Thermal properties of BaCu2SnQ4 (Q = S, Se) quaternary chalcogenides

Abstract

Quaternary chalcogenides form in different structure types and compositions and are of scientific interest, while their diversity of physical properties exemplifies why they continue to be investigated for potential technological applications. We investigate the thermal properties of BaCu2SnQ4 with trigonal (Q = S) and orthorhombic (Q = Se) crystal structures. BaCu2SnS2Se2 was also synthesized and characterized in order to investigate the effect of alloying on the thermal properties of these quaternary chalcogenides. The low thermal conductivity these materials possess originates from complex phonon spectra and local dynamics of distorted CuQ4 tetrahedra. Our results and analyses are presented in light of the ongoing fundamental interest in these materials as well as their continued interest for energy-related and opto-electronic applications.

Sn(IV) Polyanionic Materials as Efficient Visible-Light-Driven Water-Splitting Photocatalysts

“…The bonding hierarchy, as in Zintl compounds, and the presence of Sn 4+ can turn K 2 Na 2 Sn 3 S 8 and Rb 3 NaSn 3 Se 8 into promising materials for mild-band-gap applications (≤3 eV), such as water splitting. The superiority of tin chalcogenides (Sn–Q bonds) for energy applications has been established mainly because of their high carrier mobility. , However, most studied tin chalcogenides are based on Sn 2+ , in which the hybridization of lone-electron pair (Sn-5s) with p-states of chalcogen atoms adds an extra state around the Fermi level that reduces the band gap. So, they are ideal for low-band-gap applications requiring high mobility such as thermoelectricity: SnSe with an energy gap of 0.86 eV shows the highest-record thermoelectric efficiency. , The presence of active lone-electron pairs on Sn 2+ also hints at why SnS has achieved only relatively poor performance on photovoltaic devices …”

“…The superiority of tin chalcogenides (Sn−Q bonds) for energy applications has been established mainly because of their high carrier mobility. 18,19 However, most studied tin chalcogenides are based on Sn 2+ , in which the hybridization of lone-electron pair (Sn-5s) with p-states of chalcogen atoms adds an extra state around the Fermi level that reduces the band gap. So, they are ideal for low-band-gap applications requiring high mobility such as thermoelectricity: SnSe with an energy gap of 0.86 eV shows the highest-record thermoelectric efficiency.…”

“…At first glance, they have a measured band gap of ≈2 eV and contain nontoxic and low-cost elements that are all key to energy materials: Sn, Q, and alkali metals. The element Sn has been critical in materials for energy-related applications such as thermoelectricity , as well as water splitting. − On the other hand, alkali metals enhance photocatalysts’ efficiency by improving charge separation and oxygen evolution reactions on the surface. , …”

Structural and thermal properties of ultralow thermal conductivity Ba3Cu2Sn3Se10

“…In particular, the thermal properties of these materials have been shown to be directly related to their specific structural features. [16][17][18][19][20] One aspect that motivates the interest in these materials is their bonding and structural arrangement, in particular the coordination preferences of the metal and chalcogen atoms that comprise complex structural features that can result in anharmonicity. Many atoms per unit cell result in a large number of optic modes that typically have lower group velocities than the acoustic modes that often dominate thermal transport.…”

“…In particular, the thermal properties of these materials have been shown to be directly related to their specific structural features. 16–20…”