Electronic structure, thermomechanical and phonon properties of inverse perovskite oxide (Na₃OCl): An ab initio study

Abstract

Summary Within first principles calculations, the electronic structure, thermodynamic, mechanical stability, magnetism, and phonon properties of the inverse perovskite (Na3OCl) have been summed up. The Birch‐Murnaghan derived lattice constant and bond‐lengths are identical, when compared to the experimental data. A direct energy gap of 2.18 eV observed from the band structure reveals the semiconducting nature of the present oxide. Also, the application of strain on electronic properties predicts the decrease in bandgap with respect to compressive strain and vice versa. The constituent nonmagnetic atoms in its crystal propose the total magnetic moment to be zero and the same is supported by susceptibility data. In addition to the negative Cauchy's pressure, the small bulk modulus compared to Young's modulus determined from elastic constants, possibly claims it as a brittle material. Also, the temperature dependent Gruneisen parameter (1.58) and Debye temperature (382.27 K) are determined to reveal the lattice thermal conductivity (κ = 6.48 W/mK) at room temperature.

The structural stability, lattice dynamics, electronic, thermophysical, and mechanical properties of the inverse perovskites A 3 OX: A comparative first‐principles study

“…All the three Li‐based Antiperovskite Li 3 OX(X = Cl, Br, and I) are vibrationally stable, as can be evident from Figure 8A‐C and have a positive frequency. In the Na‐based inverse perovskite, Na 3 OCl is dynamically unstable which is also reported by other studies 18,73 . For the A 3 OX materials follow the relation of 3 N ‐3 in which N = 5 represents the number of atoms in the primitive unit cell of the inverse A 3 OX perovskite.…”

“…To calculate the ground‐state properties of the A 3 OX materials, we have performed geometrical optimization by varying the volume and then fitting it into the Birch‐Murnaghan's equation of state 54 . The DFT calculated ground state lattice parameters are provided in Table 1 which are in well agreement with the available previous theoretical and experimental studies 18,20,21 . It can be evident from Table 1 that the lattice constants, bulk modulus, and volume of the A 3 OX materials increase as the atomic number of the elements (A = Li, Na, K and X = Cl, Br, I) increases whereas the pressure derivative of the bulk modulus decreases.…”

“…8 Indeed, antiperovskites have acquired a lot of interest due to their numerous interesting properties such as giant negative thermal expansion, 9,10 superconductivity, 11,12 giant magnetoresistance, 13 magnetocaloric effects 14 and magnetostriction, 15 and other utilities. Recent examples of antiperovskites which have drawn interest during the past decade include Sr 3 SnO, 16 Li 3 OCl, 17 Na 3 OCl, 18,19 Na 3 OBr, 20,21 f-electron antiperovskites, 22 Gd 3 AlX(X = B, N), 23 and organicinorganic hybrid antiperovskites. 3,4,24,25 Recent studies have also pointed out that some inverse nitrides and oxides are potential contenders pertaining to topological crystalline insulators 26 and 3D massless Dirac electron systems.…”

“…19,21 In 2002, Zinenko et al 39 studied the phonon spectra and lattice dynamics of the A 3 OX (where A = Na, K and X = Cl, Br) materials by employing the generalized Gordon-Kim method. Interestingly, while various several properties are discovered experimentally, but to our best knowledge, only a couple of theoretical studies 18,20 are dedicated to the cubic A 3 OX (A = Li, Na, K and X = Cl, Br, I) antiperovskite materials and also thermoelectric properties are not explored up till now. So far, there is still no DFT investigations are made on the K 3 OX (X = Cl, Br, and I) regarding their electronic structure, elastic and thermoelectric properties though it can easily enhance our understanding which can facilitate the several applications on these state-of-the-art A 3 OX materials.…”

“…We have focused particularly on the structural stability of the A 3 OX materials by calculating their cohesive and formation energies along with the elastic and vibrational properties to reveal the potential multifunctional device applications. Our selection of materials have been motivated by recent results by other authors for similar compounds Na 3 OCl 18 and Na 3 OBr. 20 Our obtained lattice parameters are wellmatched with available studies.…”