The empirical electron surface model (EESM) based on empirical electron theory (EET) and dangling bond analysis method has been used to establish a database of surface energy for low index surfaces of alkali metals such as Li, Na, K, Rb and Cs. Since the lattice electrons of alkali metals occupy large proportion of the total electron number for valence shell, the contribution of these lattice electrons cannot be neglected in surface energy calculation. Therefore, the necessary modification to EESM will be presented in this paper. The calculated results are in agreement with experimental and other theoretical values. And the calculation results show that the surface energy is anisotropic. As we predicted, the surface energy of the close-packed plane (1 1 0) is the lowest one of all index surfaces. It is also found that the dangling bond electron density and the spatial distributions of lattice electron have great influences on surface energy of various index surfaces. EESM will provide one good basis for the research of surface science phenomena, and since abundant information about valence electronic structure is generated from EET, the model may be extended to the surface energy estimation of more metals, alloys, ceramics and so on.

The interface cohesion greatly affects the longevity of thermal barrier coatings (TBCs). The adherence and stress of the interface between the bond-coat and the thermally grown oxide (TGO) are considered as crucial properties governing the life times of TBCs. In this paper, the electron density of the bond-coat/TGO interface of TBCs was calculated with the empirical electron theory in solid and molecules. The calculation results of the electron density of the bond-coat/TGO interface with various bond-coat aluminium contents were analyzed in the views of interface bonding force, interface stress and interface stability. It is shown that the suitable aluminium content of the bond-coat should be in the ranges of 8–10 wt% and about 2 wt% considering the bond-coat/TGO interface only. Taking the bond-coat/top-coat interface of TBCs into account, combining the consideration of the TGO forming ability, the suitable aluminium content becomes about 8 wt% and a little less than 8 wt%, which accords better with actual TBC applications. The deduction not only can be a useful reference to the composition design of the bond-coat of TBCs, but also shows the necessity of considering the electron density parameters of the interfaces of bond-coat/top-coat and bond-coat/TGO simultaneously in the composition design of the bond-coat of TBCs.

Most of the bonding layers of thermal barrier coatings contain some yttrium to improve the physical consistency of the substrate and the ceramics layer. But the reason of the improvement and the proper yttrium content are not clear. In this paper, the valence electron densities ρh k l and ρu v wρu v w of the two sides and their difference Δρmin of the bonding layer/ceramic layer interface of thermal barrier coatings are calculated with the empirical electron theory in solids and molecules at various bonding layer yttrium content. The results show the following. The addition of yttrium has beneficial effect on the decrease of the interface stress because it decreases the Δρmin. The addition of yttrium can also increase the valence electron density ρh k l or ρu v wρu v w of the interface and so increase the interface cohesion force. The most effective yttrium content is at 0.4 wt% or so. The deductions accord with the actual coating, so the method can be applied to design the composition of the bonding layer of thermal barrier coatings. Furthermore, the calculation and the analysis methods of the interface valence electron densities can also be extended to other crystal coatings or composites with special orientation relationship, no matter the interface is a alloy/alloy one, a ceramics/alloy one or a ceramics/ceramics one.

Because of its excellent properties, zirconia ceramics has already been widely applied. Its phase transformation affects its properties. The research on the mechanism of its phase transformation is very important to control the phase transformation as well as its properties. The valence electron structure of cubic zirconia, tetragonal zirconia and monoclinic zirconia are calculated with the empirical electron theory in solids and molecules in this paper. The results show that the total numbers of the covalent electron pairs which form their strong bond framework are 3.19184, 3.45528 and 3.79625, respectively. According to the view-point of the C-Me segregating theory in solid alloys, it can be deduced that the phase transformation order of zirconia should be liquid phase→cubic phase→tetragonal phase→monoclinic phase. The deduction from valence electron structure is completely in accordance with the experimental results, so the electron theory of phase transformation in alloys can be expanded to ceramics materials.

Diamond and cubic boron nitride films have already been applied practically because of their excellent properties. The specific orientations of the films have special meaning on their application in optics and microelectronics fields. In this paper, the relative electron density differences of the interface between the different crystal planes of silicon substrate and those of diamond and cubic boron films are calculated with the empirical electron theory in solids and molecules. Analyses on the calculation results show that in the range of the researched films, the smaller the relative electron density difference between the film and the substrate is, the stabler the film is in thermodynamics. Therefore, the electron density difference is the essential factor of determining the orientation of the texture and heteroepitaxy of the films. The deductions accord well with the experimental facts. The calculation methods and the theory not only provide a new angle of view for the research of the growth mechanism of diamond film and cubic boron nitride film on the silicon substrate, but also provide a possible direction for the prediction of the orientation of other films.