Li-O二元化合物设计及其电子性质
时间:2020-06-21 15:02 来源:毕业论文 作者:毕业论文 点击:次
| 摘\要 Li-O 系统具有丰富的相图，通过对其不同化合物在高压下的计算，可以推测出丰富的化学性质。本文利用遗传算法预测 Li-O 系统在不同压力下形成的化合物和结构相变序列，得到了新型化合物 LiO4。通过研究 LiO4的结构性质和电子性质及其在不同压力下的变化规律，发现 LiO4在6 GPa下可以形成（可认为是 ε-O8 结构接受了两个 Li 原子的两个电子）。通常氧元素只在很高的压力（>96GPa）或非常小的 Tc（<0.6K）下才变得超导，但是经过对 LiO4的测试发现它在Tc =12.2 K，P=10 GPa下呈现超导性。这表明，与其他元素形成合金不仅能降低金属化压力还能增加 TC。 该论文有图7幅，表 3个，参考文献 33篇。 51404 毕业论文关键词：四氧化锂 超导低压 第一性原理 电子性质 Novel Chemistry of Lithium Oxides and Superconducting Low-pressure LiO4 Abstract Li-O system has rich phase diagram,we study rich chemical properties according the phase transition at high pressure.With Li in battery applications and fundamental chemical interest in mind,we use the ab initio evolutionary algorithm to calculated novel compounds and structural phase transition sequence at different pressures. Meanwhile combined with first principle calculation we predict stability of novel compounds LiO4.LiO4,formed at the pressure of just 6 GPa,can be seen as ε-O8 accepting two electrons from two Li atoms. This phase is superconducting,with Tc up to 12.2 K at 10 GPa.This is remarkable,because elemental oxygen becomes superconducting at much higher pressure (96 GPa) and has much lower Tc (<0.6 K), and suggests that chemical alloying with other elements has the potential of not only decreasing metallization pressure, but also of increasing Tc . Key Words: LiO4 Low-pressure Superconducting Fist principle Electronic properties 目录 摘要-Ⅰ Abstract--Ⅱ 目录-Ⅲ 图清单-Ⅳ 表清单-Ⅳ 1绪论1 1.1引言-1 1.2研究背景-1 1.3本论文的主要原理和方法-2 2理论及计算原理3 2.1理论原理-3 2.2计算原理-4 3Li-O二元化合物物性计算--5 3.1Li-O系统基本结构及性质5 3.2LiO4的结构特征7 3.3LiO4稳定性分析7 3.4LiO4电子及超导特性-9 4总结-11 参考文献12
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