Phase transformation from tetragonal-phase to cubic-phase due to addition of titanium in lanthanum sesquisulfide

Ohta, Mitsuo; Hirai, Shinji; Morita, Shigenori; Nishimura, Toshiyuki; Uemura, Yoichiro

doi:10.1016/j.jallcom.2003.11.082

Cited by 14 publications

(10 citation statements)

References 8 publications

(7 reference statements)

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“…Scanning electron microscopy revealed the dispersion of Ti additives at grain boundaries. 11 By using electron micro-probe analysis, we found that the composition change of the surrounding of Ti promotes the formation of the ␥ phase. 11 The composition of formed ␥ phase is nearly La 2 S 2.67 .…”

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confidence: 93%

“…11 By using electron micro-probe analysis, we found that the composition change of the surrounding of Ti promotes the formation of the ␥ phase. 11 The composition of formed ␥ phase is nearly La 2 S 2.67 . Figure 1 shows the temperature dependence of the electrical resistivity for the samples with Ti.…”

mentioning

confidence: 93%

“…In a previous article, we have reported the control of the ␤ to ␥ phase transformation with the Ti additive. 11 The substitutional oxygen has no effect on this phase transformation. Moreover, we found that the ZT value of the ␥ phase with Ti is relatively large at room temperature.…”

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confidence: 98%

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Thermoelectric properties of lanthanum sesquisulfide with Ti additive

Ohta

Hirai

Kato

et al. 2005

Applied Physics Letters

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The electrical resistivity, thermopower, and thermal conductivity have been measured for the lanthanum sesquisulfide ͑La 2 S 3 ͒ of which the crystal phase is controlled by the Ti additive. In all the samples, the thermopower is negative between 300 and 1000 K. The sample with 8 wt % Ti, which consists almost of the cubic ␥ phase, behaves as a degenerate semiconductor. The thermoelectric figure of merit ZT increases with increasing temperature, reaching a value of 0.21 at 1000 K. In contrast, the sample with 2 wt % Ti consists almost of the tetragonal ␤ phase. The transport mechanism can be well explained by the model of the Anderson localization. The ZT value increases abruptly with increasing temperature. At 1000 K, this ZT value is comparable with that of the sample with 8 wt % Ti.

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confidence: 93%

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confidence: 93%

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Thermoelectric properties of lanthanum sesquisulfide with Ti additive

Ohta

Hirai

Kato

et al. 2005

Applied Physics Letters

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“…The reported preparation route for the Sm 2 S 3 consists of the sulfurization of Sm 2 O 3 using CS 2 or H 2 S gas [5][6][7][8][9]. However the Sm 2 S 3 powder prepared using CS 2 gas contains the impurities of oxygen and carbon [7], and the preparation temperature is too high.…”

Section: Introductionmentioning

confidence: 99%

Preparation of Sm2S3 thin films by liquid phase deposition method with self-assembled monolayers

Yan-chao

Huang

Zhou

et al. 2012

Journal of Alloys and Compounds

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“…19) This occurs because titanium is an efficient deoxidizer and desulfurizer. Furthermore, theLa 2 S 3 phase is stabilized at low temperature by doping with alkali metals and alkali earth metals.…”

Section: Introductionmentioning

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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Phase transformation from tetragonal-phase to cubic-phase due to addition of titanium in lanthanum sesquisulfide

Cited by 14 publications

References 8 publications

Thermoelectric properties of lanthanum sesquisulfide with Ti additive

Thermoelectric properties of lanthanum sesquisulfide with Ti additive

Preparation of Sm2S3 thin films by liquid phase deposition method with self-assembled monolayers

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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