First-principles calculations of inherent properties of Rb based state-of-the-art half-Heusler compounds: promising materials for renewable energy applications

Abstract

In the present work, we have studied structural, electronic, optical and thermoelectric properties of Rb based state-of-the-art materials RbYZ (Y=Be, Mg, Ca, Sr and Ba; Z=P, As, Sb and Bi) having 8 valence electron count (VEC) using density functional theory followed by solution of Boltzmann transport equation with constant relaxation time approximation. The exchange and correlation potential are described by the GGA of Wu and Cohen (GGA-WC); the Becke-Johnson approach modified by Tran and Blaha (TB-mBJ) has been used to model the exchange-correlation potential. The bandgap of these materials lies in the range of 0.201 eV-2.591 eV. The various optical parameters are comparable with the state-of-the-art photovoltaic materials. Thermoelectric properties have been computed at 300 K, 600 K and 900 K. At these temperatures lattice thermal conductivity have been computed using Slack's model. This detailed study shows that these compounds are promising for renewable energy applications.

Theoretical investigation of electronic, mechanical, piezoelectric and thermodynamic properties of half-heusler LiBeAsxSb1-xalloys

“…At larger temperatures, for T > 500 K, C V is closer to the Dulong-Petit limit (C V (T)~3nR ≅ 74.8 J.mol −1 .K −1 ), suggesting that the thermal energy at large temperatures excite all phonon modes. A similar trend has been reported previously for other semiconducting materials [47][48][49][50]. As one goes across LiBeSb→LiBeAs 0.25 Sb 0.75 →LiBeAs 0.50 Sb 0.50 →LiBeAs 0.75 Sb 0.25 →LiBeAs, the behavior of the Cv remained qualitatively almost similar.…”

LiAlTt (Tt = Si, Ge): Experimental and Theoretical Reinvestigation on the Thermoelectric Properties of 8-Valence-Electron Half-Heusler Compounds

“…In addition, LiAlGe featured a rather low thermal conductivity (2.4 W·m –1 ·K –1 ) compared to that of LiAlSi (10 W·m –1 ·K –1 ) at 400 K, which was quite abnormal considering the similar structure of LiAlGe and LiAlSi. On the contrary, theoretical investigations on the electronic structures and thermoelectric properties of such 8-VEC compounds were much more focused on. − For example, Zhang et al listed 488 hypothetical ABX-type compounds and explored their structure and thermodynamic stability . Alam et al presented a high-throughput ab initio study on 8-VEC HH alloys, suggesting that AgPMg and LiAlGe could be promising candidates for thermoelectric applications. , In 2018, Shah et al theoretically predicted a figure of merit ( zT ) of 0.1 for LiAlGe at 400 K, which was obviously higher than that of other 8-VEC HH compounds .…”

Ab-Initio Calculations of Structural, Optoelectronic, Thermoelectric, and Thermodynamic Properties of Mixed-Halide Perovskites RbPbBr3−xIx (x = 0 to 3): Applicable in Renewable Energy Devices

“…In this process, we have plotted a graph for the diverse volume of the unit cell alongside corresponding energies per unit cell, the optimized curves are presented in Fig. 2 for RbPbBr 3−x I x (x = 0 to 3) and adapted to Birch-Murnaghan's equation of state 25,26 which is as follows:…”