Preferential Growth Research Articles

〈111〉-orientation growth of Tb-Dy-Fe alloys induced by high magnetic fields during directional solidification

The 〈110〉 and 〈112〉 directions are the preferred growth directions of the magnetic phase in Tb-Dy-Fe alloys, but the 〈111〉 direction is the easy magnetization axis direction, and the 〈111〉-oriented alloy exhibits superior magnetostrictive behavior. In this study, Tb-Dy-Fe alloys with 〈111〉 orientation were prepared by directional solidification (i.e., the master alloy was completely melted) under high magnetic fields. The competition between the preferred growth direction and the easy magnetization direction was resolved, leading to enhanced magnetostrictive properties. During the initial solidification stage, the magnetic torque induced the 〈111〉 orientation in the magnetic phases generated by direct precipitation of the liquid phase and pseudo-eutectic reactions to rotate in the direction of the magnetic field. In the subsequent competitive growth process, 〈111〉-oriented grains grew parallel to the magnetic field direction under the influence of magnetocrystalline anisotropy energy. This work enriches the theory of magnetic orientation during directional solidification, providing novel insights into the preparation of highly oriented functional materials.

Residual Stress Mitigation in Perovskite Solar Cells via Butterfly-Inspired Hierarchical PbI2 Scaffold.

Residual stress in metal halide perovskite films intimately affects the photovoltaic figure of merit and longevity of perovskite solar cells. A delicate management of the crystallization kinetics is critical to the preparation of high-quality perovskite films. Only very limited methods, however, are available to regulate the residual stress of a perovskite film in a controllable manner, particularly for a perovskite film fabricated by a two-step method. Here, we demonstrate the construction of a hierarchical PbI2 scaffold inspired by Archaeoprepona demophon butterfly by combining an interlayer guided growth of porous structure and nanoimprinting. The hierarchically structured PbI2 that emulates the physical structure of the butterfly wing scale permits unimpeded permeation of organic amine salts and sufficient space for volume expansion during the crystallization process, accompanied by preferential perovskite growth of a defectless (001) crystal plane. The optimized perovskite film outperforms the control with reduced residual stress and defect density. Consequently, perovskite solar cells with a respectable power conversion efficiency reaching 23.4% (certified 23%) and an impressive open-circuit voltage of 1.184 V can be achieved. The target device can maintain 80% of initial efficiency after maximum power point tracking under illumination for 700 h. This work expands the range of engineering toward PbI2 by exploring a simultaneously tailored morphology and crystallinity and highlights the significance of a hierarchical PbI2 scaffold as an alternative choice to mitigate residual stress in a two-step processed perovskite active layer and boost the longevity of perovskite solar cells.

Effect of growth temperature on properties of β-Ga2O3 films grown on AlN by low-pressure chemical vapor deposition

In this work, thin films of β-Ga2O3 were prepared on AlN substrates using low-pressure chemical vapor deposition (LPCVD). The effects of growth temperature on the crystal structure, surface morphology, chemical composition, and photoluminescence properties of the synthesized β-Ga2O3 thin films were then systematically investigated. The results indicated that various films grown at different temperatures in the range of 550–850 °C had a preferred growth orientation in the planar direction (−201). The surface roughness was seen to reduce gradually as the growth temperature was raised. However, excessive temperature (850 °C) led to a reduction in the densification of the prepared films. The surface chemistry of the films was analyzed using X-ray photoelectron spectroscopy (XPS) and the O/Ga ratio of the optimal film was calculated to be 1.49, which is quite close to the optimal stoichiometric ratio of 1.5. Multiple luminescence bands were obtained in the photoluminescence spectra of the films taken at room temperature, where the blue emission formed the dominant bands. The results of the study suggest that the growth temperature has a significant impact on the film properties and that appropriately increasing the growth temperature leads to substantial improvement in the overall quality of the β-Ga2O3 thin films.

