本文選題：鍺烯 + 飽和吸附�。� 參考：《湘潭大學(xué)》2017年碩士論文

【摘要】：鍺烯和硅烯均是新型類石墨烯二維蜂窩狀結(jié)構(gòu)晶體材料,二者是具有褶皺結(jié)構(gòu)的二維單原子層薄膜,但是不同的是鍺烯的翹曲高度0.737?大于硅烯0.44?�；谶@個原因,鍺烯具有比硅烯更強的自旋軌道耦合效應(yīng)。目前,研究人員已經(jīng)成功在金屬Pt(111)面和Au(111)表面制備出單層鍺烯。為了更好的利用鍺烯的電子性質(zhì),各種調(diào)節(jié)方法得到了很大的關(guān)注。本論文采用基于密度泛函的第一性原理計算方法,開展了鍺烯與堿金屬原子構(gòu)成新型雜化相的結(jié)構(gòu)和電子性質(zhì)研究。獲得的主要結(jié)論有:1、考慮自旋軌道耦合效應(yīng),通過對鍺烯飽和吸附形成的堿金屬元素復(fù)合新相Ge2X2(X=Li、Na、K、Rb)進行分析,探索了形成的新相的穩(wěn)定性。通過對形成能的計算,發(fā)現(xiàn)它們均可能在室溫下形成穩(wěn)定的雜化結(jié)構(gòu)。Li、Na、K原子與鍺烯形成的新相的形成能比純鍺烯更低,預(yù)示了復(fù)合新相比單層鍺烯具有更高的穩(wěn)定性。通過比較Ge2Li2復(fù)合新相與鍺烯飽和氫化結(jié)構(gòu)的形成能,發(fā)現(xiàn)Ge2Li2復(fù)合新相的穩(wěn)定性甚至比鍺烯飽和氫化形成的復(fù)合物穩(wěn)定性更高。隨著最近鍺烯飽和氫化物的實驗制備成功,我們的計算預(yù)示了鍺烯飽和鋰化新相制備的可能性。通過Bader電荷分析,揭示了鍺和堿金屬原子之間主要通過離子鍵結(jié)合,但仍存在部分共價成分。能帶計算發(fā)現(xiàn),飽和鋰化鍺烯新相是直接帶隙半導(dǎo)體,具有0.14eV的能隙。其它堿金屬原子與鍺烯構(gòu)成的新相均呈現(xiàn)金屬性質(zhì)。2、考慮自旋極化效應(yīng)計算,對鍺烯半飽和吸附堿金屬原子形成的Ge2X1(X=Li、Na、K、Rb)新相結(jié)構(gòu)進行了穩(wěn)定性、電子和磁性質(zhì)研究。通過穩(wěn)定性、電荷轉(zhuǎn)移、成鍵方式進行對比,發(fā)現(xiàn)鍺烯半飽和吸附堿金屬與鍺烯飽和吸附堿金屬的性質(zhì)規(guī)律基本一致。但Li、Na、K原子與鍺烯形成的穩(wěn)定的半飽和吸附結(jié)構(gòu)均呈現(xiàn)金屬性,且在費米面及導(dǎo)帶中顯示出弱的極化性質(zhì)。計算發(fā)現(xiàn),半飽和鋰化鍺結(jié)構(gòu)在與Li相鄰的Ge原子上具有0.48μB的局域磁矩,預(yù)示了采用該種半飽和吸附鋰結(jié)構(gòu)可作為自旋器件材料開展應(yīng)用。
[Abstract]:Germane and silicene are new graphene like two dimensional honeycomb structure crystal materials, they are two dimensional single atomic layer thin films with fold structure, but the warpage height of germane is 0.737?It is larger than silicene 0.44.For this reason, germane has a stronger spin-orbit coupling effect than silicene.So far, the researchers have successfully prepared monolayers germanium on the surface of metal Ptn111 and Aut111).In order to make better use of the electronic properties of germanium, various regulation methods have been paid much attention.In this paper, the structure and electronic properties of a new hybrid phase composed of germane and alkali metal atoms are studied by using the first principle method based on density functional.The main conclusions obtained are: 1, considering the spin-orbit coupling effect, the stability of the new phase formed by saturated adsorption of germanium (GE _ 2X _ 2X _ (2) O _ (X _ (2)) X _ (Li) Na _ (+) K _ ((+)) Rb) was investigated by means of the analysis of the new phase formed by GE _ (2) X _ (2).Through the calculation of the formation energy, it is found that they can form stable hybrid structure at room temperature. The formation energy of the new phase formed by the atoms of Li-NaK and germanium is lower than that of pure germane, which indicates that the composite new germanium has higher stability than the monolayer germanium.By comparing the formation energy of the new phase of Ge2Li2 and the saturated hydrogenation structure of germanium, it is found that the stability of the new phase of Ge2Li2 is even higher than that of the complex formed by saturated hydrogenation of germanium.With the recent successful preparation of germane saturated hydride, our calculation indicates the possibility of the preparation of new phase of saturated lithiation of germane.By Bader charge analysis, it is revealed that the bonding between GE and alkali metal atoms is mainly by ion bond, but some covalent components still exist.The energy band calculations show that the saturated lithium-germanium new phase is a direct-band gap semiconductor with the band gap of 0.14eV.The new phases of other alkali metal atoms and germane show metal properties. Considering the spin polarization effect calculation, the stability, electronic and magnetic properties of the new phase structure of GE _ 2X _ (1) X _ (+) K _ (K _ (B) Rb) formed by the semi-saturated adsorption of GE _ (2) X _ (1) O ~ (2 +) on alkaline metal atoms have been studied.By comparing the stability, charge transfer and bonding methods, it is found that the properties of the semi-saturated adsorbed alkali metals of germane are basically consistent with those of germane saturated adsorbed alkali metals.However, the stable semi-saturated adsorption structures formed by Li-Na ~ (2 +) K atoms and germanium show gold properties, and show weak polarization in Fermi surface and conduction band.It is found that the semi-saturated GE structure has a local magnetic moment of 0.48 渭 B on the GE atom adjacent to Li, which indicates that the semi-saturated adsorbed lithium structure can be used as a spin device material.
【學(xué)位授予單位】：湘潭大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O641.1

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本文編號：1771971