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To study the possibility of the use of Se-doped diamond films for biomaterial applications, first-principles calculations have been performed to evaluate the adsorption and migration of selenium (Se) atoms on a hydrogen-terminated diamond [H-Ter-D] (0 0 1) surface. The calculation results indicate that while a selenium atom generally cannot be stably adsorbed on the surface, it can bond to a surface carbon atom on the surface with one open radical site (1ORS), with an adsorption energy of 2.74 eV. Moreover, selenium atoms can combine with two surface C atoms, with adsorption energies from 4.10 eV to 4.67 eV. The migration activation energy of the selenium atoms on the surface is approximately 1.34 eV. A density of states examination presents an interesting result. On the surface of the 2ORS slabs, after bonding with two surface C atoms, the selenium atom no longer has any unpaired electrons, and its magnetic moment becomes 0 μB. In this case, a deposited carbon atom can combine with the selenium atom by a triple bond, and then the C Se molecule is desorbed from the surface. This outcome implies that the direct selenium doping method can only fabricate Se-doped diamond films with very low selenium incorporation.

In this paper, the adsorption and migration behaviors of nitrogen (N) atoms on the hydrogen -terminated diamond (0 0 1) surface [H-Ter-D (0 0 1) surface] were investigated. The adsorption energy, the electron charge and the magnetic moment were calculated through first principles methods. The investigation results show that on the fully H-Ter-D (0 0 1) surface, all surface C atoms have saturated bonds. However, the N atom can abstract the H atom from a surface carbon atom nearby or lead to the bond breaking of the dimer carbon atoms to form bonds with the surface carbon atoms. The maximum energy of adsorption reaches to 3.47 eV, corresponding to a stable configuration structure. The charge analysis and the density of state analysis further reveal that the N atom adsorbed has unpaired electrons, which provides the opportunity for adsorption of CH radicals. On the H-Ter-D (0 0 1) surface with one open radical site (1ORS) slab, the N atom can abstract the H atom from a surface carbon atom nearby and bond with the dimer carbon atoms. The adsorption energy rises to 4.85 eV. On the H-Ter-D (0 0 1) surface with the 2ORS slab, the activation energy for a N atom to migrate along the dimer chain to the next dimer is 1.31 eV. Moreover, the adsorption of the N atom on the 1ORS surface promotes the adsorption of a C atom nearby and improves the ability of C atom migration, which is beneficial for the growth of the diamond grains. According to the charge transform analysis, the electronegativity of N atoms plays an important role in their adsorption behaviors. In addition, when the N atom has been adsorbed on the H-Ter-D (0 0 1) surface, it could still be abstracted by the other deposited N atoms; this phenomenon may be the reason for a low deposition efficiency of N atoms in the N-doped diamond films.

This study aimed to determine the effects of Si doping in CeO2 (111) surface on the polishing performance. For this purpose, the structure and electronic properties of pure CeO2 (111) surface and Si-doped surface were calculated and compared by the first principles based on density functional theory. The reduction capabilities of the two surface systems were analyzed. Calculated results demonstrate that the ionic structure of Si-doped surface presents a symmetric change and that the formation energy of surface O vacancy decreases by 1.388 eV, indicating that Si doping is conducive for the reduction in surface system. Two electrons left by the O vacancy in the reduction system are obtained by the nearest 2 Ce4+, and the Ce4+ are reduced to Ce3+. After Si doping, the hybridization state between Si ion and adjacent Ce and O ions occurs at the Fermi level. Therefore, the synergistic effect of Si doping and O vacancy can enhance the reactivity of CeO2 polishing particle surface.

Ti-doped diamond films were deposited through a microwave plasma chemical vapor deposition (MPCVD) system for the first time. The effects of the addition of Ti on the morphology, microstructure and quality of diamond films were systematically investigated. Secondary ion mass spectrometry results show that Ti can be added to diamond films through the MPCVD system using tetra n-butyl titanate as precursor. The spectra from X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy and the images from scanning electron microscopy of the deposited films indicate that the diamond phase clearly exists and dominates in Ti-doped diamond films. The amount of Ti added obviously influences film morphology and the preferred orientation of the crystals. Ti doping is beneficial to the second nucleation and the growth of the (1 1 0) faceted grains.

