低維納米材料的物性研究與結(jié)構(gòu)預(yù)測
發(fā)布時間：2018-12-17 06:13
【摘要】：低維納米材料具有獨特的形貌特征和優(yōu)異的物理化學(xué)性能,在物理學(xué)、光電子學(xué)、化學(xué)催化和材料制備等領(lǐng)域都具有廣泛的實際應(yīng)用價值。低維納米材料的研究對象主要包括零維、一維和二維納米材料。低維納米材料具有獨特的光學(xué),電學(xué)和磁學(xué)性能使其成為納米光電子器件的重要組成單元并被廣泛應(yīng)用于光電子、納米微電子等領(lǐng)域。隨著現(xiàn)代科技的飛速發(fā)展和實際應(yīng)用的迫切需求,在實驗上成功制備納米材料變得尤為重要。實際上許多材料的實驗研究受到了實驗設(shè)備及實驗條件的限制使得許多材料的物理性能并不能通過實驗手段進行可靠測量,因而采用計算模擬技術(shù)研究納米材料物理性能顯得尤為必要。本文采用經(jīng)典分子動力學(xué)方法,模擬研究低維納米材料的機械和熱力學(xué)穩(wěn)定性能。本文以一維Cd Se納米線、Cu納米線,零維Ni納米團簇為研究對象,建立了相應(yīng)的初始結(jié)構(gòu)模型,研究討論了不同條件參數(shù)對了三種納米材料的物理性能的影響并預(yù)測了可能發(fā)生的結(jié)構(gòu)變化。本文的研究成果為低維納米材料的實驗合成與性能研究提供了重要的理論依據(jù)。主要研究內(nèi)容如下:(一)采用分子動力學(xué)方法模擬研究了閃鋅礦、纖鋅礦結(jié)構(gòu)CdSe納米線的機械性能和纖鋅礦結(jié)構(gòu)Cd Se納米線的熱力學(xué)穩(wěn)定性。研究結(jié)果表明:(1)兩種結(jié)構(gòu)的Cd Se納米線的楊氏模量和最大拉伸強度都會隨著溫度和納米線尺寸的增大而減小;同時在纖鋅礦結(jié)構(gòu)Cd Se納米線的拉伸過程中,納米線發(fā)生了明顯的結(jié)構(gòu)相變,且首次觀測到新的TAR-4結(jié)構(gòu)Cd Se納米線。(2)纖鋅礦結(jié)構(gòu)CdSe納米線的熔點與納米線的尺寸和生長方向有很強的依賴關(guān)系:熔點會隨著尺寸的增大而增大且[0001]方向的納米線具有最高的熔化溫度;通過觀察納米線的熔解行為,可以發(fā)現(xiàn)[0001]和[10-10]方向的納米線存在表面預(yù)熔現(xiàn)象,而[2-1-10]方向的納米線觀測到內(nèi)部預(yù)熔解行為。(二)采用恒壓分子動力學(xué)方法模擬研究了不同大小的Ni納米團簇在加壓條件下的熔解性質(zhì)及行為。研究結(jié)果表明Ni納米團簇的熔點會隨著壓強和尺寸的增大而增大,且存在表面預(yù)熔現(xiàn)象。(三)通過在空心銅納米線的外層包裹以及內(nèi)部嵌入碳管,運用分子動力學(xué)的研究方法模擬研究了功能化碳納米管增強空心銅納米線的扭轉(zhuǎn)過程。分析了空心銅納米線的扭轉(zhuǎn)臨界角與溫度,扭轉(zhuǎn)率以及尺寸的變化關(guān)系,并觀察了加入碳納米管后空心銅納米線的扭轉(zhuǎn)屈曲行為。研究結(jié)果表明在碳管的支撐與保護下,臨界扭轉(zhuǎn)角在高溫和低扭轉(zhuǎn)率的條件下不會發(fā)生明顯變化,然而由于納米線存在的表面效應(yīng),空心銅納米線的臨界扭轉(zhuǎn)角會隨著納米線尺寸的增加而減小。
[Abstract]:Low-dimensional nanomaterials with unique morphology and excellent physical and chemical properties have been widely used in physics, optoelectronics, chemical catalysis and material preparation. The research objects of low-dimensional nanomaterials include zero-dimensional, one-dimensional and two-dimensional nanomaterials. Low dimensional nanomaterials have unique optical, electrical and magnetic properties, which make them become important components of nano-optoelectronic devices and are widely used in photoelectron, nano-microelectronics and other fields. With the rapid development of modern science and technology and the urgent need of practical application, the successful preparation of nanomaterials has become particularly important. In fact, the physical properties of many materials can not be measured reliably by means of experiments because of the limitation of experimental equipment and experimental conditions. Therefore, it is necessary to study the physical properties of nanomaterials by computer simulation. In this paper, the mechanical and thermodynamic stability of low dimensional nanomaterials is simulated by classical molecular dynamics method. In this paper, the initial structure model of one-dimensional Cd Se nanowires, Cu nanowires and zero-dimensional Ni nanoclusters is established. The effects of different parameters on the physical properties of three kinds of nanomaterials were studied and the possible structural changes were predicted. The results of this paper provide an important theoretical basis for the experimental synthesis and performance study of low dimensional nanomaterials. The main research contents are as follows: (1) the mechanical properties of sphalerite and wurtzite CdSe nanowires and the thermodynamic stability of wurtzite Cd Se nanowires are studied by molecular dynamics simulation. The results show that: (1) the Young's modulus and maximum tensile strength of Cd Se nanowires of two structures decrease with the increase of temperature and size of nanowires; At the same time, during the stretching process of wurtzite Cd Se nanowires, the phase transition of the nanowires takes place obviously. New Cd Se nanowires with TAR-4 structure have been observed for the first time. (2) the melting point of wurtzite CdSe nanowires depends strongly on the size and growth direction of nanowires: the melting point increases with the increase of size. The nanowires in the direction of 0001 have the highest melting temperature. By observing the melting behavior of nanowires, it can be found that the surface premelting occurs in [0001] and [10-10] directions, while the internal premelting behavior is observed in [2-1-10] directions. (2) the melting properties and behavior of Ni nanoclusters with different sizes under pressure were studied by using constant pressure molecular dynamics method. The results show that the melting point of Ni nanoclusters increases with the increase of pressure and size, and there is a phenomenon of surface premelting. (3) the torsional process of functionalized carbon nanotubes reinforced hollow copper nanowires was simulated by molecular dynamics method by wrapping them in the outer layer of hollow copper nanowires and embedding carbon tubes inside them. The relationship between the critical torsion angle of hollow copper nanowires and temperature, torsion rate and size was analyzed, and the torsional buckling behavior of hollow copper nanowires with carbon nanotubes was observed. The results show that under the support and protection of carbon tubes, the critical torsion angle does not change significantly at high temperature and low torsion rate. However, due to the surface effect of nanowires, The critical torsion angle of hollow copper nanowires decreases with increasing the size of nanowires.
