Growth and properties of lantanum and rare-earth metal sesquisulfide crystals

Kamarzin, A.A.; Mironov, K. E.; Соколов, В. В.; Malovitsky, Yu.; Vasilyeva, I.G.

doi:10.1016/0022-0248(81)90351-1

Cited by 50 publications

(16 citation statements)

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“…Moreover, each rare-earth site is surrounded by eight sulfur sites with two different nearest-neighbor distances. 16,17 The third advantage is that the melting point in the case of the c-phase is more than 2000 K. 4,9,18,19 Such a high melting point allows for high operating temperatures.…”

Section: Introductionmentioning

confidence: 98%

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] An important advantage of the c-phase is that its carrier concentration can be altered to optimize the thermoelectric power factor by changing its chemical composition. This is because the c-phase forms the cubic defect Th 3 P 4 -type structure with metal vacancies, which is written as Ln 2 V 0.25 S 3 (Ln 2.67 V 0.33 S 4 , where Ln is a rare-earth metal and V is a metal vacancy).…”

Section: Introductionmentioning

confidence: 99%

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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: 98%

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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“…5,12,[19][20][21] An important advantage of the c-phase is that the carrier concentration can be altered by changing the composition so as to optimize the Seebeck coefficient and electrical resistivity. The c-phase exists over a wide compositional range, from stoichiometric, Ln 2 X 3 (Ln = rare-earth metal; X = S, Se, or Te), to nonstoichiometric, Ln 2.25 X 3 .…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric Properties of NdGd1+x S3 Prepared by CS2 Sulfurization

Ohta

Hirai

2009

Journal of Elec Materi

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Ternary rare-earth sulfides NdGd 1+x S 3 , where 0 £ x £ 0.08, were prepared by sulfurizing Ln 2 O 3 (Ln = Nd, Gd) with CS 2 gas, followed by reaction sintering. The sintered samples have full density and homogeneous compositions. The Seebeck coefficient, electrical resistivity, and thermal conductivity were measured over the temperature range of 300 K to 950 K. All the sintered samples exhibit a negative Seebeck coefficient. The magnitude of the Seebeck coefficient and the electrical resistivity decrease systematically with increasing Gd content. The thermal conductivity of all the sintered samples is less than 1.9 W K À1 m À1 . The highest figure of merit ZT of 0.51 was found in NdGd 1.02 S 3 at 950 K.

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“…Very few optical studies on these compounds have been reported up to now, 9 and the optical absorption edge region 5,10-12 has been even less considered as compared to the far infra-red or ultra-violet ranges. This may be due both to the difficulties of preparation of pure stoichiometric RE 2 S 3 single crystals, [13][14][15] and to the lack of electronic structure models involving the 4f states. We have chosen in this work to compare the optical properties in the visible and near infra-red ranges of the two compounds Ce 2 S 3 ͑1 f electron͒ and Gd 2 S 3 ͑7 f electrons͒, which look red and purple, respectively.…”

Section: Introductionmentioning

confidence: 99%

Comparative optical studies of Ce2S3 and Gd2S3 compounds

Witz

Huguenin

Lafait

et al. 1996

Journal of Applied Physics

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A detailed comparative study of the optical properties of two rare-earth (RE) sesquisulfide compounds γ−Ce2S3 and γ−Gd2S3, shows that if the two compounds have about the same main absorption edge corresponding to band-to-band S 3p-RE 5d transitions, Ce2S3 exhibits an additional absorption band at lower energies. This band, which is ascribed to the presence of Ce 4f states at the top of the valence band, explains the difference in color between the two compounds.

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Growth and properties of lantanum and rare-earth metal sesquisulfide crystals

Cited by 50 publications

References 2 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

Thermoelectric Properties of NdGd1+x S3 Prepared by CS2 Sulfurization

Comparative optical studies of Ce2S3 and Gd2S3 compounds

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