Oxynitride Perovskite: Computational Approach to Correlate Structural, Electronic, and Optical Properties of c-BiAlO₃/N₃

Abstract

A detailed theoretical study is carried out to explore the effects of oxynitrides while considering cubic bismuth aluminate with different concentrations of nitrogen from x = 0 to x = 3. This report evaluates the structural, total, and partial densities of states (TDOS/PDOS), modification in the electronic band gap, and optical properties due to the inclusion of nitrogen based on the ab-initio method with generalized gradient approximation (GGA) as implemented in CAmbridge Serial Total Energy Package (CASTEP). All the structural parameters of BiAlO3 agree well with earlier reported values. A change in the perfect cubic structure of BiAlN3 is observed for 100% nitrogen substitution. Pure BiAlO3 is found to have an indirect band gap of 1.487 eV along with the high symmetry points between the 2p orbital of O and the 6p orbital of Bi. Reduction in band gap is reported with increasing concentration of N, due to which the material tends to behave like a conductor at a point and then the electronic band gap begins to increase as the impurity concentration increase passes this point, mainly as a consequence of the nonlinear band gap dependence on the composition of the material. A density of state (DOS) study concludes the existence of covalent bonding between O–Bi and O–Al with strong hybridization. There is an increase in the contribution of these orbitals informing energy states as the nitrogen atoms successively add up in the material BiAlO3–x N x . The BiAlN3 compound, having a perfect cubic structure, is reported here for the first time. Numerous optical characteristics have been studied comparatively at different concentrations of N, with the report that BiAlN3 has a higher value of the refractive index than bismuth aluminate, with amended optical behavior. The trend of these optical properties with respect to nitrogen concentration is also demonstrated. We propose this cubic phase of BiAlN3 as a potential material for optoelectronic applications.

Chemical vapor deposition towards atomically dispersed iron catalysts for efficient oxygen reduction

“…2b) suggest a high-intensity ratio of the D band to the G band of Fe-SA/NC catalysts, indicative of the abundant carbon defects and low graphitization degree. 33 X-ray photoelectron spectroscopy (XPS) was employed to confirm the component and surface chemical states of Fe-SA/NC catalysts. The full XPS survey spectrum (Fig.…”

One-Step Urothermal Synthesis of Li+-Intercalated SnS2 Anodes with High Initial Coulombic Efficiency for Li-Ion Batteries

“…As a comparison, Table S1 lists the rate performances of SnS 2 -based lithium-ion battery anode materials reported in the past, where the excellent rate capability of Li 0.4 SnS 2 is higher than reported for pure SnS 2 or even SnS 2 composites. The stable structure is the guarantee of excellent electrochemical performance. − The nanostructure stabilities of Li 0.4 SnS 2 and SnS 2 electrodes after cycling are investigated using ex situ SEM (Figure S4). Li 0.4 SnS 2 maintains the platelike morphology while the morphology of flowerlike SnS 2 collapses, demonstrating that Li + insertion/extraction into/from Li 0.4 SnS 2 is the topotactic reaction and its nanostructure is stable than that of SnS 2 after 100 cycles.…”

Stability and degradation of (oxy)nitride photocatalysts for solar water splitting

“…[117][118][119][120][121] Additionally, oxynitrides with varying N and O ionic composition ratios or cationic components give rise to a wide variety of mechanical, electronic, and optical properties. 58,59,[122][123][124] Highthroughput screening combined with DFT calculations can be used to explore the vast space of chemical compositions and structures, and to rapidly screen for potential oxynitrides with optimal properties for a given chemical composition. 116,125 In summary, the stability of photocatalysts is assessed based on short-and long-term performance measurements.…”