The surface behaviors of boron (B), phosphorus (P) atom, and B/P_C dimer on the reconstruction diamond (001) surface was discussed. The adsorption and diffusion energies of B, P atom, and B_C, P_C dimer on the reconstruction surface based on diamond surface were calculated by first-principle method based on density functional theory. The stable adsorption site of B and P was the bridge–dimer chain of the ring closing of diamond surface with highest adsorption energy. The bond breaking during migration of the B atom with the active energy was more difficult than that of the phosphorus atom. The two kinds of evolution pathways of B_C or P_C dimer from ring closing to ring opening were according to the atom diffusion order with the same initial and final configurations. A high active energy makes it difficult for the B atom to move out of ring closing than the C atom of B_C dimer diffusion. However, the C atom leads to the diffusion of P_C dimer out of ring closing with lower active energy. To reduce the active energy, the P atom chooses the circuitous diffusion pathway. The active atoms improved the B/P_C dimer diffusion between the ring closing and ring opening.

The uniaxial tensile mechanical properties of polycrystalline TiN with 14 different grain sizes measuring 2.0–5.8 nm were studied via molecular dynamics with the second-nearest-neighbour modified embedded-atom method (2NN MEAM). The results show that the grain size affects the movement mechanisms of the grains and grain boundaries, and the relationship between grain size and tensile yield strength. The direct and inverse Hall-Petch formula of TiN are given. The dislocation migration of grain boundaries is the main deformation mechanism when the grain size is larger than 3.2 nm. When grains are smaller than 3.2 nm, grain rotation and grain boundary sliding are the preferred deformation mechanisms, which cause an inverse Hall–Petch effect. Polycrystalline TiN is at its hardest when the grain size ranges from 3 to 4 nm. The results can serve as theoretical basis for further doping non-metallic elements with critical grain sizes in the grain boundary produce superhard TiN composites.

An artificial solid electrolyte interface (SEI) of a graphene composite lithium salt can inhibit the growth of dendrites by driving the lithium deposition behavior on the surface of the lithium metal anode. The first-principle method was used to calculate the graphene/lithium nitride SEI, including the structural form and stability of intrinsic (G-Li3N), single-vacancy defect (SVG-Li3N), and double-vacancy defect (DVG-Li3N) graphene heterostructure. The adsorption and migration behavior of lithium ions on the heterostructure surface and the interface were also calculated. This study showed that the modification of double-vacancy defect graphene improved the stability of the heterostructure, and the adhesion work of the composite SEI is the highest. The modification of defective graphene increases the adsorption energy of lithium atoms on the surface and interface of the heterostructure: the strongest adsorption of Li atoms on the single-vacancy defect region of the heterostructure, the opposition migration pathway of Li atoms on the surface and interface of the DVG-Li3N heterostructure, and the decrease diffusion energy of Li atoms on the surface and interface of the DVG-Li3N heterostructure. A composite layered SEI of graphene and Li3N was constructed to inhibit dendritic growth by adjusting the deposition behavior of lithium atoms.

The adsorption and migration activation energies of a silicon (Si) atom on a hydrogen-terminated diamond (001) surface were calculated using first principles methods based on density functional theory. On the fully hydrogen-terminated surface, the surface carbon atoms possess saturated bonds. The Si atom cannot bond with the surface carbon atoms; thus, the adsorption energy of the Si atom is low. However, on the hydrogen-terminated surface with one or two open radical sites (ORS), the adsorption energy of a Si atom increases to 3.1 eV and even up to 4.7 eV, thereby forming a stable configuration. Along the three ORS in the direction of dimer row or chain, a Si atom can migrate between two deep basins with migration activation energies at 1.5 or 1.3 eV. Given the relatively large energy barrier at approximately 3.8 or 4.7 eV, escaping from the deep basin is difficult for the Si atom. This investigation showed that the number and distribution of ORS, namely, the adsorption site of hydrogen atoms and the removal site of surface hydrogen atoms, can affect the adsorption and migration of Si atoms on the hydrogen-terminated diamond surface. Electron structure analysis further reveals that the reactivity of the surface C atoms and the charge transfer amount between the Si and surface C atoms affect the adsorption and migration of Si atoms.