【學(xué)位授予單位】：上海師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TB383.1
本文編號：2383788
[Abstract]:Low-dimensional nanomaterials with unique morphology and excellent physical and chemical properties have been widely used in physics, optoelectronics, chemical catalysis and material preparation. The research objects of low-dimensional nanomaterials include zero-dimensional, one-dimensional and two-dimensional nanomaterials. Low dimensional nanomaterials have unique optical, electrical and magnetic properties, which make them become important components of nano-optoelectronic devices and are widely used in photoelectron, nano-microelectronics and other fields. With the rapid development of modern science and technology and the urgent need of practical application, the successful preparation of nanomaterials has become particularly important. In fact, the physical properties of many materials can not be measured reliably by means of experiments because of the limitation of experimental equipment and experimental conditions. Therefore, it is necessary to study the physical properties of nanomaterials by computer simulation. In this paper, the mechanical and thermodynamic stability of low dimensional nanomaterials is simulated by classical molecular dynamics method. In this paper, the initial structure model of one-dimensional Cd Se nanowires, Cu nanowires and zero-dimensional Ni nanoclusters is established. The effects of different parameters on the physical properties of three kinds of nanomaterials were studied and the possible structural changes were predicted. The results of this paper provide an important theoretical basis for the experimental synthesis and performance study of low dimensional nanomaterials. The main research contents are as follows: (1) the mechanical properties of sphalerite and wurtzite CdSe nanowires and the thermodynamic stability of wurtzite Cd Se nanowires are studied by molecular dynamics simulation. The results show that: (1) the Young's modulus and maximum tensile strength of Cd Se nanowires of two structures decrease with the increase of temperature and size of nanowires; At the same time, during the stretching process of wurtzite Cd Se nanowires, the phase transition of the nanowires takes place obviously. New Cd Se nanowires with TAR-4 structure have been observed for the first time. (2) the melting point of wurtzite CdSe nanowires depends strongly on the size and growth direction of nanowires: the melting point increases with the increase of size. The nanowires in the direction of 0001 have the highest melting temperature. By observing the melting behavior of nanowires, it can be found that the surface premelting occurs in [0001] and [10-10] directions, while the internal premelting behavior is observed in [2-1-10] directions. (2) the melting properties and behavior of Ni nanoclusters with different sizes under pressure were studied by using constant pressure molecular dynamics method. The results show that the melting point of Ni nanoclusters increases with the increase of pressure and size, and there is a phenomenon of surface premelting. (3) the torsional process of functionalized carbon nanotubes reinforced hollow copper nanowires was simulated by molecular dynamics method by wrapping them in the outer layer of hollow copper nanowires and embedding carbon tubes inside them. The relationship between the critical torsion angle of hollow copper nanowires and temperature, torsion rate and size was analyzed, and the torsional buckling behavior of hollow copper nanowires with carbon nanotubes was observed. The results show that under the support and protection of carbon tubes, the critical torsion angle does not change significantly at high temperature and low torsion rate. However, due to the surface effect of nanowires, The critical torsion angle of hollow copper nanowires decreases with increasing the size of nanowires.
【學(xué)位授予單位】：上海師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TB383.1
【參考文獻】
相關(guān)期刊論文 前3條
1 徐光憲;;原子簇與有關(guān)分子的結(jié)構(gòu)規(guī)則Ⅰ.(nxcπ)格式[J];化學(xué)通報;1982年08期
2 羅成林,周延懷,張益;鎳原子團簇幾何結(jié)構(gòu)的緊束縛方法模擬[J];物理學(xué)報;2000年01期
3 徐延yN,王麗,邊秀房;液態(tài)Ni原子團簇演變的計算機模擬[J];原子與分子物理學(xué)報;2002年01期
，本文編號：2383788
本文鏈接：http://sikaile.net/kejilunwen/cailiaohuaxuelunwen/2383788.html
最近更新
教材專著
