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Ternary cobalt-based metal oxide (ZnCo2O4) has been successfully coated onto aluminum substrate via sol–gel method. The coatings were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and UV–Vis–NIR spectrophotometry. Thermal degradation of the coatings was probed by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). Model of crystal growth kinetics and density functional theory (DFT) calculations further probed the crystalline structure evolution. The predicted ZnCo2O4 crystalline structures were confirmed by XRD and EDX. The grain growth kinetic model for ZnCo2O4, derived from Lifshitz–Slyozov–Wagner (LSW) theory, determined that the growth of crystalline phases is unaffected by the annealing temperature; however, the crystallites' sizes decreased with the increase in precursor concentration. DFT analysis indicated that structural energy stability between the bulk state and slabs of ZnCo2O4 was at two oxygen layers (O-layers) with an optimum grain width of 17.21 Å. Interestingly, the morphology of ZnCo2O4 represented a rose-like template structure formed by inter-connecting layers of nanosheets. This unique surface morphology enhanced the optical absorptance properties up to α = 70.7%. Highlights: The kinetics, structural and absorptance properties of zinc and cobalt mixed oxides are not well understood due to lack of prior consolidated research findings. Therefore, our research focuses on the formation, grain growth kinetics, mineralogical and surface structure, as well as the absorptance properties of zinc and cobalt mixed oxides coating on aluminum substrates. This represents a novel holistic analysis within the ambit of sol-gel science. Furthermore, the novelty involves the incorporation of the experimental results complemented by grain growth kinetics modelling using LSW model and simulation of the grain size against the coating thickness of ZnCo2O4. We also developed a model at a smaller scale and utilized the density functional theory (DFT) to calculate the stability of each case in the model. [ABSTRACT FROM AUTHOR]

The equilibrium structure, elastic constants Cij and thermodynamic functions of cubic titanium nitride (TiN) were calculated within the temperature range of 0-3100 K and under a pressure range 0-60 GPa. Properties were computed using the generalised gradient approximations (GGA) exchange-correlation functional. Calculated mechanical properties (Elastic constants, Young's modulus and shear modulus) and phonon spectra of TiN obtained via robust DFT-QHA algorithm, were generally in a good agreement with available experimental and theoretical analogous values. In particular, a well-examined quasi-harmonic approximation method implemented in the Gibbs2 code is utilised herein to provide accurate estimation of thermal expansion coefficients, entropies, heat capacity values (at different combinations of temperature/volume/pressure) and Debye's temperature. Parameters calculated herein shall be useful to elucidate the superior performance of TiN at harsh operational conditions encompassing elevated temperatures and pressures pertinent to cutting machineries and surface coatings. [ABSTRACT FROM AUTHOR]

This contribution investigates structural and electronic properties as well as stability phase diagrams of surfaces of the cubic boron nitride (c-BN). Our calculated parameters for bulkc-BN agree reasonably well with both experimental and computed values available in the literature. Based on the energies of the three experimentally recognised phases of bulk boron, i.e.α-B36,β-B105andγ-B28, we estimate enthalpy of formation ofc-BN to be −2.8 eV. Thec-BN(1 0 0) surface offers separate B and N terminations (denoted asc-BN(1 0 0)_B and c-BN(1 0 0)_N), whereasc-BN(1 1 1) andc-BN(1 1 0) are truncated with combinations of boron and nitrogen atoms (denoted asc-BN(1 1 1)_BN andc-BN(1 1 0)_BN). Optimised geometries of surfaces display interlayer displacements up to the three topmost layers. Downward displacement of surface boron atoms signifies a common geometric feature of all surfaces. Bulkc-BN and its most stable surfacec-BN(1 0 0)_N possess no metallic character, with band gaps of 5.46 and 2.7 eV, respectively. We find that, onlyc-BN(1 0 0)_B configuration exhibits a metallic character.c-BN(1 1 0)_BN andc-BN(1 1 1)_BN surfaces display corresponding band gaps of 2.5 and 3.9 eV and, hence, afford no metallic property. [ABSTRACT FROM PUBLISHER]

Doping metallic element(s) serves as an effective approach in enhancing favorable electronic properties of graphene. Derived by a wide array of applications in electronic devices, addressing graphene-metal interactions have been in the center of mounting research over the last few years. Nevertheless, pertinent literature has overlooked the effect of geometrical, orientation and positional aspects of such doping systems on estimated electronic properties. In this contribution, we deployed DFT periodic slab calculations to investigate effect of orientational dependence of Al- and Si-adsorbed graphene systems. We utilized 2 × 2 and 2 × √3 graphene supercells with 1:8 (Al, Si: C) atomic ratio. We observed that the relative orientation of adsorbent atoms exerts profound influence on electronic structures in conjunction with a matching effect caused by the distinct adsorption sites (i.e. bridge, hollow or top). The orientation effects of Si-adsorbed graphene on electronic structure are greater than their Al analogous structures. We anticipate our finding herein, of low adatom concentration on graphene, to prompt re-examination of metal-graphene systems to account for the previously unnoticed - but significant - orientational effect that adds an additional degree of freedom to elemental adsorption on graphene. [ABSTRACT FROM AUTHOR]