Preparation of R2S3 (R: La, Pr, Nd, Sm) powders by sulfurization of oxide powders using CS2 gas

Ohta, Mitsuo; Yuan, Haibin; Hirai, Shinji; Uemura, Yoichiro; Shimakage, Kazuyoshi

doi:10.1016/j.jallcom.2003.11.081

Cited by 45 publications

(26 citation statements)

References 8 publications

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“…Since CS 2 gas is a powerful sulfurizing agent for rare-earth oxides, CS 2 sulfurization can be carried out at low temperature. [20][21][22][23][24] The Seebeck coefficient, electrical resistivity, and thermal conductivity of the prepared LaGd 1+x S 3 and SmGd 1+x S 3 were then measured over the temperature range of 300 K to 953 K.…”

Section: Introductionmentioning

confidence: 99%

Preparation and Thermoelectric Properties of LaGd1+x S3 and SmGd1+x S3

Ohta

Hirai

Kuzuya

2010

Journal of Elec Materi

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Thermoelectric materials are attractive since they can recover waste heat directly in the form of electricity. In this study, the thermoelectric properties of ternary rare-earth sulfides LaGd 1+x S 3 (x = 0.00 to 0.03) and SmGd 1+x S 3 (x = 0.00 to 0.06) were investigated over the temperature range of 300 K to 953 K. These sulfides were prepared by CS 2 sulfurization, and samples were consolidated by pressure-assisted sintering to obtain dense compacts. The sintered compacts of LaGd 1+x S 3 were n-type metal-like conductors with a thermal conductivity of less than 1.7 W K À1 m À1 . Their thermoelectric figure of merit ZT was improved by tuning the chemical composition (self-doping). The optimized ZT value of 0.4 was obtained in LaGd 1.02 S 3 at 953 K. The sintered compacts of SmGd 1+x S 3 were n-type hopping conductors with a thermal conductivity of less than 0.8 W K À1 m À1 . Their ZT value increased significantly with temperature. In SmGd 1+x S 3 , the ZT value of 0.3 was attained at 953 K.

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Section: Introductionmentioning

confidence: 99%

Preparation and Thermoelectric Properties of LaGd1+x S3 and SmGd1+x S3

Ohta

Hirai

Kuzuya

2010

Journal of Elec Materi

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“…The preparation of Ln 2 S 3 using CS 2 gas became feasible at low temperature in comparison with the reaction with H 2 S gas [10,11]. However, the Ln 2 S 3 powder prepared using CS 2 gas contains the impurities of oxygen and carbon [12]. While the sintering technique is a widely used method for fabricating the thermoelectric elements of the LnS y [13], the thermoelectric performance is affected by the microstructures.…”

Section: Introductionmentioning

confidence: 99%

Phase transformation and microstructures of Ln2S3 (Ln = La, Sm) with different impurities content of oxygen and carbon

Ohta

Hirai

et al. 2006

Journal of Alloys and Compounds

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“…This formation behavior is very similar to that observed during the sulfurization of La 2 O 3 powder with CS 2 gas. 30,31) During the sulfurization of La 2 O 3 powder, LaS 2 phase is formed at around 850 K, and then -La 2 S 3 phase is formed at around 1000 K.…”

Section: Methodsmentioning

confidence: 99%

Synthesis of La2S3 Thin Films by Sulfurization of LaCl3 and CS(NH2)2

et al. 2006

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La 2 S 3 thin films were prepared by dipping the substrates in methanol solutions of LaCl 3 Á7H 2 O and CS(NH 2 ) 2 , followed by sulfurization with CS 2 gas in the temperature range of 773-1073 K. The effects of the substrate and the mole ratio of LaCl 3 Á7H 2 O to CS(NH 2 ) 2 on the phase formation after sulfurization were investigated. When the mole ratio of LaCl 3 Á7H 2 O to CS(NH 2 ) 2 was 2:3, the tetragonal -La 2 S 3 coatings were obtained on silica glass and Mo substrates for sulfurization at 1073 K. On the other hand, the cubic -La 2 S 3 coating was obtained on a soda-lime glass substrate for sulfurization at 973 K. The thin films on Ta and Ti substrates were comprised of -La 2 S 3 and -La 2 S 3 phases for sulfurization at 1073 K. The LaS 2 phase was identified as an intermediate product of sulfurization at about 873 K. When the mole ratio of LaCl 3 Á7H 2 O to CS(NH 2 ) 2 was 1:1, the -La 2 S 3 coating was also obtained on silica glass substrate for sulfurization at 1073 K. Since the gaseous phases formed during sulfurization pass through the La 2 S 3 layer, the thin films obtained were porous.

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Preparation of R2S3 (R: La, Pr, Nd, Sm) powders by sulfurization of oxide powders using CS2 gas

Cited by 45 publications

References 8 publications

Preparation and Thermoelectric Properties of LaGd1+x S3 and SmGd1+x S3

Preparation and Thermoelectric Properties of LaGd1+x S3 and SmGd1+x S3

Phase transformation and microstructures of Ln2S3 (Ln = La, Sm) with different impurities content of oxygen and carbon

Synthesis of La<SUB>2</SUB>S<SUB>3</SUB> Thin Films by Sulfurization of LaCl<SUB>3</SUB> and CS(NH<SUB>2</SUB>)<SUB>2</SUB>

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