Pressure Tab And Tab < Sub > 2 < / Sub > Mechanics And The Primary Principle Of Superconductivity Research

At present, Transition metal-borides have attracted significant interest due to their unique physical and chemical properties, such as high hardness, high melting temperature, chemical stability and oxidation etc, and wide range of industrial applications. Boron compounds mostly have high temperature, wear, and many. Boron has a very important position and meaning in modern industry, widely used in the economic departments.Pressure is an important physical parameter. With the increase of the pressure, the material will present some invisible properties, and this is very important for understanding the nature of the material world. Under high pressure, atomic space and electronic structure will change, and that could eventually cause phase change. Previous work mostly involved in zero pressure of the properties and electronic structure of the material. So, on the one hand, we research the change of mechanical properties of TaB and TaB2under high pressures. On the other hand, under the pressure, the elastic constants, structural parameters, electronic structures and superconducting properties of TaB and TaB2haven’t reported. So, we also study the influence of the pressure to TaB and TaB2superconducting properties. The difference in elastic properties between TaB and TaB2is discussed with their electronic structures. This paper researchs the mechanical properties and superconducting properties of borides materials under the pressure, and the results will have the certain reference significance for the further research.The elastic constants, structural parameters, electronic structures and superconducting properties of TaB and TaB2under pressure are investigated using first-principles based on plane-wave pseudopotential density functional theory within the generalized gradient approximation (GGA) and those different physical properties of them are analyzed. It is found that the elastic constants and bulk modulus of TaB and TaB2increase with pressure, while variations of ratios a/a0, b/b0, c/c0and normalized volume V/V0decrease with pressure. Under high pressure, the a-axis of TaB is more compressible than the b-axis and the b-axis more than the c-axis, while the c-axis of TaB2is more compressible than the a-axis of TaB2. Electronic structure analysis shows that the hybridization of atomic states of TaB2is higher than that of TaB, which is in agreement with the result that the bulk modulus of TaB2is higher than that of TaB. According to Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity, values of DOS at Fermi levels of TaB and TaB2decrease with pressure, respectively, which indicates that their superconducting transition temperatures Tc decrease as pressure increases.