Helium plasma irradiation on Nickel: Nanostructure formation and electrochemical characteristics

Nanotechnology offers new avenues for the design, fabrication, and application of novel materials. Helium plasma exposure is a technique that can be used to fabricate self-supported metallic nanostructures. In this work, we explore the plasma irradiation conditions for fabricating various morphologies on planar nickel surfaces, and evaluate the electrochemical performance of these surfaces for oxygen evolution reaction (OER) in alkaline media. The preferential growth towards certain morphologies such as nano-pillars, nano-blocks, and micro-structures, is found to be primarily influenced by the applied plasma conditions and two counteracting processes of sputtering and annealing. The plasma treatment increased the electrochemical surface area of the modified samples by approximately 3 to 4 times as compared to the planar/unmodified surfaces, along with an increase in the OER performance for all morphologies. However, in addition to the increased surface area, the electrochemical performance was found to be dependent on the shape, size and thickness of the nano/micro-features. Moving ahead, the ability of this technique to achieve control over the feature size along with its effectiveness for a broad range of metals offers new routes for nanostructuring and functionalization of emerging materials.

Microstructure regulation and performance of titanium alloy coating with Ni interlayer on the surface of mild steel by laser cladding

The preparation of Ti-alloy coating on the steel surface via laser cladding is very easy to form Fe-Ti phase and large tensile residual stress, which is not conducive to the performance of Ti-alloy coating. Here, Ti-6Al-4V coating (TC4-coating) was prepared on the mild steel substrate using laser cladding technology with Ni-alloy as the interlayer, and the Fe-Ti phase inside was completely suppressed. Increasing the powder feeding rate and scanning speed can change the undercooling of the alloy melt and the preferred growth orientation of the grains, while limiting the abnormal grain growth and grain boundary segregation, which is beneficial for grain refinement and equiaxed crystal formation. Reducing the scanning speed and powder feeding rate can increase the molten pool lifetime, thereby increasing the dilution rate of the coating and facilitating the formation of Ti2Ni phase. The abundant Ti2Ni inside the coating gives the TC4-coating greater microhardness (>500 HV0.1) and better corrosion resistance (Icorr of 7.00 × 10−8 A·cm−2). Grain refinement of the coating texture caused by the increase of powder feeding rate and scanning speed, as well as the high content of β-Ti phase and martensite structure, can improve the adhesion and shear strength of TC4-coating (386 ± 31 MPa).

Entrepreneurial management, competitive advantage and SME performance: evidence from an emerging economy

PurposeThere is a paucity of empirical studies on the impact of entrepreneurial management on small and medium enterprises (SME) performance. Against this backdrop and drawing upon the resource-based view, this study aims to explore the relationship between entrepreneurial management and SME performance and the mediating role of competitive advantage in an emerging economy.Design/methodology/approachThis study adopted a survey research design and a quantitative approach. A self-reported questionnaire was used to collect data from a conveniently selected sample of 174 manufacturing SMEs in Nigeria. This study performed mediation analysis to test the proposed hypotheses using Hayes’ PROCESS macro v4.FindingsThe findings indicate that entrepreneurial management positively impacts competitive advantage and SME performance. Furthermore, competitive advantage has a positive impact on SME performance and plays a significant mediating role in the relationship between entrepreneurial management and SME performance.Research limitations/implicationsThis study only examines manufacturing SMEs in a single country, Nigeria; thus, the generalisability of its findings is limited.Practical implicationsThe findings of this study offer practical implications for SMEs and SME owners or managers. The findings suggest that to gain a sustainable competitive advantage and achieve superior performance, SMEs should pursue opportunities regardless of the available resources, promote flat and flexible organisation structures, adopt fast growth orientation and strategies, reward employees based on the value they add to the organisation and foster an entrepreneurial culture.Originality/valueTo the best of the authors’ knowledge, this study is the first to provide empirical evidence of the mediating effect of competitive advantage on the relationship between entrepreneurial management and SME performance in an emerging economy. This study demonstrates that implementing entrepreneurial management practices by SMEs can result in sustainable competitive advantage and superior performance.

Dual-template textured BNT-based ceramics with ultra-low electrostrain hysteresis

The biggest difficulty facing the grain growth (TGG) method is the compatibility between template and ceramic matrix. Different templates show great differences in texture degree. Consider the limitation of conventional single-template method, the strategy of dual-template textured ceramics and sintering aids were introduced in this work. With the addition of ST and NN templates into BNT system, the texture degree is higher than 90% and the electrostrain reach ∼ 0.5% with ultra-low hysteresis ∼ 15%, which cannot be realized in single template textured ceramics. The two templates and sintering aids play different roles in grain orientation growth, which is important for the compatibility among matrix and templates, leading to unique microstructures. Sintering processes clearly reveal the growth mechanism of textured ceramics under the joint action of two templates, and of course, the sintering aids are also indispensable. Regard to domain structure, the polar nanoregions can respond quickly under electric field, providing assistance for the realization of ultra-low hysteresis.

