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DFT is used to study various transition metal based ceramics LiAA′O 6 (A = Nb, Ta, and A′ = W, Mo) in tetragonal phase with space group 421 m (No. 113). The calculated structural and geometrical parameters are found in closed agreement with the experiments. Electronic clouds explain the chemical bonding and reveal that Li atom occupy central position and form ionic bond. Other bonds in these compounds are significantly covalent due to the sharing of electrons between O and A/A′. The electronic properties demonstrate that these compounds are wide bandgap semiconductors in the energy range of 2.18–2.60 eV. These bandgap energies confirm the suitability of these oxides in optoelectronic devices operating in the visible range of the electromagnetic spectrum. [ABSTRACT FROM AUTHOR]

Abstract: The structural, electronic and optical properties of AgTF3 (T=Mg, Zn) are calculated for the first time using the full-potential linearized augmented plane wave method within the generalized gradient approximation. Structural parameters of the compounds are found to be in reasonable agreement with the available literature. Both compounds are found to have narrow and indirect band-gaps. The calculated band gap for AgMgF3 is 0.78eV and 0.75eV for AgZnF3. It is observed that Ag-4d, Zn-3d and Ag-5s states controls the electronic properties of AgMgF3 and AgZnF3. The nature of chemical bonding in these compounds is discussed by the electron density plots. The results of complex dielectric constant, refractive index, normal-incidence reflectivity and optical conductivity are also presented in the incident photon energy range of 0–35eV. The wide absorption energy range makes these materials suitable for different devices applications. [Copyright &y& Elsevier]

[Display omitted] • A new class of MX 2 (M = Mo, W; X = S, Se) monolayers with general formula MXY or XMY, have been successfully synthesized by chemical vapor deposition of Se(S) in MoS 2 (MoSe 2). • Optimized ZrSSe, HfSSe monolayers and ZrSSe/HfSSe vdW heterostructure are indirect band gap semiconductors. • A transition from an indirect to direct band gap is achieved for tensile strain of 6(8)% for ZrSSe(HfSSe) monolayer. • ZrSSe, HfSSe monolayers and type-II ZrSSe/HfSSe vdW heterostructure heterostruture under tensile strain are efficient photocatalysts. We investigated the effects of biaxial strain on electronic structure of ZrS 2 , ZrSe 2 , HfS 2 , HfSe 2 , ZrSSe and HfSSe monolayers. Similar to ZrS 2 , ZrSe 2 , HfS 2 , HfSe 2 monolayers, Janus ZrSSe and HfSSe monolayers are indirect bandgap semiconductors. Tensile strain of 6(8)% transform ZrSSe(HfSSe) monolayer to direct bandgap semiconductor. Based on the calculation of binding energies and interlayer distance staking-(c) is found to be the most stable configuration for ZrSSe/HfSSe vdW heterostructure. Unstrained ZrSSe/HfSSe vdW heterostructure in staking-(c) is a type-II indirect bandgap semiconductor. Valence and conduction band edges show that under tensile strain ZrSSe, HfSSe and ZrSSe/HfSSe vdW heterostructure are efficient photocatalysts. [ABSTRACT FROM AUTHOR]