Structures of transition metal nitrides (TMNs) were optimized using the plane-wave pseudopotential method based on density functional theory. Energy as a function of volume curves were calculated to predict the phase transition pressures. Density of states (DOS), charge density difference, and charge transfers were calculated. The elastic constant (C11) and modulus (G) as a function of pressure were computed. Results showed that TMNs in the WC structure was most stable at normal pressure. All TMNs exhibited metallic, covalent and ionic property. Metallic character increased and covalent property reduced with increasing atomic number of TM atom. The elastic constant (C11) and modulus (G) increased linearly with increasing pressure due to stronger hybridization, bonding and covalent property. Thus, mechanical property enhanced under external pressure.

The separation and aggregation of Si atoms around TaN grains during deposition of Ta–Si–N nanocomposite films were studied, and the adsorption energies, charge transfer and atomic partial density of state of Si–2N2Ta islands on the TaN (001) surface and diffusion energy of the islands during their evolution were evaluated using the first-principles method based on density functional theory (DFT). In the lowest total energy stable configuration, N and Ta atoms tended to combine to form 2N2Ta islands, whereas Si atoms tended to stay at a position diagonal to the Ta atom outside of the island. Si atoms entered the position of the missing N atom of the TaN island and formed a substitute solid solution during Ta–Si–N growth. The Si atoms of the solid solution in the island could be easily extruded by Ta- or N-rich island during the deposition process. The process of Si atom extrusion by a N atom which was the configuration of N–by–2Ta1N1Si island evolved into Si–by–2N2Ta island in rich N-atom. The process of Si atom was extruded by the Ta atom which was the configuration of Ta–by–2N1Ta1Si island evolved into Si–of–2Ta2N island, that reduced the total energy of island. The diffusion energies of these evolutions were 0.974 and 1.712 eV, respectively. The Si atoms and TaN grain phase tended to separate during the deposition process. Si atoms could give way to Ta and N atoms during the Ta–Si–N nanocomposite film deposition process.

The solid electrolyte interface (SEI) plays an important role in the lithium–sulfur battery system. It not only protects the stability of the lithium metal anode interface but also inhibits the growth of lithium dendrites during charge and discharge. The relationship between the shape of the SEI and the transport behavior of lithium ions affects the homogeneity of lithium dendrites. In this work, first-principles calculations are used to determine the stable structure and transport properties of the La-doped LiF solid electrolyte interface (La–LiF SEI) on the Li substrate. For the vertical transport of Li ions within the La–LiF SEI, the transport of Li ions in the grain boundary and that in the crystal grain was calculated separately. Regarding the plane diffusion behavior of Li ions between the La–LiF SEI and the lithium anode, the diffusion of Li ions on the surface and interface of the lithium anode were calculated. The effect of critical tensile strain on the diffusion of Li ions on the surface and interface was investigated. The results show that doping with La solves the problem of excessive periodic grain boundary gaps caused by the difference between LiF and Li lattices during the deposition process. The periodic gap is reduced from 0.478 nm to 0.306 nm after La doping. By comparing the migration energy barriers of each path, it is found that lithium ions are more likely to be inserted and extracted at the La–LiF SEI grain boundary. The reason is that the existence of the rare earth element La causes the grain boundary to have a more stable vacancy structure and a smaller transport energy barrier (0.789 eV). The critical tensile strain reduces the diffusion energy barrier (0.813 eV) of Li ions on the surface of the lithium metal anode, which promotes the fast diffusion and uniform deposition of Li ions between the interfaces. The establishment of SEI transport characteristics under the coupling conditions of mechanical stretching and ion transport is expected to improve the Li deposition behavior.

Adsorption and migration behaviours of Nb–C atoms on a clean diamond (0 0 1) surface were investigated using first principles methods based on density functional theory to develop a new kind of diamond composition film. Firstly, the adsorption and minimum migration energies of a single Nb atom on a surface were calculated to obtain the migration activation energy. Configuration evolutions of two atoms of 1Nb1C and three atoms of 2C1Nb were then studied to determine the effect of the Nb addition. Migrations of a single Nb atom on the clean diamond (0 0 1) surface along a dimer row and along a dimer chain were found to have energy barriers of 2.008 and 2.099 eV, respectively. The barrier was smaller than the barrier of a single carbon atom migrating along a dimer chain. Thus, the migration of the Nb atom is easier than that of the carbon atom. Besides, comparison of the configuration evolution activation energy of 2C1Nb three atoms with that of 2C dimer showed the effect of adding Nb on promoting 2C dimer migration.

