C_3N_4基本性质的第一性原理研究

The First-principles study of basic properties of C_3N_4

通过第一性原理方法计算得到α-C3N4、β-C3N4、Cubic-C3N4、Pseudocubic-C3N4、Graphitic-C3N4的光学及电学性质.结果表明,α-C3N4、β-C3N4、Cubic-C3N4为间接带隙半导体,Pseudocubic-C3N4与Graphitic-C3N4为直接带隙半导体,它们的带隙依次减小,分别为3.886、3.273、3.023、2.592、1.260 eV.光学性质显示,C3N4的光吸收有2个吸收峰,而且都在紫外光区,α-C3N4、β-C3N4、Cubic-C3N4、Pseudocubic-C3N4对应的是σ的跃迁,Graphitic-C3N4对应的是σ跃迁和π跃迁.C3N4的光导率谱显示,C3N4具有较宽的光导率响应区间,且有较大的峰值,其中Pseudocubic-C3N4的峰值最大,说明它的光导性能最强.

The optical properties and electricity properties of all kinds of C3N4, such as α-C3N4,β- C3N4, Cubic-C3N4, Pseudocubic-C3N4, Graphitic-C3N4, which are obtained by First-principles method. The α- C3 N4, β- C3 N4, Cubic- C3 N4 are indirect band gap semiconductors, but Pseudocubic-C3N4 and Graphitic-C3 N4 are direct band gap semiconductors. Their band gaps are 3. 886, 3. 273, 3. 023, 2. 592, 1. 260 eV respectively, which decrease in turn. The optical properties of C3 N4 show there are two absorption peaks for light absorption in the ultraviolet region, α-C3N4, β-C3 N4, Cubic-C3 N4 and Pseudocubic-C3 N4corresponding to the transition of tr and Graphitic-C3N4 corresponding to the transition of α and π. The light permeability spectrum displays the wide photoconductive response interval and a high peak of C3N4, wherein the peak of Pseudocubic -C3N4 is maximum, indicating its strongest conductive properties.