First-principles calculations to investigate structural, electronic, magnetic, optical, mechanical and thermoelectric properties of rare-earth aluminate perovskite XAlO3 (X = Ce, Nd, Gd) compounds

Abstract

The spin-polarized full-potential linearized augmented plane wave (FP-LAPW) approach based on density functional theory (DFT) is used to investigate the structural, electronic, magnetic, optical, mechanical and thermoelectric properties of aluminate perovskite XAlO3 (X = Ce, Nd, Gd) compounds. For the exchange correlation potential, we used both GGA and mBJ approximations within the FP-LAPW approach as implemented in the Wien2k code. XAlO3 compounds are most stable in their ferromagnetic (FM) form, according to the findings of an analysis of the acquired structural optimization. The calculated negative value of the formation energy predicts that the present compounds are thermodynamically stable and could be formed. Moreover, the values of elastic constants fully satisfy the elastic and mechanical requirements. The tolerance factor of XAlO3 satisfies the condition of creation for the perovskite compounds. As all, these parameters show that XAlO3 are mechanically, elastically stable and could be created. The investigation of band structure and DOS confirms the presence of half metallic (HM) ferromagnetism (FM) in CeAlO3 and NdAlO3, as well as semiconductor behavior in GdAlO3. The HM energy gap (Eg) is 3.116 eV (GGA) and 3.156 eV (GGA + mBJ); 2.748 eV (GGA) and 2.803 eV (GGA + mBJ), respectively. The calculated net magnetic moments of CeAlO3, NdAlO3 and GdAlO3 are around 1.0 μB, 3.0 μB and 7.0 μB, respectively, indicating their ferromagnetic FM character. Magnetic characteristics of XAlO3 are mostly contributed by Ce, Nd and Gd atoms, which play a major role in FM properties. The optical properties of XAlO3 are investigated by calculating the real ε1(ω), imaginary ε2(ω) parts of dielectric function ε(ω), refractive index n(ω), extinction coefficient k(ω), reflectivity R(ω), optical conductivity σ(ω), absorption coefficient α(ω) and loss function L(ω). Also, the thermoelectric properties, Seebeck coefficient (S), electrical conductivity (σ/τ), power factor (S2σ/τ), thermal conductivity (κ/τ), figure of merit (ZT) and specific heat capacity (CV) are calculated and discussed. The current study confirms the mechanical and thermal stability of HM-FM perovskites, which candidate them for thermoelectric and spintronic applications.