Chenliang Li

First-principles study of electronic structure, mechanical and optical properties of V4AlC3

We calculated the mechanical properties, electronic structure, theoretical hardness and optical properties of V4AlC3 using the first-principles method. The results show that V4AlC3 shows a better performance of the resistance to shape change and against uniaxial tensions and has a slight anisotropy on elasticity. Moreover, it is more brittle than α-Nb4AlC3 and Ta4AlC3. The chemical bonding of V4AlC3 is a combination of covalent, ionic and metallic nature. The calculated theoretical hardness is 9.33 GPa, and the weaker covalent bonding of Al–V is responsible for the low hardness of V4AlC3. The optical properties (dielectric function, absorption spectrum, conductivity, energy-loss spectrum and reflectivity) are discussed in detail. It is shown that V4AlC3 has the potential to be used as a promising dielectric material and coating to avoid solar heating.

A new layer compound Nb4SiC3 predicted from first-principles theory

We predicted a new layer compound Nb4SiC3 using the first-principles method. The structural stability, mechanical, electronic, theoretical hardness and optical properties of Nb4SiC3 were investigated. A stable Nb4SiC3 phase appears in the ?-type crystal structure. Moreover, the predicted Nb4SiC3 is a metal and exhibits covalent nature. Nb4SiC3 has a theoretical hardness of 10.86?GPa, which is much higher than Nb4AlC3; at the same time, it is more ductile than Nb4AlC3. The strong covalent bonding in Nb4SiC3 is responsible for its high bulk modulus and hardness. Nb4SiC3 exhibits slightly anisotropic elasticity. Furthermore, its optical properties are also analysed in detail. It is shown that Nb4SiC3 might be a better candidate material as a coating to avoid solar heating than Ti4AlN3.

First-principles study of the structure, electronic, and optical properties of orthorhombic BiInO3

The structural, electronic, and optical properties of orthorhombic BiInO3 were investigated in the framework of the density functional theory. The calculated structural parameters are in agreement with the experimental data. The band structure, density of states, and Mulliken charge population are obtained, which indicates that BiInO3 has an indirect band gap of 2.08eV. Furthermore, its optical properties are also calculated and analyzed in details. It is shown that BiInO3 is a promising dielectric material.

Adjustable ferroelectric properties in paraelectric/ferroelectric/paraelectric trilayers

A trilayer paraelectric/ferroelectric/paraelectric system is studied within the framework of the Ginzburg–Landau–Devonshire theory in consideration of the elastic interactions between each layer. An analytic expression of the ferroelectric phase transition temperature for the ferroelectric layer is derived. The polarization, dielectric properties and the response to the external field are studied numerically. Our results show that there are two types of thickness effects on the properties of the film considering the effect of dislocation. By changing the thickness of each layer, the ferroelectric layer can be highly adjusted and may have very good potential applications such as transducers, sensors and actuators.

High-pressure Powder X-ray Diffraction Study of Cu5Si and Pressure-driven Isostructural Phase Transition

The structural behaviour of Cu5Si under high-pressure (HP) has been studied by angular dispersive X-ray diffraction up to 49.9 GPa. The experimental results suggest that a pressure-induced isostructural phase transition occurs around 13.5 GPa as revealed by a discontinuity in volume as a function of pressure. The lattice parameter decreases with the pressure increasing for both low-pressure (LP) and HP phases of Cu5Si. However, a plot of the lattice parameter vs. pressure shows the existence of a plateau between 11.7 and 15.3 GPa. The bulk moduli, derived from the fitting of Birch–Murnaghan equation of state, are 150(2) GPa and 210(3) GPa for the LP phase and the HP phase of Cu5Si, respectively. A change in the electronic state of the copper is assumed to govern the observed structural phase transition.