Hydrated eutectic electrolyte promotes the preferential growth of Zn (0 0 2) plane and suppresses side reaction for high-stability zinc anodes

Using deep eutectic solvent (DES) electrolytes is an efficient way to suppress the Zn dendrite growth and the side reactions resulting from the high activity of H2O in aqueous zinc-ion batteries (ZIBs). However, most DESs consist of expensive/explosive zinc salts or flammable/toxic organic ligands, which hinders their practical application in ZIBs. Herein, a low-cost and high-safety hydrated eutectic electrolyte based on ZnCl2, urea, and a small amount of H2O is prepared. Due to the low content of H2O and the strong intermolecular interaction between urea and H2O, the activity of H2O is greatly restricted and therefore H2O-induced side reactions are improved. In addition, X-ray photoelectron spectroscopy spectra and density functional theory calculations reveal that the adsorption of urea molecules on the zinc surface forms an organic protective layer, which can induce the preferential growth of the Zn (0 0 2) plane. As a result, with the optimal electrolyte, the Zn||Zn symmetric cell shows a long cyclic life of 1200 h, and the Zn||Cu half-cell delivers a high average Coulombic efficiency of 99.7 % for 2500 cycles. Meanwhile, the Zn||Bi2Te3 and Zn||polyaniline full cells with DES exhibit improved cycling performances compared to those using traditional ZnSO4 electrolyte. This work offers a new perspective to explore low-cost, non-toxic, and high-security DESs for ZIBs.

Synergistic tailoring of adsorption and vacancy enrichment in lamellar stacked layers of α-MoO3 nanorods by Mg2+ for NO2 gas sensor

Extremely toxic nitrogen dioxide (NO2) was detected using lamellar layered α-MoO3. The stable orthorhombic phase of MoO3 (α-MoO3) with preferential growth along (02k0) and the nano-rectangular rods (NRs) like morphology were observed. The incorporation of Mg2+ in α-MoO3 influenced the morphology and the oxygen vacancies (VO), which were analyzed through Raman, photoluminescence, and X-ray photoelectron spectroscopy. The core level spectra provided direct evidence for VO enrichment in 3 %Mg-α-MoO3 via emergence of peak at 531.02 eV with an area of 45.15 %. NO2 response was analyzed at 150–200 °C with various NO2 concentrations. 3 %Mg-α-MoO3 NRs provided maximum response of 133.9 % for 50 ppm with low limit of detection (LOD) of 250 ppb with good response (193 s) and recovery (260 s) transient behaviors. The fabricated sensor shows high selectivity to NO2 among H2S, SO2, N2O, and NH3, also good repeatability suggesting potential suitability for NO2 detection.

Anisotropic optoelectronic properties of lead-free Cs3Bi2I9 single-crystal photodetectors

Lead-free halide perovskites have attracted widespread research interest due to their excellent optoelectronic properties and environmental friendliness. As one of the bismuth iodide compounds, Cs3Bi2I9 perovskite has been extensively explored in the field of photovoltaic devices and radiation detectors due to their non-toxic lead-free components and excellent stability. In this work, we successfully grow large-sized Cs3Bi2I9 single crystals (SC) with (l00) and (00l) crystal exposure facets by inverse temperature crystallization method. Under 525 nm light illumination with the intensity 15 mW cm−2 and 7 V bias, the (l00) Cs3Bi2I9 SC shows 2 times higher photocurrent, 3.6 times higher responsivity, and 2.8 times higher detectivity than the (00l) Cs3Bi2I9 SC, respectively. Superior response time in the scale of millisecond is obtained in both (l00) and (00l) Cs3Bi2I9 SCs. Based on the first-principle calculation, the (l00) SC possesses a higher charge distribution density and a wider dispersion distribution than (00l) SC, suggesting that more electrons in the (l00) SC can be excited in a wider range. The tighter arrangement of Cs+ and [BiI6]− octahedra in the (l00) SC than (00l) SC leads to the anisotropic photoelectric performance in (l00) and (00l) Cs3Bi2I9 SCs. Our results provide a strategy for the oriental growth of Cs3Bi2I9 SCs and the design of anisotropic optoelectronic devices with excellent performance.

