Mechanical properties of transition metal tellurides XTe2(X=Ti,Zr,Hf,V)under high pressure:A density functional study
The first-principles calculation is employed in this research based upon Density Functional Theory,with the aim of investigating these mechanical properties of transition metal tellurides XTe2(X=Ti,Zr,Hf,V).Apart from phonon dispersion curves,elastic constants demonstrate that the four materials are steady under atmospheric pressure.The compressibility of the four materials is significantly different on the a-axis and c-axis.The variation of a/a0 is similar to that of V/V0,while c/c0 is quite different.The C11 of the four materials under zero pressure is greater than C33,indicating that the incompressibility along the a-axis un-der zero pressure is greater than that along the c-axis.As the pressure increases,the values of C11 and C33 also increase,indicating that increasing the pressure can improve the compression resistance of the four materials.When the pressure increases to a certain value,C11 is less than C33,indicating that the applied pressure has a greater impact on the c-axis compressive performance.The bulk modulus B of the four materials increases al-most linearly,and the increase rate of shear modulus G is small,indicating that increasing pressure can signifi-cantly improve the compression resistance of XTe2(X=Ti,Zr,Hf,V).The B/G values of TiTe2 and ZrTe2 at zero pressure are less than 1.75,so both materials are brittle materials at zero pressure.The B/G values of HfTe2 and VTe2 are greater than 1.75,so both materials exhibit ductility at zero pressure.In the pressure range of 20～100 GPa,the B/G of the four materials is greater than 1.75,indicating that they tend to be duc-tile under high pressure.In general,increasing pressure can significantly improve the compression resistance and ductility of these materials.The anisotropy index of the four materials is greater than zero,indicating that these materials are anisotropic.The modulus G and modulus E do not increase with the increase of pressure,so we predict that ZrTe2 and VTe2 materials will undergo a structural phase transition within 20 GPa.
First-principles calculationHigh pressureMechanical propertiesTransition metal tellurides
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