Structural, electronic, optical and elastic properties of the complex K₂PtCl₆-structure hydridesARuH₆(A= Mg, Ca, Sr and Ba): first-principles study

Abstract

We report a systematic study of the structural, electronic, optical and elastic properties of the ternary ruthenium-based hydrides A 2 RuH 6 (A = Mg, Ca, Sr and Ba) within two complementary first-principles approaches. We describe the properties of the A 2 RuH 6 systems looking for trends on different properties as a function of the A sublattice. Our results are in agreement with experimental ones when the latter are available. In particular, our theoretical lattice parameters obtained using the GGA-PBEsol to include the exchange-correlation functional are in good agreement with experiment. Analysis of the calculated electronic band structure diagrams suggests that these hydrides are wide nearly direct band semiconductors, with a very slight deviation from the ideal direct-band gap behaviour and they are expected to have a poor hole-type electrical conductivity. The TB-mBJ potential has been used to correct the deficiency of the standard GGA for predicting the optoelectronic properties. The calculated TB-mBJ fundamental band gaps are about 3.53, 3.11, 2.99 and 2.68 eV for Mg 2 RuH 6 , Ca 2 RuH 6 , Sr 2 RuH 6 and Ba 2 RuH 6 , respectively. Calculated density of states spectra demonstrates that the topmost valence bands consist of d orbitals of the Ru atoms, classifying these materials as d-type hydrides. Analysis of charge density maps tells that these systems can be classified as mixed ionic-covalent bonding materials. Optical spectra in a wide energy range from 0 to 30 eV have been provided and the origin of the observed peaks and structures has been assigned. Optical spectra in the visible range of solar spectrum suggest these hydrides for use as antireflection coatings. The single-crystal and polycrystalline elastic moduli and their related properties have been numerically estimated and analysed for the first time.

Formation of a Complex Active Center by Ba2RuH6 for Nondissociative Dinitrogen Activation and Ammonia Formation

“…The conventional unit cell of Ba 2 RuH 6 is shown in Figure a, where ionic Ru binds with six hydridic hydrogens forming octahedral [RuH 6 ] 4– anions that are stabilized by the surrounding Ba 2+ cations. In other words, the Ba 2+ cations form a K 2 PtCl 6 -type framework to isolate the electron-rich [RuH 6 ] 4– anions spatially . Based on the XRD pattern of Ba 2 RuH 6 (Figure b), three low-Miller-index surfaces including (111), (100), and (110) are cleaved from the primitive cell to explore the active surface of the Ba 2 RuH 6 catalyst, as shown in Figures c,d and S5.…”

“…In other words, the Ba 2+ cations form a K 2 PtCl 6 -type framework to isolate the electron-rich [RuH 6 ] 4− anions spatially. 21 Based on the XRD pattern of Ba 2 RuH 6 (Figure 2b), three low-Miller-index surfaces including (111), (100), and (110) are cleaved from the primitive cell to explore the active surface of the Ba 2 RuH 6 catalyst, as shown in Figures 2c,d and S5. By comparing the optimized structures, layered energies, and workfunctions of these three surfaces (Figures S5−S7 It can be learned that the pristine (100) is the most stable surface, and any vacancies formed on this surface cost considerable energy (Figure 2e).…”

Rubidium zinc trioxide perovskite materials for photovoltaic solar cell applications: A first principle calculations

“…Because of their potential in a technical range of uses asmemorycircuit chips, fuel cells, sensors, spintronics, and photocatalyst, they're also regarded as viable materials for electronic devices and communications as like for solar cells [ 10 , 11 ]. A desire to surpass the previous record of 31% has been prompted by creation of high temperature photocatalyst oxide [ 12 ] and raised perovskites solar cells with an energy converting efficiency of 21% [ 13 ]. Despite the fact that oxygen has been found in perovskites, some of them, such as oxide-perovskite, has the general formula ABO 3 , where O is oxygen.…”

A DFT study of structural, electronic, optical, thermal and mechanical properties of cubic perovskite KGeX3 (X = Cl, Br) compound for solar cell applications

“…Perovskite oxides are highly intriguing to research & employ on a massive scale because they illustrate the electrical capability parameters and processes in hard states, such as metallic, semiconducting, insulating, and superconducting characteristics [13,14]. Many ABO 3 perovskites have an approximately cubical form in their ideal form, but at relatively minimum temperatures, one or even more than one phase change could occur [15,16]. They also showed magnetic sorting in certain instances, producing a wide range of magnetic configurations [17,18].…”