Thermoelectric properties of lanthanum sulfide with Sm, Eu, and Yb additives

Abstract

The Seebeck coefficient and electrical resistivity have been measured for the La3−x Mx S4 alloys with the Th3 P4 -type structure for M=Sm, Eu, Yb, and x=0.1 to 0.9 in order to determine their potential as high-temperature thermoelectric energy conversion materials. An analysis of the lattice parameters of these alloys suggests that Sm has a valence of 2.2 over the entire composition range. Furthermore, the variation of the Seebeck coefficient and electrical resistivity as a function of electron concentration is different for the Sm-doped alloys than for the Eu- and Yb-doped alloys, which are all different from that of the pure binary LaSy alloys. A maximum in the electrical power factor at 1000 °C is found to occur at x ≂ 0.3, but when a reasonable estimate is made of the thermal conductivity the maximum in the figure-of-merit at 1000 °C shifts to larger x values (∼0.7) in all alloy systems. The long term stability of the Sm and Eu ternaries is also reported.

Crystal chemistry and thermoelectric properties of Gd2Te3

“…In particular, the chalcogenides crystallizing with the cubic Th3P 4 structure have received a great deal of attention because the solidsolution compositions extending from Ln2X 3 to Ln3X 4 have this structure and the physical parameters can be varied continuously as the cation vacancies in Ln2X 3 are filled to form the end member Ln3X4. The cation vacancies can be filled with the same or other rareearth elements as well as a great number of non-rareearth metals (Carter, Miller & Ryan, 1961;Taher & Gruber, 1981;Nakahara, Tschetter, Beaudry, Takeshita & Gschneidner, 1986). The published phase diagram of Gd-Te shows such a solid-solution region, Gd2Te3-Gd3Te 4, and electrical resistivity and Seebeck coefficients have been reported (Zargaryan & Abrikosov, 1967;Reid, Matson, Miller & Himes, 1964).…”

Thermoelectric Properties of Non-stoichiometric Titanium Oxides for Waste Heat Recovery in Steelworks

“…In the last three decades, Si-Ge alloys, 2) several metal chalcogenides, 3,4) transition-metal disilicides [5][6][7] and some boron compounds 8,9) have attracted attention and have been developed as materials for high-temperature thermoelectrics. [10][11][12] However, the abovementioned materials have never been applied practically because of expensive surface protection required to prevent oxidation or vaporization and/or inherent temperature limitation due to phase transformation at high temperatures.…”

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>

“…[1][2][3][4][5][6][7][8][9][10][11] However, in order to apply these materials to thermoelectric devices for smallscale refrigeration and power generation, it is required to prepare thin films. A majority of the previous studies have been confined to the investigation of bulk materials.…”