DFT based study on structural stability and transport properties of Sr 3 AsN: A potential thermoelectric material
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DFT based study on structural stability and transport properties of Sr3AsN: A potential thermoelectric material Enamul Haque1,a)
M. Anwar Hossain1
1
Department of Physics, Mawlana Bhashani Science and Technology University, Santosh, Tangail-1902, Bangladesh Address all correspondence to this author. e-mail: [email protected]
a)
Received: 13 February 2019; accepted: 1 April 2019
Antiperovskite materials are of high research interest because of their unusual physical properties and technological applications. Here, we report the structural stability and transport properties of Sr3AsN from firstprinciples study. The calculated equilibrium lattice parameters are in good agreement with the available data. We find that Sr3AsN is mechanically, energetically and dynamically stable at ambient conditions. Our calculated electronic structure indicates that it is a direct band gap semiconductor, with a band gap value ;1.2 eV. Sr-4d and N-2p orbitals predominantly contribute to the formation of the direct band gap. The calculated Seebeck coefficient of Sr3AsN is high (298 lV/K at 300 K), while the lattice thermal conductivity is comparatively low (1.73 W/m K). The considerable mass difference between Sr, As, and N gives rise to an intense phonon scattering that results in such low lattice thermal conductivity. Our calculated maximum thermoelectric figure of merit (ZT) is 0.75 at 700 K, indicating that it is a potential material for thermoelectric device applications.
Introduction The search for new high-performance thermoelectric materials has been extensively performed because such materials are very useful in practical energy conversion applications [1]. The efficiency of thermoelectric materials and devices can be characterized by a dimensionless quantity ZT, defined as 2 [2, 3] ZT ¼ S krT , where the quantities S, r, k 5 ke 1 kl and T, stand for Seebeck coefficient, electrical conductivity, thermal conductivity (sum of the electronic and lattice contribution) and temperature, respectively. Generally, semiconductors have high Seebeck coefficient and low thermal conductivity. Antiperovskite materials, such as Sr3SbN is a semiconductor with a band gap value of ;1.15 eV and predicted to have high Seebeck coefficient and power factor (PF) [4, 5]. Some other antiperovskites have small band gap (0–1) [6–10]. Most of the high performance thermoelectric materials have a band gap around 0.5–1.5 eV [1, 11, 12, 13]. Therefore, the isotypic compound of Sr3SbN may have band gap within this range and hence, they may show high thermoelectric conversion efficiency. Sr3AsN, an isotypic compound of Sr3SbN, was predicted by Beznosikov, from the analysis of chemical bonding and admissible atomic radius [14]. Recently, some authors have
ª Materials Research Society 2019
reported the elastic, electronic and optical properties of Sr3AsN, without considering its energetic and dynamic stability [15, 16, 17]. The dynamical stability is an essential criterion for a compound to be synthesized successfully in the laboratory [18]. Some compounds coul
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