BaCuTP2 (T = Al, Ga, In): a semiconducting black sheep in the ThCr2Si2 intermetallic family

Sarkar, Arka; Porter, Andrew P.; Viswanathan, Gayatri; Yox, Philip; Earnest, Rae Ann; Wang, Jian; Rossini, Aaron J.; Kovnir, Kirill

doi:10.1039/d4ta01063a

Cited by 2 publications

(1 citation statement)

References 66 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Dense polycrystalline pellets (94–95%) were used for thermoelectric property measurements in the range of 10–623 K (Figure ). The break-points in all the plots in Figure around room temperature is due to a change in the instruments and methods used, which is a common observation for combining data from two different instruments . All three compounds show a positive Seebeck coefficient throughout the temperature range, establishing holes as the majority carriers (Figure a).…”

Section: Resultsmentioning

confidence: 94%

ABa₆Cu₃₁Te₂₂ (A = K, Rb, Cs) Featuring Polyanionic Copper–Telluride Frameworks with Ultralow Thermal Conductivity

Sarkar,

Cerasoli,

Viswanathan

et al. 2024

ACS Appl. Mater. Interfaces

Self Cite

View full text Add to dashboard Cite

Three polyanionic tellurides, ABa 6 Cu 31 Te 22 (A = K, Rb, Cs), were synthesized in salt flux. The isostructural tellurides crystallize in a new structure type, in the cubic Pa3 space group with a Wyckoff sequence of d 10 c 2 b 1 and large unit cell volumes of over 5500 Å 3 . The structures feature a framework of [CuTe 4 ] tetrahedra and [CuTe 3 ] trigonal pyramids with disorder in the Cu sites. The polyanionic frameworks have large square antiprism and cuboctahedral voids where Ba and alkali metal cations are situated, forming [BaTe 8 ] and [ATe 12 ], respectively. The overall compositions are close to being charge balanced. The large [ATe 12] cuboctahedra allowed for significant anisotropic displacement of the A cations, as observed from both single crystal X-ray diffraction and heat capacity studies. Alkali cations rattling together with Cu atom displacement and disorder leads to the dispersion of phonons, thus softening the lattice and subsequently reducing the thermal conductivity. Evaluations of the electronic band structure revealed the occurrence of a narrow bandgap together with the presence of a flat band near the valence band maximum, giving rise to the high thermopower. The Cs and Rb analogues show a slope change in the temperature dependence of electrical resistivity around room temperature, which is typical for semimetals or degenerate semiconductors. For the as-synthesized and unoptimized materials, high values of the thermoelectric figure-of-merit of ∼0.2 were observed at 623 K.

show abstract

Section: Resultsmentioning

confidence: 94%

ABa₆Cu₃₁Te₂₂ (A = K, Rb, Cs) Featuring Polyanionic Copper–Telluride Frameworks with Ultralow Thermal Conductivity

Sarkar,

Cerasoli,

Viswanathan

et al. 2024

ACS Appl. Mater. Interfaces

Self Cite

View full text Add to dashboard Cite

show abstract

Cause, Consequence, and Control of Ag Vacancies in BaAg_2–xAs₂

Kyveryga,

Yox,

Viswanathan

et al. 2024

Inorg. Chem.

View full text Add to dashboard Cite

The impact of transition metal (Ag) deficiencies on the structural and transport properties of ThCr 2 Si 2 -type arsenides are investigated. We experimentally confirm a partial occupancy of Ag in BaAg 2−x As 2 , which can be predictably controlled within 0.053(5) ≤ x ≤ 0.19(1) by varying the quenching temperature during the crystal growth. Density functional theory calculations reveal that substoichiometric concentrations of Ag lower the density of states at the Fermi level, providing an electronic cause for the tendency of Ag to form vacancies. This vacancy concentration is linked to a characteristic kink in electrical resistivity that can be substantially shifted from 22 to 125 K and is established as the metric of a low-temperature structural phase transition (SPT) in BaAg 2−x As 2 . Along with electrical resistivity, the Seebeck coefficient and heat capacity for selected BaAg 2−x As 2 samples are presented, which also exhibit anomalies due to the SPT.

show abstract

BaCuTP₂ (T = Al, Ga, In): a semiconducting black sheep in the ThCr₂Si₂ intermetallic family

Abstract: The ThCr2Si2 structure type has been well explored for decades with diverse magnetic, superconducting, and heavy-fermion behavior. For transition metal-containing ThCr2Si2-type compounds, metallic band structure and properties are typical. In...

Cited by 2 publications

References 66 publications

ABa₆Cu₃₁Te₂₂ (A = K, Rb, Cs) Featuring Polyanionic Copper–Telluride Frameworks with Ultralow Thermal Conductivity

ABa₆Cu₃₁Te₂₂ (A = K, Rb, Cs) Featuring Polyanionic Copper–Telluride Frameworks with Ultralow Thermal Conductivity

Cause, Consequence, and Control of Ag Vacancies in BaAg_2–xAs₂

Contact Info

Product

Resources

About

BaCuTP2 (T = Al, Ga, In): a semiconducting black sheep in the ThCr2Si2 intermetallic family

Abstract: The ThCr2Si2 structure type has been well explored for decades with diverse magnetic, superconducting, and heavy-fermion behavior. For transition metal-containing ThCr2Si2-type compounds, metallic band structure and properties are typical. In...

Cited by 2 publications

References 66 publications

ABa6Cu31Te22 (A = K, Rb, Cs) Featuring Polyanionic Copper–Telluride Frameworks with Ultralow Thermal Conductivity

ABa6Cu31Te22 (A = K, Rb, Cs) Featuring Polyanionic Copper–Telluride Frameworks with Ultralow Thermal Conductivity

Cause, Consequence, and Control of Ag Vacancies in BaAg2–xAs2

Contact Info

Product

Resources

About

BaCuTP₂ (T = Al, Ga, In): a semiconducting black sheep in the ThCr₂Si₂ intermetallic family

ABa₆Cu₃₁Te₂₂ (A = K, Rb, Cs) Featuring Polyanionic Copper–Telluride Frameworks with Ultralow Thermal Conductivity

ABa₆Cu₃₁Te₂₂ (A = K, Rb, Cs) Featuring Polyanionic Copper–Telluride Frameworks with Ultralow Thermal Conductivity

Cause, Consequence, and Control of Ag Vacancies in BaAg_2–xAs₂