Uniaxial‐Stress Driven Performance Enhancement of Multi‐Beam Spark Plasma Sintered BiSbTe/Epoxy Flexible Films

AbstractThe multi‐beam discharge plasma sintering (MB‐SPS) method is successfully applied to the preparation of Bi2Te3‐based thermoelectric (TE) films with insulating substrates. Herein, the impact of uniaxial stress on the microstructure evolution and TE performance are explored systematically. The results indicate that the increase of uniaxial stress promotes the preferential growth of Bi0.5Sb1.5Te3 (BST) grains along the (000l) crystal plane, leading to the remarkable increase in carrier mobility. The maximum (000l) preferential orientation factor reaches 80% for the BST/epoxy (EP) film sintered under 25 MPa, which is 3.08 times higher than that of BST/EP film sintered at 10 MPa. While the highest power factor reaches 2.36 mW m−1 K−2 at 300 K for the BST/EP film sintered under 20 MPa, increased by 97% as compared with that of the film sintered under 10 MPa. This work once again confirms that the MB‐SPS technology is an effective approach to prepare high‐performance Bi2Te3‐based films with insulating substrates and demonstrates that the (000l) preferential orientation and TE performance of the films can be further enhanced by an appropriate uniaxial stress.

Directed growth of quinacridone chains on the vicinal Ag(35 1 1) surface.

The formation of self-assembled domains and chains of monomolecular width of quinacridone (QA) on the vicinal Ag(35 1 1) surface was investigated by scanning tunneling microscopy and low-energy electron diffraction. The focus was on the influence of the steps on the QA structures and their preferential azimuthal orientations with the aim of achieving a selective orientation. After deposition at a sample temperature of 300 K, QA forms the same kind of molecular chains as on the nominally flat Ag(100) surface because of strong intermolecular hydrogen bonds, which we reported in a previous publication [Humberg, N.; Bretel, R.; Eslam, A.; Le Moal, E.; Sokolowski, M. J. Phys. Chem. C 2020, 124, 24861-24873]. The vicinal surface leads to one additional chain orientation, which is parallel to the Ag step edges. However, most chains nucleate on the Ag terraces between steps with four distinct azimuthal orientations that are identical to those on Ag(100), and which are determined by the interactions with the (100) surface. At 300 K, the chains grow across the Ag steps, which do not break the azimuthal chain orientations. In contrast, during the deposition at sample temperatures of 400 and 500 K, the nucleation of the chains takes place at the Ag step edges. Hence, these have a strong influence on the azimuthal orientation of the molecules, resulting in a preferential growth of the chains in two of the four azimuthal orientations. We explain this by the adaptation of favorable adsorption sites, which involve the replacement of Ag atoms by QA molecules with specific azimuthal orientations at the step edges.

Research on cobalt-molybdic sulfide composite coatings deposited by magnetic jet electrodeposition under different magnetic field intensities

Co-MoS2 composite coatings were deposited by the magnetic jet electrodeposition under different magnetic field intensities. The growth orientation and deposition mechanism of Co-MoS2 composite coatings under magnetic jet electrodeposition were analyzed based on the weak adsorption theory of nanocomposite co-deposition. Research showed that the coating topography changed from a blade-like structure to a cellular structure, and the cellular structure became a granular protrusion structure with increase of the magnetic field intensity. Compared with Co-MoS2 composite coating in jet electrodeposition, the orientation of Co shifted from (110) to (101) as the magnetic field intensity increased in magnetic jet electrodeposition. The adhesion, microhardness, adhesion, corrosion and wear resistance of the composite coatings were enhanced, which was attributed to the influence of the magnetic field on the growth orientation of the composite coating and the coordinated lubrication effect in the Co-MoS2 composite coating.

