Prediction And Performance Study Of New Structure Of Carbon And Arsenic

The searching for new elemental allotropes with unique properties and potential applications has been a hot topic in the fields of condensed matter and materials science.Arsenic is the 33rd element in the periodic table.Because arsenic atoms can form the 4s²4p³hybrid bond,so it has a variety of allotropes.The allotropes of arsenic include black arsenic,gray arsenic,yellow arsenic composed of As₄molecules and sc phase arsenic under high pressure.In the VA group elements,the physical properties of K₄nitrogen and K₄phosphorus have been studied,and there is no study on K₄arsenic.In this paper,we identify a new phase of arsenic by ab-initio calculations in space group symmetry of T5(I2₁3,No.199),named K₄arsenic.Carbon is the 6th element in the periodic table.As a very popular element in nature,carbon is known for its extremely flexible bonding ability,it can form a large number of allotropes of carbon.It is well known that there are three well-known allotropes of carbon in nature,namely diamond,graphite and amorphous carbon.Subsequently,a large number of carbon allotropes have been synthesized under laboratory conditions,among which the most representative ones are two-dimensional graphene,one-dimensional carbon nanotubes and zero-dimensional fullerenes.G.Benedek et al first proposed the of sc-C₄₆carbon structure,but its structural characteristics and physical properties have not been studied.In this paper,the structural characteristics,mechanical and electronic properties of K₄arsenic and sc-C₄₆carbon were calculated and studied by first principles calculation.The main contents and results are as follows.In the first part of this paper,the structure characteristics of K₄arsenic are studied.The conventional cubic crystal cell of K₄arsenic contains 8 atoms and the equilibrium lattice parameter is 5.735(?).In the unit cell of K₄,all arsenic atoms are sp³hybridized,and the bond length is 2.52(?).This paper also studied the energy variation with volume,mechanical properties and electrical properties of K₄arsenic,and found that the structure of K₄arsenic is stable.The electronic energy band indicates that it is a semiconductor with a band gap of 1.28 e V.In this paper,the XRD patterns of K₄arsenic and some other allotropes of arsenic were simulated,which provides a theoretical reference for future experiments.We found that the band gap of K₄arsenic can be effectively regulated by applying pressure.The band gap decreases continuously with pressure and is almost closed at 5 GPa.Finally,we found that the light absorption intensity of K₄arsenic in the visible region(1.6 e V?3.0 e V)is higher than that of diamond,which indicates that K₄arsenic is a good photoelectric candidate material.In the second part of this paper,the structural characteristics of sc-C₄₆carbon are studied.There are 46 atoms in the cubic cell of sc-C₄₆carbon,which is composed of five carbon rings and has a complete sp³hybridization network in the pm 3 n(O_h³)symmetry.In this paper,the relationship between energy and volume,phonon spectrum and mechanical properties of sc-C₄₆carbon were also studied.Molecular dynamics simulation of sc-C₄₆carbon was also carried out at 1000 K.It was found that sc-C₄₆carbon had mechanical stability and a high Vickers hardness value of90.51 GPa,which is similar to diamond.We calculated that the ideal tensile strength of sc-C₄₆carbon is 93.5 GPa and the ideal shear strength is 72.3 GPa.The electronic band indicates that it is an insulator with a direct band gap of 5.11 e V.By simulating the X-ray diffraction of sc-C₄₆carbon,we found that it may be present in detonation and chimney dust.These results laid the foundation for further research on the carbon allotropes.The third part of this article is a summary and prospect of the full text.Our research on K₄arsenic and sc-C₄₆carbon has enriched the family of arsenic and carbon allotropes,and enhanced people's understanding and knowledge of arsenic and carbon.