Charge transport mechanisms in layered perovskite ACr2O7 (A= Be, Mg, Ca, Ba) structures: DFT perspectives
Journal of Energy Storage
First-principles calculations were performed to analyze the effects of oxygen vacancies (Vo) and the combined effect of Vo and copper doping on layered perovskites ACr2O7 (A = Be, Mg, Ca, Ba), to enhance the performance of resistive switching (RS) materials in non-volatile and low-power memory devices using PBE-GGA and HSE06 functionals. This study examined the structural, thermodynamic, elastic, electronic and optical properties. Formation energy is calculated to check the stability of all studied structures. Negative values of formation energy confirm that all studied layered perovskites is stable. Formation energy of BaCr2CuO7+Vo layered perovskite is lowest (−2.72 eV) as compared to other studied structures. Moreover, phonon calculation is also performed to confirm the thermodynamic stability of all investigated layered perovskites. Absence of negative frequency at gamma point confirms the thermodynamic stability of all studied structures. Elastic constant are calculated to check mechanical stability of all structures. Result of mechanical properties show that all layered perovskite structures is ductile, making these structures promising candidate for the fabrication of nanodevice. Electronic properties are calculated using PBE-GGA and HSE06 functionals, and compare the results with each other. HSE06 functional gives more accurate results as compared to PBE-GGA. By using the HSE06 functional, band gaps of Be-based compounds are 2.31 eV (BeCr2O7), 0.51 eV (BeCr2O7+Vo), and 0.15 eV (BeCr2CuO7+Vo). In the case of Mg-based systems, the corresponding band gaps are 2.70 eV, 0.80 eV, and 0.60 eV, respectively. The Ca-based structures exhibit band gaps of 2.61 eV for pristine CaCr2O7, 2.52 eV for CaCr2O7+Vo, and 0.30 eV for CaCr2CuO7+Vo. Lastly, for Ba-based compounds, the calculated band gaps are 2.66 eV (BaCr2O7), 0.96 eV (BaCr2O7+Vo), and 0.098 eV (BaCr2CuO7+Vo). These results clearly demonstrate that the introduction of oxygen vacancies leads to a reduction in the band gap, while the combined effect of copper doping and oxygen vacancies causes a more pronounced decrease. Among all the studied configurations, the BaCr2CuO7+Vo layered perovskite exhibits the lowest band gap. Optical properties are carried out using PBE-GGA, and HSE06 functional. Among all investigated layered perovskites, BaCr2CuO7+Vo exhibits the lowest band gap, along with high structural, mechanical, and thermodynamic stability, as well as high conductivity and absorption coefficient. These combined features indicate that BaCr2CuO7+Vo is promising candidate material for Resistive Random Access Memory (RRAM) applications.
Optimizing electronic structures and incorporating additional active sites in metal oxides can significantly enhance the performance of the oxygen evolution reaction (OER), which is a pivotal…
First-principles calculations were performed to analyze the effects of oxygen vacancies (Vo) and the combined effect of Vo and copper doping on layered perovskites ACr2O7 (A = Be, Mg, Ca…
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