Effect of phosphorus-doping on ternesite: Structure, thermal stability and hydration

The successful synthesis of the solid solution Ca5(Si1-x/2O4)2S1-x/2PxO4 (C5S2S̅Px, x = 0.05, 0.10, 0.15, 0.20) was confirmed through analysis of X-ray diffraction and energy dispersive spectrometer data. Rietveld refinement revealed that the purity of ternesite can reach up to 99.42 % at a doping concentration of 5 %. Furthermore, changes in X-ray diffraction peaks and morphology suggest a shift in the preferred growth direction of crystallites as a result of the introduction of impurity element. The incorporation of P elements in C5S2S̅Px not only effectively reduces weight loss under high-temperature conditions but also elevates the temperature at which decomposition occurs. Isothermal calorimetry data indicates that C5S2S̅Px-CSA samples display higher cumulative heat release compared to C5S2S̅–CSA. Furthermore, the presence of C5S2S̅P0.20 accelerates the hydration kinetics of CSA cement by hindering ettringite formation. Moreover, varying levels of phosphorus doping in C5S2S̅Px have resulted in enhanced compressive strength at various ages of CSA cement maturation.

Biomimetic-inspired piezoelectric ovalbumin/BaTiO3 scaffolds synergizing with anisotropic topology for modulating Schwann cell and DRG behavior

The treatment of peripheral nerve injury is a clinical challenge that tremendously affected the patients' health and life. Anisotropic topographies and electric cues can simulate the regenerative microenvironment of nerve from physical and biological aspects, which show promising application in nerve regeneration. However, most studies just unilaterally emphasize the effect of sole topological- or electric- cue on nerve regeneration, while rarely considering the synergistic function of both cues simultaneously. In this study, a biomimetic-inspired piezoelectric topological ovalbumin/BaTiO3 scaffold that can provide non-invasive electrical stimulation in situ was constructed by combining piezoelectric BaTiO3 nanoparticles and surface microtopography. The results showed that the incorporation of piezoelectric nanoparticles could improve the mechanical properties of the scaffolds, and the piezoelectric output of the scaffolds after polarization was significantly increased. Biological evaluation revealed that the piezoelectric topological scaffolds could regulate the orientation growth of SCs, promote axon elongation of DRG, and upregulate the genes expression referring to myelination and axon growth, thus rapidly integrated chemical-mechanical signals and transmitted them for effectively promoting neuronal myelination, which was closely related to peripheral neurogenesis. The study suggests that the anisotropic surface topology combined with non-invasive electronic stimulation of the ovalbumin/BaTiO3 scaffolds possess a promising application prospect in the repair and regeneration of peripheral nerve injury.

Synthesis of microporous titanium surface with aligned pores through changes of currents during electrochemical process

This paper reports the synthesis of microporous Ti surfaces with aligned pores by applying a different current during electrochemical process for application in cell-surface interaction study and biomedical implants. As the microporous Ti surfaces were synthesized by current from (0.5–4)A, the microstructure of the Ti surfaces was shifted from a relative smooth to microporous one that was observed to have an aligned pore surface. Optical images showed that the micropore sizes in ∼(85.4–224.4)µm. The roughness of the microporous Ti was significantly higher than that of the Ti by a factor of approximately 5 to 7. Confocal laser scanning microscope showed excellent cell attachment and preferential growth on the microporous Ti with aligned channels after 72 h of culturing which could be important for cell-surface interactions study and biomedical implants.

Characterization of the interfacial structure and fracture behavior of in situ synthesized ceramics to reinforce Ni-based composite coatings

This work used the in-situ synthesis of molten-state nitride ceramic phase-reinforced Ni-based alloy coatings, aiming to improve the phase-interface bonding through the interdependent co-solidification between molten droplets. The XRD was used to analyze the physical phases of the composite coatings. The microstructure and phase-interface structure were characterized in detail by combining SEM, TEM, HRTEM, FFT, and SAED techniques. Microhardness tester and microforce microhardness tester were employed to measure the surface hardness and elastic modulus of the composite coatings. The fracture behavior of the composite coatings was characterized by observing the fracture morphology of the coatings using SEM combined with the EDS technique. It was found that the formation mechanisms of interfacial misfit dislocation assistance, lattice distortion, aggregation of stacking faults, and specific growth orientation between the γ-Ni matrix phase and each ceramic phase in NiCrBSi-TiCrN composite coatings improved the lattice matching between the two-phase interface, which resulted in the formation of atomically corresponding coherent lattice relations and stepped interfacial semi-coherent lattice relations, and enhanced the degree of phase-interface bonding. On this basis, the composite coatings with high Cr content further inhibited the expansion of interphase penetration cracks due to the existence of Cr-rich zones at the phase interface, thus exhibiting high fracture toughness. This work provides new opinions on the improvement of phase-interface bonding and composition design of Ni-based composite coatings.

