Thermoelectric Properties of p-Type Cu₂O, CuO, and NiO from Hybrid Density Functional Theory

Abstract

The electronic transport coefficients of three Earth-abundant metal oxides Cu2O, CuO, and NiO were investigated using hybrid density functional theory (DFT). Hybrid DFT methods combined with local Gaussian-type basis sets enabled band structure studies on both non-magnetic and magnetic p-type metal oxides without empirical corrections. The CRYSTAL code was used for obtaining the wavefunction, and the transport properties were calculated with two different methodologies to benchmark their accuracy: a numerical approach as implemented in the BoltzTraP code and an analytical approach recently implemented in CRYSTAL17. Both computational methods produce identical results in good agreement with experimental measurements of the Seebeck coefficient. The predicted electrical conductivities are overestimated, owing likely to the used approximation of a constant electronic relaxation time in the calculations, as explicit electron scattering is neglected and relaxation time is considered only as a free parameter. The obtained results enable us to critically review and complement the available theoretical and experimental literature on the studied p-type thermoelectric metal oxide materials.

Ultralow Thermal Conductivity and Large Figure of Merit in Low-Cost and Nontoxic Core–Shell Cu@Cu2O Nanocomposites

“…So far, good oxide TE materials are p-type conduction NaCo2O4, NaxCoO2 and Ca3Co4O9+δ and n-type conduction SrTiO3, CaMnO3 and ZnO 9 . In this context, significantly large value of S in ptype cuprous oxide Cu2O with direct band gap (~ 2.17 eV) 10 and melting point ~1508 K has been reported in experimentally 11,12,13,14,15 and theoretically 16,17 . For instance, Young et al 11 reported S around 1050 µV/K at 500 K for single crystalline Cu2O.…”

Influence of Impurities on the Front Velocity of Sputter Deposited Al/CuO Thermite Multilayers

“…It is important to remark, as depicted in Figure 1 , that the final layer of the stack is an aluminum layer. The electrical resistivity of bulk CuO (≈2.5 m [ 24 ]) is several orders of magnitude higher than the bulk resistivity of Al (2.650 × 10 −8 m [ 25 ]). Hence, it can safely be assumed that the electrical resistivity of the multilayer is defined by the film properties of Al because the resistivity of the multilayer can be approximated by a parallel circuit model [ 26 ].…”

Crystal Structure Prediction of Magnetic Transition-Metal Oxides by Using Evolutionary Algorithm and Hybrid DFT Methods

“…In particular, it has been shown that the electronic properties and the geometry of NiO are reliably described with hybrid DFT methods even though the band gap is overestimated. 14 , 71 For comparison, GGA-PBE functional severely underestimates the band gap of NiO, predicting a value of only 0.5 eV. 21 An interesting possibility for further improvement is the utilization of self-consistent hybrids, as implemented in CRYSTAL, in which case the amount of exact exchange is self-consistently obtained for different types of materials.…”

“…Transition-metal oxides play a crucial role in a wide range of applications from catalysis to electronics. 8 − 14 It is well known that standard generalized gradient approximation (GGA) functionals such as Perdew–Burke–Ernzerhof (PBE) fail to correctly treat the magnetic moments and electronic structure of systems such as strongly correlated transition-metal oxides, sometimes even favoring a wrong magnetic ground state. 15 − 22 Even in the case of nonmagnetic transition-metal oxides such as Cu 2 O, the band structure may not be correctly described by GGA functionals.…”