The electronic structure and elastic properties of pure CeO2 and the nonmetal doped system CeO2–X (X = F, Si, B, and P) were investigated using plane-wave pseudopotential method and generalized gradient approximation (GGA+U) by first-principles. The calculated lattice constant, band gaps and elasticity of pure CeO2 are in good agreement with the experimental results. F-doped CeO2 exhibits increased band gap at the Fermi level and enhanced nonmetal characteristics. Conversely, P-doped CeO2 features reduced nonmetal characteristics. Moreover, Si- and B-doped systems manifest disappearing band gap and metal characteristics. In nonmetal doped systems, the quantity of electric charge transferred by atom decreases, covalent binding is enhanced, and covalent bond length shortens. After nonmetal doping, the system presents mechanical stability and decreased elastic constants (C11, C12, and C44) and elastic moduli (B, G, and E). Si, B, and P doping enhances the ductility of CeO2 and the elastic anisotropy of the system. Furthermore, F doping slightly reduces the ductility but enhances the elastic isotropy of the system.

The elastic properties of the interface structure of nanodiamond composite films are investigated using first-principles calculations. The nanodiamond grains in the films are surrounded by a monolayer heterogeneous interface. The interface phase comprises B, Si, P, and Ge. The elastic constants, bulk, shear and Young's modulus of the interface structures are all obtained with first principle calculations. Calculated elastic constants of the diamond (0 0 1) interface are larger than those of the (1 1 1) interface. For the B, Si, P, and Ge interface structures, as the average atomic distance increases, the average Young's modulus decrease, which follows the sequence E ¯ B > E ¯ Si > E ¯ P > E ¯ Ge , with corresponding values of 927.05, 843.841, 840.152, and 819.805 GPa. The ductility and plasticity, as well as the anisotropy values (A and AU) of the interface structures were discussed based on the obtained mechanical parameters. The results show that P interface structures demonstrate ductile property when stressed longitudinally, whereas the other interface structures are all brittle. Then the visualization of the directional dependence of the Young's modulus are also presented. These reflected an interesting results. For the B, Si, and Ge interface structures, whether they show isotropy or anisotropy depends on the crystal structure, while it depends on the direction of the applied strain for the P interface structures.

The elastic constants ( C ij ), bulk modulus ( B ), shear modulus ( G ) and elastic modulus ( E ) of cubic fluorite CeO 2 under high pressure have been studied using the plane-wave pseudopotential method based on density functional theory. The calculated results show that the mechanical properties ( C ij , B , G and E ) of CeO 2 increase with increasing pressure, and the phase transition of CeO 2 occurs beyond the pressure of 130 GPa. From the calculated phonon spectrum using Parlinsk–Li–Kawasoe method, we found that CeO 2 appears imaginary frequency at 140 GPa, which indicates phase transition. The energy band, density of states and charge density of CeO 2 under high pressure are calculated using GGA+ U method. It is found that the high pressure makes the electron delocalization and Ce–O covalent bonding enhanced. As pressure increases, the band gap between O2p and Ce4f states near the Fermi level increases, and CeO 2 nonmetallic nature promotes. The present research results in a better understanding of how CeO 2 responds to compression.

The adsorption and migration energies of a single carbon atom and the configuration evolution energies of two carbon atoms on a clean diamond (0 0 1) surface were calculated using the first principle method based on density functional theory to investigate the formation of ultra-nanocrystalline diamond (UNCD) film. The activation energy of a single atom diffusing along a dimer row is 1.96 eV, which is almost the same as that of a CH 2 migrating along a dimer row under hydrogen-rich conditions. However, the activation energy of a single atom diffusing along a dimer chain is 2.66 eV, which is approximately 1.55 times greater than that of a CH 2 migrating along a dimer chain in a hydrogen-rich environment. The configuration evolution of the two carbon atoms is almost impossible at common diamond film deposition temperatures (700–900 °C) because the activation energies reach 4.46 or 5.90 eV. Therefore, the high-energy barrier could result in insufficient migration of adatoms, leading to the formation of amorphous in UNCD films in hydrogen-poor CVD environment.