Symmetry Engineering of Epitaxial Hf0.5Zr0.5O2 Ultrathin Films.

Robust ferroelectricity in HfO2-based ultrathin films has the potential to revolutionize nonvolatile memory applications in nanoscale electronic devices because of their compatibility with the existing Si technology. However, to fully exploit the potential of ferroelectric HfO2-based thin films, it is crucial to develop strategies for the controlled stabilization of various HfO2-based polymorphs in nanoscale heterostructures. This study demonstrates how substrate-orientation-induced anisotropic strain can engineer the crystal symmetry, structural domain morphology, and growth orientation of ultrathin Hf0.5Zr0.5O2 (HZO) films. Epitaxial ultrathin HZO films were grown on the heterostructures of (001)- and (110)-oriented La2/3Sr1/3MnO3/SrTiO3 (LSMO/STO) substrate. Various structural analyses revealed that the (110)-oriented substrate promotes a higher degree of structural order (crystallinity) with improved stability of the (111)-oriented orthorhombic phase (Pca21) of HZO. Conversely, the (001)-oriented substrate not only induces a distorted orthorhombic structure but also facilitates the partial stabilization of nonpolar phases. Electrical measurements revealed robust ferroelectric properties in epitaxial thin films without any wake-up effect, where the well-ordered crystal symmetry stabilized by STO(110) facilitated better ferroelectric characteristics. This study suggests that tuning the epitaxial growth of ferroelectric HZO through substrate orientation can improve the stability of the metastable ferroelectric orthorhombic phase and thereby offer a better understanding of device applications.

Cell-Autonomous and Non-Cell-Autonomous Mechanisms Concomitantly Regulate the Early Developmental Pattern in the Kelp Saccharina latissima Embryo.

Brown algae are multicellular organisms that have evolved independently from plants and animals. Knowledge of the mechanisms involved in their embryogenesis is available only for the Fucus, Dictyota, and Ectocarpus, which are brown algae belonging to three different orders. Here, we address the control of cell growth and cell division orientation in the embryo of Saccharina latissima, a brown alga belonging to the order Laminariales, which grows as a stack of cells through transverse cell divisions until growth is initiated along the perpendicular axis. Using laser ablation, we show that apical and basal cells have different functions in the embryogenesis of this alga, with the apical cell being involved mainly in growth and basal cells controlling the orientation of cell division by inhibiting longitudinal cell division and thereby the widening of the embryo. These functions were observed in the very early development before the embryo reached the 8-cell stage. In addition, the growth of the apical and basal regions appears to be cell-autonomous, because there was no compensation for the loss of a significant part of the embryo upon laser ablation, resulting in smaller and less elongated embryos compared with intact embryos. In contrast, the orientation of cell division in the apical region of the embryo appears to be controlled by the basal cell only, which suggests a polarised, non-cell-autonomous mechanism. Altogether, our results shed light on the early mechanisms of growth rate and growth orientation at the onset of the embryogenesis of Saccharina, in which non-cell-specific cell-autonomous and cell-specific non-cell-autonomous processes are involved. This complex control differs from the mechanisms described in the other brown algal embryos, in which the establishment of embryo polarity depends on environmental cues.

Crystal orientation of epitaxial film deposited on silicon surface

Direct growth of oxide film on silicon is usually prevented by extensive diffusion or chemical reaction between silicon (Si) and oxide materials. Thermodynamic stability of binary oxides is comprehensively investigated on Si substrates and shows possibility of chemical reaction of oxide materials on Si surface. However, the thermodynamic stability does not include any crystallographic factors, which is required for epitaxial growth. Adsorption energy evaluated by total energy estimated with the density functional theory predicted the orientation of epitaxial film growth on Si surface. For lower computing cost, the adsorption energy was estimated without any structural optimization (simple total of energy method). Although the adsorption energies were different on simple ToE method, the crystal orientation of epitaxial growth showed the same direction with/without the structural optimization. The results were agreed with previous simulations including structural optimization. Magnesium oxide (MgO), as example of epitaxial film, was experimentally deposited on Si substrates and compared with the results from the adsorption evaluation. X-ray diffraction showed cubic on cubic growth [MgO(100)//Si(100) and MgO(001)//Si(001)] which agreed with the results of the adsorption energy.