Thermoelectric Properties of NdGd1+x S3 Prepared by CS2 Sulfurization

Abstract

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.

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

“…15 Our results indicated their significant potential for use as high-temperature thermoelectric materials: NdGd 1.02 S 3 exhibited a ZT value of 0.51 at 950 K.…”

“…The preparation method for the self-doped rareearth sulfides used in this study is almost the same as that used in previous studies. 6,14,15 The selfdoped ternary rare-earth sulfides LnGd 1+x S 3 (Ln: La, Sm) were prepared from the binary rare-earth sulfides and gadolinium hydride GdH 3 . A mixture of Ln 2 S 3 , Gd 2 S 3 , and GdH 3 (99.9%, Kojundo Chemical Laboratory Co.) powders was placed in graphite crucibles and reacted at 1573 K for 2 h under vacuum (10 À3 Pa).…”

“…[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).…”

High performance thermoelectrics for power generation using earth-abundant and low toxicity elements

“…The third strategy is to use chemically stable minerals as references for developing thermoelectric sulfides. To carry out these strategies, we have focused on copper (Cu)-containing sulfides; these would be widely rare-earth sulfide NdGd 1.02 S 3 , [16] titanium disulfide Ti 1.008 S, [18] layered sulfides (LaS) accepted in society because of their abundance and low toxicity of S and Cu.…”

Preparation of Single-Phase Pb-Filled Chevrel-Phase Sulfide and Its Thermoelectric Properties

“…[1][2][3][4][5] Thermoelectric materials are evaluated by thermoelectric figure of merit ZT ¼ ðS 2 T=Þ, where S is Seebeck coefficient, T is temperature, is electrical resistivity, and is thermal conductivity. The thermal conductivity can be separated into the electronic thermal conductivity e and the lattice thermal conductivity l , such that ¼ e þ l .…”