To develop a new type of diamond composite film, the adsorption energies and minimum migration energies of a single yttrium atom on a diamond (001) surface were calculated with the first principle method based on density functional theory (DFT). Moreover, the total energies of some 1C1Y and 2C1Y configurations and their evolution energies were calculated to study the effect of yttrium additions. The investigation results showed that (1) the migration activation energies of a single yttrium atom along a dimer row and a dimer chain were 0.3505 eV and 1.0128 eV, respectively, indicating that migration of an yttrium atom on a diamond (001) surface is relatively easy; and (2) the migration activation energies of the carbon atoms in configurations of 2C1Y three atoms were obviously reduced, manifesting that the yttrium addition has promotion effects on migration of the carbon atoms on a clean diamond (001) surface.

The solid electrolyte interface (SEI) not only play the role of surface protective film for lithium metal anodes in lithium-sulfur batteries but also use to suppress the growth of lithium dendrites during the charging process. The relationship between the morphology of the SEI and the deposition behavior of lithium atoms determines the effect of homogenization of the dendrites. The Li-halide (LiF, LiCl, and LiBr) solid electrolyte interface is comparatively investigates by comprehensive first-principles calculations on Li metal anodes. Surface adsorption, surface diffusion, and charge transfer of Li atoms during the deposition process on the Li-halide SEIs with aggregated Li–Ha2Li2 island configurations is systematically calculates to achieve the orientation of Li atoms from deposition. However, the Li atom has high migration energy regardless of the uniformity of the surface of LiF-SEI, which has high stability making the charge transfer of Li atoms less affected by the subneighbor and subsurface Ha atoms. The Li atom deposition behavior makes the charge transfer and lithium halide (LiHa) SEI potential tend to be evenly distributed, which in turn leads to uniform deposition of Li atoms.

The separation and aggregation of Nb, Si, and N atoms around the NbN grain during the deposition of the Nb–Si–N nanocomposite film were discussed. The evolution behavior of the 2N2Nb island and the adsorption and diffusion energy of Nb, Si, and N atoms around the island on the NbN (0 0 1) surface were investigated using the first-principles method based on density functional theory. Results indicated that the most stable configuration of the Nb–Si–N island was the combination of Nb and N atoms to form the island and the possible aggregation of the Si atom to diagonal Nb atom outside the island. Substitution solid solution was eventually formed, in which the Nb atom of the 2N2Nb island was replaced by the Si atom during deposition. However, the Si atom was easily replaced by the Nb atom at the site with abundant Nb atoms. The diffusion energy of the evolution from Nb-2N1Nb1Si to Si-2N2Nb was 1.58 eV, and the total energy of the configuration decreased. Moreover, the interface of Si and NbN grains tended to separate. The highest energy adsorption sites for Nb, Si, N atoms adsorbed on the NbN (0 0 1) surface around the 2N2Nb island were P3, P1, and P2, respectively. The adsorption energies of Nb, Si, and N atoms on the NbN (0 0 1) surface around the 2N2Nb island were 7.3067, 5.3521, and 6.7113 eV, respectively, and their diffusion energies around the 2N2Nb island were 2.62, 1.35, and 5.094 eV, respectively. The low adsorption and diffusion energies of active Si atoms promoted the distribution of Nb and N atoms during deposition. Furthermore, the NbN grain was easily separated through Si atom diffusion into the 2N2Nb island. The grain was refined, and its growth was inhibited by the Si atom during deposition.

A novel type of diamond/Si nano-composite thin films is proposed to improve the performance and quality of nano-diamond films. The function of Si atoms in the formation was explored by analysing the evolution of C and Si atoms in diamond/Si nano-composite films. The adsorption, migration, and evolution of the C–Si island configurations on the diamond (0 0 1) surface was studied by using first-principle method based on the density functional theory (DFT). The results indicate that the maximum adsorption energy of the C and Si atoms on the diamond (0 0 1) surface are 4.96 and 4.39 eV, respectively, which implies Si atoms tend to diffuse out of the diamond crystal and formed C–Si interface on the grain boundary. In the same migration pathway, the migration activation energy of the Si particle was 0.865 eV, and the C particle was 1.957 eV. Therefore, the Si atoms migrated easily onto diamond (0 0 1) surface. In the 3C–1C-1 configuration, the C atoms outside the 3C island migrated into the island to form a 4C island in the diamond structure. However, in the 3C–1C-2 configuration, the C atoms outside the 3C island did not migrate into the 3C island, which destroyed the diamond surface. In the 3C–1Si-1 and 3C–1Si-2 configurations, Si atoms migrated into the 3C island to form the 3C1Si island. The Si atoms stabilized the structure of the diamond and eliminated non-diamond carbon atoms, hydrogen atoms and defects in the nano-diamond films.

