Quaternary carbide Ti3NiAl2C ceramics has been investigated as a potential nuclear fusion structural material,and it has advantages in certain aspects compared with Ti2AlC,Ti3AlC2,and Ti3SiC2 structural materials.In t...Quaternary carbide Ti3NiAl2C ceramics has been investigated as a potential nuclear fusion structural material,and it has advantages in certain aspects compared with Ti2AlC,Ti3AlC2,and Ti3SiC2 structural materials.In this paper,quaternary carbide Ti3NiAl2C ceramics is pressurized to investigate its structural,mechanical,electronic properties,and Debye temperature.Quaternary carbide Ti3NiAl2C ceramics still maintains a cubic structure under pressure(0–110 GPa).At zero pressure,quaternary carbide Ti3NiAl2C ceramics only has three bonds:Ti–Al,Ni–Al,and Ti–C.However,at pressures of 20 GPa,30 GPa,40 GPa,60 GPa,and 70 GPa,new Ti–Ni,Ti–Ti,Al–Al,Ti–Al,and Ti–Ti bonds form.When the pressure reaches 20 GPa,the covalent bonds change to metallic bonds.The volume of quaternary carbide Ti3NiAl2C ceramics can be compressed to 72%of its original volume at most.Pressurization can improve the mechanical strength and ductility of quaternary carbide Ti3NiAl2C ceramics.At 50–60 GPa,its mechanical strength can be comparable to pure tungsten,and the material changes from brittleness to ductility.However,the degree of anisotropy of quaternary carbide Ti3NiAl2C ceramics increases with the increasing pressure.In addition,we also investigated the Debye temperature,density,melting point,hardness,and wear resistance of quaternary carbide Ti3NiAl2C ceramics under pressure.展开更多
The local crystal structures and electronic structures of LiMxFe1-xPO4 （M = Co, Ni, Rh） are studied through first-principles calculations. The lattice constants and unit cell volumes are smaller for the Co and Ni do...The local crystal structures and electronic structures of LiMxFe1-xPO4 （M = Co, Ni, Rh） are studied through first-principles calculations. The lattice constants and unit cell volumes are smaller for the Co and Ni doped materials than for pure LiFePO4, while larger than for the Rh doped material. The local structures around M atoms in the doped materials are studied in details. The total density of states （DOS） and atomic projected DOS （PDOS） are all calculated and analysed in detail. The results give a reasonable prediction to the improvement of electronic conductivity through Fe-site doping in LiFePO4 material.展开更多
基金Project supported by Fujian Science&Technology Innovation Laboratory for Energy Devices of China(21C-LAB)(Grant No.21C-OP-202013)the National Natural Science Foundation of China(Grant No.12064027)+1 种基金the International Science and Technology Cooperation Program of China(Grant No.2015DFA61800)the Scientific Research Fund of Jiangxi Provincial Education Department,China(Grant No.GJJ180973).
文摘Quaternary carbide Ti3NiAl2C ceramics has been investigated as a potential nuclear fusion structural material,and it has advantages in certain aspects compared with Ti2AlC,Ti3AlC2,and Ti3SiC2 structural materials.In this paper,quaternary carbide Ti3NiAl2C ceramics is pressurized to investigate its structural,mechanical,electronic properties,and Debye temperature.Quaternary carbide Ti3NiAl2C ceramics still maintains a cubic structure under pressure(0–110 GPa).At zero pressure,quaternary carbide Ti3NiAl2C ceramics only has three bonds:Ti–Al,Ni–Al,and Ti–C.However,at pressures of 20 GPa,30 GPa,40 GPa,60 GPa,and 70 GPa,new Ti–Ni,Ti–Ti,Al–Al,Ti–Al,and Ti–Ti bonds form.When the pressure reaches 20 GPa,the covalent bonds change to metallic bonds.The volume of quaternary carbide Ti3NiAl2C ceramics can be compressed to 72%of its original volume at most.Pressurization can improve the mechanical strength and ductility of quaternary carbide Ti3NiAl2C ceramics.At 50–60 GPa,its mechanical strength can be comparable to pure tungsten,and the material changes from brittleness to ductility.However,the degree of anisotropy of quaternary carbide Ti3NiAl2C ceramics increases with the increasing pressure.In addition,we also investigated the Debye temperature,density,melting point,hardness,and wear resistance of quaternary carbide Ti3NiAl2C ceramics under pressure.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10604023 and 10564002）, the Natural Science Foundation of Jiangxi Province （Grant No 0512017）, the Science Foundation of Jiangxi Provincial Education Department （Grant No GJJ[2005]73）, and Science Foundation of Zhejiang Sci-Tech University （Grant No 0613271-Y）.
文摘The local crystal structures and electronic structures of LiMxFe1-xPO4 （M = Co, Ni, Rh） are studied through first-principles calculations. The lattice constants and unit cell volumes are smaller for the Co and Ni doped materials than for pure LiFePO4, while larger than for the Rh doped material. The local structures around M atoms in the doped materials are studied in details. The total density of states （DOS） and atomic projected DOS （PDOS） are all calculated and analysed in detail. The results give a reasonable prediction to the improvement of electronic conductivity through Fe-site doping in LiFePO4 material.
