Magnetic and thermoelectric properties of the ternary pseudo-hollandite Ba_xCr₅Se₈(0.5 < x < 0.55) solid solution

Abstract

The structure of Ba0.5Cr5Se8 has been recently resolved, and its thermoelectric and magnetic properties have been studied. A ZT of 0.12 was found at around 800 K. Here, we report a study on the pseudo-hollandite BaxCr5Se8 solid-solution with 0.5 ≤ x ≤ 0.55 and its thermoelectric and magnetic properties. There is no significant impact either on the cell parameters depending on the cation content or on the magnetic properties. However, thermoelectric properties are radically changed depending on x content. While the low thermal conductivity, around 0.8 W m(-1) K(-1), remains similar for all samples, a respective increase and decrease of the resistivity and the Seebeck coefficient are observed with increasing Ba content. The maximum Seebeck coefficient is found with Ba0.5Cr5Se8 at around 635 K with 315 μV K(-1), and the Seebeck coefficient then decreases and is correlated with an activation of minority charge carriers confirmed by Hall measurements. A similar but steeper behavior is observed for the Ba0.55Cr5Se8 temperature dependence plot at around 573 K. Finally, the best thermoelectric performances are found using the lowest content of Ba, unlike when x tends to 0.55, ZT approaches a tenth of the initial best value. BaxCr5Se8 compounds are antiferromagnetic with TN = 58 K. A large peak in thermal conductivity is observed around the antiferromagnetic transition for all stoichiometry.

Substitution of indium for chromium in TlIn5−xCrxSe8: crystal structure of TlIn4.811(5)Cr0.189(5)Se8

“…Pseudo-hollandites are compounds with general formula AM 5 X 8 , (A = alkali metal, alkaline earth metal, Tl; M = V, Ti, Cr; X = S, Se, Te), the structures of which are made up from CdI 2 -type layers and double chains of MX 6 octahedra sharing edges and faces in such a way that channels are created along one axis in which the A cations are located. Monoclinic TlCr 5 Se 8 and the related triclinic compound Ba 0.5 Cr 5 Se 8 have thermal conductivities well below 1 W m À1 K À1 from room temperature to 873 K (Lefè vre et al, 2015(Lefè vre et al, , 2016. As part of our project, we successfully synthesized a solid solution of TlV 5-x Cr x Se 8 (x = 0, 1, 2, 3, 4, 5) and studied the magnetism and thermoelectric properties of TlV 5 Se 8 (Maier et al, 2015).…”

Synthesis, Crystal and Electronic Structure, and Thermal Conductivity Investigation of the Hollandite-like CsxCr5Te8 Phases (0.73 < x < 1)

“…Such structural features are particularly attractive in the field of thermoelectricity where a very low thermal conductivity is required . Indeed, the lattice component (κ l ) of the thermal conductivity is primarily governed by phonon scattering which is generally large in highly complex structures. , Consequently, an efficient strategy to reach low thermal conductivity is to aim at synthesizing low-dimensional structures containing large scattering centers in order to reduce effectively the phonon mean free path. − This is the case, for instance, of the chromium chalcogenide compounds Tl x Cr 5 Se 8 and Ba 0.5 Cr 5 Se 8 , which exhibit remarkably low thermal conductivities of 0.7 and 0.8 W m –1 K –1 at 300 K, respectively. Motivated by these findings, we have conducted a complete study on related compounds possessing similar structural features with the aim of exploring their potential in thermoelectric applications.…”

Temperature‐dependent electrical transport behavior and structural evolution in hollandite‐type titanium‐based oxide

“…[1][2][3][4][5][6] Among the numerous hollandites, titaniumbased materials have attracted considerable attention due to their improved light scattering properties, chemical stability, biological inertness, ion exchangeability, and good ionic conduction, 7,8 enabling the development of a series of new functional ceramic materials. [1][2][3][4][5][6] Among the numerous hollandites, titaniumbased materials have attracted considerable attention due to their improved light scattering properties, chemical stability, biological inertness, ion exchangeability, and good ionic conduction, 7,8 enabling the development of a series of new functional ceramic materials.…”

“…Hollandites belong to a well-known family of materials with many potential applications in energy, environment and catalysis fields. [1][2][3][4][5][6] Among the numerous hollandites, titaniumbased materials have attracted considerable attention due to their improved light scattering properties, chemical stability, biological inertness, ion exchangeability, and good ionic conduction, 7,8 enabling the development of a series of new functional ceramic materials. [9][10][11][12][13] In addition to the use of solid matrices for the immobilization of radioactive cesium and anode materials for lithium-ion batteries, [14][15][16][17] hollandite K x Ti 8 O 16 with large (2 × 2) tunnels could accommodate a large number of sodium ions and facilitate Na + diffusion in sodium ion batteries.…”