The elastic properties and electronic structure of the solid solution of CeO2–M (M = Ti, Zr, Hf, V, Nb, Ta) are studied using first principle methods based on density functional theory (DFT). The investigation shows that the elastic constants (B, G, E, C11 and C12) of the solid solution structure of the CeO2–M system have increased, resulting in improved mechanical properties, particularly for CeO2–Zr. The elastic constant C44 in CeO2–Ti and CeO2–V shows a marked reduction. The elastic modulus of CeO2–Nb significantly increased, and its anisotropy is not significantly different from CeO2. By calculating the energy band and density of states, it is shown that CeO2 is an insulator, and there are two band gaps. For transition metal solid solutions, the lattice constant of the CeO2–M system decreases, and the second band gap disappears because the Ce atomic contribution reduces, and there is overlap of the 4f and 5d orbital energies. The valence and conduction bands of the CeO2–M system (Ti, Zr, Hf) were found to shift slightly, with the band gaps reducing to 2.03 eV, 2.477 eV, and 2.44 eV respectively. The band structure of the CeO2–M system (V, Nb, Ta) as a whole moves down, and the second band gap disappears. For bands near the Fermi level, the band gaps are 1.37 eV, 2.51 eV, and 2.73 eV respectively.

The adsorption energy of the 4C1Si island configurations and the diffusion activation energies of carbon and silicon atoms on diamond (0 0 1) surface were calculated with first principle method based on density functional theory (DFT) to study the growth of diamond films and the growth position of silicon particles after they are mixed into the composite film. The 4C1Si island configurations consist of five types of C-by-3C1Si configurations and four types of Si-by-4C configurations. The adsorption energy and total energy of the 4C1Si island configurations were calculated firstly. In addition, the diffusion activation energies of the carbon and silicon atoms were calculated. The results show that: (1) the adsorption energy of the Si-by-4C island configurations is higher than that of the C-by-3C1Si island configurations. This indicates that it is not easy for silicon atoms to remain stable in the 3C1Si island. In contrast, silicon atoms are easy to move out of the island so that the carbon atoms out of the 3C1Si Island can enter the island to form the 4C island; (2) Compared with the carbon atom, silicon atom needs lower diffusion activation energy to move into or out of the island. This shows that silicon atoms are more active than carbon atoms. Thus, it is easier for silicon particles to fill the vacancy defects in diamond/Si films, improving the compactness of the diamond composite films.

In order to improve the quality of nano-diamond films, a new type of diamond/Si nano-composite films was proposed. The monolayer Si interface and monolayer SiC interface were studied in this paper. The system total energies and adsorption energies of monolayer Si and monolayer SiC on diamond (001) surface were calculated with first principle method based on the density functional theory (DFT) to investigate the stability of the two kinds of interface structures in the Diamond/Si nano-composite films. Moreover, the variation of the configuration energy and structures when the hydrogen atom and CH2 radical adsorbed on the two kinds of interfaces were researched to verify whether the diamond phase was able to nucleate and grow or not in the process of diamond/Si nano-composite films deposition. It turned out that (1) the diamond surface structure which is terminated by monolayer silicon atoms is not very stable. It is difficult to form the stable monolayer Si interface in diamond/Si nano-composite films; (2) the monolayer SiC interface with the carbon and silicon atomic ratio of 1:1in which the carbon and silicon atoms are located in the same row respectively is a more stable structure. The interface is conductive to the second nucleation in the process of diamond growth.

This study presents novel nanodiamond composite films, in which nanodiamond grains are surrounded by a monolayer heterogeneous interface. Calculations of diamond (0 0 1) and (1 1 1) with and without the interface were conducted using the first-principles method. Results showed that silicon particles cannot become a solid solution in diamond crystallites. Thus, the silicon interface can exist among diamond grains. The interface in diamond (0 0 1) is more stable than that in diamond (1 1 1).

