ga 0.5 Se 2 nanocrystals as a function of time. Control experiments indicated that the phase changes of CuIn 0.5 Ga 0.5 Se 2 nanocrystals are temperature-and time-dependent. The change in the stoichiometry of CuIn 0.5 Ga 0.5 Se 2 during growth was estimated using Vegard's law.

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Heat capacity, structural and thermodynamic properties of synthetic klockmannite CuSe at temperatures from 5 K to 652.7 K. Enthalpy of decomposition

Cited by 29 publications

References 18 publications

Self-propagating high-temperature synthesis for compound thermoelectrics and new criterion for combustion processing

Self-propagating high-temperature synthesis for compound thermoelectrics and new criterion for combustion processing

Chemistry and Dynamics of Ge in Kesterite: Toward Band-Gap-Graded Absorbers

Evolution Pathway of CIGSe Nanocrystals for Solar Cell Applications

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