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arXiv 1606.04066cond-mat.mtrl-sci
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Ce2CrN3和U2CrN3的电磁结构和成键性质的第一性原理研究

Electronic and magnetic structures and bonding properties of Ce2CrN3 and U2CrN3 from first principles

Samir F. Matar, Charbel N. Kfoury

摘要:

用DFT方法计算了A_2CrN_3(A = Ce,U)三元化合物的电子和磁性结构,发现nf元素(n = 4,5)的电子和磁性行为不同。电荷分析允许将这两种化合物正式表示为A2 Cr 5+ N3 5-,从而将它们分类为共价氮化物,即远离+-9电子的正式交换。通过建立能量-体积状态方程,得到两种化合物的硬度值分别为:B 0(A=Ce)=192 GPa和B 0(A=U)= 243 GPa,均在基于重叠矩阵分析的金属-氮共价键的氧化物范围内。铀化合物由于体积更小并且U相对于Ce金属的可压缩性更小而更硬。Ce_2CrN_3在Cr上表现出大的磁化强度(1.94BM),在Ce上表现出非常小的磁矩(0.14BM),指出了中间价态,而在U_2CrN_3中,M(Cr)= 0.49BM,M(U)= 0.97BM。这些结果强调了宽带状态密度(DOS)行为的A=U和局域DOS的A=Ce。这两种化合物在基态都具有铁磁性

英文摘要:

The electronic and magnetic structures of A2CrN3 (A = Ce, U) ternary compounds calculated based on band magnetism within DFT exhibit different behaviors of the nf elements (n = 4, 5 resp.). Charge analysis allows to formally express the two compounds as A2Cr 5+ N3 5- thus classifying them as covalent nitrides, i.e. far from formal exchange of +- 9 electrons. From establishing the energy-volume equations of state, the two compounds are found with hardness magnitudes: B0(A=Ce) =192 GPa and B0(A=U) = 243 GPa, within range of oxides due to covalent metal-nitrogen bonding shown as based on overlap matrix analysis. The uranium compound is harder due to a smaller volume and less compressible U versus Ce metals. Ce2CrN3 exhibits large magnetization on Cr (1.94BM) and a very small moment develops on cerium (0.14 BM) pointing out to an intermediate valence state while in U2CrN3, M(Cr) = 0.49 BM and M(U) = 0.97BM. These results are stressed by broad band-like density of states (DOS) behavior for A=U and localized DOS for A=Ce. Both compounds are found ferromagnetic in the ground state

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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