The La2S3–LaS2 system: Thermodynamic and kinetic study

Vasilyeva, I.G.; Nikolaev, R. E.

doi:10.1016/j.jssc.2010.05.026

Cited by 11 publications

(6 citation statements)

References 10 publications

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“…[2][3][4]6]). Considerable interest has also been paid to elucidate phase relations and stability ranges of the respective polychalcogenides of one particular rare-earth metal [3,[8][9][10]. As has been shown from thermoanalytical and tensimetric studies, polysulfides and polyselenides LnX 2-d generally decompose at elevated temperatures by a stepwise release of molecular chalcogen X 2 until the sesquichalcogenide Ln 2 X 3 is obtained.…”

Section: Introductionmentioning

confidence: 99%

High-pressure synthesis of rare-earth metal disulfidesand diselenides LnX ₂ (Ln = Sm, Gd, Tb, Dy, Ho, Er and Tm; X = S, Se)

Müller

Doert²,

Schwarz

2011

Zeitschrift Für Kristallographie

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A series of rare-earth metal disulfides LnS 2 and diselenides LnSe 2 (Ln ¼ Sm, Gd, Tb, Dy, Ho, Er and Tm) has been prepared by high-pressure high-temperature synthesis at 8(1) GPa. The dichalcogenides LnX 2 (X ¼ S, Se) are found to crystallize in the a-LaS 2 type with the monoclinic space group P12 1 /a1 (no. 14). The crystal structure is a twofold superstructure of the ZrSSi aristotype and consists of puckered cationic [LnX] þ double slabs which are sandwiched by planar chalcogen sheets containing X 2À 2 dumbbells.

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Section: Introductionmentioning

confidence: 99%

High-pressure synthesis of rare-earth metal disulfidesand diselenides LnX ₂ (Ln = Sm, Gd, Tb, Dy, Ho, Er and Tm; X = S, Se)

Müller

Doert²,

Schwarz

2011

Zeitschrift Für Kristallographie

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“…Concerning the formation enthalpy of La 3 X 4 , there are some recent experimental data for La 3 Se 4 , La 2 Se 3 and La 2 S 3 [64][65][66]. In addition Hepler and Singh [67] have discussed the available literature data and have mentioned that the data for La 2 Te 3 have to be taken with caution.…”

Section: Crystal Structure and Stabilitymentioning

confidence: 99%

“…The calculated values of the reduced position of the chalcogen atoms x X , of the lattice constants a, of the formation enthalpies and of the bulk modulus and its pressure derivative are listed in Tables 1 and 2 together with the available experimental data [10][11][12][13][63][64][65][66][67][68]. Globally the calculated lattice constants are overestimated by at most 1.5% which is certainly due to the use of the GGA since it is well known that this approximation overestimates the lattice constants or the equilibrium volume [69].…”

Section: Crystal Structure and Stabilitymentioning

confidence: 99%

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Physical properties of the thermoelectric cubic lanthanum chalcogenides La3−yX4(X= S, Se, Te) from first principles

2013

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We report ab-initio calculations of the stability, lattice dynamics, electronic and thermoelectric properties of cubic La 3-y X 4 (X=S,Se,Te) materials in view of analyzing their potential for thermoelectric applications. The lanthanum motions are strongly coupled to the tellurium motions in the telluride, whereas the motions of both types of atoms are decoupled in the sulfides. Nevertheless, this has no impact on their thermal properties because experimentally all compounds have low thermal conductivity. We believe that this is due to Umklapp scattering of the acoustical modes, notably by the low energy optical modes at about 7-8 meV found in all three chalcogenides, as in cage compounds such as skutterudites or clathrates, even though there are no cages in the cubic Th 3 P 4 structure. We find that the energy bandgap increases from the telluride to the sulfide in good agreement with the experiments. However, due to their similar band structure, we find that all three compounds have almost identical thermoelectric properties. Our results agree qualitatively with the experiments, especially in the case of the telluride for which a great amount of data exists. All our results indicate that the sulfides have strong potential for thermoelectricity and could replace the tellurides if the charge carrier concentration is optimized. Finally, we predict also a larger maximum ZT for the p-type doped materials than for the n-type doped ones, even though compounds with p-doping have still to be synthesized.Thus our results indicate the possibility to make high temperature performing thermo-generators based only on La 3 X 4 compounds.PACS numbers: 63.20.dk,71.15.Nc, 72.15.Jf, 72.20.Pa 1

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“…In 1984, Kay et al proposed a phase stability diagram for lanthanum versus the vapor pressure of O 2 and S 2 at 1100 K 31 . Vasilyeva described the thermodynamic of the La 2 S 3 -LaS 2 system in 2010 32 .…”

Section: Introductionmentioning

confidence: 99%

Liquid State Properties and Solidification Features of the Pseudo Binary BaS-La2S3

Boury

Allanore

2021

Preprint

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The high temperature thermodynamic properties of chalcogenides materials based on BaS remain elusive, and herein the La2S3 pseudo binary system is investigated above 1573 K. The liquid properties of BaS-La2S3 are measured by means of high resolution in-situ visualization coupled with thermal arrest measurements in a thermal imaging furnace. This enables to report for the first observation of such melts in a containerless setting. The melting points of BaS and La2S3 are revisited at 2454 K and 2004 K respectively. La2S3 demonstrates a high stability in its liquid state, in strike difference with the sublimation observed for BaS. BaS is however partially stabilized with the addition of few percents of La2S3.The remarkable chemical and thermal stability of La2S3-rich samples, contrasts with the partial decomposition and high vapor pressure observed for BaS-rich samples. Observations and analysis of the solidified samples suggests three different solid solutions. Solid and liquid densities are investigated along the different compositions, supporting a first estimate of the volumetric thermal expansion coefficient for La2S3.

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The La2S3–LaS2 system: Thermodynamic and kinetic study

Cited by 11 publications

References 10 publications

High-pressure synthesis of rare-earth metal disulfidesand diselenides LnX ₂ (Ln = Sm, Gd, Tb, Dy, Ho, Er and Tm; X = S, Se)

High-pressure synthesis of rare-earth metal disulfidesand diselenides LnX ₂ (Ln = Sm, Gd, Tb, Dy, Ho, Er and Tm; X = S, Se)

Physical properties of the thermoelectric cubic lanthanum chalcogenides La3−yX4(X= S, Se, Te) from first principles

Liquid State Properties and Solidification Features of the Pseudo Binary BaS-La2S3

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The La2S3–LaS2 system: Thermodynamic and kinetic study

Cited by 11 publications

References 10 publications

High-pressure synthesis of rare-earth metal disulfidesand diselenides LnX 2 (Ln = Sm, Gd, Tb, Dy, Ho, Er and Tm; X = S, Se)

High-pressure synthesis of rare-earth metal disulfidesand diselenides LnX 2 (Ln = Sm, Gd, Tb, Dy, Ho, Er and Tm; X = S, Se)

Physical properties of the thermoelectric cubic lanthanum chalcogenides La3−yX4(X= S, Se, Te) from first principles

Liquid State Properties and Solidification Features of the Pseudo Binary BaS-La2S3

Contact Info

Product

Resources

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High-pressure synthesis of rare-earth metal disulfidesand diselenides LnX ₂ (Ln = Sm, Gd, Tb, Dy, Ho, Er and Tm; X = S, Se)

High-pressure synthesis of rare-earth metal disulfidesand diselenides LnX ₂ (Ln = Sm, Gd, Tb, Dy, Ho, Er and Tm; X = S, Se)