NaBeAs and NaBeSb: Novel Ternary Pnictides with Enhanced Thermoelectric Performance

Abstract

Thermoelectrics is a clean energy technology that converts thermal energy into electrical energy and provides an environmentally friendly and viable route to produce electricity. In this work, we thoroughly explore the thermoelectric performance of two novel ternary pnictide compounds, NaBeAs and NaBeSb, using full ab initio calculations and solving linear Boltzmann transport equations. We predict that both compounds exhibit excellent dynamical and thermal stability. The combined effect of low phonon group velocity and weak bonding interaction results in intrinsic low lattice thermal conductivities of 1.41 and 0.59 W/mK for NaBeAs and NaBeSb, respectively, in the z-axis direction at 600 K. The electronic structure exhibits high conduction band degeneracy, which results in favorable electrical transport characteristics. The unique combination of very low lattice thermal conductivity and good electrical transport properties leads to excellent n-type thermoelectric properties. Furthermore, in n-type doping, the figures of merit reach 1.82 and 4.26 for NaBeAs and NaBeSb at 600 K. Our findings show that both compounds are promising n-type thermoelectric materials at medium temperatures.

Crystal and electronic structure of the ternary Zintl bismuthide BaLiBi

“…For BeNaAs and BeNaSb, the ZrBeSi structure type was reported [27,28] . However, in contrast to the Li‐containing AEAPn compounds with this structure, the alkaline‐earth metal site (Be in this case) adopts trigonal‐planar coordination by the Pn atoms, while the alkali metal atoms (Na) are located in the octahedral voids made up of the Pn atoms.…”

Probing the opto-electronic, phonon spectrum, and thermoelectric properties of lead-free fluoride perovskites A2GeSnF6 (A = K, Rb, Cs) for energy harvesting devices

“…The band structure is crucial due to the fact it may convey a material’s intrinsic physical characteristics, such as its thermoelectric, optical, photocatalytic, and other traits 43 . In the present research, GGA and mBJ have been employed to recognize the band structures of A 2 GeSnF 6 (A = K, Rb, Cs) while taking into account the optimized unit cell.…”

Theoretical Investigation of the Lattice Thermal Conductivities of II–IV–V2 Pnictide Semiconductors

“…The II–IV–V 2 ternary pnictides have been studied theoretically and experimentally for their potential applications in optoelectronic devices, including solar cells, due to their stability, dopability, high carrier mobility, and favorable optical absorption/emission properties. − Some of these properties also make them interesting materials for thermoelectric applications. Pnictide compounds often exhibit favorable electronic structures that enhance electrical transport, such as the coexistence of flat and highly dispersive bands near the Fermi level, which has motivated previous investigations of their thermoelectric properties. − …”