The adsorption and pathway processes of atomistic Nb, Si, and N at high-symmetry sites on NbN (0 0 1) and (1 1 1) surfaces were studied using first-principle method, which is based on the density functional theory. This investigation presents some of the results obtained. The potential energy surface (PES) was obtained by calculating the adsorption of Nb, Si, and N atoms on NbN (0 0 1). The most energetic site for the Nb atom adsorbed on NbN(0 0 1) was the site ‘on-top of face–center cubic’ (HL), whereas those for N and Si were both at the site ‘between TopN and HL’ (TopN-HL). The minimum energy paths of the single atom on NbN (0 0 1) surface diffusion were obtained using the PES calculation results. The Nb and Si atoms were diffused from the TopN to the HL position. The N atom was diffused from the TopNb, whereas the TopN–HL to HL position. The diffusion energies of the Nb, Si, and N atoms on the NbN (0 0 1) surface were 0.32, 0.69, and 1.32 eV, respectively. The pathways of the atomistic diffusion involved the diffusion of atoms from the FCC to the HCP site on the NbN (1 1 1) surface. The results showed that the diffusion energy of Si on the Nb layer was smaller than that on the N layer. Si and N can easily form stable structures while bonding on the N layer. Moreover, Si atoms can stabilize the activity of N atoms while promoting the spread of Nb atoms during deposition.

To investigate the interface formation during Ti–Si–N film growth, a series of calculations were outperformed using the first-principles method to determine the total energies and adsorption energies of 4N–1Ti–1Si, 4N–2Ti–1Si, 4N–3Ti–1Si, and 4N–4Ti–1Si island configurations on a TiN(0 0 1) surface. The study also investigated the activation energies of these island evolutions. The calculations present interesting results. First, configurations in which the titanium atom is inside the island are generally stable and have relatively low energy. This finding implies that silicon atoms outside the TiN island stabilize the structure. Second, of the four types of island evolutions, 4N4Ti1Si has relatively low activation energy. Third, the phase separation of SiN and TiN readily occurs in the evolution of 4N4Ti1Si islands compared with those in the 2Ti2N1Si and 3N1Ti–1Si island evolutions. Finally, when the nitrogen-to-titanium ratio reaches 4:3 or 1:1, interface formation is relatively easy.

La-doped diamond films were deposited through a microwave plasma chemical vapor deposition (MPCVD) system. The effects of La addition on the morphology, microstructure, and quality of the diamond films were systematically investigated. The analysis of secondary ion mass spectroscopy and X-ray photoelectron spectroscopy indicates that lanthanum atoms were incorporated into the diamond films through MPCVD with lanthanum (III) acetate as a precursor. The characterization results reveal that different lanthanum dopant flows can affect the morphology, the preferred orientation of the crystal, and the diamond phase fraction in the films. Upon the lanthanum addition with the dopant flow of 30 sccm, the intensity ratio of the (220) to (111) peaks [I(220)/I(111)] decreases from 20% to 17% and the sp3/sp2 ratio is reduced from 8.53 to 5.89. However, with the increase of the lanthanum dopant flow to 90 sccm, the intensity ratio of I(220)/I(111) rises up to 39% and the sp3/sp2 ratio increases to 8.99. Therefore, a certain amount of lanthanum addition can promote the growth of (110) orientation grains and enhances the sp3 phase fraction in the deposited diamond films. The results obtained from this study provide a hint for adjusting the morphology and microstructure of diamond films with rare earth element doping.

Recent years, various information theoretic based measurements have been proposed to remove redundant features from high-dimensional data set as many as possible. However, most traditional Information-theoretic based selectors will ignore some features which have strong discriminatory power as a group but are weak as individuals. To cope with this problem, this paper introduces a cooperative game theory based framework to evaluate the power of each feature. The power can be served as a metric of the importance of each feature according to the intricate and intrinsic interrelation among features. Then a general filter feature selection scheme is presented based on the introduced framework to handle the feature selection problem. To verify the effectiveness of our method, experimental comparisons with several other existing feature selection methods on fifteen UCI data sets are carried out using four typical classifiers. The results show that the proposed algorithm achieves better results than other methods in most cases.